Department Systems Analysis, Integrated Assessment and Modelling

Landuse and climate change impact in Kagera, Lake Victoria Basin

The global climate change is expected to lead to a more vigorous hydrological cycle, including more extreme rainfall events as a result of increasing evapotranspiration due to higher temperatures. If rainfall amounts and intensities increase as expected, erosion will also increase, unless amelioration measures are taken. Soil erosion rates, already at an alarming rate for many parts of the world, are expected to increase in response to changes in climate for a variety of reasons. The most direct is the change in the erosive power of rainfall. Other reasons include: a) changes in plant canopy caused by shifts in plant biomass production associated with moisture regime; b) changes in litter cover on the ground caused by changes in both plant residue decomposition rates driven by temperature and moisture dependent soil microbial activity; c) changes in soil moisture due to shifting precipitation regimes and evapotranspiration rates, which changes infiltration and runoff ratios; d) soil erodibility changes due to decreases in soil organic matter concentrations that lead to a soil structure that is more susceptible to erosion and increased runoff due to increased soil surface sealing; e) a shift of winter precipitation from non-erosive snow to erosive rainfall due to increasing winter temperatures; f) melting of permafrost, which induces an erodible soil state from a previously non-erodible one; and g) landuse and cover changes made to accommodate new climatic regimes. The objectives of this study is to determine the potential impacts of projected changes in precipitation and temperature on soil erosion and water quality in the Kagera Basin.