Download 10b: langstone and chichester harbours

10B: LANGSTONE AND CHICHESTER HARBOURS
The Kench saltmarsh - HCC Countryside Service Site near entrance to Langstone
harbour -with house boats backdrop of Portsmouth and Portsdown Hill.
Entrance to Langstone harbour – Mill Rythe – North creek tidal inlets Racing in Langstone – backdrop of
Eastney pumping station background which almost completely dry out at Fort Widley
low water.
Hayling Bridge
- Wadeway in Fowley Island – remnant Oyster bed Mulberry harbour Hayling ferry, relic
foreground. Algal summer bloom – Chichester harbour
WW2 Mulberry mid distance and
over mud flats.
Portsdown Hill backdrop
Hampshire County
Integrated Character Assessment
1
Status: Draft March 2010
Langstone and Chichester Harbours
Hampshire County
Integrated Character Assessment
2
Status: Draft March 2010
Langstone and Chichester Harbours
1.0
1.1
Location and Boundaries
This character area is
located in the far
southeast of the County
adjoining West Sussex. It
is defined by the mean
high water mark of the
harbours and includes the
harbour mouths.
1.2
Component County
Landscape Types
Intertidal Harbour
1.3
Composition of
Borough/District LCAs:
Havant Borough
Langstone Harbour
Chichester Harbour
This LCA includes the harbour mouths and is different to the Borough character
area boundaries in this regard. The harbour mouths are seen as part of the
harbour seascape rather than the coastal sea particularly in terms of recognised
‘management areas ’ i.e. the Chichester Harbour AONB boundary and Langstone
Harbour Board boundary. The AONB character areas are also closely aligned with
the Borough ones.
1.4
Associations with NCAs, Natural Areas and England’s Historic Seascapes
NCA: None
Marine NA 109: Solent and Poole Bay, Solent and Waters off the Isle of Wight:
Langstone Harbour and Chichester Harbour.
2.0
Key Characteristics
•
A shallow marine basin enclosed by a low lying natural and man made sea
defence shoreline of low walls and embankments.
•
A varied underlying geology of clays and sands and chalk overlaid with beach,
tidal flat deposits with some raised marine deposits predominantly of thick
gloopy, anaerobic mud.
•
A hugely fluctuation seascape from almost completely covered at high water
to about 90% exposed muds, shingle and sand at low water.
•
Small islands and areas of saltmarsh in upper reaches of the harbours which
dissipate wave action on the shore.
•
A nationally renowned recreational sailing area, with a much reduced
commercial shipping use, although fishing and in particular oyster and clam
fishing is important to the local economy.
•
Within the harbours there is strong sense of remoteness and separation from
the surrounding highly populated areas.
•
A skyline of contrasts from the city skyline of Portsmouth to the hills of
Portsdown, South Downs chalk ridge and profile of the Isle of Wight.
Hampshire County
Integrated Character Assessment
3
Status: Draft March 2010
Langstone and Chichester Harbours
•
•
•
Rare and internationally important coastal habitats with many layers of
designation.
Remains of well preserved archaeological sites in intertidal areas including
prehistoric forest, peat deposits, stone tools, Bronze Age settlement and
burial remains, Roman pottery and salt workings, Saxon watercraft and fishing
related structures and a few modern ship wrecks.
A coastline which been subject to much change and realignment due to
reclamation, natural processes and hardening.
3.0
3.1
Physical Characteristics and Uses
The underlying geology comprises sedimentary rocks, with older White chalk in
the northern part of the character area and Tertiary deposits of London clay and
Reading beds in the south. The different geological members have been flexed into
a series of eastwest folds which have been eroded to produce a narrow sequence
of geological bands.
3.2
Langstone and Chichester harbours are shallow marine basins characterised
predominantly by mud flats but also sand banks particularly in the southern reaches
and raised marine beach deposits of shingle particularly on lee shores. There are
two small sand shingle spits which project into the harbours on either end of
Hayling. The Langstone harbour shoreline is less indented by small creeks and
rithes than the east side of Hayling. Much of the coastline has sea defences in
varying degrees of condition which have gradually restricted the area of the upper
parts of the littoral zone, squeezing this habitat. The main channels include
Emsworth, Sweare Deep in Chichester and, Broad Lake, North and South Lake and
Broom channel in Langstone. The channels are not particularly deep but at the
harbour mouths are up to 13m at Mean Low Water Springs (MLWS). Mineral
dredging has taken place in the harbour mouths and elsewhere to maintain
navigation such as New Cut at Northney which was on the Portsmouth to Arundel
canal. An area at Sinah sands is licensed for gravel extraction but not currently
worked due to the environmental sensitivity of the area.
3.3
The wide tidal range, coupled with the shallow gradient of the mud flats, produces
contrasting environments at high and low water. At MLWS, between 15% and 20%
of the character area is covered by water compared with close to 95% at MLWS.
The short fetch and shallow waters leads to a short ‘chop’ small high frequency
waves in the stronger winds of a predominant south westerly especially against the
tide. The Chichester harbour side is noticeably flatter in these conditions. Tidal
flows at the harbour entrances are particularly fast and can be distinctly choppy and
even dangerous with wind over tide. The mean spring tide maximum tide streams
at a very fast 6.4 knots. The shallow water over mud and tidal regime leads to
significantly warmer waters in the harbour (1or 2 degrees higher than the coastal
waters of the eastern Solent).
3.4
There is a mix of uses and slightly different intensity of uses between the harbours.
The management of both harbours is particularly geared towards recreational and
conservation uses. There are eight sailing clubs adjoining the character area and
more on surrounding shores in Chichester. There are several marinas especially on
the Chichester side where there is a greater intensity of recreational sailing.
Hampshire County
Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
Moorings tend to be adjacent to main channels and around sailing clubs and
marinas, with many drying out at low water. The harbours are an important
nursery for many species of fish71 including flat fish (Dover Sole), bream, sprat,
herring, pilchard and mullets and in particular bass. There is a closed fishing season
in the summer. The harbours have been historically important for oyster growing
which has a substantial continental market and also clams. The water quality of
Langstone was improved dramatically in 2004 with the construction of a waste
transfer tunnel connecting Eastney and Budds Farm sewage works at Havant. The
old outfall no longer discharges sewage continuously into the harbour.
4.0
4.1
Experiential/Perceptual Characteristics
Views from within the harbours are varied depending on the state of the tide, but
generally expansive. The eye is draw to the landward horizons which are extremely
varied from the city skyline of Portsmouth, to the Portsdown Hill and the forts to
the wooded shore of Hayling and land between Langstone and Emsworth, with the
South Downs in the distance. Views out to the Solent are restricted by the narrow
harbour mouths, but the sweeping high landform of the Isle of Wight is an enduring
backdrop in views to the southwest.
4.2.
Buoyage (channel buoys and marks for navigation) is fairly complex because of the
number of branching channels, broad and minor inlets. Larger vessels such as those
that ply Bedhampton Wharf can only gain access a few hours either side of high
tide. The channels at the heads of the harbours at Emsworth, Langstone,
Bedhampton, Farlington and north east Portsea are unnavigable or very limited at
low water with many dry moorings. The wadeway connecting Northney to the
mainland at Langstone is a historical crossing point severed by New Cut.
4.3
The harbour seascape is a contrast of expansive and more enclosed creeks and
narrow upper reaches. The character area has a tangible sense of remoteness
despite neighbouring large areas of population, especially in Langstone harbour. The
backdrop of woods and farmland on the Hayling shore and the mainland of
Chichester harbour shores including the hill backdrops of the Isle of Wight and
South Downs give the sense of a rural setting. The predominance of natural
habitats (mudflats/saltmarsh) and presence of wildfowl species, especially in winter,
heighten the sense of naturalness and closeness to wildness. Tranquillity varies with
the seasons, time of the week and state of the tide and is particularly influenced by
recreational sailing.
5.0
5.1
Biodiversity Character
Langstone Harbour is an internationally important habitat for a range of water fowl
and waders, designated as a RAMSAR site, an SPA, SAC and SSSI. It is a tidal basin
which at high water resembles an almost landlocked lake. At low water extensive
mud flats are exposed, drained by main channels which unite to make a common
and narrow exit to the sea from each harbour. The harbour includes one of the
largest areas of mixed saltmarsh on the south coast, and extensive cord-grass
marsh in an advanced state of degeneration. This is of international importance as a
rich intertidal system supporting high densities of intertidal invertebrates and large
populations of migrant and overwintering waders and wildfowl. The harbours are
amongst the twenty most important intertidal areas in Britain as a summer and
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Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
autumn assembly ground for waders. Langstone Harbour and the adjoining and
connected harbours of Portsmouth and Chichester form a single, coherent
ecosystem which is among the ten most important intertidal areas for waders in
Britain.
5.2
The area comprises extensive mud and sand flats, with algal beds. There are
patches of both scattered and continuous saltmarsh which tend to be larger and
more extensive in the east than in the west. In the northeast of the area some
saltmarsh has stabilised and supports very small patches of scattered scrub and
coastal grazing marsh. Harbour channels represent constantly inundated sea
channels, supporting marine species.
5.3
The Chichester/Langstone Harbours and Hayling Island BOA cover much of this
landscape character area. The BOA covers a range of habitats and important plant
communities, whilst tongues of land extending into the harbour give a long and
varied coastline and produce a large volume of sheltered saline water. This is an
internationally designated landscape with few SINCs. Existing SINCs are designated
for the unimproved grassland, coastal habitats and notable species they support.
5.4
The most significant areas of reclamation to coastal grazing marsh, by the
embankment of mudflats, was at Farlington (reclaimed late 18th C), Southmoor and
the east side of Hayling. They were often areas of common grazing marsh. These
are outside the character area but would naturally have fallen within the boundary
before reclamation. Upper saltmarsh by its geographic inference has been very
susceptible to reclamation and coastal squeeze from landward development
particularly along the Portsmouth and north shores of Langstone. This has
historically been an extremely dynamic landscape and species composition subject
to varying forces. In the case of the harbours the threats have included
eutrophication (sewage was up until very recently released into the north of
Langstone harbour), local sediment starvation from natural processes and historic
channel dredging. Zostera sp. and Enteromorpha form extensive mats and create the
appearance of green carpet over exposed mudflats in late Spring and Summer.
However the degenerative disease which decimated the Solent’s Zostera
population from the 1930s almost completely wiped out the population apart from
two small strongholds in north Langstone harbour at Long and North Binness
Island. Since then the population has generally increased, declining slightly in the
late 80s and 90s. It occurs in the more sheltered northern and eastern parts of
Langstone and upper parts of Chichester.
5.5
The hummocky cord grass (Spartina sp) with associated creeks and pans are a
particularly distinctive feature of the harbour seascape. The hybridised version,
Spartina anglica formed from a cross of the native and North American varieties
was particularly invasive and by the end of the 19th century had spread into this
character area – comparatively late in the Solent area. The subsequent spread of
cord grass was very rapid and a dramatic visual change to the harbours by the early
20th century. The picture is very different today – as the population has declined
due to creek enlargement and wave scouring and decline in pan areas due to
anaerobic conditions and ferrous sulphide from underlying organic soils in
saltmarsh pans. From 1946 to 1980 the area of cordgrass was reduced by over 80%
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Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
in Langstone Harbour. The rate of decline has slackened in recent years and the
area may even be increasing78.To date, there have been no saltmarsh creation
schemes in the character area.71&76
6.0
6.1
6.1.1
Historic Character
Archaeology
In the late Mesolithic the harbours were two rias which provided a route from the
coast to the chalk downs. Temporary hunting camps existed in this basin, where
there was grassland and fen. In the late Neolithic and early Bronze age the fen
became alder carr fen and woodland, with evidence of tidal and saline effects over
time. With open grassland in the lower area and woodland on the higher ground
cattle grazing is likely, but with any associated settlement being beyond the valley
which is now the harbour. By the late Bronze Age there is evidence of salt marsh
and the more marine environment associated with tidal rivers. The evidence does
not suggest settlement in this lower lying area although it was probably utilised for
grazing and salt production. By the Iron Age the maritime environment had evolved
and salt working took place on the margins of the harbour. Within the harbour,
there is evidence for maritime exploitation including suggested Roman oyster
industry, a Saxon long boat and post medieval oyster beds.
6.1.2
The islands within the harbour have revealed evidence of the occupation of the
harbour since earliest times, and the margins of the harbour have archaeological
evidence which demonstrate its maritime exploitation in the later periods. There
are also military features within the harbour, including evidence of a bombing decoy
site on one of the islands and a Mulberry Harbour (D-Day pontoon) section whose
back broke in the harbour and remains in situ.
6.2
6.2.1
Historic Landscape/Seascape
The sheltered nature of the harbours have been historically exploited for various
uses including; salt production, oyster farming, wildfowling, sheltered navigation,
fish nursery stocks, land reclamation as coastal grazing marsh and localised gravel
extraction. More recently the recreational market has driven the increase of
marinas and boatyards.
6.2.2
Salterns were a particular feature of the more shetltered western shores of
Langstone and Chichester harbour. By the early 18th century there were extensive
areas at north east Portsea (Gatcombe Haven/Great Salterns), south east Hayling
and Northney. By the 19th century these systems were in decline and uneconomic
from mined salt sources (particularly Cheshire). Great Salterns is now a golf
course, Northney a marina, whilst on the south east Hayling coast although there
has been some land reclamation to farmland there is still tangible evidence of these
systems through survival of some of the banks.
6.2.3
Oyster beds were located in slightly more exposed locations close to main
channels, the most significant area being off northwest Hayling. The area supported
a strong oyster smack fishing fleet until the early 20th century when the industry
was devastated by an outbreak of typhoid related to several discharges of effluent
into the harbours affecting the oysters. The industry was effectively dormant from
the 1920s to 1960s but has continued despite setbacks including inadvertent
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Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
introduction and competition from non native species such as slipper limpets.
Predation from marine snails in the mid 1970s saw the spread of disease from
Bonamia ostrea. However, harbour oysters still command a strong continental
market value. Today, some of the northwest Hayling beds have been recently
restored which have benefited local populations of little tern.
6.2.4
The historic importance of sea trading is evident from the many wharves both in
current or disuse. The harbours were used as a sheltered alternative route
connecting Portsmouth at the canal at Eastney via cuts at the head of the two
harbours and across the north of Thorney to Chichester basin and Arundel which
was part of the Chichester ship canal opened in 1823. This trade ceased in 1906
form more competitive forms of transport. Great Saltern Quay, Kendalls and
Brockhampton wharves are still active for the sand and gravel industry. Fishing and
cargo vessels make up a very small percentage of craft today. Today it is modern
leisure facilities such as marinas, boatyards and sailing clubs that have become the
dominant shoreline activities.
6.3
6.3.1
Built Environment
The first bridge was built in 1824 and signalled the end of the wadeway connecting
Northney with the mainland to the east of the bridge crossing. A rail crossing with
lifting bridge section was built in 1867 and dismantled in the 1960s. The current
road bridge is the only bridge crossing to the island from Langstone and was
constructed in 1955.
6.3.2
There are several examples of house boats on the shores of the Kench. Some of
these are lived in permanently and are of varying design, some purpose built while
others are boat conversions. They are distinctive elements that contrast with the
undeveloped shoreline.
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Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
EVALUATION
7.0
FORCES FOR CHANGE
1.
Harbour side development.
2.
Recreation pressures.
3.
Climate change in particular sea level rise and increase in frequency of
storms and adaptation responses.
Fishing trends.
4.
5.
Shoreline Management Plan,
KEY QUALITIES AND EFFECTS OF FORCES
7.1
Visible remains of features associated with the oyster fishing industry, wharves, tide mill
structures and channels as reminders of the historical importance of the area for trading
that the sheltered harbours provided.
FORCES FOR CONSEQUENCES
CHANGE:
3
Threats:
A limited knowledge and information on the history and archaeology of the harbours.
Sea level rise and erosion of low lying features such as the oyster beds remains.
Opportunities:
Greater communication and awareness raising of the cultural heritage to the wider
community and targeting of which historic features could be conserved and provide a
modern function. In particular tide mill and mill pond walls which provide sea defence
function.
Investigate effect of sea level rise impact a on the historic built environment.
7.2
Internationally important marine intertidal habitat of mud and sand flats algal beds and
saltmarsh and is one of the ten most important intertidal areas for wading birds in
Britain.
FORCES FOR CONSEQUENCES
CHANGE:
All
Threats:
The potential loss of important habitats from sea level rise and lack of compensatory
intertidal habitats from coastal squeeze.
Impact of bait digging on intertidal habitats.
Lack of comprehensive knowledge on the impact of oyster dredging on the marine
environment.
Inability to locate compensatory habitat from sea level rise and competition with
economic and social land uses (e.g. farmland and recreation) adjoining the character area
reducing the intertidal habitat area.
Opportunities:
Investigate ways of working with partners to identify, map and design opportunities for
habitat creation through managed realignment of the shore.
particularly along the Warblington coast, west Hayling, Gutner point and Southmoor; in
line with the objectives of the Solent Dynamic Coast Project (SDCP)and Shoreline
Management Plan (SMP) – in particular in relation to former Saltern sites.
Hampshire County
Integrated Character Assessment
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Status: Draft March 2010
Langstone and Chichester Harbours
7.3
Part of the harbours are designated as a sea bass nursery area and important spawning
ground for demersal fish and oyster growing as well as being popular for recreational
angling.
FORCES FOR CONSEQUENCES
CHANGE:
4.5
Threats:
The diminishing stocks of fish and shell fish within the harbours.
Lack of baseline data and monitoring of the maritime habitats and species.
Illegal bass fishing.
Physical damage to the harbour bed of benthic and marine habitats from trawling.
Opportunities:
Possible resurgence of the market for locally caught fish and oysters.
Enforcement of byelaws and implementation of fishing policies (Sea Fisheries Committee).
7.4
A combination of large open water areas and narrow inlets and intimate creeks and
overall sense of wilderness and high degree of natural beauty with a predominantly
wooded/undeveloped edge. One of the most important areas for water recreation in the
country
FORCES FOR CONSEQUENCES
CHANGE:
All
Threats:
Not achieving the right balance between the demand for more and improved boating
facilities with environmental considerations.
The creation of unsightly sea defences and realignment and change in natural shoreline
appearance through maintenance with unsuitable materials.
Not achieving the right balance between dredging works in order to maintain safe
navigation with conflicting requirements of the international nature conservation
designations.
Possible loss of coast path from rights of way from sea level rise or only access at low
tide.
Opportunities:
Support countryside access initiatives and outcomes of coastal access audits / green
infrastructure strategy to identify where new or realigned shoreline routes are to be
located and influence their design.
Look into opportunities to work with the local community on identifying popular and
valued views and landmarks in the harbours.
Hampshire County
Integrated Character Assessment
10
Status: Draft March 2010
Langstone and Chichester Harbours