A. P. Bhattacharya

Abstract

It is a well known fact that unplanned and complete deforestation in any area leads to increased run-off from rivers and torrents, and floods become more frequent and intense. No systematic studies, however, seem to have been carried out in India on this subject. For the state of U.P., some investigations have been carried out for the catchment areas of three mountain torrents, for which records of gauges, rainfall and the management of forest areas were available. Fortunately in U.P. complete deforestation or denudation and wholesale burning of forests is nowhere resorted to. Where some areas are deforested by fellings, others are generally afforested in the vicinity of the some. It was thought feasible to study whether even the limited deforestation being carried out in U.P. was having any undesirable effects of increased floods or not. The torrents taken into consideration were Pathri, Ranipur and Ratmau. These are Himalayan torrents with shingly and sandy beds which join the Upper Ganga Canal near Roorkee. The width at their junction with the Upper Ganga Canal varies from 200 to 300 feet. These torrents pass over areas which are at the foothills of the Himalayas and form a part of the Siwalik range. Correlation analyses were carried out for these catchments for a number of variates, namely, frequency and intensity of floods as well as total and monsoon rainfall, with net deforestation. It was found that the planned and limited deforestation was not having any untoward consequences for Pathri and Ranipur catchments. It was only for Ratmau that some effect was felt on the frequency (and not intensity) of floods, meaning thereby that floods were recurring at somewhat more frequent intervals consequent on deforestation. It was also found that planned deforestation in either of the catchments was not having any significant effect on rainfall, which did not exhibit any marked change in either its intensity or distribution.

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