International Environmental Modelling and Software Society (iEMSs)
Abstract
Abstract: The assessment of the ecological status of running waters at a mesohabitat scale is commonly based on fish. Nevertheless, due to their strong dependence on a good physical and chemical habitat, macroinvertebrate species can also be used for this assessment. A new approach is presented by applying the MesoCASiMiR module of the CASiMiR modeling system. In this way, the habitat suitability for the mayfly Baetis rhodani was modeled at a mesohabitat scale in the river Zwalm (Flanders, Belgium). The model inference system was based on fuzzy logic. Fuzzy variable sets and rules were derived from expert knowledge and from a database of biological samples. The suitability of the different mesohabitats for Baetis rhodani in the river Zwalm could be reliably described by three hydromorphological variables (depth, velocity and dominating substrate) and by the oxygen concentration. As a result, the habitat suitability was calculated and a habitat map of the studied reach was generated. Validation of this map was performed by biological samples at different sites along the reach, indicating that predicted habitat suitability was closely correlated to the observed abundances in most of the sampling sites. Due to the universality of the MesoCASiMiR module, the presented approach is applicable on other rivers and can be used for quick assessment of the ecological river status. This allows identification of the bottlenecks in the river basin and definition of restoration options. By adjusting the input parameters, the model can predict the impact of these restoration actions at a mesohabitat scale. Due to its transparent design and graphical user interface, the model has proved to be a useful tool for river management
