Impact of a low-permeability lens on dune-induced hyporheic exchange

ABSTRACT

Hyporheic exchange induced by dunes is a key process controlling water fluxes and biogeochemical processes in river networks. Owing to the limitations of instrumental detection at small spatial scales, previous studies have focused mainly on dune-induced hyporheic exchange in homogeneous systems. A low-permeability lens is a natural, widespread heterogeneity in stream beds, and probably affects the processes of water flow and contaminant transportation significantly. To quantitatively analyse the response mechanism of hyporheic exchange to a low-permeability lens, a two-dimensional dune-generated hyporheic exchange model was developed using the VS2DH model. The results indicate a lens in a stream bed can hinder or enhance hyporheic exchange processes, depending on its relative spatial location to dunes. Both the increase in length and thickness of the lens could strengthen its impacts on hyporheic exchange. Regional groundwater–surface water interactions of higher intensity suppress the flow of hyporheic exchange in a stream bed with a low-permeability lens.

KEYWORDS:

• low-permeability lens
• dune
• hyporheic exchange
• VS2DH

Editor A. Castellarin Associate editor A. Fiori

Editor A. Castellarin Associate editor A. Fiori

Acknowledgements

The authors would like to express their appreciation for the suggestions and edits provided by Professor Andrew Binley, Lancaster University, UK. The authors also would like to express their appreciation to the suggestions and comments provided by Dr Kuangjia Li, Tianjin University. The data for the numerical model can be obtained from the corresponding author (contact: [email protected]).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant no. 41201029 and 41572210], the Fundamental Research Funds for the Central Universities of China [Grant no. 2015B14414 and 2016B40114], and the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin [Grant no. IWHR-SKL-201502]. The authors would like to acknowledge the financial support provided by the China Scholarship Council.