Impact of climate change on abstraction for hydropower and public water supply in Wales, UK

Abstract

The impact of climate change on the hydrological cycle and catchment processes has been extensively studied. In Wales, such changes are projected to have a substantial impact on hydrological regimes. However, the impact on the water abstraction capability of key sectors in the country, such as hydropower (HP) and public water supply (PWS), is not yet fully understood. We use the Soil and Water Assessment Tool (SWAT) to generate future (2021-2054) daily streamflows under a worst-case scenario of greenhouse gas emissions (Representative Concentration Pathway 8.5) at two large catchments in Wales, the Conwy and Tywi. SWAT streamflow output is used to estimate the abstractable water resources, and therefore changes in the average generation characteristics for 25 run-of-river HP schemes across Conwy and Tywi and the total unmet demand for a single large PWS abstraction in the Tywi. This unmet PWS demand is assessed using the Water Evaluation And Planning (WEAP) system under increasing, static, and declining demand scenarios. Mann-Kendall trend analysis is performed to detect and characterise the trends for both sectors.