Influence of Streambed Heterogeneity on Hyporheic Flow and Sorptive Solute Transport

Water

Yuanhong Liu¹  Lianqing Xue¹  CoreyD. Wallace²  Reza Ershadnia²  Faranak Behzadi²  MohamadReza Soltanian²  Dipankar Dwivedi³  YaoQuan Zhou⁴ 

[1] College of Hydrology and Water Resources, Hohai University, 211100 Nanjing, China;Department of Geology, University of Cincinnati, Cincinnati, OH 45220, USA;Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA;School of Earth Sciences, The Ohio State University, Columbus, OH 43210, USA;

关键词: hyporheic exchange;    riverbed heterogeneity;    solute transport;    sorption;    mixing;   

DOI  :  10.3390/w12061547

来源: DOAJ

【 摘 要 】

The subsurface region where river water and groundwater actively mix (the hyporheic zone) plays an important role in conservative and reactive solute transport along rivers. Deposits of high-conductivity (K) sediments along rivers can strongly control hyporheic processes by channeling flow along preferential flow paths wherever they intersect the channel boundary. Our goal is to understand how sediment heterogeneity influences conservative and sorptive solute transport within hyporheic zones containing high- and low-K sediment facies types. The sedimentary architecture of high-K facies is modeled using commonly observed characteristics (e.g., volume proportion and mean length), and their spatial connectivity is quantified to evaluate its effect on hyporheic mixing dynamics. Numerical simulations incorporate physical and chemical heterogeneity by representing spatial variability in both K and in the sediment sorption distribution coefficient (). Sediment heterogeneity significantly enhances hyporheic exchange and skews solute breakthrough behavior, while in homogeneous sediments, interfacial flux and solute transport are instead controlled by geomorphology and local-scale riverbed topographies. The hyporheic zone is compressed in sediments with high sorptive capacity, which limits solute interactions to only a small portion of the sedimentary architecture and thus increases retention. Our results have practical implications for groundwater quality, including remediation strategies for contaminants of emerging concern.

【 授权许可】

Unknown