Author(s): M. Noack; S. Wieprecht
Keywords: No Keywords
Abstract: The hyporheic zone plays an important role in both ecology and morphology, and is characterized by multifaceted interstitial processes. From the biological point of view, the interstitial zone between ground water and surface water plays a significant role in riverine ecosystems as many aquatic organisms have life-cycle stages related with the hyporheic zone. From a morphological point of view, the hyporheic interstitial is characterized by complex morphologic processes such as the interactions between river bed grain size composition and sediment-transport. The intrusion of fine sediments in the coarser river bed impacts both roughness characteristics and can also alter porosity and permeability. This may lead to a reduction of the intragravel flow which in turn has ecological effects. During the incubation period of salmonids, sufficient intragravel flow is required in terms of supply of dissolved oxygen and the rate of removal of carbon dioxide and metabolic waste. When describing the changes in habitat quality of the hyporheic zone, the challenge is to use output data of highly sophisticated morphodynamic models (3D) in order to describe the biological knowledge about habitat preferences in the hyporheic interstitial. Adaption and optimization of existing approaches (Fredle-Index, Sorting Coefficient, Porosity Models etc. ) or the combination with additional parameters such as the vertical hydraulic gradients must to be tested and correlated to counts of individual emerged fry. This research is based on a close collaboration with biologists to describe the exchange processes between interstitial and surface water from both the engineering and biological perspectives.