Assessment of permeability test results of susceptibility of utilizing water quality in prediction synthetic drainage envelope's mineral clogging potential

This research was carried out through laboratory tests by two physical models of permeameter. Considering the necessity of entranced water quality assessment in our laboratory tests, besides utilizing a sample of normal water by EC=0.78 dS/m and SAR=1.23 (mEq/lit)0.5, two samples of saline drainage water from Khorram-shahr area with EC=124, 22.2 dS/m and SAR=79.28, 26.27 (mEq/lit)0.5 and a sample of saline-sodic soil (EC= 169.3 dS/m and SAR=45.18 (mEq/lit)0.5) were also applied in permeability tests. A PP450 synthetic envelope which was suitable for the selected soil was applied. Permeability tests were implemented in 1, 2.5, 5, 7.5 and 10 hydraulic gradients in three replications and indicators as hydraulic conductivity and gradient ratio (GR) were measured and statistically investigated as factorial experiments in a form of randomized complete design. The results showed that gradient ratio was less than 1.0 in all tests; however, applying the highest water salinity resulted in its critical amount (1.0). Hence, the results demonstrate that the more salinity of water the lower the hydraulic conductivity. The average hydraulic conductivity was calculated 3.55 by applying normal waterand1.25 times of average hydraulic conductivity was measured via applying saline water with EC= 124 dS/m and EC= 22.2 dS/m. In sum, remarkable reduction of hydraulic conductivity of soil-envelope system and considerable increase of gradient ratio were obtained with applying higher saline water.