HYDROLOGIC SOIL CLASSIFICATION USING GIS TECHNIQUE

Abstract

Hydrological soil classification refers to a group of soil series that can be considered homogenous in respect of soil characteristics that influence the runoff. Hydrologic soil classification is essential for the accurate estimation of runoff and agricultural development. The main soil parameters considered for the hydrologic soil classification are effective soil depth, soil texture, soil structure, clay percentage, infiltration and soil permeability. Since large volumes of spatial data are required for the hydrological soil classification, therefore the use of GIS is beneficial to merge these data on the basis of a given criteria. In the present study, soils of a catchment in Madhya Pradesh (Distt. Mandala) are classified into their hydrologic classes using SCS approach of hydrological soil classifications. ARC/INFO GIS package was used for this work. Thematic maps were prepared from topo sheets, NATMO maps and NIH reports. Maps were digitized in ARCEDIT module maps, namely clay percentage, effective depth, infiltration, rainfall and landuse map. Attributed data was added to these maps. Maps were registered together and then overlayed using query based modelling. According to soil conservation service (scs) classification criteria hydrologic soil class was assigned to each polygon. Using these hydrologic soil classes and SCS empirical relationships, runoff was computed for each polygon. It was found that about 2% area was covered by hydrologic class A having runoff of 13687.05 mm/year, with dense forest area. Hydrologic class B covered 62.16% of area having runoff of 352157.71 mm/year with mostly agriculture land. Hydrologic class C occupied 33.68 % area having runoff of 206068.73 mm/year and covers grass land. Only 2.14% area was covered by class D having runoff of 44136.17 min/year,in barren land. GIS facilitated the area analysis and query based overlay quickly and accurately. GIS is found to be an effective tool to establish relationship between the coverages. Although soil classifications are done for agriculture purposes but its applications can be expanded further so that it is used in urban and sub urban areas.