The Influences of a Clay Lens on the Hyporheic Exchange in a Sand Dune
1
State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, Jiangsu, China
2
Water Resources Service Center of Jiangsu Province, Nanjing 210029, Jiangsu, China
3
Hydraulic Research Institute of Jiangsu Province, Nanjing 210017, Jiangsu, China
*
Author to whom correspondence should be addressed.
Water 2018, 10(7), 826; https://doi.org/10.3390/w10070826
Received: 4 April 2018 / Revised: 19 June 2018 / Accepted: 20 June 2018 / Published: 22 June 2018
(This article belongs to the Special Issue Recent Progress in River Biogeochemistry Research)
Abstract
A laboratory flume simulating a riverbed sand dune containing a low-permeability clay lens was constructed to investigate its influence on the quality and quantity of hyporheic exchange. By varying the depths and spatial locations of the clay lens, 24 scenarios and one blank control experiment were created. Dye tracers were applied to visualize patterns of hyporheic exchange and the extent of the hyporheic zone, while NaCl tracers were used to calculate hyporheic fluxes. The results revealed that the clay lens reduces hyporheic exchange and that the reduction depends on its spatial location. In general, the effect was stronger when the lens was in the center of the sand dune. The effect weakened when the lens was moved near the boundary of the sand dune. A change in horizontal location had a stronger influence on the extent of the hyporheic zone compared with a change in depth. The size of the hyporheic zone changed with the depth and position of the clay lens. There was a maximum of hyporheic extent with the lens at a depth of 0.1 m caused by changes of water flow paths. View Full-TextKeywords:
hyporheic exchange; clay lens; sand dune; tracer experiment
▼
Figures
Figure 1
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
Share & Cite This Article
MDPI and ACS Style
Lu, C.; Yao, C.; Su, X.; Jiang, Y.; Yuan, F.; Wang, M. The Influences of a Clay Lens on the Hyporheic Exchange in a Sand Dune. Water 2018, 10, 826.
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.