Fresh water resources Ireland
Vulnerabilities - Ireland
The increased demand for water comes mainly from the industrial and domestic sectors, with domestic demand increasing both as a result of population growth and rising water consumption per capita. Most of the present water supply in Ireland comes from surface water, with between 20% and 25% coming from groundwater (1).
It is in some of the areas where the greatest percentage change is predicted that present demand for water is highest and most likely to increase in future. These areas include the Dublin region and the eastcoast between Dublin and Belfast. A large proportion of the water supplied to Dublin is abstracted from rivers draining the Wicklow Mountains, including the upper Liffey. The reduction in rainfall in the winter months to recharge stores within these catchments could exacerbate problems caused by reduced summer rainfall and increased evaporation rates. Reduced storage would mean that less water would be available during the drier months to sustain low flows and could result in water shortages (1).
Water resources are greatest in the west, while demand is greatest along the eastern seaboard, from Belfast to
Cork. This disparity between demand and supply is likely to increase with climate change (7).
In the east and south-east, lower flows than at present are predicted for both the winter and summer months. It is in these areas that demand is highest and there is a rapid increase in demand where urban expansion is occurring. The most notable example is the Greater Dublin region, where the water supply infrastructure is likely to come under growing pressure in the near future, especially during the summer months. In order to meet future demand, careful planning will be required to maximise the available supply and further research to provide more accurate predictions of future water availability are essential (1).
Low river flows
A widespread reduction in annual runoff is likely that will be most marked in the east and south-east of the country. Winter runoff is predicted to increase in most of Ireland. All areas will experience a major decrease in summer runoff, particularly in the east of the country. These reductions are likely to average approximately 30% over large parts of eastern Ireland by mid century. During the summer months, long term deficits in soil moisture, aquifers, lakes and reservoirs are likely to develop. It is likely that the frequency and duration of low flows will also increase substantially in many areas (2).
Seasonal fluctuations in flow are likely to increase in western areas, with wetter winters and dryer summers. In the east and south-east, lower flows than at present are predicted for both the winter and summer months. It is in these areas that demand is highest and there is a rapid increase in demand where urban expansion is occurring (1).
The projected changes in water availability pose potential problems for the dilution of waterborne effluent. With a greater frequency of low flow conditions, additional precautions will be required to ensure that concentrations of water pollutants do not give rise to acute effects. It is recommended that minimum flow constraints are determined more conservatively, particularly where new urban or agricultural discharges are envisioned. Greater incorporation of groundwater protection considerations is also recommended as aquifers assume increasing importance, since sources of water supply, when competition for reduced surface resources intensifies (2).
If groundwater recharge drops and groundwater levels fall at critical times of the year, this could alter the groundwater–surface water dynamics for entire river systems and ecosystems. Rapid run-off during flash floods could mean that, despite the volume of water, aquifers do not have a chance to recharge. A dry winter could leave
groundwater systems unable to recharge and recover for the subsequent summer; this would be exacerbated by the severe droughts predicted for mid- to late-century. The most vulnerable catchments are those dominated by surface run-off; those with a sizable groundwater flow component are less at risk (7).
Climate change will affect water quality both directly and indirectly. Direct effects include warmer water temperatures, and salt contamination of coastal aquifers caused by rising sea levels; indirect effects will come from increasing demands on increasingly limited resources. Climate change, a growing population and greater commercial demands could threaten water quality, particularly during droughts (when assimilative capacity is down), and floods (when sewerage networks and treatment works overflow) (7).
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 (5):
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.
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.
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.
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 (6):
- 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 (8), 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 (9,10). 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 - Ireland - Supply management
It will be necessary to increase the available supply of water in some areas by constructing new reservoirs, transferring water between drainage basins and the conjunctive use of groundwater (1).
The supply to Dublin could potentially be enhanced on a seasonal basis by increasing the operational limits of the Poulaphuca dam to increase winter storage in the reservoir and allow greater drawdown in the summer months (3).
With rainfall patterns changing both seasonally and regionally, we need to review how we deal with low flow situations, storing water when and where possible to deal with future shortages. Options could include bankside storage, aquifer storage and recovery (ASR) and use of ‘cut away’ bogs as reservoirs. We should also review the cost / benefit analysis of connecting the water networks between our main centres of population as a means of reducing risk and dealing with low flow situations (7).
There are considerable supplies of groundwater that are currently unused for water supply (4) and that could be exploited. In doing this, it would be necessary to consider the role of groundwater in maintaining low flows, especially under the climate change scenarios considered. The availability of groundwater in karst areas, where there is a rapid throughput of water, could be significantly reduced during the dryer months. Karst aquifers are also extremely vulnerable to contamination from landfill sites, agricultural pollution and septic tanks (4).
Strategic bulk transfers
Another option is the transfer of water between drainage basins. A relatively small scale transfer has already been proposed to pump water from the upper Barrow to the Liffey in order to enhance flow into the Poulaphuca reservoir, the main reservoir supplying Dublin. Future climate-induced reductions in runoff could result in a flow deficit in both catchments, especially if the available runoff was underestimated on the basis of the current flow regime. Transfers over longer distances are also feasible, and supplying Dublin with water from the Shannon catchment has been suggested as a possibility (3). Again, changes in runoff would need to be considered as the results of this investigation suggest that all regions will experience drying during the summer months when demand is highest (1).
A long-term plan is needed in both the Republic of Ireland and Northern Ireland to ensure the necessary infrastructure is provided in a timely and appropriate way. These plans should ensure that sustainable water supplies, both surface and groundwater, are available across the island, while recognising the needs of individual stakeholders and protecting water quality (7).
Saltwater is virtually limitless, but desalination is expensive – though new membrane technology has reduced costs significantly – and it can be difficult to produce potable water. Any comparison between desalination and other options must take account of the environmental impacts, including greater energy use and disposing of the brine residue (7).
Adaptation strategies - Ireland - Demand management
Attention should also be given to demand management, which could postpone the need to develop new sources of supply in the short- to medium-term.
At present up to 30% of the water supplied to Dublin is lost through leakage from the ageing supply network (3). This problem is currently being addressed although the location and repair of leaking pipes is a time-consuming and expensive process. Regular monitoring and maintenance would make substantial savings (1).
Programmes to educate and encourage water conservation through greater public awareness, incentives for installing water-efficient appliances or more aggressive strategies such as compulsory water metering should also be given serious consideration (1).
Water usage in Ireland is significantly higher than elsewhere in Europe. This, coupled with climate change and a growing population, could lead to water shortages in Ireland in the medium and long-term. We need a fresh approach if scarce supplies are to be conserved. People who are not charged for water have no incentive to conserve it and reduce consumption. Measures to improve demand management should include regulation and universal water pricing for all users, while making due allowance for people’s ability to pay in the domestic sector (7).
Plan for competing demands
New policies are needed to establish priorities to deal equitably with competing demands for available water resources. Both climate change and demographic projections predict a serious imbalance between areas where rainfall will be most plentiful (the west and northwest), and areas of greatest need (the east and southeast). Climate change will also alter the needs and demands of water users in Ireland, particularly where irrigation will be required. The continuing use of water for energy also needs to be considered (7).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Ireland.
- Environmental Protection Agency (2003)
- Department of the Environment, Heritage and Local Government
- Department of the Environment (1996), in: Environmental Protection Agency (2003)
- Daly and Warren (1998), in: Environmental Protection Agency (2003)
- Kuusisto (2004)
- Commission of the European Communities (2007)
- Irish Academy of Engineering (2009)
- Faunt (2009), in: Taylor et al. (2012)
- Scanlon et al. (2012), in: Taylor et al. (2012)
- Sukhija (2008), in: Taylor et al. (2012)