Assessing Nature-Based Infiltration Solutions through hydrological modelling to identify suitable areas for groundwater recharge and potential water quality benefits

Groundwater recharge is a major challenge for the sustainable management of water resources, particularly in territories facing increasing water stress linked to climate change and anthropogenic pressures. Nature-Based Solutions (NbS), particularly Nature Water Retention Measures (NWRM), represent a promising approach to enhance natural infiltration processes, with potential benefits for groundwater quality and the territorial resilience.

This study is part of an exploratory approach aimed at analyzing the potential of NbS to promote groundwater recharge at the scale of a rural watershed, located in southern France and characterized by a Mediterranean climate with recharge predominantly driven by precipitation. The objective is to identify suitable areas for the future implementation of NbS and to assess their effects on groundwater recharge and water quality.

The methodology is founded on a scenario-based hydrological modeling approach at the watershed scale, using the SWAT+ model and relying on the integration of spatial data, including topography, soil properties, vegetal cover type, land use. The watershed is discretized into homogeneous hydrological response units (HRUs) in order to coherently represent the main characteristics and associated hydrological processes. Climatic data are then integrated into the model to represent the meteorological conditions required for hydrological simulations. The model is first calibrated using in situ measured discharge data. Sensitivity analyses will allow to identify the parameters that most strongly influence the hydrological functioning of the watershed.

In a second phase, nature-based land management scenarios focusing on NWRM will be simulated, including in particular the implementation of hedgerows and ditches, as well as infiltration basins, in order to assess their potential to improve groundwater recharge compared to a reference situation.