MATEC Web Conf.
Volume 246, 20182018 International Symposium on Water System Operations (ISWSO 2018)
|Number of page(s)||11|
|Section||Main Session: Water System Operations|
|Published online||07 December 2018|
Spatial Variability Pattern of Hyporheic Exchange in a braided River
1 Department of water resources, Changjiang River Scientific Research Institute, Wuhan, Hubei, China
2 Hubei Key Laboratory of watershed water resources and ecological environment, Changjiang River Scientific Research Institute, Wuhan, Hubei, China
3 Changjiang Institute of Survey, Planning, Design and Research, Wuhan, Hubei, China
The streambed flux is variable in space; the spatial variability results in part from bedforms, but few works on streambed fluxes in channels with strongly abrupt varying bedforms are carried out. Heat as a tracer to delineate the streambed flux pattern has been widely adopted in numerous fields. In this paper, a braided channel with complicated topography was selected as study site, where the temperature was monitored. One-dimensional (1-D) analytical method based on the amplitude attenuation (Ar) and 1-D numerical method were used to interpret the temperature. As a result, streambed fluxes of a total of 50 sites in the braided channel are obtained. From the results we can know the magnitude and direction of streamed flow velocity are spatially variable, even within a 1-m distance. Then, this study summarizes five bedform-driven flux patterns: ① downward flow driven by the head difference between groundwater and stream, ② downward flow related to a meter-scale pool, ③ a transition from upward to downward flow associated with a centimeter-scale riffle, ④ horizontal flow in braided bars and ⑤ upward flow driven by vegetation roots. Overall, multiple physical mechanisms together contributed to the complex streambed flow system, which reflected great challenges for the scaling up of point-in-space seepage flux.
© The Authors, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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