Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Assessment of Potential Impact of Climate Change on Coastal Zone
Document related concepts
Effects of global warming on human health wikipedia , lookup
Surveys of scientists' views on climate change wikipedia , lookup
Public opinion on global warming wikipedia , lookup
Hotspot Ecosystem Research and Man's Impact On European Seas wikipedia , lookup
Climate change, industry and society wikipedia , lookup
Years of Living Dangerously wikipedia , lookup
Climate change and poverty wikipedia , lookup
Sea level rise wikipedia , lookup
IPCC Fourth Assessment Report wikipedia , lookup
Transcript
Assessment of Potential Impact of Climate Change on Coastal Zone Areas of Yemen FINAL REPORT July 2000 Lead Authors : Contributors : Reviewer : Abdulkarim Alsubbary and Mohammed Abu Baker Ahmed Al-Darwish, Ahmed Hajer, Mohammed Abdul Rahim, Saleh Al-Dhabbi and Mohammed Al-Safani. Theo Sturm. Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 1. GENERAL INTRODUCTION ...............................................................................4 1.1 BACKGROUND ..........................................................................................................4 1.2 PROJECT OBJECTIVES AND PHASING......................................................................6 1.3 METHODOLOGY .......................................................................................................6 1.4 SOURCE OF DATA AND DATABASE ..........................................................................6 2. COASTAL CHARACTERISTICS ........................................................................8 2.1 GEOMORPHOLOGY ..................................................................................................8 2.2 POPULATION ..........................................................................................................10 2.3 SALT WATER INTRUSION ......................................................................................11 2.4 SAND TRANSPORT AND BEACH EROSION..............................................................12 3. MARINE ENVIRONMENT .................................................................................14 3.1 CLIMATE AND CLIMATE CHANGE ..........................................................................14 3.2 GEOGRAPHICAL LIMITS AND DIMENSION ............................................................15 3.3 BATHYMETRY ........................................................................................................16 3.4 METEOROLOGICAL CONDITIONS ..........................................................................17 3.4.1 Wind....................................................................................................................17 3.4.2 Air and water temperature .................................................................................18 3.4.3 Rainfall ...............................................................................................................18 3.4.4 Monthly mean sea level and tides ......................................................................19 3.4.5 Tidal Currents ....................................................................................................20 3.4.6 Salinity ................................................................................................................20 3.5 MARINE BIOTIC HABITATS AND SPECIES ..............................................................20 3.5.1 Habitats...............................................................................................................20 3.5.2 Benthic flora.......................................................................................................21 3.5.3 Mangroves and halophytes ................................................................................22 3.5.4 Marine Fauna ....................................................................................................23 3.6 FISH ........................................................................................................................24 3.7 TURTLES ................................................................................................................24 3.8 MARINE MAMMALS ...............................................................................................25 3.9 SEA AND SHORE BIRDS ..........................................................................................25 3.10 UTILISATION OF MARINE RESOURCES ...............................................................25 3.10.1 Red Sea Fisheries Resources ...........................................................................26 3.10.2 Utilisation of other resources ..........................................................................26 4. RISK ASSESSMENT ............................................................................................27 4.1 ACCELERATED SEA-LEVEL RISE............................................................................27 4.2 SELECTION OF PILOT AREA ...................................................................................27 4.3 ASLR INDUCED RISKS ...........................................................................................28 5. CHARACTERISTICS OF THE PILOT AREA .................................................29 5.1 NATURAL CONDITIONS ..........................................................................................26 ____________________________________________________________________________________________________ Final Report July 2000 2 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 5.2 SELECTION OF ASLR SCENARIO ……………………………...………………………..…27 5.3 DESCRIPTION OF THE COASTAL ZONE...................................................................31 5.4 SOCIO-ECONOMIC CHARACTERISTICS OF HODEIDAH ..........................................33 5.5 INSTITUTIONAL FRAMEWORK...............................................................................43 5.6 LEGISLATIVE FRAMEWORK ..................................................................................44 6. IMPACTS OF SEA LEVEL RISE ON THE PILOT AREA.............................47 6.1 BIOLOGICAL IMPACTS ...........................................................................................47 6.2 IMPACT ON THE SHORELINE .................................................................................................48 6.2.1 Shoreline and beaches .......................................................................................... 6.2.2 Impact on Coastal structures .............................................................................51 6.3 IMPACTS ON THE PILOT AREA ...............................................................................51 6.3.1 Power station ......................................................................................................51 6.3.2 The spit ...............................................................................................................52 6.3.3 City beaches and revetments ...................................................................................... 44 6.4 HODEIDAH CITY .....................................................................................................52 6.4.1 Population and houses .......................................................................................45 6.4.2 Roads ..................................................................................................................53 6.4.3 Agricultural facilities .........................................................................................54 6.4.4 Educational and health facilities: .....................................................................54 6.5 SALINE WATER INTRUSION ....................................................................................57 7. MITIGATING MEASURES.................................................................................60 7.1 AUTONOMOUS ADAPTATION OPTIONS...................................................................67 7.2 RECOMMENDED MESURES ................................................................................... 51 8. CONCLUSIONS AND RECOMMENDED ACTION PLAN............................70 8.1 GENERAL 8.2 ACTION PLAN ____________________________________________________________________________________________________ Final Report July 2000 3 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 1. GENERAL INTRODUCTION 1.1 Background Coasts in many countries currently face ever increasing problems as a consequence of the gradual rise of the sea level over the last century. An estimated 46 million people currently are at risk of flooding from storm surges. The presently ongoing climate change will affect coastal systems through sea-level rise and an increase in stormsurge hazards and possible changes in the frequency and/or intensity of extreme events inducing an accelerated rise of the sea level, will exacerbate these problems and will lead to impacts on ecosystems and human coastal infrastructure. The numbers of people involved is very large, for example tens of millions of people in Bangladesh would be displaced by 1-m sea level increase (the top of the range of the Intergovernmental Panel on Climate Change (IPCC) Working Group I estimates for 2100) in the absence of adaptation measures. A growing number of very large cities are located in coastal areas, which means that large amounts of infrastructure will also be affected. Although annual protection costs for many nations are relatively modest, amounting to about 0.1% of gross domestic product (GDP) of developed nations, the average annual costs to underdeveloped nations and small island states total several percent of GDP. For some island nations, the high cost of providing storm surge protection would make it essentially not feasible, especially given the limited availability of capital for investment. A rich diversity of ecosystems and a great number of socio-economic activities are characterising the coastal zones. Coastal human populations in many countries have been growing at double the national rate of population growth. It is currently estimated that about half of the global population live in coastal zones, although there is large variation among countries.. Beaches, dunes, estuaries, and coastal wetlands adapt naturally and dynamically to changes in prevailing winds and seas. In areas where infrastructure development is not extensive, planned retreat and accommodation to changes may be possible to rebuild or relocate capital assets at the end of their design life. In other areas, ____________________________________________________________________________________________________ Final Report July 2000 4 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ however, accommodation and planned retreat are not viable options, and protection using hard structures (e.g., dikes, levees, flood walls, and barriers) and soft structures (e.g., beach nourishment, dune restoration, and wetland creation) will be necessary. Factors that limit the implementation of these options include inadequate financial resources, limited institutional and technological capability, and shortages of trained personnel. In most regions, current coastal management and planning frameworks do not take account of the vulnerability of key systems to changes in climate and sealevel or long lead times for implementation of many adaptation measures. Inappropriate policies encourage development in impact-prone areas. Given increasing population density in coastal zones, long lead times for implementation of many adaptation measures, and institutional, financial, and technological limitations (particularly in many developing countries), coastal systems should be considered vulnerable to changes in climate. The coastal environments are unstable, and are particularly vulnerable either to natural forces or to human interference. Coastal areas vary greatly in character and in the kinds and intensity of geologic processes that occur along them. Rising sea levels are a major reason why shoreline-stabilisation efforts repeatedly fail. One of the problems are rising water levels bringing waves farther and farther inland, pressing ever closer to and more forcefully against more and more structures developed along the coast. Erosion is causing shorelines to retreat landward along the coastal areas. Harmful effects of climate change can also include loss of productive low-lying areas, altered coastal vegetation and agricultural productivity, loss of mangroves, intrusion of sea water into fresh water supplies, including drinking water, reduced inshore fisheries and increased pollution. In order to investigate this problem the present research project with regard to the effects on the Yemeni coastal zones has been executed. This project is part of a climate change programme funded by the Netherlands Government. The project will be integrated into existing and planned actions to deal with the vulnerability of the coastal zone of Yemen. ____________________________________________________________________________________________________ Final Report July 2000 5 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 1.2 Project Objectives and Phasing The main topic of this study is how changes in sea level will affect the population and infrastructure of the coastal areas. The study comprises the following elements: Conduct a desk study on the potential impact/s of climate change on the coastal zone as well as coastal resources Assess the vulnerability on the coastal zone of Yemen, Organise a national training/co-ordination workshop, and Draft a national action plan. 1.3 Methodology The procedure utilised in this study involves a description of the environmental characteristics of the Yemen coastal zones, a selection of a high risk area as pilot area, the collection of data on infrastructure, land, buildings and population along the coastline that would potentially be vulnerable to sea-level rise. The most likely scenario of a rise of one meter by the year 2100 is examined in some detail. An analysis of the cost involved in adopting measures to adapt to the risk is carried out. The adaptation options of do nothing for a particular stretch of shoreline makes that segment at risk. Full protection of a segment eliminates the vulnerability of that segment. Land and infrastructure that is at risk is considered lost and the population that is at risk is assumed displaced. Wetlands subjected to inundation are considered lost. This project is part of a greater climate change project for Yemen and is funded by the Netherlands government. The coastal zone element started in June/July of 1999 and will be finalised in May 2000. 1.4 Source of Data and Database In Yemen data are scattered and not always easy to obtain. Exchange of information, does not take place between ministries and/or agencies. No data bank on ____________________________________________________________________________________________________ Final Report July 2000 6 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ environmental issues and hazards exists or is planned. Meteorological, geological, physical oceanographic and socio-economic data have being collected under this program to the extent possible. The Government has not been able to acquire the funding necessary to collect sufficient data, a fact that hampers evaluation and progress to some degree. The database for this study comprises: a base map, covering the Southern Red Sea and Tihama Plain, Western Yemen Series of 1: 250 000 scale topographic maps covering Western Yemen Geological maps used were 1 : 1,000,000 and 1 : 250,000 scale, (Printed by the Ministry of Oil and Mineral Resources, 1992). ____________________________________________________________________________________________________ Final Report July 2000 7 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 2. COASTAL CHARACTERISTICS 2.1 Geomorphology Yemen is situated in the southern Red Sea area of the Arabian peninsula, bordered by Saudi Arabia to the north, Oman to the east and Red Sea to the west (Figure 1). The young ocean basins of the Red Sea and Gulf of Aden formed as a result of thinning of the African and Arabian lithosperic plates. This formed the great exposed coastline, which is over 2,000 km. The Red Sea is an example of a present day rift zone, where rifting was initiated due to the emplacement of the Afar plume, causing extensive volcanism between 27-24 million years ago. Such heating of the Upper Lithosphere caused significant weakening. Regional stresses caused the propagation of a rift zone in this weakened area. Surface uplift of up to 3660m produced the Yemen highlands, and is attributed to this plume heating. Subsequent erosion of the Yemen high lands has occurred, this is expressed through an extensive incised drainage network. The western part of Yemen can be divided into a number of distinct geomorphologic areas (See Figure 2.1). a) The Tihama plain is a north-south trending plain, approximately 40 km across, rising gently from the Red Sea in the west to an altitude of 200 m above sea level in the east where it meets the great escarpment. This plain is drained by westward flowing streams. b) The Great Escarpment is a NNW-SSE trending feature traced from SW Yemen, northwards into Saudi Arabia for over 1000 km. This feature abruptly increases topography from 200 m to over 1000 m above sea level. c) Beyond the Great Escarpment, the Rift mountains of North-Western Yemen form a broad plateau of average elevation >2000 m above sea level, peaking at 3660 m at Jabal Nabi Shuyab, the highest point on the Arabian Peninsula. This region is transversed by deeply incised valleys. Uplift of the Yemen highlands has been produced through a variety of processes; a) Erosion causing isostatic rebound.b) Thermal uplift induced by the Afar plume and c) Magmatic underplating and overplating. ____________________________________________________________________________________________________ Final Report July 2000 8 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 9 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ The straight Red Sea Coastline of Yemen has a low relief with very few mountains near by the shore. Elsewhere, a fairly wide coastal plain in the north, narrowing toward the south separates the foothills from the sea. Most of the coastline is characterised by sandy plains, while some cliffs are composed of carbonate cemented sands and loam's. Several ephemeral rivers (wadis) drain to the coastline from the mountains. Because these rivers carry only a limited sediment load during the wet season, deltaic plains are not well developed in the Yemeni Red Sea coasts. Two dominant drainage systems are identified in the studied area. The drainage patterns in the NW area dominantly drain towards the west, into the Red Sea, and have an east / west trend. However, those drainage patterns within the SW drain towards the SE, and have a dominant NW / SE orientation. 2.2 Population The population as in census of 1998 is about 17,071,000 inhabitants, with annual growth rate of 3.5% the population will be doubled each 19 years. The Yemeni community is considered young, as the population under 15 years of age is about 47%, this will increase the expenses of family, which consist of 7 individuals, where each 3 share one room. The illiteracy among the population (47.3% in 1998) increases the cost of living, and joining the primary education is less than 58.85% in 1998. The increase of illiteracy rate among the rural citizens, which represents 74.4%, (females 80%) will complicate the problem. Also these decreases the responses to family planning program (13%) among married women, which will keep the problem of increase in population, remain unsolved even for the long run. The length of the coastal line starting from borders with Saudi Arabia (Al Musim town) up to Bab el-Mandab is 730 km (included the islands). Great deals of socioeconomic activities are concentrated along this coastal area, which is more intense than any other parts of the Red Sea coastal area. There are many important Yemeni cities and towns located along the coastal line. Table (2 .1) lists the most important towns and cities located along the Yemeni Red Sea coast together with their populations and housing. ____________________________________________________________________________________________________ Final Report July 2000 10 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Table 2.1 Lists the main Cities and Towns along the Red Sea coast of Yemen, with their number of Houses and population as per census of 1994 Name of town No. of No. of Populatin Houses families Literacy rate Joining school rate Midi 764 786 4369 76 39 Al Luhia 740 702 3976 78 31 Al Salif 226 222 1211 52 70 Al Hodeidah 49152 45398 302586 37 78 Al Khokha 1592 1429 8782 00 00 Al Mukha 1604 1502 10355 72.2 17.3 Dhubab 402 400 2643 75.7 17.5 Total 52888 50439 66132 00 00 2.3 Salt Water Intrusion The expected seawater level rise will impact on water resources and cause rising water tables in groundwater aquifers and salt-water intrusion. Groundwater rise may extend in the inland area into distances up to tens of kilometres. This inland extension depends on the topography, and hydrogeological parameters of the aquifers in the coastal areas. On the other hand, salt-water intrusions may exacerbate due to groundwater developments especially in areas where intensive water abstractions are applied. Many analytical methods are presented for assessing the nature of saltwater – freshwater interface in coastal aquifers. An availability of the local information of the aquifers and groundwater flow determines the approach followed by the different methods. For the purpose of this study as a primary assessment for the current and future situation of the salt-fresh water interface in the inter-Wadi zone between Wadi Surdud and Wadi Siham, the "sharp–interface" approach will be followed assuming a natural situation of equilibrium between the two fluids. This approach based on Ghyben-Hersberg principle between two fluids of different densities. Reference is made to Annex A, presenting the study carried out. ____________________________________________________________________________________________________ Final Report July 2000 11 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ According to previous studies, water in the area was categorised into three categories based on water electrical conductivity (EC) values to include fresh water (EC <3000 mS/cm), brackish water (3000>EC<6000 mS/cm), and saltwater (EC>6000 mS/cm). Fresh water is present at shallow depths in both the major wadi areas and in the interwadi areas, but quality in the wadi areas is better than the inter-wadi areas. The distribution of the EC values is changing from the east to the west with high values at the east where the brackish and salt water may found at the shallow depths (as in the Sebekha zones). The interface between the seawater and the fresh water gets its maximum depth within a distance less than 10 km from the cost. The vertical changes in this interface estimated in the north and south zones due to sea level rise has been estimated as a sharp interface using the Ghyben-Herzberg relation. This estimation for both the vertical and horizontal movements of the interface is a primary estimation and does not take into account both the abstraction factor and the diffusion that occurs due to the variations in the aquifer hydrogeologic properties. Therefore, this report recommended pursued this study using one of the numerical simulation models, which take into account the different hydrogeologic measures. 2.4 Sand Transport and Beach Erosion The sands or sediments of the beaches may have been produced locally by wave erosion, transported overland by wind from behind the beach or delivered to the coast and deposited there by streams or coastal currents. The action of the waves results in the transport of sediments put into suspension by the waves and transported by waveinduced currents along the shores. The rate of transport is depends on the energy of the waves, the period of the waves and the direction of the waves. The wave characteristics as well as the particles size characteristics of the sediments determine the amount of material that can potentially be transported along the shores. Coastal erosion is a problem in Yemen, especially along areas of the Red Sea.. The causes of this phenomenon comprise probably the reduction of the amount of sand transported by littoral currents, the effect of a rise in sea level and human activities ____________________________________________________________________________________________________ Final Report July 2000 12 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ along the beach such as constructions and sand mining. Unconsolidated materials, such as beach sand, are rapidly eroded in particular during storms. The slope of the coastal areas is very gentle, so that a small rise in sea level results in a large inland retreat of the shoreline. In fact, information on the rate of the coastline erosion obtained from people who have lived in the area for some times, shows that in some low-laying coastal areas such as north of Hodeidah and Ras Kathib; the rates of shoreline retreat is several centimetres per year in this area (see Figure 1 & Picture 1), while the average recreational beach in the study areas is only about 30-40 meters wide now. With respect to accelerated sea-level rise; some estimates put the anticipated rise at 1 meter by the year 2100. To protect the shoreline directly hard structures maybe built, such as (i) breakwaters offshore and parallel to the shoreline to reduce the energy of the pounding waves; (ii) revetments and sea defences, and (iii) groynes. So called "soft" solutions comprise shoreline stabilisation through sand supply to beaches. ____________________________________________________________________________________________________ Final Report July 2000 13 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 3. MARINE ENVIRONMENT 3.1 Climate and climate change Changes in the earth's climate caused by human activities or natural processes, hold critical consequences for human health and the survival of many plant and animal species. Climate is controlled by the long-term balance of energy of the Earth and its atmosphere. Incoming radiation from the sun, mainly in the form of visible light, is absorbed at the Earth's surface and in the atmosphere above. On average, absorbed radiation is balanced by the amount of energy returned to space in the form of infrared "heat" radiation. Greenhouse gases such as water vapour and carbon dioxide, as well as clouds and small particles trap some heat in the lower part of the Earth's atmosphere. This is called the greenhouse effect. If there were no natural greenhouse effect, the average surface temperature would be about 34°C colder than it is today. Winds and ocean currents redistribute heat over the surface of the Earth. The evaporation of surface water and its subsequent condensation and precipitation in the atmosphere redistribute heat between the Earth's surface and the atmosphere, and between different parts of the atmosphere. Natural events cause changes in climate. For example, large volcanic eruptions put tiny particles in the atmosphere that block sunlight, resulting in a surface cooling of a few years' duration. Variations in ocean currents change the distribution of heat and precipitation. El Niño events (periodic warming of the central and eastern tropical Pacific Ocean) typically last one to two years and change weather patterns around the world, causing heavy rains in some places and droughts in others. Over longer time spans, tens or hundreds of thousands of years, natural changes in the geographical distribution of energy received from the sun and the amounts of greenhouse gases and dust in the atmosphere have caused the climate to shift from ice ages to relatively warmer periods, such as the one we are currently experiencing. Human activities can also change the climate. The atmospheric amounts of many greenhouse gases are increasing, especially that of carbon dioxide, which has ____________________________________________________________________________________________________ Final Report July 2000 14 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ increased by 30% over the last 200 years, primarily as a result of changes in land use (e.g., deforestation) and of burning coal, oil, and natural gas (e.g., in automobiles, industry, and electricity generation). If current trends in emissions were to continue, the amount of carbon dioxide in the atmosphere would double during the twenty-first century, with further increases thereafter. The amounts of several other greenhouse gases would increase substantially as well. The accumulation of greenhouse gases in the atmosphere will change the climate by enhancing the natural greenhouse effect, leading to an increase in the Earth's average surface temperature. The current best estimate of the expected rise of globally averaged surface temperature relative to 1990 is 1 to 3.5°C by the year 2100, with continued increases thereafter. Because most greenhouse gases remain in the atmosphere for a long period of time, even if emissions from human activities were to stop immediately, effects of accumulated past emissions would persist for centuries. The man induced climate changes are superimposed on, and to some extent masked by, natural climate fluctuations. Natural changes in climate result from interactions such as those between the atmosphere and ocean, referred to as internal factors, and from external causes, such as variations in the sun's energy output and in the amount of material injected into the upper atmosphere by explosive volcanic eruptions. 3.2 Geographical Limits and Dimension The Red Sea is a long narrow basin separating Africa from Asia, and extending from NNW to SSE between latitudes of 30 oN to 12o 30’N almost in a straight line. Its total length is 1932 km and the average breadth is 280 km. The maximum breadth is only 306 km in the southern sector near Massawa. It attains its minimum breadth of 26 km at the southern end in the Straits of Bab el Mandab. The mean depth is about 500 m. the maximum recorded depth is 3039 m in the axial trough at 19o 35’ N, 38 o 40’ E. Yemen is one of the seven countries which have shore lines on the Red Sea. Most of the Yemen coast along the Red Sea is characterised by a very shallow shelf and by wide coastal plain. Yemen has a large number of islands in the Red Sea, the Gulf of ____________________________________________________________________________________________________ Final Report July 2000 15 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Aden and the Arabian Sea, the largest and most important of which are those forming Socotra and Hanish Archipelago, Miyun, Kamaran, Tikfash, Humar and Antufash islands. With the exception of the two archipelagos and Miyun Island the islands are formed from a low laying plateau of reef rocks and sandy shores. Hanish Archipelago and Miyun Island coastal area consists of volcanic lava with raised beaches and wadi mouths. The Socotra region is an extension of Somali horn and geologically joined to Africa. Most of the coastline consists of beaches or cliffs with some gravelled shorelines around wadi mouth. The permanent fresh water runoff forming an estuaries environment are also occur in Socotra Island. The coastline of Yemen stretches over a length far over 2500 km. Its nature has endowed it with numerous habitats of ecologically and economically importance and natural harbours such as, Al-Salif, Al-Hodeidah, Al-Mukha, Aden and Mukala . 3.3 Bathymetry The bottom relief of the Red Sea can be divided into the following regions: 1. The coral reef zone. In the Red Sea, there is a large area of vigorously growing coral of depths of less than 50 m. Diverse and spectacular coral reefs occur on in its northern and central half. Greatest development occurs in the offshore barrier reefs which are located 10-40 km off the Saudi Arabian coast and about 400 km long and several kilometres wide. Better developed reefs remain around the Farasan and Dahlak islands which also support extensive mangroves. 2. Coastal shelves. They extend from the shore to a depth of 300-600 m. From the coral reef zone the sea bottom descends abruptly but the descent to the greater depth is by a series of steps, generally low in proportion to breadth. 3. The main trough. It extends from a depth of 600 to 1100m. 4. The axial trough. In the axial through the 1000m isobath encloses a continuous deep, the axial trough which develops within the main trough. The Strait of Bab el Mandab. It extends between Ras Bab el Mandab and Ras Siyan and is divided by Miyun Island into two channels. ____________________________________________________________________________________________________ Final Report July 2000 16 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 3.4 Meteorological Conditions 3.4.1 Wind Prevailing winds Bab el Mandab, the Gulf of Aden, and the Red Sea south of lat. 20 oN are subject to the reversing monsoon. Because of the mountains, during the NE monsoon (October to May) winds blow into the Gulf of Aden from easterly direction and into the Red Sea from the SSE; during the SW monsoon (June to September) winds are from the NNW over the southern Red Sea and from NSW over the Gulf of Aden. In regards to the wind conditions, the Red Sea can, generally be divided into the following regions: (i) Northern Red Sea (northward of lat. 20 oN). Here the prevailing wind is mainly NNW all year round. Occasional winds from this direction are slightly more frequent in summer than in winter. Southerly winds occasionally blow during winter months only. (ii) Southern Red Sea (southward of lat. 20 oN). From May to September winds blow from the same direction as in the northern Red Sea. In October, the winds start to change to SSE and retain this direction until April. They end, however, somewhere earlier, in January in the region between 20 oN and 18 oN. (iii) Intermediate region. This develops only in the winter between NNW wind of the northern Red Sea and the SSE winds of the southern half of the Sea. This area is characterised by relatively low pressure calms. The region varies is size and oscillate in position by the beginning of summer conditions, it moves gradually to the south giving way to a transition from the SSE winds to the NNW winds. In summer, sea breezes in the main body of the Red Sea build up strongly during the afternoon. They are not perpendicular to the shore but strike the coast obliquely due to the influence of prevailing winds. In the African shore the sea breeze is usually from the north or north east, while on the Arabian side it is generally from the north-west. In the central part of the Red Sea these afternoon winds in summer produce a medium wave height of nearly 0.6 m along the unprotected outer edges of the central Red Sea barrier reef. ____________________________________________________________________________________________________ Final Report July 2000 17 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 3.4.2 Air and Water Temperature The region south of lat. 18 oN and the shore of the Gulf of Aden is considered to be among the hottest regions of the world. In the northern Red sea, the average air temperature in august is 17.5 ºC, while in the southern part of the sea it is 37.5 ºC with maximum values of 47 ºC. In January, the average air temperature decreases to 15-20 º C in the northern Red Sea and to 20-25 ºC in the south. Generally, there is a close relationship between air and sea surface temperatures. Both increases southwards from Suez to a maximum in the southern Red Sea and then decreases towards Bab el Mandab. The zone of maximum sea surface temperature increases from >25ºC in winter (December - February) to >31ºC in summer (June September). The sea surface temperature attains its minimum values in February, while maximum temperatures occur in August (north of lat. 20 ºN) and in September (south of lat. 20ºN). Across the Red Sea, there is a tendency of sea surface temperature to be higher on the Asiatic side in winter, while in summer it is higher on the African side of the Red Sea. 3.4.3 Rainfall The rainfall over the Red Sea and its coasts is extremely small. The rain occurs mainly during the period from October to March, mostly in the form of showers of short duration often associated with thunder storms and occasionally with dust storm. As is usual in very dry climate, the annual rainfall is subjected to great variations from year to year. The high mountains surrounding the Red Sea influence its weather, notably the rainfall. This is due to the fact that the summer rains are produced by the south-west monsoon, which often crossing central Africa invades Abessynia where it loses most of its moisture content before reaching the Red Sea. Average annual rainfall over the Red Sea generally decreases from 21 mm at Suez to 3 mm at Ghadaqa (Hurgada), then it increases southward reaching a maximum (193 mm) at Massawa. A decline in the amount of rain appears again at the southern end of the Red Sea, where at Miyun the average annual rainfall has a value of 43 mm. The average annual rainfall over the whole Red Sea is equal to 50 mm. ____________________________________________________________________________________________________ Final Report July 2000 18 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 3.4.4 Monthly mean sea level and tides The predominant factors affecting the sea level fluctuations in the Red Sea are winds, atmospheric pressure, circulation patterns and the hydrographic structure of the sea. In the northern and central regions winds and the circulation patterns are the controlling factors in the oscillation of the mean sea level. In the southern Red Sea, the atmospheric pressure and variations account for almost all of the variations in mean sea level. In the Red Sea the monthly mean sea level is generally higher in winter and lower in summer than the annual mean (MSL). This indicates an absolute increase of volume of sea water in winter and a decrease in summer. In the northern and central regions of the Sea the level is higher than MSL during the period from November to May. Maximum positive deviations of mean sea level at Suez (+11.7 cm) and at Port Sudan (+13 cm) occur in January. At Miyun, sea water levels below MSL (-9 cm) are observed in May. In the northern and southern regions of the Red Sea, minimum values occur in September, when the level is lower than the annual mean by 16.2 cm at Suez and 15 cm at Miyun. In the central Red Sea mean sea level reaches its lowest level (-22 cm) in August. Thus, it is clear that the highest value of sea level fluctuation is observed at Port Sudan (+35 cm) while the lowest value (-24 cm) is at Miyun. The tidal heights are not very marked anywhere in the Red Sea, and ranges of 0.25 to 0.75 m are most common. They are essentially oscillatory and mainly of the semidiurnal type. There is a difference of 6h between the time of high water in the north and in the south, so that it is high water at the southern end of the Red Sea when it is low water at the northern end and vice versa. The average spring range is 0.5 m in both the north and south, but decreases from both ends towards the central, where near Port Sudan and Jeddah there is no appreciable semidiurnal tide, in this region an anticyclonic amphidromic system exists. Another nodal zone, with negligible tidal range occurs just to the north of Bab el Mandab, between Assab amd Al Mukha. From this region southwards, the time of high waters changes by several hours and the spring range increase to about 1.0 m at Miyun. ____________________________________________________________________________________________________ Final Report July 2000 19 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ In places where the semi-diurnal tides are very weak, the diurnal character appears. 3.4.5 Tidal Currents Tidal streams are maximum at the two extremities of the Red Sea, the Gulf of Suez and the Strait of Bab el Mabdab; but moving away from these two zones the intensity of the currents decreases rapidly. Tidal streams passing through constrictions caused by reefs, current formed sand bars, and low islands commonly exceed 1-2 m sec-1.. Tidal currents are important mechanisms of water and nutrient movement. In general, the currents flow to north when the tide is ebbing and to the south when it is flooding. 3.4.6 Salinity The Red Sea generally has the most saline water of the world’s oceans; its salinity is significantly higher than that of the open oceans in the same latitudes. The surface salinity decreases from 40-41ppt. at the southern tip of the Sinai peninsula to less than 36.5 ppt. near Miyun Isaln, and salinity at every latitude is generally higher in summer than in winter. The annual variation decreases from north to south, being more than 1 ppt in the north to about 0.5 ppt in the south 3.5 Marine Biotic habitats and species In the following section eco-systems, habitats and species will be described which are important for the economic activities of the coastal zone population. 3.5.1 Habitats The coastline of Yemen is characterised by a variety of habitats, which supports a closely inter-linked and form a unified system of major ecological and economical importance. Table ( 1 ) presents an over view of the main coastal / marine habitats of Yemen and their occurrences. Among these habitats a number of sites are of special scientific, ecological and economical interest along the coast line of Yemen. Marine / coastal habitats are endowed and combined with a high biodiversity in terms of total number of flora and fauna species. They also provide natural ecosystems suitable for almost all kinds of commercial fisheries. ____________________________________________________________________________________________________ Final Report July 2000 20 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Table (1) : Main coastal and marine habitats of ecological importance along the coast of Yemen. Turtle Coral reef Mangrove Reed & Rock / Halophyta Algal Palm trees Seagrass Sabkhan Nesting Beds Sites Abu Zahr Al Khawbah Abu Zahr Miyun Al Island Luhayah Wadi Riam Al Jabanah Ar Ruays N. Dhubab Al Luhayah Ar Ruays N. Mujaylis Ras Isa Al Urj Al Urj Al Kawkhah Humar Is. Al Urj Al Fazzah Al Fazzah Dhubab Dhubab Ar Rauys Al Khobat N. Az- Jebel Bab El- Hunish Ar Rauys Al Jabanah Mandeb Arch. Habl N. Dhubab Is. near Midi Mawshij Habl Hanish Arch. Gholafgah Zahari Ras Isa Dhubab Al Manzar Tikfash Is. Habl Al Mujaylis Murad Al Swada Hanish Arch. Ukban Is. Kamaran Is. Al Urj Midi Mawshij Yakhtul Midi Az Zahari Salif Midi N. Ibn N.Bab El- Abbas Mandeb Hudaydah Gholayfigah Nukhaylah Salif Nukhaylah Salif Al-Hohiedah Qatabah N. Al-Moka Miyun Island Al-Zobir N.Wadi Arch. Raim Al-mulk Yakhtul 3.5.2 Benthic flora Two distinct types of plants exist in the Yemen benthic environment; large marine algae (Kelps and rock weeds) and flowering plants (Seagrass and mangrove). As will all primary products, benthic flora play an important role in deriving energy from the sun and passing it up the food chain. Benthic flora is therefore limited to waters which are sufficiently shallow to allow penetration of sunlight in adequate quantities for photosynthetic processes. ____________________________________________________________________________________________________ Final Report July 2000 21 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Macroalgae such as Kelps are attached to the substrate with a hold fast. This attachment system limits their distribution to rocky shores. They occur below the lowtide level so that their large blades, or lamina may be constantly bathed in nutrients. Rock reeds also require a rocky substrate, but occur chiefly between high and low-tide levels where they are adapted to withstand periods of drying. The seagrasses have a true root system and are usually found in more sheltered areas than macroalgae. There roots must be able to penetrate the substrate and hens they are found in softer, more sedimented substrate than macroalgae. They harbour juveniles of various commercial fish and crustaceans forming a nursery areas. Seagrass may also play an important role in promoting the stabilisation of the seabed against wave action and other erosion forces. Fisheries associated with these habitats are particularly rich and abundant; such as the substantial fisheries resources off the coast of Hadramout and Al-Maharah (algal beds) and Penaeid shrimp off the coast between Al-Salif and Midi in the Red Sea (Seagrass beds). 3.5.3 Mangroves and halophytes Mangrove are an important biological feature of Yemeni coast along the Red Sea; where saline Khors are frequently fringed with the mangrove trees Avicennia marina. This species is among the hardiest plants in the terms of its resistance to salt and desiccation. A. marina distribution in the Red Sea coast of Yemen covers a 12% of the coastal strip with 100-200m wide and up to 5m high. Mangrove swamps accumulate and retain sediments; preventing coastal erosion and form an oasis of high primary productivity in an otherwise barren zone. Mangrove swamps provide the basis for important marine food chains. Their leaves fall into the water where they decomposed. The resulting detritus and bacteria form the food for meiofauna molluscan and crustacean species, including some commercially important species of shrimps. They also provide a nesting sites for a wide range of sea and shore birds. ____________________________________________________________________________________________________ Final Report July 2000 22 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Halophytic vegetations are usually found along the Yemen coastal area where a fresh ground water supply is limited or absent and where saline intrusion is rare. These salt bushes vegetations thrive along sides sabkhats, covering almost 58% of the coastal line. This type of flora has an important role in limiting beach erosion and allow other less tolerant species to germinate. Some species also support a variety of fauna such as insects and birds, and provide a nesting places for several sea birds. Moreover, they form a grazing ground for goats and camels. 3.5.4 Marine Fauna Coelenterata (Anthozoa-Corals) Corals and coral reef are distinctive features of Yemen sublittoral marine waters of the Red Sea, Socotra Archipelago and many areas in the Gulf of Aden and Arabian Sea. Coral growth is found both as coral reefs and coral communities on a variety of substrates. The coral reefs show two types of development: 1)fringing reefs off the southern coast and some offshore islands and 2) semi submerged patch reefs. Coral reefs ecosystems are among the most biologically productive and diverse in Yemeni water and in the world.. They form the main fishery areas in the Red Sea . With potential tourists attraction, coral and rock are used for building. Corals are only one element of the reef community, and reef ecosystems structured with primary produces, herbivores and carnivores; such as algae, other invertebrates and large number of fish species. There is a high percentage of coral mortality in the Yemen waters due to coral bleaching, caused by elevated or rapid changes in sea water temperatures, UV light, low salinity and higher than usual turbidity and bacterial infections. Reefs are also susceptible to damage by sedimentation caused by coastal works, by oil or effluent pollution or by eutrophication from sewage or fertiliser runoff from agricultural coastal plateau and high land. The global climate-change effects likeable to effect coral reefs comprise increases in sea water temperature, a too fast rise of the sea-level, and especially increases in sedimentation. There are no important areas of coral reefs along the coast of the pilot area ____________________________________________________________________________________________________ Final Report July 2000 23 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Mollusca In the Red Sea water a total of 950-1000 species of molluscs were recorded; in which about 850 live species were from the southern and central regions. The molluscan community from the Yemeni Red Sea form a total of 625 species representing five classes. Crustacea The crustacean marine fauna include members of potential and commercially significance; such as the shrimp Penaeus semisulcatus, the spiny lobster Panulirus homarus and the swimming crab Portunus pelagiacus. There are 53 crustacean species in the Red Sea region. A total of 24 and 45 species were recorded from the southern region and Socotra Archipelago respectively. 3.6 Fish The fish fauna of the Yemen Red Sea , Gulf of Aden / Arabian Sea is mainly of IndoPacific origin. The Yemen Red Sea fish group is large and more diverse than that of the Gulf of Aden and the Arabian Sea due to the different habitats. Reef fish inhabit the coral reef strand along almost all the coastal line. A total of 65 families and 416 species were recorded from the Yemeni Red Sea water. Fishes from the Socotra Archipelago are formed from 35 families, which contain a total of 169 species. 3.7 Turtles Five species of turtles are found in the Yemen marine environment. Their resting and breeding groups extend along the sandy shores of the coast. These turtles species are: 1- Chelonia mydas (Green turtle) 2- Eretmochelys imbricata (Hawksbill turtle) 3- Lepidochelys olivacea (Oliveridley turtle) 4- Caretta caretta (Loggerhead turtle) 5- Dermochelys coriacea (Leatherbacks turtle) Although, turtles are among the endangered species, which have great concern world wide, and protected under national legislation, they are under threat from human ____________________________________________________________________________________________________ Final Report July 2000 24 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ exploitation in Yemen. Nesting beaches along the southern coast of Yemen are suggested to be some of the best remaining nesting ground in the world for green turtle. 3.8 Marine Mammals Two classes of marine mammals occur in the Red Sea of Yemen. These are the dugong Dugong dugong (Sirenia) and several species of dolphins and whales (Cetacea). The common dolphin Delphinus delphis and the sperm whale Physeter macrocephalus were the only marine mammals recorded from Socotra Archipelago area. 3.9 Sea and Shore Birds A total of 82 species of sea and shore birds were recorded from the coastal area of Yemen along the Red Sea; in which 14 species were endemic to the region, and 15 species from the southern coastal area. In the Socotra Archipelago, 70 species have been found. Yemen has major regional significance for a variety of bird species and support a small population of the Bald lbis Geronticus eremita of the rarest birds in the world. Yemen is also one of the richer countries in the region for birds, because : a) Its great diversity of habitats. b) Its location at the centre of the main flyway between Europe, Asia and Africa for millions of birds which annually migrate along north south routes. c) Its biological isolation by deserts and seas which leads to endemism. 3.10 Utilisation of Marine Resources The exploitation of the sea for food is one of the most important national resources for local consumption as well as export income, although, the level of utilisation of marine resources is limited. It is concentrated on certain species and groups of organisms, which could be threatened. ____________________________________________________________________________________________________ Final Report July 2000 25 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 3.10.1 Red Sea Fisheries Resources Compared to other parts of the Red Sea, the shallow, nutrient rich waters above the wide continental shelf of Yemen are rich fishing grounds. The standing stocks of demersal fishes and shrimps in the Yemeni Red Sea are estimated at roughly 23,00032,000 mt. There are five main landing centres along the Red Sea coast of Yemen: Midi, Khoba, Hudaidah, Khaukha and Mokha. Shrimps are sold by weight at the landing sites and wholesale fish markets. Fish are auctioned and sold by the bundle or by size in the case of larger dishes. Some fishery products are destined for export. The shrimping season is October to April. At present, shrimping is done by local fishermen using sambuq equipped with surface trawl nets. The present official catches of shrimps from the Red Sea are still below the highest estimate of MSY of 2,000 mt/season made in the 1970s. however, it should be noted that often foreign shrimpers from countries of the region and outside are caught fishing for shrimp illegally. 3.10.2 Utilisation of other resources Utilization of other resources include the collection of the molluscan clam for fish bait, collection of gastropods for their opercula in Khor Omira and Ras Omran. In Socotra, fishing of mother of pearl for pearl collection . Turtles are killed for their eggs and meat by locals when they come ashore to breed Dolphins are fished for bait material for shark nets and lobster traps in Socotra. Many species of fish are also fished and thrown away as by-product. Marine and coastal flora are used and consumed by different sources. The dome palm H. thebaica is used as a source of fire wood for cooking, making ropes and mattress in Al-Urj area. Grasses and Reeds are heavily grazed by domesticated livestock in AlUrj, south Al-Hudydah to Yakhtul, Ahwar and Al-Mahra. Mangroves are used in the form of wood for fuel or construction and cooking . It is also grazed by camels and used as drugs . ____________________________________________________________________________________________________ Final Report July 2000 26 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 4. RISK ASSESSMENT 4.1 Accelerated sea-level rise One of the more certain consequences of global climate change is accelerated sealevel rise (ASLR), which will intensify the stress on many coastal zones, particularly those where human activities have diminished natural and socio-economic adaptive capacities. However, owing to the great diversity of both natural and socio-economic coastal system and their dynamic response to anticipated changes, future impacts are not always easy to predict. Further, appropriate adaptation will vary with site, depending on environmental and socio-economic circumstances. Thus, careful studies are required to assess possible impacts as well as to identify suitable adaptation options. Over the last 100 years the global sea-level rose by 1.0-2.5 mm/yr. A commonly accepted estimate of future sea-level rise is 1.0 m by the year 2100. An important point to bear in mind is that this estimate represents a rate of sea-level rise that is about four to ten times the rate experienced over the last 100 years. The current projections of sea-level rise should therefore be of major concern in the context of coastal zones and small islands. 4.2 Selection of pilot area Because of the great length of the Yemen coastline a pilot area has been selected for further and more detailed study. From table 2.1 it can be concluded that cities and towns located along the Red Sea coast (except Hodeidah) are small in size with a low level of economic activity. These towns are usually also poorly provided with basic services. In many places an increase in sea level will cause erosion and inundation. The city of Hodeidah is the only big city on the Red Sea coast with a considerable economic and trade activity, centred around the port which is the second largest port of the country. The level of the area is low and the city has suffered a considerable rate of erosion of the sea front. These factors make Hodeidah an appropriate site for further study. ____________________________________________________________________________________________________ Final Report July 2000 27 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ The pilot area comprises the city and port of Hodeidah, the low lying sandy spit extending about 12 km north-westward from the city, and the coast south of the city to a distance of 10 km, where two wadis abound on the shore and where a few fishery settlements are situated close to the beach. 4.3 ASLR induced risks The potential consequences of sea-level rise will be felt world wide, but the less developed countries at low latitude will find it hardest to bear these consequences. Such consequences include: increased frequency and extent of flooding rearrangement of coastal unconsolidated sediments and soils increased soil salinity in areas previously unaffected changes of wave climate accelerated dune and beach erosion upward and landward retreat of the boundary between freshwater and brackish water greater upstream intrusion of salt-water wedges, and changes to bank and wetland vegetation. Many of these firsts order impacts are linked and many will be influenced by feedback from changes to other environmental parameters such as increased temperature, changed rainfall and/or wind patterns, and alteration to other human activities in river catchments. As a consequence of first order impacts in coastal zones a variety of second order impacts can be identified which include the following: changes in offshore bottom profile changes in sediment and nutrient flux rates changes in marine primary production changes in terrestrial (coastal) primary production. Soil erosion in a catchment may therefore change primary production in coastal marine environment positively, by enhancing nutrient levels or negatively, by reducing light penetration through increased turbidity. ____________________________________________________________________________________________________ Final Report July 2000 28 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 5. CHARACTERISTICS OF THE PILOT AREA 5.1 Natural conditions There are hardly any data on natural conditions such as waves and tides in the area of Hodeidah. Two reports have been identified which have been very useful for assessing the conditions and for defining the most vulnerable zones in the pilot area: 1. Coastal Erosion and Siltation Study 1991, by Hydraulic Research Ltd, England; the study identifies erosion problems along the Red Sea coast, also discussing the Hodeidah region; [Ref.1]. 2. Feasibility Study for the 7th berth of Hodeidah Port, 1982, JICA [Ref.2] These two documents describe the natural conditions as follows: Wind: strong south-west winds are predominant in winter; in summer cool northerly breezes prevail in the afternoon, with some occasional violent squalls from the land; wind data of 1978-1980 show maximum wind speeds in the winter might obtain 30 knots, while one reading shows a maximum wind of 40 knots in May 1979. According to [Ref.2] it should be noted that the wind data offshore as derived from the U.S. Navy Marine Climate Atlas of the World, Vol.III, Indian Ocean of 1976, show a predominant wind from the north over nearly the whole year, which is quite different from the situation along the Hodeidah shoreline in winter. Waves: waves come from the south with wave heights generally less than 2 m offshore, but occasionally 2.5 - 3 m. Wave periods amount to 5 to 6 sec. Tidal conditions: according to Ref.2 tide levels are as follows: Highest High water HHW +2.0 m Mean High Water MHW +1.4 m Mean Sea Level MSL +1.0 m Mean Low Water MLW +0.6 m Lowest Low water LLW +0.0 m (Chart Datum) ____________________________________________________________________________________________________ Final Report July 2000 29 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ The difference of 0.6 m between HHW and MHW is caused probably by a combination of spring tide (estimated at + 1. 7 m) and a storm surge of 0.3 m. This surge is mainly a combination of barometric pressure and wind set up effects. There are some current measurements [2], indicating a northerly drift of about 0.4 m/s. Sediment transport: there is a northward long-shore drift, responsible for the formation of the sand spit. 5.2 Selection of ASLR scenario Along all coasts of the world sea levels show much variation. Levels are subject to a considerable number of factors, whereby in many areas tidal forces are the most important. In some areas wind driven surges in hurricane conditions are dominant, such as for instance in the North Sea. In addition there are atmospheric influences. In any area a combination of the extreme values of each effect will give the highest sea level, although with a very low level of probability. When sufficiently long recordings of wind, wave and sea level data are available a frequency of exceedence graph for the sea level can be constructed, showing the chance that a certain water level will be exceeded. Normally this graph will form the basis for the assessment of the vulnerability of a coastline, because it allows distinction to be made between areas which will be flooded and be lost to the sea and areas at risk of flooding. Areas lost for instance will be defined as those areas which will be flooded every day due to normal tidal events. The areas at risk are then defined as situated above the flooded zone and below the highest attainable sea water level. In view of the lack of long term data concerning natural conditions such as tidal levels, a simple approach has been adopted for this study. A conservative approach has been taken whereby the lost area has been defined as the area below the HHW + 1 m mark (or Chart Datum + 3m), and whereby the area at risk is not separately ____________________________________________________________________________________________________ Final Report July 2000 30 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ distinguished. In the following chapters this "flooding" level will be related to as Mean Sea Level as follows: (MSL) + 2 m. 5.3 Description of the coastal zone From the viewpoint of ASLR the pilot study area can be divided into the following parts going from south to north: South of the city This is the area of Duraihmi between Al Mandhar town and Wadi Siham, where there are some small facilities, population and houses. The small town of Al Mandhar with only 1200 inhabitants, with two schools and clinics, is not subjected to hazards induced by an increase in sea level as it is 300m from the high water line and located approximately three meters above sea level. But the new Duraihmi road which is under construction is quiet close to the coast and may be at risk of flooding in future. There are no facilities other than the salt basins which considered the main source of living for the citizens of the area. City of Hodeidah During the last decades the sea front of Hodeidah has suffered considerable erosion. The following stretches can be distinguished: The southern part of the sea front of the city is protected by a rock revetment; a higher sea level will give increased attack; strengthening of the revetment will be needed. Over a short distance directly south of the fishing harbour considerable accretion of the beach has occurred; at the same time dredging is in process to deepen the harbour which has silted up over the last years [ref. 1]; this accretion and siltation is expected to contribute to the erosion problems to the north of the fishing port, since the long shore current is directed to the north-west. The fishing port is protected by an elaborate system of breakwaters; strengthening will be required to resist the increased wave attack due to deeper water in the future. In addition the level of the port area will have to be heightened in order to prevent frequent flooding. ____________________________________________________________________________________________________ Final Report July 2000 31 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ From the fishing port a rocky revetment extends for a few km’s to the north; strengthening will be required to cater for the sea level rise. To the north of this coastal stretch a corniche road has been constructed fronted by a small beach; the beach is so low that a rise of the sea level will destroy it completely. During the site visit it was observed that the level of the corniche seems to be at about 1 m above the level of neap high water, estimated at + 1.3 m above Chart Datum, thus at about + 2.3 m. Consequently with the sea level rising by 1 m the MHW will attain + 2.4 m, thus flooding the road every day. A combination of storm surge with mean high water will give a water level of about +2.7, causing considerable flooding. Raising the sea wall will be required to provide a continuous defence. Ras al Kathib sand spit and the naval base The sand spit at which northern end naval facilities are situated is already under present conditions effected by erosion; this situation will rapidly worsen when the accelerated sea level rise occurs When the Navy would insist on maintaining the facilities, over a length of about 15 km a raised dike carrying the road with proper seawards stone defences will have to be constructed. Port of Hodeidah According to [ref.2] the level of the container berths at the Port of Hodeidah seems to be at +2.47 m. Given a sea level rise of 1 m in combination with MHW the sea would attain + 2.4 m twice daily, making port operations impossible. Consequently the level of whole area of the port has to be increased and the quays heightened. Katneeb Power Station At the northern end of the pilot area a power station is situated. According to [ref.1] the outfall and intake structures of the station clearly interrupt longshore transport. This has caused serious erosion of the coast facing the power plant and also to some erosion downdrift of the intake. Ref. 2 concluded that damage to the actual installations is not expected to occur for the next few years (the report was written in 1996), but the situation would warrant careful monitoring. ____________________________________________________________________________________________________ Final Report July 2000 32 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 5.4 Socio-economic characteristics of Hodeidah Population and housing The population of Hodeidah City is about 298,452 inhabitants. The number of families are about 45398 living in 49152 houses. The illiteracy rate is about 37.8% for citizen above 10 years of age. Enrolment in primary education percentage is 78.6% for citizens of 6-15 years of age. Where as the percentage of population under 15 years old is about 47.5%, similar to that of the other areas in the Republic. The rate of unemployment is the lowest in the Republic, in 1994 it was 8.9% while in other areas it was 9.3% and concentrated among illiterate people who represent 65% of the unemployed people. The economically active people of Hodeidah can be classified according to their activities into sectors as table 5-2 described: Table (5.2) lists type and percentage of activities distribution among population above 10 years of age in Hodeidah as per 1994 census. Sector Agriculture and Fishing Fishing Mining and quarries Converting industry Water & Electricity Constructions (Whole sales, retails) trade and aintenance Hotels and restaurants Transportation and storing Financial broker Real estate and commercial projects General Administration, and social security Education Health and social work Social and personal services Home jobs servants International Organisations Others Total Percentage 6.33 2.69 0.39 10.29 0.79 7.01 25.53 3.59 14.0 0.56 3.07 10.89 7.03 1.15 1.9 0.7 0.01 3.96 100 Source: Central Organisation for statistics – final results of Hodeidah Province (second report) General Census of populations, houses and facilities 1994. ____________________________________________________________________________________________________ Final Report July 2000 33 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ From table 5.2, It was found that workers concentrate in the production and service sectors, the percentage of workers in the sectors of Trade and maintenance is 25.53%, the sector of transportation and storing 14% and the sector of hotels and restaurants 3.59% with total of 43.12% of the total economically active people. If the percentages of workers in the sector of converting industry 10.29%, worker in the sector of general administration 10.99%, sector of construction 7.01% and education 7.03% are added, the total percentage in these sectors rise to 78.33%, while the rest work power distributed in other sectors. Indicating that the sector of agriculture and fishing is very limited with percentage of 6.33% in agriculture sector and 2.69% fishing sector. This also means that the major attracting activity in Hodeidah is the field of commercial and transportation services because of the role of the Hodeidah Sea Port in the economic life in addition to the industrial activity, which will be explained later. Economic Activity of Hodeidah Port As the main port of Yemen along the Red Sea coast, Hodeidah plays a vital role in receiving imports and shipments of exports. Table (5-3) shows the import percentages of Hodeidah port in comparison to the rest of Yemen Ports. Table (5-3): The percentage of Consumable imports volume through Hodeidah Port in 1998. Items Beans Rice Sugar Living cattle’s Frozen goods Cement Wood Iron Cars Equipment & machinery General goods Total Quantity Total imports to Yemen Imports though Hodeidah % of Hodeidah to all Yemen 1000/mt 1000/mt 1000/mt No.s 1000/mt 1000/mt 100/mt 1000/mt No.s 1000/mt 1846 153 339 516054 29 509 193 269 7046 5.4 1370 71 239 7054 14 17 185 192 6204 - 74.2 46.4 70.5 1.4 48.3 3.7 95.6 71.4 88.0 - 1669 1163 69.7 1000/mt 1000/mt 5031 3205 63.7 ____________________________________________________________________________________________________ Final Report July 2000 34 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ From table (5-3), it can deduce the vital role of Hodeidah Port played in Yemen trade relations world-wide. This reflected in the economic activity in Hodeidah as mentioned previously, which made Hodeidah one of the most important sources of customs in Yemen. Hodeidah International Airport International airport of Hodeidah is considered one of the important gates of Yemen to the foreign world. As it handles a great part of goods and passengers coming and departing from Yemen, and expected to play a vital role in the export of fishes and marine products which is considered one of the promising activities in the future. Civil Service facilities Hodeidah is considered one of the main urban areas, therefore the state pay large attention by implementation of public services projects. Table No. (5.4) describe the main civil services facilities of Hodeidah city. Description Number of Beneficiaries Covering percentage Total house supplied with water project (public, co-operative, private) 41768 86.2 Total houses supplied with sewage (public, cooperative, private) 26570 54.8 Total houses supplied with electricity (public, co-operative, private). 34914 72.0 Total of houses use cooking gas 25967 53.6 Total of houses in Urban of Hodeidah Province 487478 100 From table (5-4) it is observed the acceptable level of services comparing to other provinces areas. These percentages reflect the general coverage of these services by national economic, which still the main aim of the development of this promising city. Therefore, increase of sea level during half a century requires knowledge of the losses involved. ____________________________________________________________________________________________________ Final Report July 2000 35 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Sewage Services During the a meeting with specialised officials in water Corporation in Hodeidah the problems of seal level increase and its effect on the water net, water reservoirs and wells were discussed. The main finding were as follow: a) The net is designed to resist humidity and salinity as it is from good Plastic materials and it is not expected to be damaged or effected due to increase in sea level. b) Water discharge basins of the city located at reasonable height, far from the shore and well designed, therefore, no problems expected to happen. c) Old wells (about 10 wells) are five km from the coast, and it is observed that salinity increases due to the decrease in the level of fresh water table and replaced by sea- water intrusion. But the water corporation replaced the old wells gradually and has dug new wells in AL-Zawia area 12 km far from the coast, now implementing the salvation line carrying water of Hodeidah from AL- Zawia area with a cost of 300 million YR financed by the Government of Netherlands. Water Corporation plans to make ALZawia area the source for Hodeidah water on the medium run, by allocating an area of 7km2 for the wells. These wells of maximum 100 m deep will not be affected by the increase of sea level. On the long run the Corporation plans to make Wadi Siham area the source of Hodeidah for water due to ground water availability and the location of wells will be far from the coast and will not be affected by the increase in sea level. Wells for agricultural purposes There are very limited wells used for agricultural purpose located near the coast to the extent that it may be subjected to hazard of the increase in sea level. However, the major agricultural wells were made far from the coast and will not be subjected to hazard of increase in the sea level or transgression. ____________________________________________________________________________________________________ Final Report July 2000 36 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Sewage The Water Corporation covers an important part of Hodeidah by sewage service, most of which far from the coast, and along or near the coast line there is no sewage net in the sea-faced region. The inhabitants of this area usually dig sanitation wells, which emptied or water absorbed due to the effect of tidal movements. The treatment station located 6 km far from the coast at 8 m height from mean sea level and well not be affected by the rise in the sea level. The Corporation plans to launch a comprehensive study for sewage and treatment station of Hodeidah, as the current net and station are not functioning as requested. The length of the main sewage net is 14 km with 25 km branches, and 40 thousand connections at depth of 2.5m. The capacity of treatment unit is about 80–120 thousand m3. The cost of current treatment station is about 80 million YR. Due to the above it can deduce the large cost of implementation of new modern sewage net for Hodeidah city. Accordingly, and before executing such project, measured should be considered to protect it from the effect of sea level rises. Electricity Services The electricity network be affected by the rise in sea level since it is built at considerable height. The ground part will not also be affected, as it is resistant to humidity. Any protections to the area near from the coast will results no danger to electricity net. The main danger in case of hazards will be the losses of the commercial station at Ras Kathib Communication Services The data of the annual Statistic book for Hodeidah shows the capacity of telephone lines in Hodeidah in 1997 about 20000 lines, 18400 of which is functioning and there is no direct hazards to communication net due to its high location from the sea level. Except in case for the housing and economic facilities located near the shore. ____________________________________________________________________________________________________ Final Report July 2000 37 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Roads According to the data of the Statistic Annual Book for 1998 the length of roads during 1996-1998 were presented in table (5-5). Table 5.5 Length of roads in Hodeidah Province during 1996-1998 Years Asphalt Roads Pebbles Road 1996 489 178 1997 503 206 1998 560 280 Table (5-5) shows a very limited network of road comparing to the size of the area. According to the data, an important part of these roads in Hodeidah city located parallel to/or near the coast which, will make it subject to hazards of increase in sea level. The table also shows the tangible development in the length of roads which increased from 1996-1998 with percentage of 14.5% due to increase in economic movement especially in the field of goods transport to / from Hodeidah. This is also confirmed by the increase in the number of transport means during 1996-1998 according to the table (5-6). Therefore; any problems may effect the situation of Hodeidah due to sea level rise will effect the activity of land transport sector or the owner of the trucks in first and then owners of rent cars. Table (5.6) Licensed cars working in Hodeidah Province Years Private Cars Taxies Trucks 1996 11420 5728 25802 1997 12599 6118 26400 1998 14899 6118 26400 Health Facilities Table (5-7) summarised the health facilities according to the data modernisation survey of Hodeidah city executed by the Central Statistic Organisation in 1999. ____________________________________________________________________________________________________ Final Report July 2000 38 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Table (5.7) Lists the number of Health Facilities in Hodeidah Government Hospital 5 Health centre 20 Private hospital 3 Total 28 In addition to that a number of health centres without beds and primary health care units are found in Hodeidah. Educational facilities According to the survey of data modernisation of Hodeidah city data executed in 1999 the educational facilities in Hodeidah are explained table (5-8). Table (5.8) Educational facilities in Hodeidah Province in 1999 Description Number Primary Education schools 28 Secondary schools 2 Primary and secondary schools 35 Hodeidah University Building 10 Technical institutions 2 Others 20 Total 97 Table (5-8) shows that, there are a numbers of educational facilities in Hodeidah. However, an important part these facilities located near the coast in low lands. Such as the Faculty of Education and some other colleges of the University of Hodeidah which, have been recently built, and therefore could be subjected to hazard from the rise of sea level. Tourism facilities There are many tourism facilities in Hodeidah which, can listed in table (5-9). Table (5.9) Tourism facilities along the coast of Hodeidah Description Four stars hotel Three stars hotel One star hotel Total No. of Hotels 1 8 6 15 Number of beds 124 479 464 1067 Number of rooms 66 252 193 511 However, a limited number of large hotels in Hodeidah located near the coast and may be subjected to the hazards of increase in sea level. ____________________________________________________________________________________________________ Final Report July 2000 39 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Agricultural facilities According to the data surveyed of Hodeidah province the important agricultural facilities in Hodeidah can briefed in table (5-10). Table (5.10) Agricultural facilities in Hodeidah Name of facility Number Agricultural facilities 2 Veterinary Facility 1 Agricultural offices 1 Archaeology sites 1 Total 5 From table (5.10), It’s clear that the number of agricultural facilities in Hodeidah is very limited. The percentage number of workers in this field in Hodeidah province is approximately 6%, and may reflect the limited agricultural activity in the study area of Hodeidah. Therefore, the expected losses in the agricultural field due to the sea level rise could be very limited as well. Industrial facilities Table (5-11) lists the main industrial facilities of Hodeidah city according to the industrial survey made in 1996. Hodeidah was ranked in the second position after Taiz with respect to the number of large facilities with15.7% working power of the total number of large facilities in Yemen. It also occupied the second position in the number of medium facilities with 18.82% of the total number of medium facilities in Yemen. Concerning the small facilities it comes in the sixth position with a percentage of 6.5%. The percentages reflect the importance of Hodeidah with respect to the contribution in the industrial production, which may enhances the attraction of new investments especially in the field of industry and services. Indicating that Hodeidah city formed an important part of the industrial facilities in Yemen. ____________________________________________________________________________________________________ Final Report July 2000 40 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Low cost of labour and availability of water as well as low price of land in addition to the presence of infrastructure and general services, location near the port, all these merits make the cost of production reasonable and competitive. It also indicate that, any hazards may take place in Hodeidah will result in a great losses to the economy. Particularly to the private sector which control 57% of the large facilities, 91.6% of medium facilities and 95.6% of small facilities. The individual style of these facilities will increase the problem, (the individual style percentage reach 33.6% in large facilities and 87.1% in medium ones). ____________________________________________________________________________________________________ Final Report July 2000 41 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Table 5.11 Distribution of Industrial facilities 1996 Description Large Medium Small Total in Hodeidah Province 57 236 2065 Extracting industries (quarries) 3 - - Food and beverage 19 103 613 Tobacco 1 4 30 Textiles 4 8 109 Clothes and food - 3 155 Bags, shoes and leather 1 10 - Wood products 1 4 190 Paper and paper products 2 - - Printing, publishing, photocopy - 8 3 Oil products & refining 1 - - Chemical products - 4 - Plastic products 4 - - Non-metal products 4 25 240 Mineral products 8 21 273 Equipment & machinery 1 - - Electric equipment & machinery - - - Medical and measuring equipment - - - Other transport equipment - 28 13 Furniture 2 3 21 Gold smith - 2 51 Water & Electricity 6 13 367 Electricity supply 3 7 50 Water assemblage and distribution 3 6 317 393 1191 31730 Total in Yemen As a consequence of any natural hazards economical problems will enforce the private capital to give up the field of production sector to financial stocks field or migrating abroad. This will badly affect the National Economy in general. ____________________________________________________________________________________________________ Final Report July 2000 42 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 5.5 Institutional Framework The main problem concerning the Yemen coastal zone and its structures is really related to the administration and the organization of the coastal zone assuring to face the expected catastrophes and the quitrent disasters, which become lately to threaten probably most of the economical establishments on the coastal regions. The Governorate have the right to study the situation, and the real expected dangers of water rising above sea level. They also have the right to put suggesting for possible remedies starting from now. The proposals and remedies have to be submitted to the governor who coordinating with the ministry of housing, construction and urban planning to put the subject in hand of the ministry of planning and development who has to scale that within the state infestation balance. Once the act become approved officially by the state, the project in full has to be enrolled into projects of the ministry of housing which guides its execution under the guardianship of the governor and the ministries office in the governorate in charge, but its found that there is a lack in consultation between government agencies concerning the coastal areas. The ministry of planning is considered the linkage between Yemen and the outer world in concerns of coordination, and administering funds as aides, donations and credits entitled for this sorts of major schemes and projects. The ministries and government agencies functions and responsibilities pertaining to the coastal zone is shown in Table (5.12) which give a brief in formation on the following points. 1. description of authorities in charge, taking into account the following aspects: the ongoing process of decentralisation of powers to the Governorate and provinces EPC's plans to set up a coastal zone management unit within the local government for Hadramout (pilot project); the same should be done for Hodeidah: the city area: municipality. fishery harbour: Ministry of Fisheries. port: Port Authority sand spit: Governorate/province and Min. of Defence. coastal area outside the city: Governorate/province. private sector. ____________________________________________________________________________________________________ Final Report July 2000 43 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 2. what are bottlenecks and impediments for effective action?, like: lack of clear delineation of authority strength and influence of the agencies lack of enforcement capacity (for instance when the government would set up a "set back" zone parallel to and at a distance of say 100 m from the high water line prohibiting construction; what would happen if an important and well connected private investor would build tourist facilities in the forbidden area?) 5.6 Legislative Framework We found that despite the lack of clear legislation issues the local authority and the Governors office, therefore the following points are still not clear and need more search to get answer for : 1. description of laws and regulations pertaining to the coast: environmental laws is it forbidden to extract sand from the beaches? is there a set-back zone? 2. what are bottlenecks and impediments for effective action, like: lack of relevant laws and regulations vague and unclear clauses laws which are in conflict with each other. ____________________________________________________________________________________________________ Final Report July 2000 44 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 45 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 46 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 6. IMPACTS OF SEA LEVEL RISE ON THE PILOT AREA The following section describes the various impacts on the pilot area and the losses that may occur as a result of a sea level rise of one meter. 6.1 Biological Impacts Some studies and reviews have attempted to evaluate potential impacts on particular biological communities such as coral reefs, mangroves, or coastal ecosystems in particular regions (Buddemeier and Hopley, 1988; Chou and Yap, 1991). Coastal wetlands are frequently associated with deltas, tidal rivers, estuaries, and sheltered bays. Along the Yemen coastline wetlands are only found associated with sheltered bays. Mangrove swamps provide the basis for many important marine food chain. Their leaves fall into the water where they decomposed. The resulting detritus and bacteria form the food for meiofauna molluscan and crustacean species, including some commercially important species of shrimps. They also provide a nesting sites for a wide range of sea and shore birds. It is now becoming increasingly clear, that coastal wetlands (marshes and mangrove) can undergo a number of responses to sea-level rise. Responses may be different in muddy, tide-dominated systems, than in more organic systems, in areas of high or low tide range, and in areas of high or low sediment and freshwater input. Thus, the balance between accretion and submergence will be complex, and a range of morphological responses is likely for different coastal types and coastal settings. Although some marshes and mangroves may be under threat from sea-level rise over the next century, human impact has been the major threat up to the present and may be far more important locally than climate change in the long term. In low island environments and areas with low inputs of terrigenous sediments, mangrove ecosystem may be able to keep up with a rise of 8 cm per century but at rates in excess of 12 cm per century such communities may not persist. Stratigraphic ____________________________________________________________________________________________________ Final Report July 2000 47 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ evidence from high islands where more sediments are derived from land-based sources indicates that mangrove ecosystems my be capable of keeping pace with rises as high as 25 cm per century. The survival of mangrove ecosystem in low island environments is therefore threatened by the current projected rates of sea-level rise. Temperature is the most important factor in determining the global distribution of mangroves, which are generally confined to frostfree regions. A global mean temperature rise would therefore be likely to cause an expansion in the zone where mangrove grow, especially as the projected upper temperature will be below the thermal stress limits of these plants (37° to 38° C). Increased rainfall and run-off would also stimulate mangroves since they prefer low to moderate salinity. The other crucial factors would be the rate of sea-level rise and coastal topography and sediment supply. A sustained rise of 100 cm per century would be beyond the tolerance of these plants, but a sea-level rise of at least 8 cm and possibly 10 -25 cm per century they should keep pace with. The wetlands and mangroves found in the pilot area are located in the bay to the east of the sand spit. A sea level rise of 1 m in 100 years would destroy the existing vegetation. On the other hand the shoreline would move inland creating new opportunities for wetland and mangrove development. 6.2 Impact on the shoreline 6.2.1 Shoreline and beaches An important limitation for the quality of data available for this assessment has been the data on coastal topography to the required scale and accuracy. The Risk Zone has been defined as the area within the coastal zone and below the 2 m contour. Available topographic data for the pilot area is usually in the form of 1:50,000 scale maps but unfortunately these could not be obtained. Further, a map obtained from the Municipality of Hodeidah does not show contour lines or spot heights. Consequently an 1:100,000 scale topographic map has been taken as base map. In fact such map is not accurate enough for the intended purposes, showing contour lines at 10 m levels ____________________________________________________________________________________________________ Final Report July 2000 48 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ only. The location of the MSL+ 2m contour line has been found by interpolation between the 0 and the 10 m contour. Climate change is expected to impact on beaches in two ways: 1. The rise in sea levels expected from climate change would accelerate the rate of recession on sandy shores. 2. Increases in littoral transport capacity arising from increases in the intensity and duration of storms. This report deals only with the first case -shoreline recession due to sea-level rise. The loss of land attributable to sea-level rise will occur from erosion of sandy shores and erodible cliffs. Shoreline recession results from the offshore transport of sand. On steep rock coasts, sea-level rise may have an insignificant impact. Loss of land on low-lying coasts sheltered from wave attack is usually from inundation. By classifying the coastline according to geomorphology, the appropriate land loss mechanism can be determined following which the loss of land can be decided upon Lt Rt St .G. Bh t by modelling. The recession comes from the adjustment of the active profile to a new elevated water level. The cross-shore profile adjusts itself by re-distribution of sediment such that the active zone rises with the rise in sea level while maintaining the same cross-sectional profile. This results in a loss of beach area. The apparent loss of sediment is proportional to the width of the active zone. The beach profile is expected to move horizontally by shoreline recession and vertically upward. Bruun (1962) proposed a method for determining the movement of shorelines due to increases in water levels. The formula now known as the Bruun Rule states that: Where Rt is the shoreline recession in year t St is the relative rise in sea level (m) G is the inverse of overfill ratio ____________________________________________________________________________________________________ Final Report July 2000 49 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Lt is the active profile width B is the coastal land height (m) ht is the depth of closure (m). For the present study the following values pertain: St = 1 m G=1 Lt is estimated at 500 m B is estimated at 2 m ht is the depth of closure (m), see below. The Bruun Rule requires knowledge of the closure depth which would provide information on the active profile width. Hallermeier (1981) provides the following for the computation of closure depth. H2 d L,1 2.28 H s 68.5 s2 gT s Where dL,1 is the annual depth of closure, Hs is the annual exceeded wave height in a 12-hour period and Ts is the associated wave period. The depth of closure for a century, dL,100, is given by d L,100 1.75 d L,1 For the pilot area, available wave data indicates that Hs = 1.5 m and Ts =6 sec giving a depth of closure of 3 m. Consequently the recession due to a sea level rise of 1 m is estimated at about 100 m. This translates to a potential land loss along the shoreline of the pilot area (length 20 km) of about 200 ha. Shorelines with substantial amounts of clays or peat would erode even faster than the Bruun Rule suggests for sandy shores. Peat has not been found in the pilot area, but silty soils abound in the bay where the Port of Hodeidah is situated. This area is sheltered from wave attack by the sand spit, so as long as this spit survives erosion in this area will not occur. ____________________________________________________________________________________________________ Final Report July 2000 50 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 6.2.2 Impact on Coastal structures With rising sea-levels coastal structures are expected to become more vulnerable to failure Increases in water levels would sustain higher amounts of wave energy coming closer to shore. For design purposes, the weight of armour stone required to protect a coastal structure or area for a particular wave climate is proportional to the cube of the wave height. Therefore, increases in wave energy (height) would require heavier armour stone to offer the same level of protection to the shores. The same applies to breakwaters of harbours in the coastal area. While water level increases would permit larger waves to come closer to shore, increases in the intensity and duration of storms generating the waves would further increase the vulnerability of coastal structures. The changes in the intensity and duration of storms would translate into changes in the wave climate. At present not much is known about the possibility of the occurrence of more intense storms along the shores of Yemen. The structures in the pilot area that could be affected in this manner are the breakwaters of the fishing port, the revetments and sea walls of the city and the shoreline defence along the road leading to the naval base. The maintenance of these structures would demand the re-assessment of their structural integrity in the light of new evidence of water level increases. Indeed, the structures may be performing well for now and probably for some to come owing to the factor of safety that might have been included during its design. Obviously, a point would come when the limits of safety would have been exceeded. 6.3 Impacts on the pilot area The ongoing erosion of the coastline described in Ref. 1 will be aggravated by the onset of the accelerated sea-level rise. Below various hot spots will be described. 6.3.1 Power station The actual situation in the area is not known at the moment. As stated in section 5.3 the situation along the coastline in this area needs careful monitoring. ____________________________________________________________________________________________________ Final Report July 2000 51 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 6.3.2 Sand spit As stated before, the road leading to the naval base is at present under attack in high water conditions. Over a length of 4 km a stone protection has been provided. Details of this construction could not be found, but it is doubtful whether proper design criteria has been applied. The ongoing ASLR will aggravate the erosion. It is also foreseen that in the event of a major breach and part of the spit being washed away there could be significant changes to the tidal regime in the bay area. Such change could be increased siltation of the access channel to the port. Maintaining or not maintaining the spit will have a number of financial consequences. Maintaining will mean providing a proper defence at the outside of the road. Such construction would cost about US$ 2 million per km, so total cost of this option would amount to some US$ 30 million. If the decision would be taken not to maintain the spit, the consequences to the access channel to the port would have to be investigated by carrying out a computer modelling study. 6.3.3 City beaches and revetments All beaches and revetments along the shoreline are under major threat from wave attack and erosion. The situation is already serious and will be aggravated by the ongoing ASLR. It is considered that an investigation should be carried out to assess the present problems and to compare the situation with the findings of the 1991 report [Ref. 1]. In addition the construction details of the existing revetments and stone walls of the corniche should be checked, including the depth of foundation. If required new designs of protection structures would have to be made. 6.4 Hodeidah city According to the maps prepared by the coastal team which demonstrate the areas which may be affected by the sea water rise in Hodeidah, and according to the map of Hodeidah prepared by bureau of municipality and housing in Hodeidah and the results of census of population in 1994. The areas that expected to be covered with water are listed in table (5.12) ____________________________________________________________________________________________________ Final Report July 2000 52 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Population and houses Table (5.12) Houses and populations in the areas expected to be covered with seawater in Hodeidah City. Area Zafran Baiydah Al-Umal Commercial area Qala’a Mitrarig AL-Sour Al-Qadim Al-Sham Cornish Yemen area Hamdi Road Mina Road 26th Sept. Road Al-Thawra Road Duraihmi Road The College Umal City Total Percentage Houses 1423 1872 1328 1073 1044 197 594 1129 759 1305 161 103 107 107 62 66 697 12027 24.47 Families 1371 1742 1238 990 991 187 541 1105 699 1221 145 88 95 99 56 47 624 11239 24.47 Population 9015 10722 8172 6047 6415 1115 3440 6771 5412 7735 926 449 482 564 684 286 4451 72686 24.0 From table (5-12) it is clear that 24 % of the Hodeidah population and families are expected to be affected by the sea water rise, according to the estimates of the central organisation for statistics (Journal of National Accounting 1990-98). The rate of houses growth in Hodeidah Governorate is about 5.8% annually, consequently the number of houses expected to be affected will reach 15070 houses inhabited by 14050 families and 91.000 inhabitants. According to the statistical estimations of the houses area in Hodeidah as an average, is 44 m2 with cost of $US 286/ m2 and the cost of building and houses in the area will reach $US 12593. Considering the average cost of building equals to 40% of the cost of the house including the land, then the cost will reach about $US 50,370. 6.4.2 Roads According to the available data obtained from the maps prepared by the coastal team and the bureau of Municipality in Hodeidah; the length of roads expected to be ____________________________________________________________________________________________________ Final Report July 2000 53 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ covered with water is estimated to be about 50 km. According to the estimations of the Roads Department the cost of the paved kilometre is $US 177,778. . The ……. Roads according to the maps has been estimated about 15 km, while the cost for one kilometre is about $US 37037. 6.4.3 Agricultural facilities Two agricultural facilities are expected to be covered with sea- water, the cost of each one is about $US 222,222. 6.4.4 Educational and health facilities: The number of educational facilities expected to be covered with seawater is about 22 schools for the primary education (12 classes in each school) with a cost of $US 296,296 and 8 secondary schools (9 classes in each school) with a cost of $US 222,222. The cost of the Faculties of Education and Omer AL-Mukhtar is about $US 25,925,926, where as the Marine College building costs about $US 29,629,630. There is one government hospital expected to be in risk due to the sea level rise which may costs about $US 5,925,926 and a Health Center which costs about $US 222,222 each, and a private hospital which may cost about $US 370,370 Tourism facilities Four stars hotel which costs $US 4,444,444 is expected to be affected by the sea level rise. Also about eight other medium size hotels may be affected, and may cost $US 1,481,480 each. Government Buildings The number of government facilities and offices expected to be covered with seawater is about 26 which, cost $US 2,222,222 each. In addition to the Presidential hose which costs about $US 14,814,815. ____________________________________________________________________________________________________ Final Report July 2000 54 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Mosques: Twenty mosques of different sizes, closed to the coastal area in Hodeidah expected to be covered with seawater with cost of about $US 740,740. Parks Fifteen parks expected to be at risk, and the loose in case of sea level rise may cost approximately $US 222,222. Water and sewage facilities The damage of water facility in case of the high tide of the sea level rise affected the area, may cost approximately $US 3,703,704. The cost of sewerage net expected to covered with water is estimated by $US 2,962,963 for (3600 houses) as there is no net on the coastline Electrical facilities There is a possibility to move the electricity network from the areas expected to be covered with water with a cost of $US 740,740 in addition to the cost of construction of Ras Kathib Electric station which is $US 7,407,407. Communication facilities It is possible to transfer some of the net equipment and lines from the areas expected to be covered with water while a part of it will be damaged, and losses estimated by $US 2,222,222. ____________________________________________________________________________________________________ Final Report July 2000 55 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Industrial facilities The industrial facilities expected to be in risk due to sea level rise in Hodeidah can be summarised as; Four large sizes of industrial facilities estimated cost made by the industrial survey in 1996 is about $US 2,470,370. While 20 medium facility, of $US 33,333 each, and about 150 small facility with mean cost of $US 7407 each.. Hodeidah Port The facilities of the port is expected to be covered with sea water and we can enumerate these facilities as follows: 7 platforms, the cost of construction of each platform about. 6 million USD. Two floating platforms for oil, the cost of each platform 6 million USD. An area for marketing goods and containers estimated by 1333 500 m2 + 18 000 m2 + the area for dangerous materials 300 000 m2 + the area for extension 30 million m2 Roofed warehouse to storing goods with an area of 345 6000 m2, the total cost of these facilities will reach $US 185,185,185. According to the above we can summarise the losses in the Table 6.1 Table 6.1 losses in $ Description Houses Asphalt roads Paved roads Agricultural facility. Prim. Educ. facility. Seco. Educ. facility. High. Educ. facility. Marine College facility. Health facility. Tourism facility. Govt. Buildings Mosques Parks Electric facility. Sewage facility. Water facility. Communication facility. Industrial facility. Hodeidah Port Others Cost in $ US 759,075,900 8,888,900 555,555 444,444 6,528,512 1,777,778 25,925,926 29,629,630 6,518,520 16,296,292 72,592,587 14,814,800 3,333,330 8,148,148 2,962,963 3,703,704 2,222,222 11,825,855 239,185,185 74,074,075 ____________________________________________________________________________________________________ Final Report July 2000 56 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 6.5 Saline water intrusion The sea – fresh water interface is present at surface in the north and south zones in the study area. It has a maximum depth of 300m within inland distance of less than 10Km from the coast or 3-Km between the shallowest and deepest points of the interface. Brackish water is also present in layer II-IV (see Annex 1) representing the transition zone between salt water with EC greater than 6000 mS/cm and fresh water. This situation of the interface was considered to represent the current situation of the area because no changes might occur due to current abstractions that concentrated in the west. The affect of the sea level rise of 1m was analysed herein considering the sharp interface approach. This approach presents the changes in the position of the interface in both directions vertically and horizontally. The vertical changes according to Ghyben-Herzberg relation will be 40 times the change in the aquifer water table relating to the original sea level, while the horizontal changes estimated using trigonometry relationships. This distance estimated in the study area to be 400 times the changes in the seal level. An area of 20 km2 would be affected by the saline intrusion. This implies that wells or boreholes located in this zone would start withdraw saline water causing losses in cultivated areas. At present there are no wells for domestic or agricultural uses. in this zone. In the future development of agricultural enterprises in the affected zone should be discouraged. The geographical information system (GIS) has been used in the study region. The required plans have been drawn to topographical maps scale 1:100,000 Committed by the Yemen Geophysical Department. The contour lines have been drawn for the case study region as contour lines (1,2,3,10 meters), see Figure 6.2. These lines have to be estimated for the region that would be overflown by water surging, followed by the estimated damages of life surrounding the sea shore. ____________________________________________________________________________________________________ Final Report July 2000 57 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ It has also been assisted and utilized by results of previous studies to ratify positions of some existing environment in the Red Sea and its shores where as chura trees and the Margot, grow and other positions and locations where lich palm trees grow. Using civil engineering plans and comparing the regions that are built with other regions, some information has been collected through the performance of field survey for the case study regions, that will be threatned by water overflow and the estimation for the damages expected in eco-social fields. The shores in Hodeidah are sandy, with slanting character. This plays a great role in the water over flow in the residential and commercial regions and in the coastal, region specially near the old city of Hodeidah (Figure 6.1). Figure 6.2 illustrates some of sea plants of the Red Sea that would be affected by the sea rise because of climate change. Because of expected rise of water in the coming 50 years, many plants would be covered by water and this will cause a great damage to the sea Creatures, as well as to the production of the shrimp fields. It will also affect the coastal palm trees where too much salty water could be of disadvantage. Figure 6.3 show exposes with the variety of water rise due to the contour lines over the threatened region. Colors are implemented to clarify as keys – visual aid. Figure 6.4 clarifies the new coastal line after 50 years when the sea water rise flow will surge covering a lot of the infrastructure for civil and military establishments, commercial and economical establishments. The red line shows where the water will reach 2 mm. Height. This change will affect on the sabkhas, salt basins, sea grasses and other plants, therefor it will be necessary to make some changes in the Hodeidah Port and the fishery industry to go along with the new environment. This will also affect the old town specially the area close to the sea which is now affected by the waves. (See Pictures 1-5) ____________________________________________________________________________________________________ Final Report July 2000 58 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Figure 6.5 show the sea water effect in the past and the steps taken by the government to prevent the streets and establishments from the wave surge. Barriers to stop the wave surges causing damages to buildings and to street roads were built. Wall barrier No.1 in Figure 6.5 to preserve the location of the part for tourist purposes and to stop water flowing to other neighboring street. There lately erected stones as wall barrier No.2 shown on the same Figure 6.5 and the wall barrier No.3. Which collapsed because it was not strong enough to resist the waves. This now causes water to flow in to the streets whenever there is strong waves. The government also has completed barrier wall No.4 on the same plan, to preserve the street leading to Ras Kateeb. Along the spite the waves still break through the barriers onto the street and the surrounding area. The same map (Figure 6.4) shows number of pictures that have been taken during the study surveys in the region. Picture 6.1 shows the waves crash against a building and cause damage on part of it, whereas this building was about 30m away from the building 35 years ago. The second picture 6.2 shows the reconstruction of a major part of stone wharf – (line No.3) in the same map. This has been damaged before completing it building. Picture 6-3 shows a building while construction being subjected to violent waves beats. While picture 6-4 shows a part of the stone wharf path (Line No. 1 on the map) towards the sea where the sea wave surge covering it completely. Picture 6-5 shows the same path 40cm in height above the street level. All this barriers that the wall bevies built till now, will not be able to stop the damage coming from the sea waves. Table 6-1 Clarifies some estimated measurement taken while field case study survey for the region. Table 6.1 Field measurements for the water flow walls in case study region Location no. 1 2 3 4 Height of street in cm 90 80 60 20 Height of Barrier wall in cm A70 A70 Damaged 150 Length of Barrier wall in m 900 1500 1500 4300 ____________________________________________________________________________________________________ Final Report July 2000 59 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 60 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 61 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 62 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 63 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 64 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 65 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ ____________________________________________________________________________________________________ Final Report July 2000 66 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 7. MITIGATING MEASURES 7.1 Autonomous adaptation options Managing shorelines in the environment of global rising sea levels has been a great challenge. Historically, the primary choice of measure of managing coastal erosion has been the protection of shorelines with hard-engineered structures. The high cost of protection, in the order of US$2,000 per meter of protected shoreline for sandy shores, should be born in mind when making decisions about the construction of hard defences. Besides the high cost associated with coastal protection, protecting one segment of shoreline often translates the problem to the downdrift shores. The case of protection on sandy beaches with the bedrock not shallow enough to provide a good foundation for coastal structures has rendered such structures under these environments to serve only a temporary measure. Either beach will have to be replenished periodically at great cost or armour rock will have to be added to maintain the structure with time. The long-term cost can be prohibitive. In response to lessons learnt on managing shorelines and the high cost associated with shoreline hardening, it has become prudent to manage shoreline considering all options available. Retreating inland from the existing line of flood defence may be necessary or coastal protection, while monitoring and maintaining an awareness of the consequences of retreat. The concept requires an understanding of the entire processes influencing shoreline dynamics to enable appropriate intervention when necessary. It includes: Set back, which means allowing space between the shoreline and associated coastal hazard and property to act as buffer; This measure is most suited for coastal areas that are not yet developed. Knowledge of historical rates of erosion for the particular coastal segment is required. With the assumption that this rate will remain the same in the future, a line (set back) is determined where the shoreline position will not reach during the life of proposed structures within the area. The usual trend is to fix the set back using the projected shoreline position after 60 years. So that if the rate of erosion is 2 m per year, the set back will be set at 120 m from the shoreline. ____________________________________________________________________________________________________ Final Report July 2000 67 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ The advantages for such a measure is that it enables nature to take its own course and avoids the need to put up expensive protection with resources which, are often not available. Even in the event that resources are available they could be used for other developmental purposes. Controlled abandonment, which requires abandoning existing line of defence and allowing nature to redefine the shoreline position. Monitoring would be required regularly and possible intervention in the form of protection applied when necessary to achieve objectives in respect of environmental enhancement. Full protection, deliberate actions to maintain the shoreline position at a particular location often through the design and construction of artificial structures. The structures include revetments, sea walls, groynes, artificial headlands and beach nourishment. The are some suggested criteria to determine the areas for full protection. Various reports have suggested the protection of all areas with a population density of 10 persons per square kilometre. Do nothing, refers to the option that involves abandoning the existing line of defence without any future monitoring or intervention of any kind. The various options of managed retreat will be considered for each of the shoreline segments. For shores that have been undeveloped, more detailed assessment of the situation is possible to come up with a rational response. 7.2 Recommended measures City area The losses associated with do nothing or abandoning about a quarter of the city amount to some US$ 1,3 billion. It is clear that this option is not acceptable and that full protection should be provided. This protection will vary along the coast line according to local requirements, and will comprise a number of elements: southern part of the city: raising of the level of the rock revetment; fishing port: raising of area level; in the long term probably strengthening of the breakwaters; north of fishing port: raising of the level of the rock revetment; corniche area: raising of the level of the wall; check on the stability of the foundations of the sea wall since it is expected that the beach will be eroded away; ____________________________________________________________________________________________________ Final Report July 2000 68 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ construction of a sea wall at the northern part of the city area. Summing up, considerable strengthening of the existing constructions will be required over a length of approximately 10 km. Assuming an average cost of US 2 million per km the total cost will amount to US$ 20 million. Sand spit There is a risk that in the next years an increasingly longer length of road will be provided with a stone protection to prevent the road being washed away. Before this happens the relevant authorities should decide whether to indefinitely maintain this road to the naval base at large costs in the future, or to abandon the sand spit and move the naval base. As described before, abandoning will probably mean a breaching of the spit and a changed current regime in the access channel to the port, leading to increased siltation. The decision to be made must also weigh these consequences. ____________________________________________________________________________________________________ Final Report July 2000 69 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ 8. CONCLUSIONS AND RECOMMENDED ACTION PLAN 8.1 General In the coastal areas of Yemen including Hodeidah substantial economic development is foreseen for the next decades, particularly in the field of free economic zones, industrial complexes, fishing and trade. The ongoing and future accelerated sea level rise (ASLR) due to man induced climate change will pose new challenges to the management of the coastal zone. Probabilities of flood frequencies will increase, shorelines will recede, low-lying areas in the coastal zone will be inundated, rising water tables might harm the foundations of buildings, saltwater intrusion in ground waters will impact on existing water supplies in the coastal zone; and biological activity within the coastal zone will be influenced. The study of the Hodeidah pilot area, carried out under this project, has shown that already at the present time ASLR is have an effect on that part of the coast by aggravating the existing erosion problems. It is likely that similar problems occur along other parts of the Yemen shoreline. Therefore it is recommended to extend the coastal vulnerability study to other parts of the coasts of the Red Sea and Arabian Ocean in a second project phase. The problems described in this study have a very strong institutional and legal component. The responsibility of managing the coastal zone is divided among a number of governmental agencies, such as those listed in Table 5.12 Such split of responsibilities and interests is common and unavoidable. In order to provide a platform for consultation of all interested parties in the coastal zone the Government could envisage establishing a coastal zone management authority in the future. At present a move has been made to stress the importance of the coastal zone and to build of local management capacity by setting up an administrative management unit within the Governorate of Hodeidah, called Integrated Coastal Zone Management Unit. ____________________________________________________________________________________________________ Final Report July 2000 70 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ Legal actions that could be taken in the near future comprise: control of coastal development through establishing a "set-back" line at a certain distance from the high water line. Development activities should be forbidden in the zone located between the high water and the set-back lines. control land reclamation activities to assure that the construction levels take the ASLR into account; The most important issues to be addressed during a second phase of this project in the management of the coastal zone in Yemen are contained in the Action Plan presented below. 8.2 Action Plan The plan comprises the following tasks: Task 1 Organisation of CZM and ASLR workshop It is recommended to organise a workshop on coastal zone management and sea level rise issues at the end of this year. All relevant governmental agencies, universities and scientific institutes should participate. This workshop will serve the following purposes: consolidation of knowledge and capabilities gathered during the first phase; dissemination of information concerning the subjects mentioned; preparation of second phase activities; increasing awareness of ASLR and CZM issues. Task 2 Delineation of other flood and erosion hazard areas Efficient management of coastal erosion and flooding can be achieved only through the gathering of data to enable the delineation of potential areas that are prone to erosion. Under the current study, it was not possible to assess accurately the areas that could be affected by any of these hazards along the Red Sea and Arabian Ocean coasts. ____________________________________________________________________________________________________ Final Report July 2000 71 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ The study should be based on the Seven Steps approach for vulnerability studies and will comprise the following activities: definition of the locations and the extent of land area affected by the hazards and probabilities of the hazards occurring; identification of vulnerable shorelines could be carried out by using the available topographic maps, scale 1:50,000 or 1:100,000, or RS images, some of which are reported to be available in the country; description of the natural environment of these locations; description of the socio-economic characteristics of the locations; impact of ASLR on natural and socio-economic conditions; definition of the vulnerability profile; Processed data can be stored in the COZMIS (Coastal Information System), developed by Delft Hydraulics and made available to the EPA in November 1999. Task 3 Monitoring of the Hodeidah coast Sub-task 3.1 Beach monitoring It will be prudent to gather more data to monitor the development of the coast in the pilot area. In this manner accurate rates of erosion will be defined enabling proper management to be carried out. The monitoring of beach profiles should be carried out monthly for the first year to establish trends of erosion within all sandy shores and thence monitoring should be carried out at intervals of three months. It will be necessary to link the monitoring of offshore profiles with those of the beaches. On account of the expensive nature of determining offshore topography, it is proposed that the offshore profiles be determined at intervals of 6 months. Sub-task 3.2 Increase of understanding of coastal processes Current understanding on coastal processes is practically non-existent. In particular, the causes of erosion, the ability to predict erosion both in the short and long term, ____________________________________________________________________________________________________ Final Report July 2000 72 Climate Change Impact on the Yemen Coastal Zone Environmental Protection Council ____________________________________________________________________________________________________ and the prediction of shoreline dynamics or morphology with time have a profound influence on shoreline management. The tidal gauge which has just been established in the Port of Hodeidah will provide the necessary information on sea level changes. The most practical approach seems to strengthen the new unit to be set up in the Governorate of Hodeidah through assistance and training. ____________________________________________________________________________________________________ Final Report July 2000 73
