Wetlands in brook catchments: Modelling land-use change and its impact on soil organic carbon (2010 – 2020 – 2050)

Nature-based solutions (NbS) in brook catchments, for example wetlands, are considered as climate measures to adapt to hydrometeorological weather extremes (storms, floods, droughts) and human-induced water demand. Furthermore, NbS can also contribute to carbon sequestration. However, implementing wetlands in brook catchments is entangled in anthropogenic land-use change (LUC) and it is unknown how this effects soil organic carbon (SOC). To elucidate this, a system analysis based on 2010 and 2020 of a brook catchment (Dutch Aa/Weerijs; 147 km2; S of Breda) determines the spatio-temporal dynamics of LUC towards 2050 and its connection to SOC including the climate mitigation impact of wetlands. Spatio-temporal in-situ soil datasets are used to establish SOC stocks for nine land-use categories while considering the interdependence between soil specific SOC, land-use, and management practices. For the 2050 land-use outlook, LUC between 2010 and 2020 served as input. Land-use developments are determined by machine learning and a neural network (TerrSet 2020 - Land Change Modeler). Land-use has been predicted in a Technical-physical scenario (LUC development considering the trends between 2010 and 2020) and a NbS/Wetlands scenario (LUC development with emphasis on wetlands) Findings indicate: (1) For the Technical-physical scenario a minor increase of SOC. Tree nursery especially emerges in the catchment. (2) For the NbS/Wetlands scenario, which emphasizes wetlands, a major increase of SOC. Wetlands especially emerges in the catchment. This modelling approach, based on existing soil and land-use datasets, could help rapid outlook studies and opportunity mapping to model different types of local measures and other NbS.