ESTIMATION OF UNSATURATED SOIL PARAMETERS

Abstract

Unsaturated zone plays an important role in hydrological cycle because infiltration. subsurface flow, aquifer recharge etc. occurs through this zone. Richards equation is used to analyze the movement of water in the unsaturated zone. Richards equation is non linear in nature since hydraulic conductivity is a function of dependent variable that is pressure head. Knowledge of unsaturated soil parameters is essential for analysis of moisture flow in unsaturated zone. In the present study unsaturated soil parameters have been estimated by using both direct and indirect methods. For estimating parameters by direct methods, particle size distribution data and moisture content pressure head relationship has been used. For indirect methods, estimation of parameters is done by minimising the difference between observed and predicted infiltration rates obtained from infiltration test and moisture contents obtained from internal drainage test. The parameters obtained by both the methods are compared. Parameters estimated from infiltration and internal drainage test are almost identical and either of them can be used for parameter estimation