Theme 2-19-Characteristic equations for estimation of unsaturated hydraulic conductivity - Case study

Abstract

The knowledge of the physics of soil water movements in the unsaturated zone is very important for the studies related to watershed hydrology, irrigation and recharge to groundwater. The design and functioning of subsurface drainage systems also depends to a great extent on unsaturated hydraulic conductivity of the soil. Direct prediction of unsaturated hydraulic conductivity is difficult and it can be indirectly evaluated through the soil moisture characteristic curve. In view of the above, an attempt has been made to derive the characteristic equations for the estimation of unsaturated hydraulic conductivity using a regional data base, for different types of soil of Narsingpur, India. Total soil samples collected from 24 locations are about 120 numbers (5 samples from each location). Extensive field and laboratory measurements have been carried out for each of the soil samples. Soil Textures are determined using the mechanical sieve analysis and hydrometer analysis. Saturated Hydraulic Conductivity is determined using Guelph Permeameter (for In-Situ measurement). The soil moisture characteristic data were obtained through Pressure Plate Apparatus in the laboratory. The unsaturated hydraulic conductivity function has been derived from the Brooks and Corey relationship by non-linear regression analysis. These characteristic equations can be used for estimating the unsaturated hydraulic conductivity of the different soil in the study area.