L.C.P.M. Stuyt

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.

Zouttolerantie van gewassen afhankelijk van het groeistadium?: Resultaten van een literatuuronderzoek

In order to answer the question to what extent the salt tolerance of agricultural crops is growth stage dependent, a literature study has been carried out. For the plant’s reaction to salt in the root zone, various mechanisms are responsible. They can be summarized in an osmotic effect and an ion effect, each with their own dynamics. The variability of salt tolerance at successive growth stages can only be addressed qualitatively. The lack of data collected under Dutch growth conditions means that cropwise quantification is not possible, and application in water management is problematic. New experiments are needed to get a finger behind the ‘genesis history’ of salt damage.