CLIMATOLOGICAL WATER BALANCE ESTIMATED BY DIFFERENT METHODS OF POTENTIAL EVAPOTRANSPIRATION IN MATO GROSSO DO SUL

Abstract

Agriculture is an activity that depends mainly on the climatological water balance. For its estimation, it is necessary to know the reference evapotranspiration (ETP). There are several methods for estimating evapotranspiration, the most used being Penman and Monteith (PM), however, it requires many input variables. In this context, this study aimed to compare the climatological water balance estimated by the standard PM method with other ETP models. It was used historical series of climatic data such as global solar radiation, average, maximum and minimum air temperatures, relative humidity, wind speed and rainfall during the period 1983-2018 for Mato Grosso do Sul. ETP was estimated by several evapotranspiration calculation methods. The methods were compared by statistical indices that evaluate accuracy, precision and trend.  The mean monthly values of soil water storage (MRA), water surplus (EXC) and water deficit (WWS) by the PM method were 74.18 mm; 38.31 mm and 12.35 mm, respectively. The method of Hamon (1961) proved to be the most similar to PM for the estimation of water balance in the state of Mato Grosso do Sul.