Spatial variability in streambed hydraulic conductivity of contrasting stream morphologies: channel bend and straight channel

Streambed hydraulic conductivity is one of the main factors controlling variability in surface water‐groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kₕ) were theref...

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Bibliographic Details
Published in:Hydrological processes 2015-01, Vol.29 (3), p.458-472
Main Authors: Sebok, E, Duque, C, Engesgaard, P, Boegh, E
Format: Article
Language:English
Subjects:
Bend properties
Channels
Fluid dynamics
Fluid flow
hydraulic conductivity
Hydraulics
hydrology
Mathematical analysis
sediments
spatial and temporal variability
Straight channels
stream channels
stream morphology
streambed hydraulic conductivity
Streambeds
Streams
temporal variation
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Summary:Streambed hydraulic conductivity is one of the main factors controlling variability in surface water‐groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kₕ) were therefore determined from in‐stream slug tests, vertical hydraulic conductivities (Kᵥ) were calculated with in‐stream permeameter tests and hydraulic heads were measured to obtain vertical head gradients at eight transects, each comprising five test locations, in a groundwater‐dominated stream. Seasonal small‐scale measurements were taken in December 2011 and August 2012, both in a straight stream channel with homogeneous elevation and downstream of a channel meander with heterogeneous elevation. All streambed attributes showed large spatial variability. Kₕvalues were the highest at the depositional inner bend of the stream, whereas high Kᵥvalues were observed at the erosional outer bend and near the middle of the channel. Calculated Kᵥvalues were related to the thickness of the organic streambed sediment layer and also showed higher temporal variability than Kₕbecause of sedimentation and scouring processes affecting the upper layers of the streambed. Test locations at the channel bend showed a more heterogeneous distribution of streambed properties than test locations in the straight channel, whereas within the channel bend, higher spatial variability in streambed attributes was observed across the stream than along the stream channel. Copyright © 2014 John Wiley & Sons, Ltd.
ISSN:0885-6087
1099-1085
DOI:10.1002/hyp.10170