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Last update:16th May 2007 Quick links:
Water resources in the South West Water resources trends in the South West SW river flows and groundwater levels SW water demand and availability Household Growth and Water Supply to 2030 SW Catchment Abstraction Management Schemes (CAMS) SW Water Level Management Plans European & worldwide perspective Useful websites: |
Water resourcesWhat's new on this page...
Water is essential for natural life, supporting a vast variety of plants and animals in wetland environments in the South West. It is also essential for human use in terms of domestic (homes and gardens), manufacturing, industry and agriculture. Unlike many natural resources, water is renewable. However, the replenishment of surface and ground water from the relatively high rainfall we receive in the South West is dependent upon the careful management of water abstracted for our needs. How are water resources measured?Measurements of rainfall quantity, groundwater levels, river flows, and demand trends are all indicators of water availability. Rainfall is recorded by a number of rain gauges across the South West, belonging predominantly to the Environment Agency and the Met Office. The EA monitors river flows, with around 180 gauging stations located in the south West, and groundwater levels using a vast network of boreholes. The National Water Strategy outlines long term (25 years) strategies that aim to ensure the sustainable use of water. This concentrates on improvements in water efficiency and recovery in order to provide for extra demand, in terms of agriculture, industry, and public water supply. Water resources in the South WestThe South West is experiencing a number of pressures on regional water resources, including housing demand, economic development and climate change. The South West Regional Environmental Strategy identifies four key issues that require attention in order to meet the demands of the Water Resources vision. These are as follows:
The South West is one of the wettest regions, with prevailing westerly winds bringing moisture-laden air from the Atlantic. As a result we receive approximately 7500 litres of water as effective rainfall per person per day, which feeds back into surface water or percolates into the ground. However, some areas of the South West currently face:
On average groundwater provides 35% of our drinking water, although this figure varies greatly between regions. Groundwater levels measured from the South West chalk aquifer at Woodyates Farm show fluctuation around the 1961-90 mean over the past decade. The general trend appears to be one of increasing water levels. This positive trend is comparable to the national picture of groundwater levels. However, groundwater levels are highly influenced by a number of factors, and so such short term trends may not necessarily represent any impacts of abstraction. Trends in water resources in the South WestQuantity of rainfallThe amount of rain that falls dictates the amount of water that is available for human consumption. In the South West the long-term average annual rainfall is around 1100mm, although within the region this varies between over 2000mm on Dartmoor to around 600mm in parts of southern Dorset (more information about the South West's climate is available here). However, it is not only the amount of rain that falls but also the timing, frequency and duration of rainfall events that determine rates of aquifer recharge and reservoir replenishment. Reservoir levels provide a good impression of the balance between effective rainfall and water usage. In the South West, reservoir levels have been increasing since 1990 - although there has been a decline in the (filled) capacity observed over the last 5 years. This short-term trend has been influenced by recent periods of dry weather, for example approximately 930mm of rainfall, (80% of the long-term average) fell in the region in 2003 (Defra Rainfall Statistics). average capacity for reservoirs in 3 water company areas in the South West
source: Environment Agency (2005) The map below shows that reservoir storage increased in all Regions during January, apart from North East where it remained constant. Average storage now exceeds 70% of capacity in all Regions as stocks increased from 68 to 75% and 61 to 74% of capacity in South West and Southern Regions respectively. Overall, the combined storage for England and Wales increased to 92% of capacity representing 2% more than at the same time last year. Generally, reservoir stocks appear healthy and within the normal range for the time of year. Reservoir Storage in England and Wales and EA Regions as a percentage of total capacity (2004 and 2005
Source: Environment Agency (2005) Climate change in the South West is expected to bring wetter winters but drier summers (UK Climate Impacts Programme). This may lead to further rationing of water supplies in the summer and the adoption of measures to safeguard water levels for both the human and natural environment (e.g. hosepipe bans, reviews of abstraction licenses etc) outlined in the EAs Drought Management Plan.
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Regional total abstractions 1995 - 2003
NB Environment Agency regions |
South West total abstractions 1995 - 2003
|
Source: Environment Agency (2005) (regional data available on Defra website) |
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Supply and demand graphs for companies in the South West show that although demand is set to rise over the next 30 years, supply can be maximised (by increased efficiency, winter storage etc) in order to maintain a water surplus.
In 2002, electricity supply was responsible for over half (60%) of abstractions in the South West, followed by public water supply (22%). Abstractions for fish farming decreased by around 33% in 2002 in comparison to 2001 (751 Ml/d and 2,269 Ml/d respectively).
(click
to enlarge)
Source: Environment Agency (2003) (regional data available on Defra website)
Household Growth and Water Supply to 2030 takes data provided in water company plans and models the consequences for public water supplies of accelerating the rate of household growth across the region by up to 50% above current rates.
The Regional Planning Guidance for the South West (RPG 10) set annual average target growth in new houses of 20,200 across the South West region from 1996 to 2016. This growth rate informs many aspects of public policy including the provision of water supplies.
Water Companies are responsible for planning and managing public water supply. Water resource plans focus on the need to ensure that water companies maintain security of supply to customers in a way that is economically, socially and environmentally sound. The companies last provided plans in May 2004 covering the period to 2030.
This study informs the work of the South West Regional Assembly to develop the Regional Spatial Strategy for the South West (RSS10). It reviews the impact on public water supplies of accelerating growth over the period up to 2030. Housing growth is modelled against the background provided in water company plans including:
At high rates of growth (25% and 50% greater than RPG) deficits in public water supply begin to occur from 2009 in some parts of the region. The options available to address these shortfalls are outlined. Maintaining secure water supplies at high rates of household growth requires immediate steps to greatly improve the water efficiency of new homes. In some areas further action may be required to maintain public water supplies, including:
The Habitats Regulations (1994) require sites of European
conservation interest (including Special Areas of Conservation
designated under the Habitats Directive1 and Special Protection
Areas designated under the Birds Directive2 to achieve favourable condition
by 2010. Similar targets apply to Sites of Special Scientific
Interest. To achieve these aims abstractions may need to be reduced (these are known as ‘sustainability
reductions’). At
some sites, the scale of reductions is still being investigated and has
not been applied to the calculations in this report. This issue
is particularly pressing in the Hampshire Avon catchment in the
east of the region and is likely to affect the supply of water to Wessex Water’s
North, South and East zones; Bournemouth and West Hampshire Water’s Bournemouth zone and Thames Water’s
zone.
Water consumption used by each individual at home (known as household per capita consumption) has been steadily increasing in the South West, from just over 146 litres / head / day in 2000-2001 to almost 155 litres / head / day in 2003 / 2004 (an increase of 9 l/h/d over 4 years) Ofwat (2005).
The highest rates (of over 190 l/h/d) can be found in the South East, where rainfall is relatively low and population high. The differences in consumption between water resource zones shows greater variation on a national scale than observed for the South West.
In 2004/2005 an average of 158 litres/head/day of water was used by household without a water meter in the region, slightly higher than the national average of 154 l/h/d. In households with a water meter however, the average reduced to almost 144 l/h/d, although this was again just over the national average of 139 l/h/d. The average water use in household with and without water meters show a slight reduction on 2003/2004 (by 3 l/h/d and 4 l/h/d respectively). NB. no figures were available for Cholderton District Water.
Company estimates of unmetered household consumption (l/head/d) 2004 / 2005
Source: Ofwat (2006) |
Company estimates of metered household consumption (l/head/d) 2004 / 2005
Source: Ofwat (2006) |
NB. no figures available for Cholderton & District |
|
Click here for more information about water meters in the region.
The Environment Agency promotes the efficient use of water at both domestic and industrial scales in accordance with the Water Act (2003). Abstracted water for public supply is commonly lost through leaks in the supply pipes. Nationally, the total industry leakage has declined by around 30% between 1994-95 and 200-05 (from 5,112 Ml/d to 3,608 Ml/d). There has been a slight increase in leakages in recent years due to prolonged hot and dry summers, leading to ground movement which can result in burst pipes.
(click to enlarge)
Source: Ofwat (2006)
Losses vary across the region due to a number of factors, including the investment from water companies into their supply systems. As can be seen from the table below, total leakages (in Ml/d) have remained relatively stable over the past few years.
Thames Water has consistently the highest leakage rate in the South West, however it also supplies the greatest amount of water (2,965 Ml/d) to the largest number of consumers (8 million). After three years of increases, leakages in the Thames Water area have appeared to stabilise and declined between 2003/2004 and 2004/2005..
Water company |
2000-2001 |
2001-2002 |
2002-2003 |
2003-2004 |
2004-2005 |
Severn Trent |
340 |
340 |
514 |
512 |
502 |
South West |
84 |
83 |
84 |
84 |
83 |
Thames |
688 |
865 |
943 |
946 |
915 |
Wessex |
84 |
79 |
75 |
75 |
73 |
Bournemouth & W Hampshire |
23 |
22 |
22 |
22 |
22 |
Bristol |
55 |
55 |
53 |
53 |
53 |
Water companies covering the South West total |
1274 |
1444 |
1691 |
1692 |
1648 |
Industry total |
3,243 |
3,414 |
3,605 |
3,649 |
3,608 |
click to enlarge
NB. Thames and Severn Trent Water cover a relatively small proportion of the South West Region. No figures available for Cholderton & District.
Household water meters helps to promote the effective management of water resources by encouraging customers to consider the costs of excess water usage. In 2004/2005 approximately 26% of households in England and Wales had a water meter (a 2% increase on 2003/2004). An average of 28% of properties in the South West had water meters (up from 22% in 2003/2004) (Ofwat, 2006).
In 2004/2005 South West Water had the highest number of properties using water meters with almost 47%, followed by Bournemouth and West Hampshire Water with almost 40%. Both water companies showed a marked increase on 2003/2004, South West Water's by 11% and Bournemouth & West Hampshire by 13%.
Cholderton and District Water had the lowest percentage of households with a water meter with 13.5%.
In terms of non-household premises, all water companies had at least 60% on water meters. The highest rates were found in Severn Trent with almost 93%, closely followed by Bournemouth & West Hampshire with almost 92%. The lowest rates were again found in Cholderton & District Water's area with under 62%.
click to enlarge
Source: Ofwat, 2006
All water companies are planning for increased household metering over the next 25 years. On average, it is forecast that the percentage of metered properties in the region will increase by almost 39% by 2010 and around 60% in 2030.
(click
to enlarge)
N.B forecast not available for Cholderton & District for 2030
Source: Environment Agency (2004)
Click here for more information about the impact of water meters on consumption in the region.
All water suppliers in the South West have installed water resources plans that set out the company’s supply/demand balance and options that can be implemented to resolve forecast deficits. These plans are summarised in the Environment Agency’s document Maintaining Water Supply (2004). Within these plans the following information is provided for each water company:
Water Suppliers also have developed drought plans, which not only consider measures to reduce demand, but also contingencies to makeup shortfalls of available water during droughts. The Environment Agency’s 2003 Review of Water Company Drought Plans provides details for each water company in the South West. These plans are formulated in conjunction with the Environment Agency's 2003 South West Region Drought Management Plan, which aims to:
The South West region drought plan uses a range of indicators to help determine the onset of a drought and what action is required. This includes groundwater, river and reservoir levels. It also takes into account rainfall and demand for water.
Differences in water availability for new abstractions exist between catchments in the South West. Catchment Abstraction Management Schemes (CAMS) reports break catchments into smaller areas with common characteristics called ‘Water Resource Management Units’, which covers both groundwater and river water.
CAMS are strategies for the management of water resources at a local level. They strive to make licensing practice publicly available, and act as a mechanism in the process of license renewal. A map of completed CAMS in the South West is shown below.
(click
to enlarge)
Source: Environment Agency (2004)
Exe |
This study covers the rivers Exe, Barle, Clyst, Creedy and Culm and incorporates many sites designated as natural conservation areas, including AONBs, SSSIs etc. Water availability for abstraction depends on the minimum flow that is trying to be protected for environmental reasons. Availability is generally low from rivers and groundwater in the Exe CAMS. Water is available in more downstream reaches, and in particular the Clyst. The availability of water in a number of management units is affected by the status of more sensitive downstream stretches near the estuary, and thus made unavailable during times of low flow (e.g Creedy, Culm). This ‘hands off’ flow condition has been applied widely in order to protect variability of flow. Downstream areas of over licensing (and thus potential damage if these licenses are fully realised) occur at the Crediton East Aquifer, and the Duckaller aquifer to the west of the Exe estuary. No major streams are supported by this aquifer, although several small streams feed into the Exe Estuary SPA – due to be investigated by the Restoring Sustainable Abstraction Programme |
Tone |
The Tone is a major tributary of the River Parrett on the Somerset Levels. Unlicensed abstraction from the Taunton and Bridgwater Canal exacerbates low flows in an area that is prone to such conditions. The middle reaches of the Tone are classified as over-licensed with no available water, as are those reaches within the tidal limit. Here water feeds the Curry and Hay Moor SPA/RAMSAR and SSSI and thus flow requirements represent a precautionary estimate. In order to reach sustainable levels, resources need to be recovered by improved efficiency and voluntary changes to licenses. Licenses exempt from abstraction and public water supply combine to account for 82% of consumptive abstraction. |
Dorset Stour |
Generally management units have been classified as ‘no water available’. This mainly refers to summer periods of low flow, and water may be abstracted during high flows as long as restrictions are employed. The Middle Stour groundwater unit is over-licensed, reflecting concerns that environmental deterioration may occur if abstractions rise to licensed limits. |
Kennet and Pang |
The Kennet and Pang catchment is part of the larger Thames catchment, and so water availability here considers the impacts of abstractions on the downstream Thames. As a result, water availability is low during low flows – the head reaches of the Kennet are over abstracted as are the Lambourn, Pang and Og, and other units in the catchment are over licensed (e.g.Enborne). No consumptive surface or ground water abstractions will be allowed at low flows from any water resource management unit. |
Frome, Piddle and Purbeck |
Heavy abstraction of water from the underlying chalk aquifer has resulted in low flow problems along the lower reaches of the River Piddle. This river, along with the Frome and some of its tributaries are designated as UK Biodiversity Action Plan (BAP) chalk stream priority habitats, home to otters, water voles, and clawed crayfish. Both ground and surface water resources in the Frome are in a healthy condition, with a surplus of flow above that required by the environment. However, due to the aforementioned problems of relatively heavy abstraction, the Piddle has been classified as an area with ‘no water available’. |
Severn Corridor |
The River Severn supplies public water to six million people as well as industry and agriculture, and thus represents a river of great strategic importance in the South West. Along the Severn Corridor and estuary there are a wide variety of habitats that are affected by water availability, ranging from carr woodland to saltmarsh meadows. The Severn Corridor has been split into 13 water resource management units, of which none have been classified as over-licensed or over-abstracted (as of 2002). Water availability is high within the tributary WRMUs. However, the main branch of the river Severn has been licensed for abstraction within the sustainable limit for this part of the catchment, and effectively has ‘no water available’ for further abstractions. |
Prepared by the EA, Internal Drainage Boards and local authorities, these plans set water level objectives for a given area. These are primarily undertaken for conservation purposes, and a list of 91 SSSIs requiring WLMPs in the South West can be found on the relevant Defra site.
According to the Water Management Institute (2006), a third of the world's population currently faces water scarcity.
The Comprehensive Assessment, carried out by 700 experts from around the world over the last five years, indicates that one third of the world’s population is currently living in places where water is either over-used - leading to falling groundwater levels and drying rivers - or can not be accessed due to the absence of the appropriate infrastructure.
Predictions made in 2000 forecast that one third of the world's population would be affected by water scarcity by 2025. However, the findings of this new report reveal that the situation could be worse than expected - with over one third of people affected by water by 2005. Countries such as India, China and the Colorado River basin in the USA & Mexico are seeing a growing scarcity water crisis.
The Assessment, the first of its kind critically examining policies and practices of water use and development in the agricultural sector over the last 50 years, was co-sponsored by the CGIAR, FAO, the Ramsar Convention on Wetlands, and the Convention on Biological Diversity in a bid to find solutions to the challenge of balancing the water-food-environment needs. It was spearheaded by IWMI, one of 15 agricultural research centres supported by the CGIAR that are striving to increase food production, increase rural incomes, and safeguard the environment.
Results show that one quarter of the world’s population live in river basins where water is physically scarce - water is over-used and people are affected by environmental consequences from falling groundwater levels to dying rivers that no longer reach the sea. Another one billion people live in river basins where water is economically scarce - water is available in rivers and aquifers, but the infrastructure is lacking to make this water available to people.
Access to reliable, safe and affordable water is understood and accepted as a key step out of poverty for the world’s 800 million rural poor. Many more people dependent on rivers, lakes and other wetlands risk falling into poverty because of declining groundwater supplies, loss of water rights and access, pollution, flooding and drought.
Agriculture uses up to 70 times more water to produce food than is used in drinking and other domestic purposes, including cooking, washing and bathing. As a rule of thumb, each calorie consumed as food requires about one litre of water to produce. In Thailand, the daily water required to grow food is about 2800 litres per person per day - 405 for cereals, 20% for animal products and the rest for pulses, fruits, sugar and oils. Italians use 3300 litres per person per day, half for ham and cheese and a third for pasta and bread. Clearly livestock and fish will play a significant role in future water use, but remarkably their importance is underestmated in water resources management.
Despite the impending threat, the Assessment identifies numerous bright
spots – innovative approaches that hold potential for the future.
These include very low cost technologies that facilitate access to, and
use of water by, the rural poor. With health issues addressed, for example,
people can effectively use urban wastewaters as a productive resource.
Irrigation could also be reformed and transformed to reduce water wastage
and increase productivity.
There will be many difficult choices entailing tradeoffs between city
and agriculture users, between food production and the environment, and
between fishers and farmers. There is simply not enough water to go around
for all needs, yet allocation choices have to be made. In closed basins,
where all water has already been allocated, giving water to one group
means taking water away from another.
All data & information used here that has been provided by the Environment Agency is covered by the Agency's standard data re-use licence. The licence conditions are viewable at http://www.environment-agency.gov.uk/other/help/196644/?version=1&lang=_e
