Impacts of climate change on agricultural subsurface drainage hydrology in France

The durability of agricultural subsurface drainage being questioned over the 21st century, the future of French subsurface drainage hydrology under climate change is assessed using the SIDRA-RU model forced by 30 climate projections, for three Representative Concentration Pathways (RCPs): RCP2.6, RCP4.5 and RCP8.5. The results show that the greater greenhouse gases emissions, the greater its effects. Under the RCP8.5, leading to the largest greenhouse gases emission, two major impacts are highlighted: (1) an increase in winter flows leading to an increase of 20% of drained water during winter by the end of the century and to more intense and more frequent flood events; (2) a longer dry season leading to a potential intensification of periods of water stress during summer. Second, an evaluation of the elasticities of hydrological indicator anomalies showed that precipitation is the main contributor over the 21st century.