Spatial planning for lowland stream basins using a bioeconomic model

Most lowland stream drainage-basins have a high population density and the land use is very intensive. The permeable subsoil acts as an integrating medium, thus providing a widespread dispersal of leached nutrients and transmission of water-table lowering. This leads to eutrophication and desiccation of stream ecosystems. For providing suggestions with respect to cost-effective and sustainable spatial planning solutions, the ‘Waterwise’ bioeconomic model has been developed. It combines the accuracy of simulation models with the versatility of optimization techniques to generate land-use patterns along with the appropriate water management, taking into account the preferences of stakeholders with respect to peak discharges, nutrient loading on groundwater and surface water, the biological value of nature areas, and the revenue from agriculture. Computational experiments with the model show, for instance, that a certain goal for the nitrogen load on surface water can be reached at a 40% lower cost if the measures are ‘tailored’ to the region instead of using generic-style measures towards the same end.