SOIL EROSION STUDIES IN A PART OF ARRIVAL HIMALAYAS WITH THE AID OF REMOTE SENSING TECHNIQUES

Abstract

Soil is a sine qua non of environment and human surrival. However, it is the most unstable of all major resources. Soil erosion is a menace, which, apart from destroying and impove.hing, agricultural land, has other consequences threatening the permanence of investments ammounting to millions of rupees in power, flood control, and irrigation projects. One of the objectives of soil erosion research entails studying the distribution of ero-sion phenomena and areas in need of erosion control meas-ures. The advent of Remote Sensing techniques has given a boost to pursue this objective. This study attepts to delineate the erosion prone areas and prepare an erosion Hazard Map the study area using remote sensing data pro-ducts. Both, visual and digital interpretation techniques have been used. The study arEa is a part of the Garhwal Himalayas bounded by latitudes 30'0' and 3045'N and lonnitudes 78°0' and 78°30'E covering an area of about 4000 sq.km.The study was done in three, steps. First, eroded and severely eroded areas were delineated from the aerial photographs which covered 50% of the t: t :1 area-'It was.- f and'th~t, 146% of the area x4as eroded and - 0.43% severely-eroded. The., next step was to'-.rprepare an Erosion Hazard Map of the area. Three factors were considered for this purpose, namely relief landuze and geology. A relief classification map was *prepared by carrying eut slope analysis of the available contour map of the area. For landuse, visual interpretation was done on False Colour composite of landsat imagery .and a landuse map prepared. The' geologi-cal information was taken from 'Preliminary Geological Map of the western Kumaon Himalayas' (Rupke and Sharma, 1974) and a map prepared for the area. Those three maps were overlaid, and with the help of a scoring system, hazard classification was done. it was found that about 10% of the study area demands top priority regarding'soil conservation, and whole of this area lies in the lesser Himalayas. Finally, a CCT covering the study are was analysed, and the results of digital classification were compared with that of visual interpretation of aerial photographs for a part of the study area.