Integrating Wetlands and Riparian Zones in Regional Hydrological Modeling

Wetlands, and in particular riparian wetlands, are at the interface between well drained land and the aquatic environment, where they control the exchange of water and related chemical fluxes from catchment areas to surface waters like lakes and streams. Integrating wetlands and riparian zones in regional hydrological modeling is challenging because of the complex interactions between soil water, groundwater and surface water. The model must be able to reproduce the special hydrologic processes in wetlands like groundwater dynamics, plant water and nutrient uptake, nutrient degradation and leaching to surface waters. An additional problem at the regional scale is the identification of riparian zones based on regionally available data. The model used in this study is the eco-hydrological model SWIM (Soil and Water Integrated Model), in which a riparian zone and wetland module was incorporated. SWIM was chosen because it integrates the hydrological processes, vegetation, erosion and nutrient dynamics which are relevant at the watershed scale. The study shows simulation results of river discharge, groundwater dynamics and plant groundwater uptake and first results of simulated nutrient fluxes in wetlands.