M Nakhaei,
Volume 8, Issue 4 (3-2015)
Abstract
For prediction of exact effect of soil temperature, soil water retention, unsaturated hydraulic conductivity and water flow of soils on seep development, information about soil hydraulic, physical properties soil temperature is necessary. In this study, using geophysical and thermal methods the hydraulic properties and thermal conductivity of unsaturated porous media was estimated. Infiltrated water temperature was 50° C and the temperature data used in inverse solution technique was recorded by 2 thermal sensors during 3255 sec. One of thermal sensor was installed at a depth of 50 cm and the soil hydraulic and thermal parameters were estimated using 48 collected data of the injection water temperature variations. In this research 121 geoelectrical sounding with the Wener, Schlumberger and polar-polar arrays configuration were used. Evaluation and interpretation of the sounding curves show that the water table is located at depth of 75 meters. Top alluvium layer (unsaturated zone) is composed of three layers. In this study, to investigate the distribution and diffusion of pollutants in the unsaturated zone, the brine concentration of 20 g/L was used. Wener and polar-polar arrays were used to detect and image the contaminants plume. The polar-polar configuration shows less spreading of contaminated plume in both vertically and horizontally direction than the Wener array. Particularly by the Wener configuration the plume depth is more underestimated than the real value. Based on water injection visibility in the vicinity of the trenches and observing the water seepage at the trench face, the real velocity of the water at direction of 35 degrees relative to the horizon was measured equal to 0.159 m/h. Horizontal and vertical contaminant plume expansion coefficient was determined equal to 1.4. Evaluation of thermal and hydraulic properties of unsaturated porous media was done by HYDRUS-2D software. In this study five hydraulic parameters &thetar, &thetas, &alpha, n and Ks and five soil heat transfer parameters including the &lambdaL, &lambdaT, Cn, Co and Cw were included in the parameter estimation process. After implementation of the parameter estimation (adjusted for observed and predicted temperature values) Coefficient of Determination R2 was equal to 0.97 and the objective function value was equal to 11.5. Computational error in the mass balance was about 67 percent.
