Mapping of erosion intensity in the Garhwal Himalaya

Abstract

Erosion and denudation in the Garhwal Himalaya have anracted much aucntion in recent years and several workers have emphasized the natural and human controls of these mass wasting processes in this region (Narayan et a/. 1983, Valdiya 1985, Pachauri and Pa n t 1992. Choubcy and Litto ria 1990, G errard 1994. Owen et a/. 1995, Pachauri eta/. 1998, Valdiya 1998, Barnard eta/. 2001). The Garhwal l-lima laya forms the western end of the Centra l Hi malaya in northern India and is situated in a seismic gap along the Main Central Thrust (MCT ) tha t separates t he Lesser Himalaya to the south from the Greater Himalaya to the north (Valdiya 1988). A numbe r of high magnitude earthquakes have occurred in the recent past , e.g. 20 October 1991 (Mb = 7. 1) and 28 Ma rch 1999 (M• = 6.6). The entire .-egion has been undergoing rapid uplift and intense fluvial and glacial incision as manifested in steep gullies and deep valleys. Erosion and mass movemen 1 arc also accentuated by the monsoonal climate with heavy rainfall. and cause severe problems including fil ling of rese rvoirs. reduction in water quality and loss of soil cover among a host of others. Many engineering projects meet untimely demjse because of increased sedimen t yield in the catchment due to excessive erosion .