Spatial and Temporal Variations of Streambed Vertical Hydraulic Conductivity in the Weihe River, China

This study demonstrates the spatial and temporal variations of streambed vertical hydraulic conductivity Kv from October 2011 to November 2014 along the Weihe River, the largest tributary of the Yellow River. The streambed Kv values of a total number of 385 locations from five test sites were estimated on the basis of in situ falling-head standpipe permeameter tests. The difference of Kv values for all test locations reaches five orders of magnitude with a range from 5.87E-04 to 61.3 m/d and a median value of 1.62E-01 m/d. The streambed Kv values are neither normally nor log-normally distributed, but display significant spatial variability among the five test sites. The highest Kv values occur at the site with mainly sandy sediment, while the Kv values at the other four sites with mainly silt-clay sediment are relatively close and have less variability than those at the sandy sediment site. The median Kv values from all of the sites exhibit no statistically significant temporal trends. However, the median Kv values indeed show temporal variations that might be influenced by changes in silt-clay content of the sediment, especially for the sandy sediment site and the combined data from all sites. Weak evidence demonstrates that streambed Kv values decrease with depth.