Modelling wetland processes in regional applications
2008
Hattermann, Fred F. | Krysanova, V. | Hesse, Cornelia
Wetlands represent an interface between the terrestrial environment and the surface water systems in river basins, functioning as important buffers and filters for water flow, sediments and dissolved nutrients, and pollutants. They mitigate impacts of floods, improve water quality in rivers, and reduce erosion. However, most model applications at the regional scale do not consider hydrological and eco-hydrological processes in wetlands. This study describes two approaches which allow integration of the most important wetland processes in hydrological and water quality models for regional applications. Both approaches consider water and nutrient fluxes, but they have different levels of complexity depending on data availability and objectives of the study. They are implemented in the model SWIM (Soil and Water Integrated Model). The first approach is rather simple, and can be introduced in a basin-scale ecohydrological model using two basic assumptions. This method illustrates how a very simple supply/demand approach can help to notably improve the modelling results in terms of seasonal river discharge and nutrient loads in catchments with a notable share of wetlands. The second, more advanced, approach is introduced at the level of hydrological response units (HRU) or hydrotopes, and takes into account fluctuations in groundwater table and hydrotope-related flow distances. This method allows for: (a) improving simulated water discharge in summer; (b) improving validation of nutrient-related processes; (c) estimating the impact of wetlands on water flow and nutrient load; and (d) better identification of areas in the catchment responsible for diffuse source pollution.
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