Response of mean annual evapotranspiration to vegetation changes at catchment scale

Abstract

It is now well established that forested catchments have higher evapotranspiration than grassed catchments. Thus land use management and rehabilitation strategies will have an impact on catchment water balance and hence water yield and groundwater recharge. The key controls on evapotranspiration are rainfall interception, net radiation, advection, turbulent transport, leaf area, and plant‐available water capacity. The relative importance of these factors depends on climate, soil, and vegetation conditions. Results from over 250 catchments worldwide show that for a given forest cover, there is a good relationship between long‐term average evapotranspiration and rainfall. From these observations and on the basis of previous theoretical work a simple two‐parameter model was developed that rel