CS(AR)-5/99-2000 : Spatial variation of soil and Hydrological characteristics of selected watersheds in hard rock region

Abstract

One of the major problems in hydrological modelling is accounting for spatial and temporal heterogeneity of soil hydraulic properties. Since the 1970s, there has been an upsurge in studies connected with the spatial heterogeneity of hydraulic properties connected with agricultural and forest lands. In contrast, temporal variability of soil hydraulic properties such as infiltration parameters have received only limited attention under field conditions In catchment hydrology, the spatial and temporal variations in rainfall intensity and the properties of the soil make simple application of soil physics difficult. With respect to temporal variation in rainfall intensity it is reported that prediction of time of occurrence can be made from an estimate of the infiltrated volume. The spatial variation of infiltration parameters determines the patterns of surface and subsurface flow. Ponding begins from preferred locations with a low values of infiltration parameters due either to intrinsic soil properties or to high moisture contents resulting from subsurface flow. It is believed that detailed prediction of infiltration in catchment hydrology will depend on the prediction of time and space locations of occurrence of ponding and hence the location and magnitude of overland flow and interflow source areas. The algorithms which incorporate these predictions will be based on soil physical principles and use information from detailed field observations. Therefore, the present study is taken up to understand the spatial variability of soil hydrological properties under varied land use conditions and also to characterize the watershed based on the above parameters determined from field investigations which will be useful in unsaturated flow modelling. The present study is carried out by Dr. B.K.Purandara, Scientist B, Mr.C.P.Kumar, Scientist E , Mr. Venkatesh B, Scientist C and P.R.S.Rao, Research Assistant.