Water Resource Impacts

Water availability is key to the success of a number sectors in Ireland and Wales, but this is especially the case for public water supply, with 80% and 95% of supplies coming from surface waters (rivers & lakes) for the two nations respectively. Understanding how this surface water resource will change is therefore crucial in helping to ensure that future water supply is greater than future water demand.

The impact of future climate change on the quantity and quality of water in rivers in Wales has been assessed using the Soil and Water Assessment Tool (SWAT) hydrological model. Using the latest Climate Projections from the UK Met Office, we have projected daily streamflow in five catchments to 2080 and analysed changes in seasonal and annual average flows. These projections are based on a worst-case scenario of future climate change (Representative Concentration Pathway 8.5), due to the critical nature of future water supply provision, as well as water availability being key to economic activity and growth in the region.

Our results show that annual average flows between 2021 and 2080 are likely to see little change, but that seasonal flows will be much more variable. Summer and autumn flow are likely to decline substantially across the five catchments studied in detail, while winter and spring streamflows show the opposite trend. When looking at very high and very low flows (floods and droughts), we see both winter high flows, and summer low flows, increasing in frequency and severity. In addition, the streamflow changes seen, as well as increasing temperatures, bring about a decline in all seasons, and annually, for the water quality factors studied (suspended sediment, phosphorus, nitrogen, and dissolved oxygen), further complicating the use of future resources.

The work presented here forms part of a paper published in the Hydrological Sciences Journal, which is available for free and open access at the following link: https://doi.org/10.1080/02626667.2022.2044045.