The effect of long-term irrigation with municipal treated wastewater on the saturated hydraulic conductivity of a silt loam soil and its estimation- a case study

Treated wastewater may influence soil structure, porosity and as a consequence soil saturated hydraulic conductivity. Main aims of this investigation were to assess the effect of wastewater on saturated hydraulic conductivity; and to determine the suitable soil solids fractal dimension to incorporate into the pedotransfer function by Rawls et al (1993) for estimation of saturated hydraulic conductivity (Ks). Soil saturated hydraulic conductivity was measured by disc permeameter. Soil particle fractal dimension was calculated from linearized forms of mass-time, mass-diameter and mass-diameter as modified by Kravchenko-Zhang (1998) relations. Wastewater irrigation for 13 years increased the saturated hydraulic conductivity three folds from 7 mm/hour to 21 mm/hour, but longer application of wastewater did not further increase it. Rawls et al (1993) pedotransfer produced acceptable and relatively close saturated hydraulic conductivity values to that of disc permeameter when fractal dimension obtained from the linearized forms of mass-diameter and Kravchenko-Zhang relations were used. Therefore, Rawls et al (1993) pedotransfer was capable of reflecting the effect of wastewater application on soil saturated hydraulic conductivity