Season-Dependent Hedging Policies for Reservoir Operation—A Comparison Study

• Main Authors: Nikhil Bhatia, Roshan Srivastav, Kasthrirengan Srinivasan
• Format: Article
• Language: English
• Published: MDPI AG 2018-09-01
• Series: Water
• Subjects: parameterization; simulation; optimization; direct policy search; hedging policy; shortage ratio: Vulnerability; NSGA-II
• Online Access: http://www.mdpi.com/2073-4441/10/10/1311

During periods of significant water shortage or when drought is impending, it is customary to implement some kind of water supply reduction measures with a view to prevent the occurrence of severe shortages (vulnerability) in the near future. In the case of operation of a water supply reservoir, this reduction of water supply is affected by hedging schemes or hedging policies. This research work aims to compare the popular hedging policies: (i) linear two-point hedging; (ii) modified two-point hedging; and, (iii) discrete hedging based on time-varying and constant hedging parameters. A parameterization-simulation-optimization (PSO) framework is employed for the selection of the parameters of the compromising hedging policies. The multi-objective evolutionary search-based technique (Non-dominated Sorting based Genetic Algorithm-II) was used to identify the Pareto-optimal front of hedging policies that seek to obtain the trade-off between shortage ratio and vulnerability. The case example used for illustration is the Hemavathy reservoir in Karnataka, India. It is observed that the Pareto-optimal front that was obtained from time-varying hedging policies show significant improvement in reservoir performance when compared to constant hedging policies. The variation in the monthly parameters of the time-variant hedging policies shows a strong correlation with monthly inflows and available water.