ESTIMATION OF SPATIALLY DISTRIBUTED MONTHLY EVAPOTRANSPIRATION

摘要

Evapotranspiration is the most complex component of the hydrologic cycle. Accurate estimation of Evapotranspiration (ETo) is essential for all the water management practices such as reservoir operation, agricultural water management, estimating the components of water balance, etc. The traditional method of using an average value or point values of the meteorological factors as inputs for the estimation of ETo, for a large complex water shed provides a crude estimate of evapotranspiration. This paper investigates the estimation of evapotranspiration using Food and Agricultural Organisation Penman-Monteith (FAO PM) equation considering the spatial variation in the meteorological factors influencing ETo. The applicability of the spatial model was tested using the spatial parameters of the Amaravathi River Basin of Tamil Nadu, India. The performance of the model was evaluated by using the statistical parameters such as Correlation coefficient (R) root mean square error (RMSE) and Mean Absolute Error (MAE). A good agreement was achieved between the spatially modelled value and the estimated value at three stations within the water shed.