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

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

doi:10.1016/j.jhydrol.2012.05.037

Cited by 38 publications

(32 citation statements)

References 35 publications

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“…Higher average percentages of sand and lower percentages of silt and clay generally generated a larger average median grain size, corresponding to higher Kv values (Table 3, Figure 3a,b). The present study showed high content of slit and clay corresponded to low Kv values (Figure 7), which was consistent with the results by Dong [35]. A negative power relation between the proportion of fine grains and hydraulic conductivity was also found by Miller [36].…”

Section: Sediment Grain Sizesupporting

confidence: 92%

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Song

Jiang

et al. 2017

Preprint

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Abstract:Channel bends are one of the most important characteristic features of natural streams. These bends often create the conditions for a hyporheic zone, which has been recognized as a critical component of stream ecosystems. The streambed vertical hydraulic conductivity (Kv), vertical hydraulic gradient (VHG) and Darcian flux (DF) in the hyporheic zone were estimated at 61 locations along a channel bend of the Beiluo River during July 2015 and January 2016. All the streambed attributes showed great spatial variability along the channel bend. Both upward fluxes and downward fluxes occurred during the two test periods, most of studied stream sections were controlled by downwelling, indicating stream water discharge into the subsurface. The average downward flux was higher at the downstream side than at the upstream side of the channel bend, especially in July 2015. The distribution of streambed sediment grain size has a significant influence on the variability of Kv; high percentages of silt and clay sediments generally lead to low Kv values. Higher Kv at the depositional left bank at the upstream site shifted toward the erosional right bank at the downstream site, with Kv values positively correlated with the water depth. This study suggested that the variabilities of Kv and VHG were influenced by the stream geomorphology and that the distribution of Kv was inversely related, to a certain extent, to the distribution of VHG across the channel bend. Kv and VHG were found to have opposite effects on the DF, and the close relationship between Kv and DF indicated that the water fluxes were mainly controlled by Kv.

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Section: Sediment Grain Sizesupporting

confidence: 92%

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Song

Jiang

et al. 2017

Preprint

View full text Add to dashboard Cite

show abstract

“…Higher average percentages of sand and lower percentages of silt and clay generally generated a larger average median grain size, corresponding to higher K v values (Table 3, Figure 3a,b). The present study showed high content of slit and clay corresponded to low K v values (Figure 7), which was consistent with the results by Dong [35]. A negative power relation between the proportion of fine grains and hydraulic conductivity was also found by Miller [36].…”

Section: Sediment Grain Sizesupporting

confidence: 92%

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Song

Jiang

et al. 2017

Water

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Abstract:Channel bends are one of the most important characteristic features of natural streams. These bends often create the conditions for a hyporheic zone, which has been recognized as a critical component of stream ecosystems. The streambed vertical hydraulic conductivity (K v ), vertical hydraulic gradient (VHG) and Darcian flux (DF) in the hyporheic zone were estimated at 61 locations along a channel bend of the Beiluo River during July 2015 and January 2016. All the streambed attributes showed great spatial variability along the channel bend. Both upward fluxes and downward fluxes occurred during the two test periods, most of studied stream sections were controlled by downwelling, indicating stream water discharge into the subsurface. The average downward flux was higher at the downstream side than at the upstream side of the channel bend, especially in July 2015. The distribution of streambed sediment grain size has a significant influence on the variability of K v ; high percentages of silt and clay sediments generally lead to low K v values. Higher K v at the depositional left bank at the upstream site shifted toward the erosional right bank at the downstream site, with K v values positively correlated with the water depth. This study suggested that the variabilities of K v and VHG were influenced by the stream geomorphology and that the distribution of K v was inversely related, to a certain extent, to the distribution of VHG across the channel bend. K v and VHG were found to have opposite effects on the DF, and the close relationship between K v and DF indicated that the water fluxes were mainly controlled by K v .

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“…This winnowing process sorts streambed sediments and leaves coarse materials in streambeds. As a result, the hydraulic conductivity becomes larger in the top layer of streambeds (Dong et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Gaining and losing stream reaches have opposite hydraulic conductivity distribution patterns

Chen

Dong

et al. 2013

Hydrol. Earth Syst. Sci.

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Abstract. In gaining streams, groundwater seeps out into the streams. In losing streams, stream water moves into groundwater systems. The flow moving through the streambed sediments under these two types of hydrologic conditions is generally in opposite directions (upward vs. downward). The two opposite flow mechanisms affect the pore size and fine particle content of streambeds. Thus it is very likely that the opposite flow conditions affect the streambed hydraulic conductivity. However, comparisons of the hydraulic conductivity (K) of streambeds for losing and gaining streams are not well documented. In this study, we examined the K distribution patterns of sediments below the channel surface or stream banks for the Platte River and its tributaries in Nebraska, USA. Two contrasting vertical distribution patterns were observed from the test sites. In gaining reaches, hydraulic conductivity of the streambed decreased with the depth of the sediment cores. In losing reaches, hydraulic conductivity increased with the depth of the sediment cores. These contrasting patterns in the two types of streams were mostly attributed to flow directions during stream water and groundwater exchanges. In losing reaches, downward movement of water brought fine particle into the otherwise coarse sediment matrix, partially silting the pores. For gaining reaches, upward flow winnowed fine particles, increasing the pore spacing in the top parts of streambeds, leading to higher hydraulic conductivity in shallower parts of streambeds. These flux directions can impact K values to depths of greater than 5 m. At each study site, in situ permeameter tests were conducted to measure the K values of the shallow streambed layer. Statistical analyses indicated that K values from the sites of losing reaches were significantly different from the K values from the sites of gaining reaches.

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

Cited by 38 publications

References 35 publications

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Variability of Darcian Flux in the Hyporheic Zone at a Natural Channel Bend

Gaining and losing stream reaches have opposite hydraulic conductivity distribution patterns

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