CRITERIA FOR STORAGE CAPACITY FIXATION

Abstract

Correct estimation of reservoir capacity is of the utmost importance. If the planned storage capacity is small, it may not serve the purpose for which it has been designed or a greater risk will be involved. On the other hand, over -estimation of storage capacity results in considerably high cost of the project, which many a times renders the project to be uneconomical. The existing practice of irrigation planning with 75 percent dependable flow and storage fixation with the criterion of 75 percent success on the basis of number of failure years, appears to be arbitrary and restricts the optimum utilization of water resources. Shortage index is based on the quantum of shortage in different\fajlure years and has considerable merit over the existing practice of con-sidering only the number of failure years, but it does not account the incident of failure or quantum of failure on monthly or shorter duration periods. In the present study, the various aspects of reser-voir operation have been evaluated and studied in details by analysing different alternatives of planned annual utilization and storage capacity. The monthly shortages have been eva-luated in view of 1. Proposed use of water, 2. Critical timing of growth of individual crops, and 3. The relative importance of water use in different months.