Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 1 1 1997 10.5194/hess-1-93-1997 http://www.hydrol-earth-syst-sci.net/1/93/1997/ http://www.hydrol-earth-syst-sci.net/1/93/1997/hess-1-93-1997.html http://www.hydrol-earth-syst-sci.net/1/93/1997/hess-1-93-1997.pdf 93 100 0000-00-00 Determination of evaporation from a catchment water balance at a monthly time scale H. H. G. Savenije International Institute for Infrastructural, Hydraulic and Environmental Engineering (IHE), P.O. Box 3015, 2601 DA, Delft, Netherlands A method is presented to determine total evaporation from the earth's surface at a spatial scale that is adequate for linkage with climate models. The method is based on the water balance of catchments, combined with a calibrated autoregressive rainfall-runoff model. The time scale used is in the order of decades (10 days) to months. The rainfall-runoff model makes a distinction between immediate processes (interception and short term storage) and the remaining longer-term processes. Besides the calibrated rainfall-runoff model and the time series of observed rainfall and runoff, the method requires a relation between transpiration and soil moisture storage. The method is applied to data of the Bani catchment in Mali, a sub-catchment of the Niger river basin.