EVALUATING 3 EVAPOTRANSPIRATION METHODS IN THE SLURP MACROSCALE HYDROLOGICAL MODEL

Hydrological models simulate the land phase component of the global wa ter cycle and provide a mechanism for evaluating the effects of climat ic variation and change on water resources, Evapotranspiration (ET) is a critical process within such models, This study evaluates three dif ferent methods for estimating ET in the simple lumped reservoir parame tric model (SLURP), over a five-year period in the Kootenay Basin of e astern British Columbia. The three ET methods were the Morton implemen tation of the Bouchet complementary relationship, the Granger modifica tion of Penman's method and the Spittlehouse energy-limited versus soi l moisture-limited method. We evaluated the three ET methods indirectl y, based on the ability of the SLURP hydrological model to simulate da ily stream flow over several annual cycles. Although the ET methods af fected simulated stream flow differently, the Spittlehouse method had more physical significance and gave better agreement between simulated and recorded stream flows. The results showed that using an ET method that included a soil moisture limitation to ET produced a worthwhile improvement in hydrological performance. (C) 1997 John Wiley & Sons, L td.