System analysis of water quality management for the Elbe river basin

A decision support system for integrated river basin management of the German part of the Elbe river basin (Elbe-DSS) is currently under development. It considers water quantity, chemical quality, and ecological status of surface waters. User needs were identified and refined by repeated consultation of water managers. A list of management objectives, measures, and external scenarios emerged, which was taken as the basis for the DSS development. A comprehensive system analysis was carried out to meet the various spatial and temporal scales when dealing with hydrologic, ecologic, economic, and social aspects related to water quantity and quality. System diagrams for the catchments and the river network were constructed. They describe the properties, processes, and data influencing the water flow and substance load. One model for the calculation of the long-term nutrient discharges in 132 sub-catchments from non-point sources, one simulation model for wastewater pathways (point sources) and aquatic fate assessment, and one model for hydrological dynamics were selected for integration into the Elbe-DSS. The interaction of management objectives, external scenarios of climate, agro-economic and demographic change, and selected measures to achieve the desired state of good water quantity and quality is investigated.