Impact of the Future Climate and Land Use Changes on the Hydrology and Water Resources in South East England, UK

Abstract

The combined effects of climate and land use changes on water resources availability in river catchments in the UK is key for planning and management of water resources for different sectors and uses such as agriculture practices, urbanisation, leisure, industry, ecological services, environment, fishing industry and tourism. To study the impacts of climate and, land-use changes on water resources availability, this study applied the physically-based distributed catchment-scale (DiCaSM) model to simulate the water balance components such streamflow, groundwater, GW recharge, evapotranspiration, Soil Moisture Deficit, SMD, and Wetness Index, WI of the root zone in the catchment area of river Pang in Berkshire, UK. The model was calibrated, then validated using the observed streamflow data. Following the successful calibration and validation, the model then was run with different future climate and land use changes scenarios. Climate change scenarios of UKCP09, for three thirty-year periods: 2020s (2010-2039), 2050s, (2040-2069) and 2080s (2070-2099) and three emission levels, low, medium and high were applied. To assess the future drought risks, a number of drought indices were applied. They are the SMD, evapotranspiration, WI at root-zone and Standardised Precipitation Index (SPI) and the Reconnaissance Drought Index (RDI). The findings of the study suggest a decrease in streamflow up to 47 % and ground water recharge up to 70% during the summer season by the end of century in comparison to the 1961-1990 baseline period and an increase in drought severity under different climate change scenarios. The increase in temperature and decrease in summer rainfall could have a significant impact on drought risk and water resources availability in the future. The impact of land use changes on the streamflow and the groundwater recharge was less significant than the climate change. The catchment area which is generally considered rain-fed under current land use practices, would change, therefore, the most efficient irrigation strategy and land use practices would be required to minimise the impacts of climate change.