Environmental impact assessment of a few selected watersheds of the Chamoli district (Central Himalaya) using remotely sensed data

Multi-temporal satellite data along with other collateral information have been used to assess and monitor the environmental changes experienced by the three severely degraded watersheds of the Chamoli district (Central Himalaya) after the 1970s Alaknanda flood. We find that the popular Chipko movement launched in 1973 by Chandi Prasad Bhatt helped significantly in regenerating the denuded forest cover in these watersheds. Monitoring studies carried out from 1972 to 1991 suggest that there is a steady growth of the forests on the denuded slopes which show a quantum jump from 1980 onwards. The 1991 IRS-LISS-II satellite data suggest that the forest loss of pre-1972 has nearly been regained indicating for the first time that a deforested area will require at least 20 years to rejuvenate in the Central Himalaya provided the area is protected from outside interference. There is a linear correlation with the magnitude of landslides and the forest cover. However, the stabilization process of active landslide zones seems to be quite slow due to the presence of sheared carbonate rocks and the proximity of the watersheds to the Main Central Thrust. There is a marginal 0-8 per cent improvement of the area prone to active landslides in the past two decades.