Factors affecting the measurement of the vertical hydraulic conductivity of a streambed sediment using standpipe tests

摘要

The vertical hydraulic conductivity () of a stream or lake sediment is often determined in the field using standpipe tests. Calculation of is based on the assumption that the hydraulic head in the pipe is equal to that of the stream or lake stage. In this work, a modified equation for is developed for the standpipe test which is applicable when this assumption is not valid. The equation involves not only the hydraulic head at different times but also the difference in the hydraulic head () between the groundwater level and river stage. The effects of certain factors on , such as the ratio of the hydraulic head at different times (/), the difference , and the initial water table height (), are also discussed. The results show that when / is constant, the relative error () in increases with the ratio /. Furthermore, if /  <  0.05, then for any value of /, is less than 5% using the modified equation. Also, if / is large, hydraulic head readings with larger / ratios must be used to avoid large values. The results of a field test also indicate that the error in decreases as the value of increases. Copyright © 2013 John Wiley & Sons, Ltd.