The Significans Of The Hyporheic Zone For The Groundwater

The exchange between groundwater and channel flow takes place in the hyporheic zone as part of the river bed. This zone is relevant to numerous aspects in river ecology. Along a pool - riffle sequence at the River Lahn, a medium scaled river in Germany, a multidisciplinary research project has been established. The interaction between sur- face water, hyporheic zone and groundwater occur at a variety of temporal and spatial scales depending on the substrate permeability, hydraulic gradients in surface and sub- surface water bodies and the river bed morphology. Small, medium and large scale ex- change mechanisms are roughly separated by a numerical models, which are based on tracer experiments. The presentation will discus the question: How does the exchange processes in the hyporheic zone effect the groundwater? Effects of spatial variability on parameter estimation and prediction uncertainty will be discussed.