Irrigation–climate feedbacks in coupled climate simulations: First results using an integrated hydrological modelling tool

Human interactions with the water cycle are increasingly recognised as critical drivers of land-climate feedbacks, yet they have long been under-represented in climate modelling.  With ongoing climate change, water management strategies and irrigation practices are becoming more important across many parts of the world. Since these activities can significantly alter surface energy and water fluxes, and thus local and regional climate, it is important to study these processes in more detail.

Although some Earth system models and regional climate models have started to incorporate irrigation routines, they still lack a representation of water availability from different sources and the competing demands of other sectors. To address this gap, we are developing the flexible water modelling tool C-CWatM that can be easily coupled with existing (regional) climate models. Based on the socio-hydrological model CWatM, it simulates river discharge, groundwater, reservoirs and lakes, as well as water demand and consumption from industry, households and agriculture.

In this contribution, we present initial results from coupled simulations using C-CWatM and the regional climate model REMO to study the impact of large-scale irrigation on regional climate conditions. The coupling is implemented via the OASIS3-MCT coupler, which manages synchronised data exchange and regridding of coupling fields. REMO provides the forcing fields required by C-CWatM and receives irrigation water amounts from C-CWatM, which are then applied within REMO's irrigation scheme. 

The development and coupling of C-CWatM allows climate models to realistically account for irrigation constraints, which is particularly important in water-scarce regions and under the increasing risk of droughts driven by climate change. Thus, our approach is an important step towards next-generation land surface modelling and promotes collaboration between hydrology and climate modelling communities to advance understanding of land-climate feedbacks and inform future adaptation strategies.