Crop evapotranspiration and water productivity in Loess Plateau: A case study of Shanxi province based on SEBAL model

Abstract

This study focuses on Shanxi Province, located in the typical rain-fed agricultural region of the Loess Plateau, where farmland water reserves are limited and water scarcity is a significant challenge. To achieve stable and high grain yields while addressing these constraints, the primary focus must be on reducing agricultural water use while balancing productivity with water conservation, provided that sufficient irrigation sources are available. The research utilized Landsat 8 satellite data and meteorological information to simulate crop evapotranspiration (ET) in Shanxi using the SEBAL model. Based on the simulated ET values and field survey data of crop yields, the study calculated crop water productivity (WP). It then analyzed the relationship between WP and natural factors such as elevation, air temperature, and precipitation. Key findings include: Crop ET in Shanxi generally increased from northeast to southwest, with simulation results closely aligning with FAO Penman-Monteith equation calculations (relative error of no more than 5%). Crop yields ranged from 386.794 to 754.896 kg/mu, with WP varying significantly across regions—from 0.824 kg/m3 in the Jindongnan district to 2.532 kg/m3 in the Jinnan district. Regional variations in crop WP were influenced by elevation, annual temperature, and precipitation patterns. Notably, the linear correlation between WP and these factors was weaker in the Lvliang mountainous area. These findings emphasize the importance of implementing appropriate field management practices (e.g., optimized irrigation scheduling, soil moisture management) to improve both crop yields and WP.