DEVELOPMENT OF SOIL MOISTURE RETENTION AND CONDUCTIVITY RELATIONSHIP

Abstract

Soil moisture and conductivity relationship is one of the major portion in Hydraulic Engineering. Soil moisture is the relationship between moisture content (o) and pressure head (si). Moisture content is obtained by applying a soil sample in a calculated volume into pressure plate apparatus, the soil is in saturated state when it is apply on pressure plate apparatus. After removal of soil from the apparatus it is keep in owan for 24 hours and then moisture content can be calculated. While in conductivity relationship a sample of soil whose conductivity has been found filled in the tank. With the different discharge we can found the different pressure head and different hydraulic conductivity. It has been experimentally observed that the unsaturated soil hydraulic properties estimated from field measured data usually show large variability because of measurement of errors and natural spatial heterogeneity exhibited by many field soils. In such situations, a probabilistic approach is necessary to account for this uncertainty in parameters whereby the coefficients in the resulting partial differential equations are treated as random quantities. Soil in the unsaturated zone is characterized by the presence of voids which are partly filled with water and partly with air. Water is held in the voids due to the surface tension forces. The pressure in the unsaturated zone is always less than atmospheric pressure. The flow in the unsaturated zone is basically a multiphase flow i.e., both air and water move simultaneously in the void space. Movement of water vapour also takes place.