J. Rosas, K.Z. Jadoon, T.M. Missimer
Environmental Earth Sciences, volume 73, issue 3, pp. 1303-1315, (2014)
Measured hydraulic conductivity,
Empirical estimated hydraulic conductivity,
Grain size analysis,
Grain size distribution, porosity, and hydraulic conductivity were
determined for 39 sediment samples collected from ephemeral streams
(wadis) in western Saudi Arabia. The measured hydraulic conductivity
values were then compared to values calculated using 20 different
empirical equations commonly used to estimate hydraulic conductivity
from grain size analyses. It was found that most of the hydraulic
conductivity values estimated from the empirical equations correlated
very poorly with the measured hydraulic conductivity values.
Modifications of the empirical equations, including changes to special
coefficients and statistical offsets, were made to produce modified
equations that considerably improved the hydraulic conductivity
estimates from grain size data for wadi sediments. The Chapuis, Hazen,
Kozeny, Slichter, Terzaghi, and Barr equations produced the best
correlations, but still had relatively high predictive errors. The
Chapius equation was modified for wadi sediments by incorporating mud
percentage and the standard deviation (in phi units) into a new equation
that reduced the predicted hydraulic conductivity error to ±14.1 m/day.
The equation is best applied to ephemeral stream samples that have
hydraulic conductive values greater than 2 m/day.