Conceptual model-based approach for improved monitoring network design, Ammer River valley floodplain, southwest Germany

Simon Martin1, Stefan Klingler1
1 Centre of Applied Geoscience, University of Tübingen

O 19.7 in Forum Junge Hydrogeologen

21.03.2018, 14:00-14:15, 3

The fate and behavior of anthropogenic pollutants on the catchment scale is poorly understood. CAMPOS (Catchment as Reactors: Metabolism of Pollutants on the Landscape scale) is a multi-disciplinary research project aimed at investigating the biogeochemical turnover within critical catchment landscape features, such as floodplains. Typical modern river valleys in humid areas with low topographic gradient show high content of fine sediments in wide floodplain areas. Such fluvial depositional environments are highly variable in both vertical and lateral direction, hence a detailed knowledge on the subsurface structure is necessary to assess the preferential pathways of groundwater flow and solute transport. The floodplain under investigation, located in the Ammer River valley near Tübingen, represents a typical fluvio-lacustrine sedimentary setting in floodplains, where a thick postglacial Quaternary valley fill overlies a Triassic bedrock. The preliminary site characterization involved a collaborative approach of geological, hydrogeological and hydrogeophysical field methods, investigating two partially separated groundwater systems. Multi-scale heterogeneity and high contents of fine sediments presented challenges for the commonly applied hydrogeological and geophysical field techniques. Furthermore, the ability to draw meaningful interpretations from the preliminary results were strongly limited by gaps in accurate conceptual knowledge concerning the floodplain boundary conditions. For this reason, a forward modeling exercise was undertaken to aid in the planning of efficient field campaigns in the future. By identifying the data-critical regions and providing insight to measurable contrast of parameters of interest, this exercise looked to better guide the choice of field methods for the future campaigns. The results of the forward modelling highlight the importance of having a conceptual model-driven approach when planning monitoring networks and choice of field methods. Within the study site, the data-critical regions were identified as areas where data is scarce and possible unidentified boundary conditions exist for the groundwater flow system. Subsequent field campaigns will look to target these data-critical regions and further investigate their control on the regional groundwater flow and solute transport within the floodplain.

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