Siltation analysis in the Neyyar reservoir and forest degradation in its catchment: a study from Kerala state, India

Impact of catchment erosion and the resultant reservoir siltation from a tr opical environment is reported here to discuss the effect of a reservoir in the natural degradation of an evergreen-forested segment. While an area of 8.01 km(2) has been affected by direct inundation at the full reservoir le vel, another 2.6 km(2) area once under thick st cover, had also lost its id entity over the last ears by indirect degradation. This zone mainly in the confluence of tributaries, namely Neyyar Mullayar, with the reservoir. The capacity of the reservoir was found to be reduced by 28.8 Mm(3) ng this per iod and the annual average loss is calculated as 0.75 Mm(3) (0.71%), indica ting the intensity of erosion from the catchment zone. In case the proposed upper dam in the reservoir comes into existence, an additional area of 2.4 km(2) from the virgin forest would be submerged and more area would face d egradation around the inundated zone.