Evaluating the impact of drought and water restrictions on agricultural production in irrigated areas through crop water productivity functions and a remote sensing-based evapotranspiration model

Abstract

In Mediterranean regions, climate change is leading to reduced precipitation, along with more frequent and severe droughts, and prolonged periods of water scarcity. In this context, as reservoir levels drop dramatically, some irrigated agricultural areas are compelled to impose water restrictions on farmers to enhance efficiency and protect crops. This study aims to evaluate the impact of varying levels of water restrictions on crop productivity across different crops, taking into account water allocation rights and the irrigation management practices of each irrigation district. Since crop yield is closely linked to the water used (crop actual evapotranspiration, ${\mathrm{ETc}}_{\mathrm{act}}$), this study proposes a novel approach based on using crop water productivity functions and a remote sensing-based surface energy balance model to spatially estimate ${\mathrm{ETc}}_{\mathrm{act}}$. The research was conducted across fourteen irrigation districts in Lleida and Girona, Spain, simulating six scenarios with different levels of precipitation and water rights reductions. The findings showed that reduced water availability significantly negatively affected both simulated evapotranspiration and crop yields across all districts, with variations between districts and crops. On average, yield reductions reached up to 18 % in Lleida and 16 % in Girona under the least restrictive scenarios, while more severe restrictions caused decreases of 48 % and 28 %, respectively. This approach offers valuable insights for water management agencies regarding the effects of water restrictions on crop yield losses, enabling them to make more informed decisions. Incorporating this methodology into emergency drought management plans is essential for fostering resilience in a changing climate.