Hydro-Pedotransfer Functions to Estimate Evaporation From Bare Soil Surface in Semi-Arid Regions

Evaporation from bare soil is a key component of the soil water balance in arid and semi-arid regions, affecting water availability, solute transport, and groundwater recharge. This study aimed to develop and validate hydro-pedotransfer functions (PTFs) and physically based models to estimate bare soil evaporation using readily measurable soil properties. Data were collected over 2 years from 92 micro-lysimeters installed in diverse soil types under a cold semi-arid climate. The models used variables such as soil water content , texture , and bulk density . The PTFs showed moderate performance, with the best empirical model (PTF-3) achieving a mean error of 1.77 mm and a root mean square error ( RMSE ) of 2.49 mm. In contrast, the best physical model (M1) yielded slightly better accuracy, with a mean error of 1.65 mm and RMSE of 2.24 mm. Overall, physically based models outperformed the empirical PTFs, demonstrating their potential for estimating evaporation in data-scarce environments. These findings support the development of practical tools for water balance modeling and irrigation planning in semi-arid agricultural systems.