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

摘要

This study demonstrates the spatial and temporal variations of streambed vertical hydraulic conductivity K v from October 2011 to November 2014 along the Weihe River, the largest tributary of the Yellow River. The streambed K v 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 K v 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 K v values are neither normally nor log-normally distributed, but display significant spatial variability among the five test sites. The highest K v values occur at the site with mainly sandy sediment, while the K v 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 K v values from all of the sites exhibit no statistically significant temporal trends. However, the median K v 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 K v values decrease with depth.