Due to the change in the environmental and socio-economic conditions, the various governing parameters for water quality, such as water abstraction or land use, are due to change in the coming decades. Which of these parameters will have a negative impact on water quality? What has to be done in order to achieve a sufficient level of water quality? The aim of this research project was to develop a prototype for a procedure to manage decision making. The prototype was to be used in two test areas. The objective was to study at the same time how water quality and ecological conditions could change in the future. To do this, a model chain was developed in which changes in the climate could be linked with effects on aquatic ecology. The forecasts from these models would then flow directly into the multi-criteria decision management system.
Four socio-economic scenarios and eight alternative plans of action were developed and tested in two medium-sized catchment areas on the Swiss Plateau (Gürbe, Mönchaltorfer Aa). The current situation was studied using existing data that was enhanced using information from a field study. Using the model simulation, it was possible to study the impact of socio-economic pre-conditions, alternative plans of action and climate change on water quality and the ecological water conditions.
Despite the significant forecasting uncertainty, the models clearly demonstrate that the future water conditions will primarily be determined by human activity in the catchment areas. The impact of climate change is no more than marginally apparent, and the changes can primarily be ascribed to higher temperatures. The forecasting uncertainty can primarily be ascribed to climate and ecological uncertainty in relation to precipitation, the use of chemicals and a lack of knowledge of the ecology of biodiversity.
From a management perspective, the significance of these results is that measures to improve the current ecological situation could also reduce most expected future problems. Measures against water pollution, both in urban areas and in the field of agriculture, are effective; maximum water temperatures can be reduced by planting trees at the water’s edge. However, the rise in average water temperatures is difficult to prevent.
The methods developed in this research project will be further explored in current and future projects. They will also be used by national working groups with experts from federal government and the cantons, and act as the basis for a practice-oriented course for hydrology specialists.
Integrated river water quality management (iWaQa)