CS(AR)-207 : Optimization of reservoir operation for Periyar-Vaigai system

Abstract

Once the structured facilities like dams, barrages, hydropower plants etc. come into being, the benefits that could be reaped depend to a large extent upon how these facilities are managed. The efficient use of water resources requires not only judicious design but also proper management after construction. Reservoir operation forms a very important part of planning and management of water resources system. Detailed guidelines are formulated for enabling the operator at the dam site to take appropriate management decisions.

In the present report, the Periyar-Vaigai system, located in the state of Tamil Nadu and Kerala, has been studied. The various purposes of the system include irrigation demands of the Periyar reservoir and the Vaigai reservoir, water supply demands of the Madurai city and the hydropower development. It may be mentioned that the power development is only incidental and the releases from the Periyar reservoir are routed through the power plant. A simulation model has been developed to simulate the operation of the Periyar and Vaigai reservoirs. The operation has been simulated for 26 years of record (1962 - 1988) and the reliability analysis for the system has been carried out. Detailed operation table with the recommended policy has also been prepared. As the system is constructed mainly for the irrigation and water supply purposes and the hydropower development is incidental. the aim of the developed policy is to satisfy the priority demands.

It is concluded that the selection or demand pattern is a very important criterion in achieving high reliability of the system. Rule levels have been prescribed for selecting the appropriate cropping pattern in a particular year. Unnecessary spill from the Periyar dam must be avoided and the excess water in this dam must be sent to the Vaigai dam before spilling. The capacity of the tunnel is also a constraint. Detailed guidelines have been prescribed towards the end of this report.