Projecting future water availability in the UK for the second CCRA

HR Wallingford developed projections of water availability for the UK for the Second CCRA.

Under the Climate Change Act 2008, the UK Government must assess the climate-related risks to the UK up to the year 2100. HR Wallingford led the first national assessment of these risks for UK Government. To inform the second assessment, we led the development of new projections of water availability for the UK.

This assessment was one of four projects commissioned to inform the second UK Climate Change Risk Assessment (CCRA2) Evidence Report, published in July 2016. We evaluated the contributing factors for the current levels of risk in water resource planning, and then projected these according to a selection of plausible climate, population, adaptation and environmental protection scenarios to 2100.

map of UK representing water availability

These new projections of water availability for the UK enable UK Government to assess the relative severity of impacts under a range of future scenarios.

A GIS-based map to compare water availability

We developed a tool to help us develop, assess and present supply and demand projections for public water for the whole of the UK. These projections then fed into a GIS-based database to map and compare water availability, taking into account other key water users and including environmental demand, to identify potential future 'hot-spots'.

Realistic assessment of future risks

We have provided a realistic and transparent assessment of future risks based upon the latest available evidence that the UK Government can use to inform its adaptation planning process. Our assessment is consistent with existing national and sub-national population projections, water company resource-management planning, demand projections and policy, such as the Water White Paper. Our approach also followed assumptions on adaptation to be taken into account in estimating the level of future risk.

Headline messages

Impacted zones are not restricted to the south-east of England

All areas of the UK may be affected by deficits in the water balance either with respect to the environment or to public water supply, or both, depending on the scenario chosen.

The relative contribution of different factors in determining the supply/demand balance varies geographically

Population, adaptation decisions (including decisions on environmental flow calculations) and climate are the drivers of the availability of water for public water supplies, other sectors and the natural environment that have been explored.