Identifying a Suitable Estimation Method for Evapotranspiration in Wasit Province

Abstract

Water is one of the important natural resources due to its applicability to a broad range of contexts, the most important of which are economic and agricultural; indeed, the largest amount of water used by humans is consumed for agricultural purposes. Water resource management is thus very important to managing crises. Referential evapotranspiration constitutes a high percentage of the water consumed in agriculture, making the accurate estimation of ETo values important to determining the quantities of water required for irrigation projects. It also contributes to the planning of water investment and improving management based on predictions about the upcoming hydrological situation. The study area for the current work suffers in particular from a lack of climatic data in the Dujaila region. The focus of this study was thus on possibility of using hydrological methods that require less climatic data as compared to the Penman-Monteith equation to estimate evapotranspiration accurately. The reference evapotranspiration was estimated using the Penman-Monteith (PM-FAO-56), Jensen-Haise, Blaney Criddle, Kharrufa and Hargreaves equations, utilising climate data from the Al Kut Meteorological Station and the Agricultural Meteorological Network for the period 2013 and 2018. The other results then were compared with the reference Penman-Monteith equation in terms of the determination coefficient and mean absolute; overall, the Hargreaves equation was found to be most accurate for predicting the value of ETo, with the values of R2 and MAPE being 0.995 and 6.2%, respectively.