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Title (Primary) A systematic model-based evaluation of the influence of hydraulic conductivity, heterogeneity and domain depth on hyporheic nutrient transformation
Author Laube, G.; Schmidt, C.; Fleckenstein, J.H.
Journal Advances in Water Resources
Year 2022
Department ASAM; HDG
Volume 159
Page From art. 104087
Language englisch
Topic T5 Future Landscapes
Abstract The hyporheic zone provides opportunities for the turnover and removal of nutrients such as ammonium and nitrate from stream water. Hyporheic flow patterns and dynamics govern the transport of nutrients and other solutes through the hyporheic zone and in turn control their transformation and removal. To better understand the links between flow and turnover, we systematically studied nutrient turnover rates with simulated sets of idealized streambed domains which varied in domain depth, hydraulic conductivity, its heterogeneity and anisotropy. We show that both aerobic (e.g. nitrification) and anaerobic (e.g. denitrification) turnover rates generally decrease monotonically with decreasing sediment conductivity at sufficiently large hyporheic zone depth. However, a reduction of the domain depth leads to an optimum of anaerobic turnover rates at intermediate conductivity due to the rate or transit time limitations of the reaction at the far ends of the conductivity range. Furthermore, conductivity heterogeneity generally lowers the turnover rates of both aerobic and anaerobic reactions. It is demonstrated how to reproduce this reduced nutrient turnover in heterogeneous sediments via a simplified anisotropy, which facilitates the prediction of turnover rates in heterogeneous sediments in certain cases. Our results foster the understanding of the interplay between hyporheic exchange and nutrient transformations and they aim to facilitate the conceptualization of large scale numerical simulations by demonstrating the effect of study design decisions like domain extent, heterogeneity and anisotropy.
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=25512
Laube, G., Schmidt, C., Fleckenstein, J.H. (2022):
A systematic model-based evaluation of the influence of hydraulic conductivity, heterogeneity and domain depth on hyporheic nutrient transformation
Adv. Water Resour. 159 , art. 104087