标题：From Flood to Drip Irrigation Under Climate Change: Impacts on Evapotranspiration and Groundwater Recharge in the Mediterranean Region of Valencia (Spain)
摘要：Agricultural irrigation is the major water consumer in the Mediterranean region. In response to the growing pressure on freshwater resources, more efficient irrigation technologies have been widely promoted. In this study, we assess the impact of the ongoing transition from flood to drip irrigation on future hydroclimatic regimes under various climate change scenarios, with a particular focus on actual evapotranspiration and groundwater recharge in the Mediterranean region of Valencia, Spain. Hydroclimatic predictions for the near-term future (2020–2049) and the mid-term future (2045–2074) were made under two emission scenarios (RCP 4.5 and RCP 8.5) using a hydrological model that was forced with data from five GCM-RCM combinations and field-based irrigation volume and frequency observations. Our findings suggest that climate change could lead to statistically significant changes in the regional hydroclimatic regime despite projection uncertainties. Major changes include a statistically significant decrease in mean groundwater recharge of up to −6.6% under flood irrigation and −9.3% under drip irrigation and contrasting changes in mean actual evapotranspiration for flood and drip irrigation in the order of 1% and −2.1%, respectively. Since sustainably available water resources in the Valencia region are entirely allocated, the expected changes and associated uncertainties create a challenging context for future water management. Our simulations further indicate that, rather than climate change, the choice of irrigation technique may have a greater impact on actual evapotranspiration and groundwater recharge. Our findings therefore highlight the importance of considering both climate change and irrigation technique when assessing future water resources in irrigated Mediterranean agriculture. Plain Language Abstract Agricultural irrigation is the major water consumer in the Mediterranean region. Climate change is expected to add additional pressure on water resources as precipitation might decrease and the occurrence of droughts might increase. To improve the resilience to water scarcity, governments in many regions are promoting a transformation from flood to drip irrigation. In this study, we assess the relative role of irrigation techniques and climate change for the availability of future water resources in Valencia (Spain). We thereby combine multiple future climate projections with a hydrological model, and with field-based irrigation volume and frequency observations. Our findings suggest that climate change could lead to significant changes in actual evapotranspiration and groundwater recharge. However, the choice of an irrigation technique may have a greater impact on actual evapotranspiration and groundwater recharge than climate change itself. We therefore highly recommend to consider both climate change and irrigation technique when assessing future water resources in irrigated Mediterranean agriculture.
