Catchment Area Treatment Plan for Thoubal Multi-Purpose Project, Manipur

Abstract

Any type ponding whether natural or artificial generally leads to filling up the pond itself in due course of time mainly due to the process of sediment deposition and compaction. As far as ponding due to dam is concerned and its subsequent sedimentation, the catchment processes play major role and it becomes incumbent on the part of the planners and executors of projects to understand the processes of sediment production, its transportation and finally sedimentation/deposition, which in most of the cases is location specific. This is of concern because of the fact that prolonged and uncontrolled deposition of sediment in the reservoir greatly reduces the capacity of the reservoir to hold sufficient water required for the intended purposes. This is of even more importance as far as a multi-purpose project like the Thoubal project in Manipur as there are multiple stakeholders. Despite the fact that the catchment processes are difficult to model and the relations among the actor variables are not exactly amenable to mathematical prediction, sediment production models are important tools and help us formulate catchment area treatment (CAT) plans. In light of the same, preparation and subsequent execution of a well-designed CAT plan was felt to be of utmost importance to reduce the rate of siltation of the reservoir to be created as part of the multipurpose project planned by the Government of Manipur, India in the river Thoubal. The CAT plan was prepared based on the findings presented in the Environment Impact Assessment (EIA) report prepared separately for the project based on appropriate Guidelines of the Ministry of Environment & Forests, Government of India (Ref. 2).