Estimation Of Potential Evapotranspiration (PET) Using Standard Meteorological Data: A Case Study In The Watersheds Of Northern Algeria

Abstract

Accurately estimating potential evapotranspiration (PET) is essential for understanding hydrological processes, managing water resources, and supporting agricultural planning especially in semi-arid regions where meteorological data are often scarce. This study presents a simplified temperature-based model for estimating PET in the watersheds of northern Algeria. Reference annual and monthly PET values were obtained from the National Agency for Hydraulic Resources (ANRH) using the Penman-Monteith method. Through a detailed grapho-analytical analysis, empirical relationships were established between mean air temperature and PET, leading to the development of a new predictive formula .Model performance was evaluated at twelve meteorological stations using statistical indicators (R², RMSE, MAE, and MBE). Results show a high correlation between estimated and reference values (R²adj = 0.90 - 0.97; RMSE = 0.1 - 0.32 mm), demonstrating the model’s reliability and robustness under diverse climatic conditions. The proposed approach offers a practical alternative to data-intensive methods, facilitating PET estimation in data-scarce regions and supporting water management, irrigation scheduling, and climate adaptation strategies across northern Algeria and similar semi-arid Mediterranean areas.