Evaluating evapotranspiration with SWAT a distributed watershed model and the FAO-56 Penman-Monteith method

Prolonged recent droughts across the High Plains have increased concern about how agricultural management practices impact the hydrological cycle of agriculturally dominated watersheds. Several hydrologie models are currently utilized to estimate the impact of land uses practices. Since an important fraction of precipitation (80-90%) is used in evapotranspiration (ET), small changes in the calculations on ET can results in significant changes in simulated water budgets. Due to this importance an analysis of simulated ET from two traditional models were studied. The hydrologic distributed model Soil Water Assessment Tool (SWAT) and the FAO-56 Penman Monteith method were used to simulate ET for crops and pasture land uses in the High Plains Region. Measured évapotranspiration data from two Eddy Covariance Systems (ECS) and a Bowen Ratio Energy Balance System (BREBS) were compared to simulated evapotranspiration.