Using a crop water stress index to determine water use efficiency in a raspberry crop in the Mediterranean Central Chile

Water availability is projected to decrease in Mediterranean Central Chile, necessitating sustainable production strategies based on improved irrigation management. This study focuses on estimating water use efficiency (WUE) in raspberry crops at two validation sites using remote sensing and soil irrigation data. By employing the crop water stress index (CWSI), we demonstrate the potential of this tool in enhancing irrigation management and establishing sustainable production practices. The results demonstrate the successful estimation of actual evapotranspiration (ET_a) using the Operational Simplified Surface Energy Balance (SSEBop) model (coefficient of determination [R²] = 0.92; root mean square error [RMSE] = 0.97 mm day⁻¹), while the CWSI indicated high stress levels after 5 days of irrigation. Moreover, validation at two sites reveals significant differences in applied irrigation, with sites A and B receiving 17,097 and 3760 m³ ha⁻¹, respectively, while the average water demand is close to 5300 m³ ha⁻¹. These variations result in discrepancies in WUE, with values of 0.79 and 3.64 kg m⁻³. By integrating remote sensing indices and soil data, this study proposes that maintaining an 85% ET_a rate during noncritical periods can enhance WUE. This work demonstrates the potential use of a water stress index to monitor crops in the Chilean central zone for efficient water resource use under future scarcity scenarios.