Evaluating Reference Evapotranspiration Models in Africa's Semiarid Regions: A Computational Analysis

Abstract

Evapotranspiration is a major component of hydrologic cycle and its accurate estimation is essential for agricultural 
water management. The Penman-Monteith (PM) equation is the universal accurate method for estimating reference 
evapotranspiration (ET _ref). Its drawback is the large climatic data required which are unavailable in many African 
semiarid regions such as Burkina Faso. The Hargreaves (HRG) conventional method which requires few data is still 
used despite of its non-universal accuracy often reported due to the model inability to capture the effect of some 
important climatic parameters. Therefore, this study assessed the performance of an artificial neural network (ANN) 
for computing ET_ref in Dédougou region, located in the Soudano-Sahelian zone of Burkina Faso. This study employed 
ANN and HRG models in order to evaluate their performance by comparing with the true PM. From the statistical 
comparison results, ANN showed a good performance than HRG which overestimated ET_ref for the observed 
condition. Furthermore, wind speed has been found as an important factor in ANN accuracy improvement. Using ANN 
under semiarid zone climatic condition of Africa for computing ET_ref is highly superior to the conventional method