Comparison of three methods for determining saturated soil hydraulic conductivity

Abstract

In this study three different methods were used for determining saturated soil hydraulic conductivity (k_s), constant head, Rosetta code and Wind Both Rosetta and Wind methods were compared with the reference method (hydraulic constant head). In addition, statistical tests using Root Mean Square Error (RMSE) and Mean Error (ME) were used to identify the best method. The results showed that the k_s estimated by both Rosetta and Wind methods were biased and underestimated comparing to the k_s measured by the reference method. The Wind method showed the least RMSE value of 0.38 cm.min^-1. Moreover, the estimated k_s values was about 5% of the measured k_s values. Furthermore, the lowest ME value of -0.27 cm.min^-1 was also observed when using Wind method. On the other hand, despite the high correlation (r=0.88) between the measured and the predicted k_s values, when using Rosetta method, a great RMSE value of 0.67 cm. min^-1 are also found. Moreover, the estimated k_s values presented about 41.9% of the measured k_s values. More generally, employing both Wind and Rosetta methods for determining k_s, provides an uncertainties in k_s values. However, Wind method appears to be the best for obtaining a reasonable estimate of k_s.