Comparison of vertical hydraulic conductivity in a streambed-point bar system of a gaining stream

Weihong Dong, Xunhong Chen, Zhaowei Wang, Gengxin Ou, Can Liu

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Vertical hydraulic conductivities (. K v) of both streambed and point bars can influence water and solute exchange between streams and surrounding groundwater systems. The sediments in point bars are relatively young compared to the older sediments in the adjacent aquifers but slightly older compared to submerged streambeds. Thus, the permeability in point bar sediments can be different not only from regional aquifer but also from modern streambed. However, there is a lack of detailed studies that document spatial variability of vertical hydraulic conductivity in point bars of meandering streams. In this study, the authors proposed an in situ permeameter test method to measure vertical hydraulic conductivity of the two point bars in Clear Creek, Nebraska, USA. We compared the . K v values in streambed and adjacent point bars through 45 test locations in the two point bars and 51 test locations in the streambed. The . K v values in the point bars were lower than those in the streambed. Kruskal-Wallis test confirmed that the . K v values from the point bars and from the channel came from two statistically different populations. Within a point bar, the . K v values were higher along the point bar edges than those from inner point bars. Grain size analysis indicated that slightly more silt and clay particles existed in sediments from inner point bars, compared to that from streambed and from locations near the point bar edges. While point bars are the deposits of the adjacent channel, the comparison of two groups of . K v values suggests that post-depositional processes had an effect on the evolution of . K v from channel to point bars in fluvial deposits. We believed that the transport of fine particles and the gas ebullition in this gaining stream had significant effects on the distribution of . K v values in a streambed-point bar system. With the ageing of deposition in a floodplain, the permeability of point bar sediments can likely decrease due to reduced effects of the upward flow and gas ebullition.

Original languageEnglish (US)
Pages (from-to)9-16
Number of pages8
JournalJournal of Hydrology
Volume450-451
DOIs
StatePublished - Jul 11 2012

Keywords

  • Fine particle transport
  • Gaining stream
  • Gas ebullition
  • Point bar
  • Vertical hydraulic conductivity

ASJC Scopus subject areas

  • Water Science and Technology

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