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WATER SUPPLY AND THE HYDROLOGICAL CYCLE : THE CASE IN IRELAND
WATER SUPPLY =
PRIMARILY A HYDROLOGICAL PROBLEM
Paul Johnston & Laurence Gill,
Civil and Environmental Engineering,
Trinity College Dublin October 2011
Joint Committee on Environment, Transport, Culture and the Gaeltacht
THE WATER BALANCE IN IRELAND : RAINFALL – EVAPOTRANSPIRATION(300mm to 1000mm per year)
Source : Mills, Irish Geography, 2000
WATER SUPPLY STRATEGY
•Ireland has plenty of water, even increasing
•‘Shortages’ are due to increasing demand in centres that do not coincide with the areas of surplus water supply
•Hydrological conditions in Ireland mean that water/rainfall moves through the system relatively quickly : residence times in surface and groundwater are short.
•Access to the needed water can be a mix of surface and groundwater : but they are interconnected and one is not necessarily an alternative to the other.
•The proposed Shannon abstraction is equivalent to approximately 28mm of net rainfall per year over the catchment, ie about 6% of the annual total
•Water management must be holistic with a view to related ecological requirements
•Water, unlike oil, is not consumed : it is the truly renewable resource
•‘Wastewater’ is effectively returned to the hydrological cycle
•Thus, water management must be holistic, as envisaged by EU legislation, involving the whole hydrological cycle
•Spatial variability in rainfall and hydrological conditions mean that water needs to be managed nationally (or regionally) to be effective.
•Conservation and innovative methods of water harvesting and wastewater disposal have an important role but need to be managed consistently.
•Care must be taken to separate the roles of regulation and protection from those of water supply and treatment/disposal.
•Consolidate the disparate roles of several state agencies in water management
WATER MANAGEMENT IN IRELAND