United Kingdom

Fresh water resources

Vulnerabilities UK - overview

The UK is near the limits of coping with the current climate in some sectors and could be pushed over the edge by climate change. For example (24):

While only 8% of water resource zones in England are currently at risk of falling short of demand during a severe drought, this could increase to around 45% by 2035 without remedial action.
Security of water supply for consumers is good and improving, but there remains an environmental cost. Environment Agency statistics indicate that 11% of rivers and 35% of groundwater aquifers in England are “probably at risk” of environmental damage due to water abstraction.

Away from Scotland, Northern Ireland and North East England, future summer water shortages were identified as being a problem, particularly in southern England (1). Water is used for a number of purposes. In Wales, for instance, the majority of water abstracted is for hydroelectricity generation (73%) and is returned to rivers downstream of the abstraction point. Industry accounts for a further 8%, agriculture 3% and public water supply 16% (2).

Key issues with respect to the vulnerability of fresh water resources are (3,4,5,6):

maintenance of critical river flows during dry conditions;
impact of longer and increased frequency of droughts on water supply;
uncertainty in replenishment rate of aquifers;
potential salinity increases in borehole and river-mouth abstraction points as a consequence of rising sea-levels and/or storm surges;
management of abstraction licences with potential increases in irrigation and industrial demands;
an increase in the demand for water for irrigation, garden watering, industry (especially food and drink) and the public(modelled 4% rise in household water demand by 2021);
vulnerability of water supply systems to long dry periods; water infrastructure may not be able to cope with long dry spells in summer, and there may be shortages of water available for direct summer abstractions.

West and Gawith (1) present an overview of expected climate change impacts on several activities for different regions of the United Kingdom, based on several regional scoping studies. The results for water resources management are listed below. A blank cell indicates that no specific issues were identified for the region besides those noted in the first row. Each region identified and discussed issues differently, so this table might not provide comprehensive coverage of all issues.

Region Positive impact on water resources management Negative impact on water resources management Majority of regions Increased risk of summer water shortages. Increase in water quality problems South West Increases in demand for household, irrigation and industrial uses. Potential salinity increases in borehole and rivermouth abstraction points South East More winter flood damage. Domestic water demand to increase from new homes. Greater risk of saline intrusion London Already one of the driest capitals in the world and facing increased demand for water in summer East of England Saline intrusion of Fens. Pollution levels become unacceptable with low flows. Pressure on drainage systems East Midlands Reduction in water abstraction West Midlands Opportunity for investment from outside region where winter water surpluses can be controlled. Opportunities for water trading between farms Wales Reduced salmonid growth. reduced dissolved oxygen. Increased chemical loading North West Increased need for dredging ports. Farm waste water systems not designed to cope with higher winter rainfall Yorkshire & Humber Humber estuary drains could be 'tide-locked' more frequently. Greater need for pumping from low-lying areas North East Domestic water requirements increase. Industrial water requirements may alter Scotland Increased demand for abstraction. Increased risk of algal blooms Northern Ireland Higher water tables likely. Capacity of waste water treatment plants may be exceeded

West and Gawith (1) present an overview of expected climate change impacts on several activities for the United Kingdom as a whole for the 2020s, the 2050s and the 2080s, based on the studies of UKCIP carried out so far (UKCIP = UK Climate Impacts Programme). The results for fresh water resources are listed below. These results assume no adaptation to climate change.

Positive impact on fresh water resources Negative impact on fresh water resources Uncertain impact on fresh water reources General Nitrate and pesticide concentrations may be diluted Significant increase in risk of multi-season droughts. Risk of saline intrusion in coastal rivers Changed seasonal flood regimes of mountain rivers 2020s Increased frequency of moderate drought conditions (up to 3 in 30 years). Reservoir yields fall by 10-15% in some areas of the UK under the Medium High Emissions scenario. Mean monthly runoff decreases by up to 30% in some areas of the UK. Average annual demand for domestic water may increase by up to 1.8% 2050s Domestic water demand may increase by 1.8 - 3.7% 2080s Frequency of serious drought conditions may increase to 10 in 30 years. Frequency of short (6 month) serious droughts could increase from 1 in 9 years (present) to 2 in 15 years (Low Emissions scenario) or 1 in 3 years (High Emissions scenario)

Vulnerabilities UK water supply - Reservoirs

Storage across the seasons becomes the main problem, particularly when extended periods of summer drought will increase demand for domestic and agricultural irrigation as well as commercial and industrial use. The quality of water is also of concern as river flows reduce and pollutants increase (5).

The larger reservoirs and aquifers provide sufficient ‘usable’ storage to sustain excess demand over summer recharge lows. However, in terms of efficiency of use and distribution, being gravity rather than pump driven supplies (pumping costs – energy consumption - for some reservoirs approach £3k-£4k per day) the smaller reservoirs close to the demand centres are the most economic (5).

Water security issues - guaranteeing a supply - means that the alternative larger pumped stores are necessary to supplement or replace the local supply as the small reservoirs are drawn down to their prescribed minimum levels. Additionally, some areas are only supplied by the local ‘small’ reservoir without access to a wider distribution network and so reserves must be maintained for these. Wetter winters will again advantage supply in the larger stores, whilst the smaller reservoirs will be more susceptible to demand pressures, not having the benefit of enhanced winter top-ups (5).

An increase in erosion by heavy rainfall may lead to more siltation in reservoirs. Some reservoirs in the East Midlands, for instance, have been silted up to 7.5% of their capacity - or around 25 days water supply (3).

Vulnerabilities UK water supply - Leakage

Historically, one of the main issues associated with water supply and management has been the issue of leakage. The major water companies in the South West have invested significantly in minimisation of leakage over the last decade. Water companies report that leakage is reduced to or below the economic threshold where cost benefit analysis determines that further leakage minimisation is not cost-effective. If future climate change were to have significant impacts on water resources then the water companies and regulators would need to re-evaluate the threshold of this economic limit (5).

Vulnerabilities UK water supply - Groundwater

Average annual recharge in UK aquifers is expected to fall by 5% to 15% (7). According to the Environment Agency (8), many river catchments and groundwater units within the West Midlands are approaching the limit of sustainable abstraction, and any further resource exploitation would lead to general environmental degradation. In some areas the Environment Agency believe that this limit has been exceeded. Consequently large areas are deemed closed to further abstractions, severely limiting the availability of new water resources.

Over-abstraction of many existing aquifers is already taking place in several parts of England (3). It is uncertain whether increased winter rainfall will result in a net increase in the recharge of aquifers: the period available for recharge will shorter due to higher temperatures and increased demand from vegetation (3). Increases in potential groundwater recharge are consistently projected for the 21st century, however, in northern Europe (Denmark, southern England, northern France) (26).

Future projections of drier summers and wetter winters indicate that summer will become a period of reduced potential recharge. The reduced potential recharge in September (historically the start of the recharge season) suggests that the period of low recharge could be extended by one to two months, thereby shortening the recharge period. However, set against this, winter recharge is forecast to increase, as winter rainfall totals increase at the expense of rainfall at other times of year. Whilst the recharge season is likely to shorten, the overall volumes of potential recharge for both England, Scotland and Wales for the second half of this century are likely to be at least as much as the present day, if not increase (33).

Wetter winters could lead to increased recharge of regional water supplies in the West Midlandse.g. aquifers and hence increased availability of water and also provide the opportunity for providing enhancement of certain habitats e.g. wetlands, that are underrepresented in the region (4). Modelling of the Sherwood aquifer in East Midlands has produced a somewhat unexpected result which is that the cumulative amount of recharge over the next 25 years compared to the baseline is likely to increase under all four UKCIP scenarios (9). The gain is up to 1 meter. On average, groundwater levels increase progressively with the different scenarios – up to 2 meters (from a 2% increase in recharge for the low UKCIP scenario by 2050s, to a 13% increase for the medium-low UKCIP scenario by the 2020s).

The reduction in abstraction of water may have adverse effects.Groundwater levels have risen in the Birmingham conurbation due to the reduction in abstraction for industrial processes (4). This has caused local flooding in basements and the rising groundwater can also move into areas of contaminated land causing it to become polluted. Transferring groundwater to the East Midlands via the River Tame to supplement water resources in that region may help to overcome this problem. This is an example of the options that water resources planners may consider in future as a response to climate change impacts.

Vulnerabilities UK water supply - River runoff

Observed changes in annual river flow

For the Atlantic part of Europe, from the south of Spain to the north of the UK, a study was carried out to disentangle the contributions of climate change versus human impacts on river discharge. Long‐term trends in annual river discharge from a very dense network of 1874 gauging stations spanning the period 1961-2012 were analysed for this (32).

Across much of the British and Irish Isles, trends of increasing river discharge dominate. In contrast, most stations across the Iberian Peninsula and southern France show decreasing trends. Both the increasing trends in the North and the decreasing trends in the South are statistically significant. Northern France and central and southern Great Britain are transitional, with few significant trends. For the British and Irish Isles most observed trends in annual river discharge are associated with climate change. These trends agree with trends in increasing annual precipitation (32).

Projected changes in high and low flows

An indication of the magnitude of possible changes in runoff (and hence water availability) in the UK during the twenty-first century was assessed along with the detection times of climate change signals in runoff projections. This was done using an ensemble of regional climate models under a SRES A1B emissions scenario. Overall, for the second half of this century, the majority of these models project an increase in runoff during winter (by 5–25% by the 2080s) and a decrease over summer, with a mixture of increases and decreases in spring and autumn, and the smallest changes occur in spring (30).

During winter, the largest percentage increases in rainfall are projected over southern England, and explain at least some of the increase in runoff projected in this region. Similarly, during summer, the largest percentage decreases in rainfall are simulated over the southern England and Wales, which roughly correspond with the large reductions in runoff in those regions. During autumn, large percentage increases in rainfall are projected over Scotland and Northern Ireland, and runoff is also projected to increase by 5–15% in this region (30).

A climate change signal is said to be detected if the null hypothesis, that the runoff for a future period and the 1970s are equal, would be rejected at the 5% confidence level in favor of the opposite hypothesis that the runoff amounts in the two periods are different. The detection times of climate change signals in the river runoff projections should be regarded as earliest possible change estimates (30):

Winter projections: a climate change signal in the 2020s over Scotland, western coastal areas of England and Wales, and the southern coastal regions of England. The climate change signal also emerges between the 2020s and 2030s over Northern Ireland and inland parts of Wales and southern England. The signal is not seen until much later in eastern parts of England.
Spring projections: a climate change signal in coastal areas of England and Wales, and over eastern Scotland only, and the signal does not generally emerge until the 2050s–2080s.
Summer projections: a climate change signal in most river basins, but at a later time than in winter. The signal is detected during the 2040s–2050s over the northern half of England and coastal parts of Wales, but earlier, during the 2020s, over southwest England, central Wales and parts of eastern Scotland. The climate change signal emerges much later in the 21st century, if at all, over Northern Ireland and the rest of Scotland.
Autumn projections: a climate change signal between the 2040s and 2050s over much of England and Wales, with the exception of the Thames basin where a signal is not seen until the 2080s.

Reduced summer precipitation could lead to a depletion on summer river flows, and unsupported river abstractions may become more unreliable (4). Although this situation could be partly offset by increased winter aquifer recharge and increased winter reservoir inflows, a potential increase in demand due to climate change could exacerbate this current problem. The general conclusion of most studies is that river volumes and levels of low flow are affected even under the lowest climate change scenario (1). Changes in high flows during this century are largely driven by changes in winter precipitation, whilst changes in low flows are determined by changes in summer precipitation and temperature (31). The response to climate change will differ from one catchment to another, partly due to differences in catchment geological conditions (31).

Low-flow pollution effects

There may be a high concentration of pollutants in the first-flush when rainfall ends a dry period. Water companies may be reluctant to abstract from rivers due to high pollutant concentrations in the first-flush events, but thereby lose water (3).

A related issue for reduced summer river flows is the potential loss of dilution for sewage and trade effluent. However, this is related to demand for water and the production of sewage effluent, which in some rivers are dependent on treated sewage effluent for the sustainability of low flows. One potential challenge for water resources planners is therefore the requirement to ensure that the discharge consent process takes into consideration potential climate change impacts on both quality and quantity of flows (4). When the dilution of wastewater effluent is reduced at lower river flows, we may need additional treatment to meet higher standards. Besides, colour and odour problems will result from higher temperatures and more intense rainfall events (10).

Lower flows in rivers have negative impacts not just in water quality but on biodiversity as well (4). Higher water temperatures will accelerate natural biodegradation of organic pollutants, but increase the risk of algal blooms, especially in rivers and lakes affected by eutrophication. Algal blooms generally cause a decrease in the oxygen concentration of the water as oxygen is used up in the decay of dead algal material. In severe cases, this can reduce the oxygen below the concentration required for fish to survive.

Lower summer river flows and higher temperatures may cause a general decrease in oxygen concentration that will tend to tip the competitive balance towards coarse fish, such as pike, and away from salmonid fishes, such as trout and salmon, which prefer highly oxygenated water (11).

Vulnerabilities UK – Demand for irrigation

As with public water supply, the potential increase in demand for water depends on social and technological change. In terms of spray irrigation, the Environment Agency demand projections study (12) concluded that this component of demand could decrease by up to 20% or increase by 50% by 2025, depending on the different scenario assumptions of customer and supermarket produce quality demands, international competition, and crop varieties.

Vulnerabilities - London

80% of London’s water comes from the Thames and the River Lee and is stored in reservoirs around London. The remaining 20% is groundwater, abstracted from the chalk aquifer that lies underneath London (23).

London is one of the driest capital cities in the world, with available water resources per head of population similar to that of Israel. Climate change could reduce the amount of water available and increase demand in summer. Lower river flows in summer will raise water temperatures and aggravate water quality problems in the Thames and its tributaries, especially following summer storms (13). London may also be particularly sensitive to increases in temperature in the future because of the urban heat island effect (6).

In the Thames region, 55% of the effective rainfall that falls annually is abstracted, amounting to about 5000 Ml/d, of which 86% is used for public water supply. Even without climate change, the present balance of supply and demand is in deficit by some 180 million l/d (14). According to Environment Agency estimates, outdoor water use will increase public water supply demand in the Thames Region by approximately 50 million l/d by 2025 due to climate change (14). The impact of climate change on industrial water use will be felt most keenly where consumer demand for products is temperature dependent (e.g., the food and drinks industry), or where industrial processes are less efficient at higher temperatures (e.g., water cooling for power generators).

Nearly a quarter of all the water distributed in the water mains network, is lost in leakage. This is due to three reasons (23):

Much of London’s mains water network is the legacy of Victorian engineering. Thames Water estimates that nearly a third of the water pipes making up its network are 150 years old, and about half of them are 100 years old;
A large proportion of London is built on clay, deposited on the former floodplain of the Thames. This clay is prone to shrinking and swelling in response to changes in soil moisture content (respectively known as subsidence and heave). This movement causes the pipes and joints to break;
London clay is particularly corrosive and weakens the pipes, increasing the risk of breakage due to subsidence and heave and vibrations from construction and transport.

The combination of a very old distribution network, corrosive soils and ground movement means that London
experiences the highest levels of leakage in the UK. More seasonal rainfall will cause soil moisture levels to fluctuate more dramatically, increasing the amount of subsidence and heave, resulting in more damage to the mains distribution network. However, warmer winters with less snow and frost will reduce the amount of water lost through frozen pipes and coldinduced heave (23).

Vulnerabilities - East Anglia versus North West England

Reduced annual rainfall in the 2020s and 2050s is reflected in reduced river flows and recharge of underground aquifers and a reduction in the amount of water available for abstraction by farmers, industry and public water supply companies. The impact of this on the ratio between demand and supply may differ from one region to another. Holman et al. (15) studied the situation for East Anglia and North West England. In parallel with the reduction in available water, there are increases in irrigation water demand in both regions. Even under a 2050s climate, there is still an excess of potential supply over demand in the North West, suggesting that it should be possible to meet increased demand. However, in East Anglia, there is a progressively increasing potential supply deficit.

The UKCIP climate change scenarios show an increase in annual average rainfall in all 2050s scenarios (in comparison to the baseline) with the winters becoming wetter, partly at the expense of the summer. The more clement climate in East Anglia and the North West leads to an increase in the length of the growing season, so that the ‘recharge’ period in the winter is shortened. It takes longer for the soils to wet up in the autumn and they start drying out sooner in the spring.

Whether the increase in rainfall in a given area leads to an increase in groundwater recharge and total annual river flows, depends upon a balance between the increase in winter rainfall, the decrease in the length of the ‘recharge’ period and the increase in winter evapo-transpiration. With the 2050s UKCIP climate change low scenario, most of East Anglia is likely to suffer slightly decreased groundwater recharge and total annual river flows, although it is only with the 2050s high scenario that parts of the North West start to experience decreased groundwater recharge and total annual river flows (15).

Vulnerabilities - Scotland

In general, water is plentiful in Scotland. Summer flows of rivers have generally declined throughout Scotland, but not sufficiently to generate significant change. Higher winter rainfall and wetter catchment conditions are likely to result in higher frequency of floods in winter. The authorities tend to start the year with full reservoirs so extra rainfall is not necessarily useful. Slightly higher precipitation without extreme variability, as suggested in the climate scenarios, will continue to ensure a plentiful supply of high quality water to Scotland. In addition, higher precipitation will also ensure the dilution of effluents through higher river flows (11).

Excess surface water can be a problem. Agricultural pollutants may find their way into rivers and lochs, possibly resulting in eutrophication. The waste water system is more sensitive to periods of extreme dry followed by intense downpours. Solids collect during the dry periods and subsequently block the sewers and culverts, which can result in flooding. Similarly, problems of water colouration and dirt from peat following wet/dry periods arise in the north and west of Scotland. Sea level rise is not a serious problem for drinking water sources, as there are few sources that could be affected by tidal intrusion. If the intensity of rainfall events change substantially, then sewers and infrastructure, particularly combined sewer outflows and storm tanks, will require upgrading for compliance with European Community Directives (11).

Demand for water is likely to rise as a result of further house building and the irrigation requirements of horticulture and agriculture, particularly in areas such as East Lothian and Fife. This will result in increased abstraction of both surface and ground water. In conjunction with lower summer river flows, such changes in water resources affect the pollution control of surface waters. With lower river flows, there is less water to dilute pollutant discharges, so tighter consents will be required, resulting in higher treatment costs for sewage and industrial discharges (11).

Europe: five lake categories

There are almost one and a half million lakes in Europe, if small water bodies with an area down to 0.001 km2 are included. The total area of lakes is over 200,000 km2; in addition the manmade reservoirs cover almost 100,000 km2. The response of European lakes to climate change can be discussed by dividing the lakes into five categories (20):

Deep, temperate lakes

Typical representatives of this class are e.g. Lakes Maggiore, Ohrid, Geneva and Constance with mean depths of 177, 164, 153 and 90 meters, respectively. Due to the great depth and relatively mild winters, there is usually no ice cover. The future climate change in Europe may suppress the turnover in deep lakes. This implies the enhancement of anoxic bottom conditions and an increased risk of eutrophication. The oxygen conditions can also be anticipated to deteriorate due to increased bacterial activity in deep waters and surficial bottom sediment.

Shallow, temperate lakes

Balaton (600 km2, 3 m) in Hungary and Müritz (114 km2, 8 m) in Germany belong to this class. Increasing water temperatures may result in intensified primary production and bacterial composition. The probability of harmful extreme events, e.g. mass production of blue-green algae, will increase. The impacts may extend to fish life; changes in species composition and reduced fish catches will be anticipated. The use of the expression 'thermal pollution' is well justified for these lakes.

Boreal lakes

Ladoga (17 670 km2, 51 m), Onega (9670 km2, 30 m) and Vänern (5670 km2, 27 m) are the largest in this class, being also the three largest lakes in Europe. This group includes about 120 lakes with an area exceeding 100 km2. Most lakes of the boreal zone mix from top to bottom during two mixing periods each year. Shortening of the ice cover period will be the most obvious consequence of climate change in these lakes. This could improve the oxygen conditions in winter and spring.

Arctic lakes

These are mainly small water bodies in northern Scandinavian mountains and in the tundra region. Arctic lakes are generally considered to be particularly sensitive to environmental changes. Melting permafrost may seriously threaten the ecosystems of arctic lakes. In some cases the whole lake may disappear as a consequence of ground thaw and enhanced evaporation.

Mountain lakes

To this class belong all high altitude lakes in central Europe and also those located in southern Scandinavia. Even if mountain lakes were connected by channels, physical and ecological constraints limit species migration between them. In a warming climate, there is no escape route; the only possibility for survival is adaptation.

Adaptation strategies - Overview

EU policy orientations for future action

According to the EU, policy orientations for the way forward are (22):

Putting the right price tag on water;
Allocating water and water-related funding more efficiently: Improving land-use planning, and Financing water efficiency;
Improving drought risk management: Developing drought risk management plans, Developing an observatory and an early warning system on droughts, and Further optimising the use of the EU Solidarity Fund and European Mechanism for Civil Protection;
Considering additional water supply infrastructures;
Fostering water efficient technologies and practices;
Fostering the emergence of a water-saving culture in Europe;
Improve knowledge and data collection: A water scarcity and drought information system throughout Europe, and Research and technological development opportunities.

Managed aquifer recharge

Comprehensive management approaches to water resources that integrate ground water and surface water may greatly reduce human vulnerability to climate extremes and change, and promote global water and food security. Conjunctive uses of ground water and surface water that use surface water for irrigation and water supply during wet periods, and ground water during drought (27), are likely to prove essential. Managed aquifer recharge wherein excess surface water, desalinated water and treated waste water are stored in depleted aquifers could also supplement groundwater storage for use during droughts (28,29). Indeed, the use of aquifers as natural storage reservoirs avoids many of the problems of evaporative losses and ecosystem impacts associated with large, constructed surface-water reservoirs.

Adaptation strategies - UK

Options to deal with the impact of climate change focus on demand or supply management (6,10,13,16), or both (the so-called twin-track approach (25)):

Demand management

conduct baseline monitoring and inventories for the size and location of businesses with high water demand;
implement enhanced conservation and demand management programs to counteract increased water demand and potential decrease in supply, e.g. leak identification and repair; metering and increased water prices; efficiency standards for appliances; restrictions in periods of drought, etc.;
prepare plans to balance the needs of competing users when water availability is reduced;
time-limited or flexible abstraction licenses;
‘Use Water Wisely’ campaigns;
restrictions on non-essential use;
guide new development to locations that are least likely to experience water supply shortages.

Water pricing policy. Abstraction charges are levied on all licensed abstractors. Charges reflect environmental impacts: use, location, seasonal impacts (21). Water meters are an important demand management measure. For instance, the Environment Agency believes that metering will reach between half and three quarters of households in the East Anglian region by 2025 (17).

Leakage. London expects not only hotter but also dryer summers. At this moment, the amount of water available per inhabitant is much smaller than in many Mediterranean countries. Water pipes should be renewed. Every day, hundreds of millions of liters of fresh purified water leak away. Moreover, only one in five households is fitted with a water consumption meter (18).

Supply management

England's water companies consider supply-side measures (reservoirs, increased connectedness of water supply provision) usually more reliable, more certain and more effective in addressing imbalances in the supply–demand balance than demand-side measures (25).

conduct baseline monitoring and inventories for the condition and capacity of water distribution and treatment systems;
develop additional reservoir capacity;
capture and reuse rainwater for irrigation and other uses;
reclaim and reuse grey water or water from sewage treatment;
strategic bulk transfers;
desalination;
small local use of rising groundwaters and artificial recharge;
improved infrastructure, treatment and supply systems;
development of innovative water resource options.

Develop additional reservoir capacity. As more water is abstracted to meet the demands of growth and the impacts of climate change, internationally important wildlife may be displaced from the reservoir. As a climate change adaptation strategy new lagoons can be developed, such as at the Rutland Water reservoir and nature reserve (10). The lagoons provide new habitats for this wildlife.In some regions more water will have to be collected over the winter months to sustain demands in the hotter and drier summer months. This will necessitate an expansion in reservoir capacity (2). According to England's water companies, reservoirs are key adaptations to the impacts of climate change (25).

Strategic bulk transfers. Parts of the West Midlands are among the driest areas of England and Wales. The transfer of water beyond the West Midlands using canals could become an important issue where climate change impacts cause potential water shortages in adjacent regions(4). A significant proportion of the region’s water is supplied from reservoirs in Wales, which has a wetter climate.

Costs of delivering water supplies. A study into potential UK adaptation strategies for climate change estimates a range of costs for developing water supplies to meet a shortfall of between 5% and 20% in England and Wales by 2030, as follows (19):

conjunctive use schemes - £1,300 million to £ 44,500 million;
bulk transfer - £5 million to £3,300 million;
reservoir development - £30 million to £900 million;
desalination - £40 million to £440 million

Adaptation strategies - London

London intents to improve the sustainability of its water supply and demand balance and make London more robust to drought by (23):

taking a strategic view on London’s waterresources;
reducing the demand for water in London;
improving the response to drought.

There are national and water company responses to drought, but there is no London-specific emergency drought plan (23).

A hierarchy of actions is proposed for managing water supply and demands in London (23):

Reduce the loss of water through better leakage management;
Improve the efficiency of water use in residential and commercial development (new and existing);
Use reclaimed water for non-potable uses (grey water recycling and rainwater harvesting);
Develop, as necessary, those water resources that have the least environmental and climate impact.

No more groundwater can be abstracted without causing damage to the environment. The options to increase supply are (23):

desalination;
effluent reuse;
increase in reservoir capacity;
artificial groundwater recharge.

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for the United Kingdom.

West and Gawith (2005)
Farrar and Vaze (2000)
Kersey et al. (2000)
Anderson et al. (2003)
C-CLIF and GEMRU (2003)
Land Use Consultants, CAG Consultants and SQW Limited (2003b)
Arnell (2003), in: Eisenreich (2005)
Environment Agency (2001b), in: Anderson et al. (2003)
STW (1999), in: Kersey et al. (2000)
Water UK (2008)
Kerr et al. (1999)
Environment Agency (2001a), in: Anderson et al. (2003)
London Climate Change Partnership (2002)
Environment Agency (2001), in: London Climate Change Partnership (2002)
Holman et al. (2007)
Clean Air Partnership (2007)
Water Resources for the Future: A Strategy for Anglian Region (Environment Agency, 2001), in: Land Use Consultants, CAG Consultants and SQW Limited (2003a)
Boer (2009)
ERM (2000), in: Land Use Consultants, CAG Consultants and SQW Limited (2003a)
Kuusisto (2004)
European Commission (DG Environment) (2007)
Commission of the European Communities (2007)
Greater London Authority (2010)
Adaptation Sub-Committee (2011)
Charlton and Arnell (2011)
Hiscock et al. (2011), in: Taylor et al. (2012)
Faunt (2009), in: Taylor et al. (2012)
Scanlon et al. (2012), in: Taylor et al. (2012)
Sukhija (2008), in: Taylor et al. (2012)
Sanderson et al. (2012)
Charlton and Arnell (2014)
Vicente‐Serrano et al. (2019)
Hughes et al., (2021)

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