Structurally optimized modeling of non-linear effects of meteorological extreme events on water and solute dynamics

DFG FOR 562 TP 4

Structurally optimized modeling of non-linear effects of meteorological extreme events on water and solute dynamics

Groundwater and stream water quality are affected by a multitude of processes that act at different scales and often interact in highly non-linear ways. As a consequence, the effects of anthropogenic impacts and natural variability, e.g. interanual climatic variability and long-term climate change are difficult to differen-tiate. Often, a few single events are much more decisive for the system’s behavior than long-term mean conditions. That renders a sound assessment of the impacts of expected climate change, including changing frequencies and intensities of meteorological extreme events, on water quality difficult. The Lehstenbach watershed has been the focus of numerous biogeochemical process studies and extensive monitoring since 1986. The obtained data provide an ideal basis for studying the interplay between different processes, linking upslope soil and groundwater bodies with riparian wetlands and streams. Using non-linear statistics, a methodology has been developed and applied to the data that allows an identi-fication of prevailing processes at the watershed scale. This information shall be used to optimize model structure (processes and data explicitly included in the model) of a physically based, numerical watershed model for water flow, solute transport and turnover that would allow an integration of the findings of single process studies at the watershed scale.

The optimized model can be used to study the effect of recent climatic variability on watershed solute turnover, and thus provide a tool for scenario analyses. As such it can help to link the findings of the different working groups of the Forscher¬gruppe 562 into an integral description of total system’s water flow and solute transport behavior.