Ecohydrological modelling to assist decision making for land- and water management: applications from The Netherlands

Ecohydrological modelling to assist decision making for land- and water management: applications from The Netherlands Biodiversity in nature areas is severely declining on both global and European levels. Many species and ecosystems are threatened by climate change, desiccation due to lowering groundwater levels and high nitrogen deposition. The Natura 2000 Network, a European-wide network of nature conservation areas, has been created to preserve and restore biodiversity. Ecohydrological processes are a key factor in the conservation of vegetation in nature areas. The relative impact of hydrological measures on biodiversity and vulnerable species is poorly understood in these nature areas, especially when uncertainty associated with climate change is taken into account. This knowledge gap delays decision making for land and water management. This study demonstrates a ecohydrological modelling approach to quantify the impact of hydrological changes on  vegetation. In recent years, research has been done at KWR Water Research Institute in collaboration with several partners [1] to construct ecohydrological models that include the process-based relationships between water-related habitat factors and vegetation types. These models are currently applied at various spatial scales (local to national) to support decision making. The Water Vision Nature (WWN, in Dutch: Waterwijzer Natuur) is a tool including the model PROBE (PRObability-Based Ecological target model) to simulate the impact of water management, climate change and nitrogen deposition on terrestrial vegetation. PROBE uses the waterlevel output of a groundwater model to calculate the important habitat factors oxygen and transpiration stresses of the vegetation. Additionally, the habitat factors nutrient availability and acidity are derived from output of the hydroloigical model and soil factors. Next, these values are translated into vegetation indicator values for moisture, nutrients and acidity, respectively, by using empirical relationships. PROBE uses these values to predict the occurrence of vegetation types and the botanical nature value of these vegetation types. To analyse the potential impact of the ecohydrological outlined approach on decision making in land and water management, WWN has been applied to evaluate local restoration and management plans of Natura 2000 areas in the Netherlands. These studies show that the process-based ecohydrological model PROBE is a useful method to analyse future management scenarios in nature areas by taking into account both water management measures and climate change scenarios. [1] Wageningen University en Research , Stowa, Nutrient Management Institute (NMI) and Hoefsloot Spatial Solutions (HSS)