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Climate Change and Its Impacts on Water Resource Management in the Southern Highlands of
Tanzania
R.Y.M. Kangalawe* and E.T. Liwenga
Institute of Resource Assessment, University of Dar es Salaam,P.O. Box 35097, Dar es Salaam,
Tanzania.
Corresponding author email: [email protected]
ABSTRACT
This paper presents findings from studies conducted in the southern highlands of Tanzania to assess
the impacts of climate change/variability on natural and socio-economic environments. Climate
change and variability seem to have considerable impacts on water management issues and
community livelihoods in the study areas and other parts of the world, particularly Africa. Data
collection included household interviews, focus group discussions, historical timelines, resource
mapping, and transect walks. Quantitative data was analyzed using the statistical package for social
science. Qualitative data were triangulated with community members during participatory
discussions. Results from these studies indicate a progressive decrease of water flows in rivers and
streams, and drying-up of some wetlands. Several rivers and streams have increasingly become more
seasonal as compared to the past. Natural springs have also decreased in water discharge or dried up
completely. Consequently, these water sources have decreased in their reliability. Climate change,
featured as the main driver of such changes particularly associated with declining amounts of rainfall,
shortened rainy seasons, delayed onset of rains, increased incidences of drought and increasing
temperatures. Unreliable rainfall in upland areas due to changing climate has resulted in increased
dependence and expansion of agriculture into wetlands during the last few decades. Among the
consequences of increased wetland use have been deforestation, loss of biodiversity, and drying
and/or shrinking of affected wetland ecosystems. Climate change is also locally perceived to have
reduced the overall amounts of water coming into the wetlands, causing them to dry much earlier in
the dry season than it used to be in the past. This means that crop cultivation in such wetlands cannot
be extended much into the dry season as was in the past. This has limited the agricultural productivity
in these areas thereby affecting the community livelihoods, which are largely dependent on
agriculture. However, in seasons with above normal rains some of these wetlands are flooded. These
findings point to the need for having appropriate water resource management strategies to ensure
environmental sustainability and community livelihoods especially within the context of changing
climate.
Keywords: Climate change, community livelihoods, environmental sustainability, water resource
management, southern Tanzania.
1. Introduction
Climate is highly variable in Sub-Saharan Africa, with the variability being also spatially diverse due
to factors such as topography, closeness to water bodies, land use, among others. Water resources are
inextricably linked with climate, so the prospect of global climate change has serious implications for
water resources and regional development (Riebsame et al., 1995). East Africa is not shielded from
global environmental change. The El-Nino Southern Oscillation (ENSO) episodes, for instance, have
become irregular and of shorter durations. Both climatic and global environmental changes have
resulted in deterioration of water quality, declining agricultural productivity and loss of biodiversity.
These have serious implications on the livelihoods of the people and the environment (Hulme, 1996).
While climate change is a global phenomenon, its negative impacts are more severely felt by poor
people because of their high dependence on natural resources, and limited capacity to cope with
climate variability and extremes (IPCC, 2001; Sperling, 2003). In Tanzania, extreme climatic events
such as droughts and floods have often resulted in crop damages and failure (Liwenga, 2003;
Kangalawe and Liwenga, 2005); and in combination with other factors, may lead to chronic food
shortages in areas affected.
Historical record show a warming up of approximately 0.7oC over most of Africa during the 20th
century, an increase of rainfall in east central Africa and a decrease over large portion of the Sahel
region. The mean rainfall is reported to have decreased by 20 to 49 percent in the Sahel region
between the period 1931-1960 and 1968-1997 and generally 5-10% across the rest of the continent
(Matondo, 2008). The continent has also experienced severe droughts and flood during the 20th
century. A decrease in the average discharge in most rivers in Africa has also been observed. The
surface area of Lake Chad decreased from 50,000 km2 in 1963 to 5000 km2 to date and has affected
millions of people whose livelihoods depended on it (Matondo, 2008).
Climate change and variability have impacts on the people’s livelihoods and natural ecosystems.
Different communities adapt differently to global changes issues such as climate change. This paper is
based on studies undertaken in Mbozi and Mbinga districts in the southern highlands of Tanzania.
Among the objectives of these studies were to assess the impacts of climate change/variability on both
natural and socio-economic environments, particularly their impacts on natural systems such as water
resources, rural development and people’s livelihoods. It also addresses issues of vulnerability and
adaptation strategies among communities, and how resource management strategies ensure
environmental sustainability and community livelihoods within the context of changing climate.
2. Methodology
Four villages were involved in the studies reported here, namely Nyimbili and Ntungwa in Mbozi
district and Buruma and Lundo in Mbinga district. Nyimbili and Buruma represent the highland agroecological settings while Ntungwa and Lundo represent the lowland villages (Kangalawe and Lyimo,
2006; Liwenga et al., 2007; Lyimo and Kangalawe, 1997; Maro et al., 2008). The data were collected
using participatory rural appraisal (PRA) techniques, which included focus group discussions,
resource ranking and transect walks. Details of these methods are described in Chambers (1992) and
Mikkelsen (1995). The aim of the PRAs was to capture aspects such as water resource management,
history of climate related events, communities’ perceptions of climate change and variability, and
identification of mechanisms for coping with climate change/variability. Discussions concerning
background information were undertaken with agricultural and natural resource management experts
in respective districts. These were followed by discussions with key informants in each of the study
villages, including village leaders and elders. Household interviews were also undertaken using
structured questionnaires, and involving a sample of 10% of the village households.
The data was analyzed using the Statistical Package for Social Science, and the sustainable livelihood
framework was used as an analytical tool to understand the adaptive capacities. The sustainable
livelihood framework takes the recognition of different assets and entitlements from which people
draw their livelihoods. The primary data was complemented by secondary data sources from literature
and relevant authorities in the study areas.
3. Results and Discussion
3.1 Climate change and the state of the water resources in the southern highlands of Tanzania
There is considerable evidence showing that climate change is taking place in the southern highlands
and other regions of Tanzania. While climate change is scientifically defined as serious disruption of
the entire world’s weather and climate patterns, local people’s perceptions on climate change is based
on certain elements of climate. Locally climate change was linked to the following elements: (i)
Changes in rainfall patterns and amount over years or months – which affect agricultural production;
(ii) Reduction of river flows and water level in most rivers as experienced in present days; (iii)
Decreasing water availability for domestic and agricultural uses - reduced water availability also make
people to walk long distances to fetch water; (iv) Increased incidences of drought, causing drying of
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some vegetation particularly trees - availability of wild fruits also becomes difficult; (v) Changes and
variations in temperature such as cooling and warming over years; (vi) Increased wind speeds above
normal - which destroys property including houses and crops; (vii) Increased sunshine experience in
recent days compared to previous; and (viii) Outbreak of some specific diseases (for instance, the
once malaria-free highland regions are no longer so. These local indicators of climate change are
similar to those reported by many scholars as impacts of climate change and variability on natural
resources and rural livelihoods. The local perception of climate change depends very much on the
social characteristics of the society and biophysical environment.
Locally, the link between climate change and water resources is anchored on the notable reduction of
river flows and water levels in most rivers as experienced today, and the perceived decrease in water
availability for domestic and agricultural uses. The other concern is the reported increase of droughts
that also negatively affect the water availability.
Among the important goods provided by the environment is water resource. During interviews water
was mentioned to be for domestic use, irrigation, construction and fish farming/aquaculture. In most
of the villages studied water for domestic use was reported to come from naturally flowing streams
and traditional wells. In some instances water is directed to the homesteads and crop fields using
traditional canals, particularly in Mbinga District. However, the water quality in rivers and streams
was considered by the local communities to be not so good, mainly attributed to, among other things,
siltation and pollution from agrochemicals applied in farms surrounding the water bodies.
Generally the aquatic ecosystems and associated water resources are very important to the livelihoods
of the local communities, especially from the ecological goods and services that they provide (e.g.
water, food, pasture, medicinal services, cultural services, and micro climate moderation). For
instance, in the vicinities of Lake Nyasa and Lake Rukwa, fishing is the major income earning activity
to the communities around. Wetlands are also important for agriculture especially for paddy and
horticultural crops.
Increasing demand for agricultural land resulting from population increases has changed the status of
the ecosystems of both Mbozi and Mbinga districts. Between 1967 and 2002 the population of Mbozi
district almost quadruped while that of Mbinga districts almost tripled during the same period (Figure
1). The population density in these districts is also very high, in some places reaching 120 persons per
square kilometre, particularly in highlands. Expansion of farmland and tree cutting for fuelwood and
other uses have negatively affected the environment, and have increased deforestation of the already
scarce forests (Knight, 1974; Maro et al., 2008). In some places, this has consequently led to soil
erosion. Further environmental degradation has resulted in frequent floods in the lowland areas,
associated with increased runoff in highlands, while at the same time some water sources are drying
up as a result of insufficient groundwater recharge.
3.2 Trends in water resources
The impacts of climate change/variability have been reported for both the natural and the socioeconomic environments. Regarding the impacts of climate change/variability on the natural
environment, villagers in Mbozi District associated them with changes of dry and rainy seasons.
Communities in the study areas are also concerned with the variations in amounts, onset and ending of
rainfall especially during the last forty-five years (Table 1). Such changes were reported to have both
negative and positive influence on water availability for different purpose. For instance, in situations
of good rains water becomes more available for various uses while in times of drought it becomes
scarcer, making the undertaking of water-dependent livelihood activities very difficult.
Interviews during focus group discussions and household surveys revealed that many of the key
aspects of ecosystem services, such as biodiversity and forest covers, wildlife and water resources
were rapidly declining. These trends reflect potential threats associated with environmental
degradation. Declining water resources was reported to be largely characterised by decreasing water
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flows in rivers and streams, decline of fish catch in the lake and rivers as well as drying up of some
wetlands. Furthermore declining water resources was also reflected by the reported decrease in the
incidences of floods. The local concern about diminishing water resources is also supported by global
experiences. For instance, IPCC (2001) reported that trends in regional per capita water availability in
Africa over the past half century show that water availability has diminished by about 75%.
Population growth and degradation of water quality are considered as significant threats to water
security in many parts of Africa, and the combination of continued population increases and global
warming impacts is likely to accentuate water scarcity in sub-humid regions of Africa (IPCC, 2001).
As a step towards sustainable land and water management in the study areas there are trees planting
campaigns through afforestation programme, and the people seemed to be sensitized and well
motivated. However, only few villagers had actually planted the trees, as reported by respondents in
Buruma (53%) and Lundo (62%) villages. One of the long-term consequences of the tree planting
activities would be the contribution towards conservation of water resources, which is expected to
improve water flows in streams and rivers, and improving its quality.
3.2.1 Changes in wetlands resources
Wetlands, like other ecosystems with water resources have undergone considerable changes over the
last few decades, mainly associated with increased use of such areas for agricultural purposes.
Interviews conducted in the study areas revealed that wetlands have either shrunk in size or dried up
completely as reported by about 38.2% of respondents. However, in seasons with above normal rains
these wetlands are subject to flooding, as expressed by about 18% of the respondents (Figure 2). This
was particularly a concern among villagers in Buruma where rivers such as Ruhekei pass. The other
reported change in the wetlands was that as a result of increased cultivation the natural biodiversity
has progressively declined, and is being replaced by the less diverse agro-ecosystem, as expressed by
21.2% of respondents. Nineteen percent of respondents claimed that there has been no change in the
conditions of wetlands of the study areas. While this may be true in some parts it may be a reflection
of the shorter time duration that such respondents have lived in the respective areas, or an indication
of low environmental awareness among such respondents.
The major drivers of change in the wetlands of the study areas are presented in (Table 2). The most
critical ones included population pressure (46.1%) and the expansion of cultivation as expressed by
26.1% of the respondents. It was reported that recurrent drought, attributed to climate change, has
forced farmers to cultivate in valleys bottoms and wetlands where soil moisture and water is readily
available during most parts of the year. However, climate change was reported to have reduced the
overall amounts of water coming into these wetlands, causing them to dry up much earlier in the dry
season than it used to be in the past. This means that crop cultivation in such wetlands cannot be
extended much into the dry season. The latter may have negative impacts on the livelihoods of
communities that depend on such wetlands for crop production.
The fact that only few respondents associated the declining water resources to climate change
indicates a low level of awareness of environmental concerns among the community members. If this
is the case then it reflects to the need for more awareness raising on environmental issues in the future
so as to increase their capacity to detect and explain the changing conditions. Increased awareness
may also improve the local adaptive strategies.
The impact of climate change on wetland utilisation seems to be a genuine concern, and has also been
reported in other parts of Tanzania. For example, in the Kilombero Valley and Usangu Plains the
changing climate has limited wetland cultivation to the early parts of the dry season (Kangalawe and
Liwenga, 2005; Lyimo, 2005). The wetlands areas, locally known as vinyungu in the southern
highlands, are regarded to have high potential for dry season crop production (Majule and Mwalyosi,
2005).
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Land scarcity in other parts of the landscape and the desire to grow off-season crops such as
vegetables to feed the ever increasing population were reported to be other drivers for the increased
need to cultivate these wetlands. The other factors of change included poverty and government
policies and deforestation. Government policies and directives have indirectly impacted on the
wetland utilisation. Programmes such as the Urgent Strategy on Land Conservation and Water
Catchments Programme implemented in various parts of the country, including the southern
highlands, has restricted cultivation in the hilltops and water catchments, compelling those who
obtained a living from such parts to move to lowlands, including the wetlands.
3.2.2 Changes in conditions of river systems
Also reported were notable changes in the river system in both study areas. However, the changes
were not uniformly distributed, with some villages reporting to be more severely affected than others.
Ntungwa and Lundo villages, for instance, were found to have a serious problem of decreasing water
flow, as expressed by 34.5% of respondents. This was locally associated with climate change and
catchments degradation in the upland areas. Similarly, there were notable increases in the seasonality
of rains in all villages concerned (Table 3). The changes in the river system also included loss of
riverine vegetation that was attributed to the increased cultivation in the valley bottoms.
Discussions with stakeholders at regional and district levels in Mbeya region, where Mbozi district is
located, revealed that generally many water courses in region have dried-up, while few were reported
to remain with very little water flowing especially during the dry season. Natural Resources Officials
interviewed in Mbeya reported that in some districts in the region, e.g. Mbarali and Chunya, the
rainfall seasons have been shortened to only about three months per year, with seasonal fluctuations,
including late start of rains, all attributed to climate change. The amounts of rainfall have also
exhibited considerable annual and monthly fluctuation over the years (Figure 3 & 4). Figure 4 depicts
that the long-term annual average rainfall has not changed much. However, there have been
considerable variations throughout the seventy-year period of the presented data. Such variations
could be representing what the studied communities referred to as climate change. This has been one
of the locally perceived causes for reduced water flows in river systems. Falkenmark et al. (1990)
argue, however, that although the climate change often referred to when explaining water shortages
globally may be a myth. Indeed, a scrutiny of the rainfall data of the past 60 years in Mbeya indicates
that while there have been erratic variations in the quantity of rainfall, there is no evidence to suggest
that precipitation rates have changed.
Other changes reported in the study areas include riverbank erosion resulting from cultivation
undertaken close to the riverbanks, thereby causing siltation of water courses.
Other reported causes of changes in river flows were deforestation and population pressures.
Deforestation was locally seen as a major concern as reported by about 43% of respondents. The tree
planting being undertaken in some villages, such as Lundo (32.8%) and Buruma (27.3%) was found
to have a positive impact by improving the vegetation cover in the landscape, with consequent
increase in water flow in the rivers making it more perennial mainly by protecting the water
catchments.
Local perceptions of changing conditions are also reported in other parts of the world. For instance,
Mehta (2001) reported that communities in Gujarat, India identified several symptoms and empirical
evidence of environmental change. The symptoms included increasing salinity of the soils and sea
water ingression in coastal areas; dwindling water aquifers; and species loss due to the planting of the
exotic salt-resistant species such as Prosopis spp. Under such conditions of dwindling water
resources, cultivators experience difficulties in getting reasonable crop yields while pastoralists face a
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growing paucity of fodder and forage (Mehta, 2001). As highlighted earlier, some of these symptoms
were also identified by communities in the areas for the current study.
3.2.3 Trends in natural springs
Many natural springs in the study areas have decreased in water discharge. Some of the natural
springs were reported to have dried up while others are still drying. At the same times some of the
natural streams associated with these springs have become more seasonal (15.7%), discharging water
largely during the rainy season and becoming dry for a larger part of the dry season. Buruma
respondents (32.6%) were more concerned with this problem. Overall these responses indicate that
natural springs and associated streams are progressively decreasing in their reliability, mainly
attributed to climate change and increased destruction of water catchments. Climate change featured
as the main cause for changes in natural springs, being associated with declining amount of rainfall
and the rather unpredictable patterns. Insufficient rainfall during the rainy season reduces groundwater
recharge, which may subsequently lead to reduced discharge from the springs. Similar effects may
result from deforestation that often leads to surface runoff and limited water infiltration into the soil,
thus limited groundwater recharge.
The impacts of climate change on natural springs, agriculture and on livelihoods have also been
reported in Kilombero valley (Kangalawe and Liwenga, 2005) and in Mbozi district (Liwenga et al.,
2007). These works reported local concerns on declining water resources associated with climate
change. The findings from the studies currently being reported are quite similar, indicating that the
changing climate has broadly altered the discharge in natural springs as well as streams and rivers.
Agricultural expansion which leads to deforestation and in some cases surface runoff and soil erosion
were reported to cause siltation and drying up of some springs. In addition, inappropriate methods of
water abstraction from the springs were also reported to cause destruction of springs. It was pointed
however that protection of some water catchments has been instrumental in ensuring that the natural
springs continue providing water, as expressed by 8.6% of respondents. Such positive attributes to
conservation are fundamental to achieving environmental sustainability especially within the context
of climate change. Thus climate change issues need to be mainstreamed in all water resources
management plans.
3.2.4 Changes in conditions of lakes and fish ponds
Some respondents (13%) in Mbinga district perceived that there has been a decrease in the water level
in the lakes, associated with declining fish catch. A similar concern was raised during discussions
with Natural Resources Office in Mbozi district and subsequent responses from Ntungwa respondents.
In Mbozi it was indicated that siltation of parts of Lake Rukwa (a short distance from Ntungwa
village) and subsequent spreading of lake water were among the factors for reduced wildlife
populations in the area, as some migrated outside those areas, except the water loving animals. In
Mbinga district, a considerable proportion of respondents in Lundo (50%) and Buruma (20.2%)
perceived that there was a decrease in fish catch. The major causes of change in the lake conditions
were reported to be low rainfall associated with climate change (12.8%), population pressure (27%)
and over fishing and use of illegal fishing gears (54.2%). The decrease in fish catch was reported by
respondents to be largely due to the use of illegal gears and increasing fishing pressures associated
with increasing number of fishermen. Villagers in Ntungwa and Nyimbili also reported an expected
increase in fish production in ponds in case water is adequately available. This was the case especially
in the highland villages where fish ponding has increased in the recent years.
3.3 Enhancing Local adaptations
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Findings from this study point to the need for having integrated management strategies for land and
water resources within the context of changing climate. Experience suggests that the best way to
address climate change impacts, particularly on the poor, is by integrating adaptation responses into
development planning. For that to be successful adaptation strategies should build upon, and sustain,
existing livelihoods and thus take into account existing knowledge and coping strategies. It is in this
context that indigenous knowledge systems used in agricultural soil and water management, for
example the Matengo pits system in Mbinga District need to be promoted. Proactive land and water
management policies can further help in reducing deforestation and other natural resources
degradation thereby avoiding the risks associated with further climate change. There is also need to
enhance environmental awareness especially on the importance of environmental conservation and
benefits that are derived from the ecosystems.
4. Conclusions
Climate change and variability have considerable impacts on water resource management issues and
on the socio-economic environment. The paper has demonstrated that water resources are
deteriorating in terms of decreasing water flows in rivers and streams. Several rivers and streams have
increasingly become seasonal, while others are drying up much earlier in the dry season as compared
to the past. Similar experiences are evident with natural springs which have significantly decreased in
water discharge or dried up completely. Consequently, the reliability of these water sources has
progressively decreased.
Climate change, featured as the main cause of such changes mainly associated with declining amount
of rainfall and the rather unpredictable patterns. Wetlands have equally been affected by impacts of
climate change, exposing them to increased cultivation. Among the consequences of increased
wetland use have been deforestation, loss of biodiversity and drying up and/or shrinking of the sizes
of affected wetlands. Furthermore, climate change was reported to have reduce the overall amounts of
water coming into the wetlands, causing them to dry up much earlier in the dry season than it used to
be in the past. This means that crop cultivation in such wetlands cannot be extended much into the dry
seasons.
Proactive land and water management policies can further help in reducing deforestation and natural
resources degradation thereby avoiding the risks associated with further climate change. There is also
need to enhance environmental awareness campaigns especially on the importance of environmental
conservation and benefits that are derived from the ecosystems.
Acknowledgement
The authors would like to thank all members of the communities for their enthusiasm and sharing
knowledge on environmental change and climate change issues based on their local experiences.
Special thanks are due to villagers in Ntungwa, Nyimbili, Buruma and Lundo villages. Further
knowledge on environmental change issues was obtained through discussions with various
stakeholders at both regional and district levels.
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Table 1. Locally observed changes of climatic conditions in Nyimbili and Ntungwa villages
Weather
Before independence
IndependenceAfter Villagisation to date
conditions
(<1961)
Villagisation (1961-1974)
(after 1974)
Nyimbili
Ntungwa
Nyimbili
Ntungwa
Nyimbili
Ntungwa
Rainfall
Enough,
Very high, Enough, well
Average
Less,
Inadequate
amount (and well
evenly
distributed
poorly
(after 1980s)
distribution) distributed distributed.
distributed
Onset of
September November
November
Decembe December
December
rains
r
End of rains June
May
March-April
May
March
April
Warm
Normal
Average
Normal (warm Average
Higher
Temperature
weather
(warm or
or cold
temperature has
(Temperatur cold
according to
since 1980s increased
e)
according
season)
(August to season)
October)
Wind
Normal
Average
Normal
Average
Strong
Strong wind
winds (JanFeb, July August)
Droughts
Few
Not often,
Few
Not often Frequent,
Occurs very
(occurrence)
occurs after
especially
often (after
6-7 years
since
2-3 years)
1990’s
Floods
No
Very often
No
Average
No
Very few
incidences.
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Table 2. Locally perceived causes of changes in wetlands
Driver of Change
Percentage
Population pressure
46.1
Expansion of cultivation
26.1
Climate change
15.0
Poverty
5.7
Government policies
3.7
Deforestation
3.3
Total
100
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Table 3. Locally perceived changes in river systems
Type of Change
Percentage
Decreasing water flow
34.5
Increasing seasonality
28.7
Increasing river bank erosion
14.8
Loss of riverine vegetation
7.9
Floods
6.2
No changes
7.9
Total
100
12
Figure Captions
Figure 1. Population of Mbozi and Mbinga districts (1967 - 2002). Source: Compiled from
Census Reports 1967-2002
Figure 2. Locally perceived changes in wetlands.
Figure 3. Mean monthly rainfall (mm) for two agro-ecological zones in Mbozi district. The
data for Mbimba Experimental Station cover the period from 1956-1967, while
that of Mkulwe Mission covers the period from 1945-1964.Source: Computed
from Knight (1974)
Figure 4. October-May rainfall in Mbeya from 1940-2008. Source: Mpeta (2009)
13
Figure 1.
600.0
Number of People (000)
515.3
500.0
Mbozi
Mbinga
404.8
400.0
331.7
271.8
300.0
235.4
196.2
200.0
147.5 144.1
100.0
0.0
1967
1978
1988
Year
14
2002
Figure 2
Percentage of Respondents
45
40
35
30
25
20
15
10
5
0
Shrinkage or
drying up
Increased
Cultivation
Floods during
rainy seasons
Loss of
biodiversity
Locally perceived changes in wetlands
15
No changes
Figure 3
Amount of rainfall (mm)
300
250
Mbimba Experimental
Station (Highland)
200
Mkulwe Mission
(Lowland)
150
100
50
0
Jan
Feb Mar
Apr May Jun
Jul
Month
16
Aug Sep Oct
Nov Dec
Figure 4.
Mbeya Oct-May Rainfall Totals (1937-2006) R2 = 0.03
1500
Oct-May
TrendLine
Mean
1400
1300
Rainfall (mm)
1200
1100
1000
900
800
700
600
500
1940
1950
1960
1970
1980
Period in Years
17
1990
2000