Potential Evapotranspiration Methods and their Impact on the Assessment of River Basin Runoff Under Climate Change

The current trend in increased amounts of green house gases in the atmosphere will likely affect both precipitation and evapotranspiration, which will in turn affect the runoff response of river basins. These impacts on river basin discharge are discussed in the context of changes in evapotranspiration estimates which are found by coupling a monthly water balance model to account for changes in soil moisture and micrometerological and empirical estimates of potential evapotranspiration. The purpose is to assess the importance of the varying methods for estimating potential evapotranspiration on climate impact assessments of river basin discharge. Four river basins of different size and hydro-climatic variability were selected as case studies