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

地下水和溪流水质受到多种过程的影响，这些过程在不同的尺度上起作用，而且往往以高度非线性的方式相互作用。因此，很难区分人为影响和自然变异的影响，例如年际气候变异和长期气候变化。通常，一些单一事件比长期平均条件对系统行为更具决定性。这使得对预期气候变化的影响，包括气象极端事件的频率和强度的变化，对水质的影响进行合理的评估变得困难。所获得的数据提供了一个理想的基础，研究不同的过程之间的相互作用，连接上坡土壤和地下水体与河岸湿地和溪流。使用非线性统计，方法已经开发和应用的数据，允许在流域尺度上的流行过程的识别。该信息应用于优化水流、溶质运移和周转的物理流域数值模型的模型结构（模型中明确包含的过程和数据），该模型应能整合流域尺度上单一过程研究的结果。优化后的模型可用于研究近期气候变化对流域溶质周转的影响，从而为情景分析提供工具。因此，它可以帮助连接的研究小组的不同工作组的结果，成为一个完整的描述整个系统的水流和溶质运移行为。

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 longterm climate change are difficult to differentiate. 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 identification 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 Forschergruppe into an integral description of total system's water flow and solute transport behavior.