Mileham L., Taylor R.G., Todd M., Tindimugaya C., Thompson J.
Department of Geography, University College London, Gower Street, London WC1E 6BT, United Kingdom; Directorate of Water Resources Management, Ministry of Water and Environment, PO Box 19, Entebbe, Uganda
Mileham, L., Department of Geography, University College London, Gower Street, London WC1E 6BT, United Kingdom; Taylor, R.G., Department of Geography, University College London, Gower Street, London WC1E 6BT, United Kingdom; Todd, M., Department of Geography, University College London, Gower Street, London WC1E 6BT, United Kingdom; Tindimugaya, C., Directorate of Water Resources Management, Ministry of Water and Environment, PO Box 19, Entebbe, Uganda; Thompson, J., Department of Geography, University College London, Gower Street, London WC1E 6BT, United Kingdom
Projected warming in equatorial Africa, accompanied by greater evaporation and more frequent heavy precipitation events, may have substantial but uncertain impacts on terrestrial hydrology. Quantitative analyses of climate change impacts on catchment hydrology require high-resolution (<50 km) climate data provided by regional climate models (RCMs). We apply validated precipitation and temperature data from the RCM PRECIS (Providing Regional Climates for Impact Studies) to a semi-distributed soil moisture balance model (SMBM) in order to quantify the impacts of climate change on groundwater recharge and runoff in a medium-sized catchment (2098 km2) in the humid tropics of southwestern Uganda. The SMBM explicitly accounts for changes in soil moisture, and partitions effective precipitation into groundwater recharge and runoff. Under the A2 emissions scenario (2070-2100), climate projections from PRECIS feature not only rises in catchment precipitation and modelled potential evapotranspiration by 14% and 53%, respectively, but also increases in rainfall intensity. We show that the common application of the historical rainfall distribution using delta factors to the SMBM grossly underestimates groundwater recharge (i.e. 55% decrease relative to the baseline period of 1961-1990). By transforming the rainfall distribution to account for changes in rainfall intensity, we project increases in recharge and runoff of 53% and 137%, respectively, relative to the baseline period. Copyright © 2009 IAHS Press.
Africa; Catchment hydrology; Climate change impact; Climate data; Climate projection; Emissions scenarios; Equatorial Africa; Ground water recharge; Heavy precipitation; High resolution; Humid tropics; Impact study; Potential evapotranspiration; Precipitation; Quantitative analysis; Rainfall distribution; Rainfall intensity; Recharge; Regional climate; Regional climate models; Temperature data; Uganda; Catchments; Geologic models; Hydrogeology; Moisture determination; Permittivity; Rain; Recharging (underground waters); Runoff; Soil moisture; Uncertainty analysis; Water supply; Climate change; catchment; climate change; climate modeling; groundwater flow; precipitation intensity; rainfall; recharge; runoff; sensitivity analysis; Africa