Floodplains are important landscape elements connecting streams with their catchment. While strong gradients of biogeochemical parameters are often observed in organic-rich floodplain sediments, the strength of groundwater flow through reducing sediments determines how important these zones are for the receiving water body.
The floodplain of River Ammer between Pfäffingen and Tübingen is fairly typical for the hilly landscapes found in Triassic geology. Like in many other cases, the hydrology of this floodplain is poorly understood regarding three main aspects:
- Origin and flow paths of water parcels collected by the drainage channels are not known.
- The lateral extent of the subsurface catchment is unclear. Groundwater recharge in the Ammer valley contributes to an unknown extent to the subsurface catchment of the adjacent Neckar-valley aquifer.
- The strength of groundwater flow in the main direction of the valley is also unclear. The latter requires a hydraulically continuous and conductive body, acting as aquifer, connected to the river or the drainage channels.
These hydrological factors influence the fate of nitrate and other pollutants introduced at the hillslopes and in the floodplain of the Ammer valley. They are determined by the internal structure of the floodplain sediments and their hydraulic properties.
