Implications of incorporating anthropogenic water use in the hydrological model simulations of the Rhine basin

Anthropogenic water withdrawals have increased substantially due to socio-economic development, changes in consumption patterns, and population growth. Despite comprising a significant portion of available water resources and influencing water availability, anthropogenic water use is often not explicitly incorporated in hydrological models due to data limitations or restricted access. Hydrological models are often calibrated with observed discharge data which implicitly corrects  for this missing process. However, parameter calibration alone is insufficient to fully address the spatiotemporal variability of anthropogenic water use and its impact on hydrological fluxes and states. In this study, we evaluated hydrological fluxes and states in the Rhine basin as part of the Horizon Europe project STARS4Water. In a previous effort, we derived high resolution irrigation maps for the Rhine basin (Purnamasari et al., 2024). These derived irrigation maps are used in wflow_sbm to assess  and quantify agricultural water use in the Rhine river basin. In addition, the wflow_sbm model also accounts for other water use (e.g., domestic, industrial, livestock). We compare the hydrological fluxes and state variables of wflow_sbm with and without water use (including irrigation) against observations, such as discharge, total water storage and water table depth. Initial assessments show an improvement in model performance that is attributed to a reduction in systematic errors of the model. Analysis of hydrological flows also indicates that high flows and low flows are sensitive to assumptions regarding water withdrawals and return flows which has implications for the model predictive capacity for water management. Finally, we provide estimates of agricultural water use for the Rhine basin in comparison to other anthropogenic water use.

 

Purnamasari, D., Teuling, A. J., and Weerts, A. H.: Identifying irrigated areas using land surface temperature and hydrological modelling: Application to Rhine basin, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-1929, 2024.