The project simulated and visualised the impact of land use changes with the STOFFBILANZ model and the WebLand tool. The functionalities, areas of application and results achieved were intensively discussed and tested together with the South African partners. In the WebLand tool, the user can select additional areas beyond the influences of land use change in the western sub-area shown here as an example and check them with regard to the changes to be expected in terms of land use change (also freely selectable). The results show that even a small expansion of the land uses "urban" and "cropland" have a significant effect on P and N concentrations. The driver for this increase is the assumed increase in the areas of unplanned settlements as well as wastewater discharge due to the increased number of inhabitants in these regions. The results of the PNV scenario again show that the natural background levels for sediment, N and P are low and thus there is likely to be a particular threat to the fynbos vegetation, which is highly worthy of protection, due to the increased nutrient input. Sustainable management of water resources is a prerequisite for socio-economic development of societies. However, especially through land use, water resources - and often also soil resources - are adversely affected, causing considerable socio-economic and ecological damage. As part of a project in the BMBF initiative SPACES (Science Partnerships for the Assessment of Complex Earth System Processes) on nearshore groundwater and the transfer of groundwater to the ocean (SGD = Submarine Groundwater Discharge) in the Western Cape Province, South Africa, a web-based simulation tool was developed in subproject D in cooperation with the Gesellschaft für angewandte Landschaftsforschung (GALF), Dresden. The tool can be used to identify areas with a potentially negative impact on water resources through land use and to simulate the effect of future land use changes. The developed tool is characterised by its ease of use and high transparency. Land use in the study areas in the Western Cape is dominated by natural fynbos vegetation, followed by arable land, forestry, settlement and forest. Viticulture and fruit growing are found especially in the Stellenbosch area. On arable land, mainly winter wheat, field grass or fodder legumes are cultivated