DESIGN OF RESERVOIR BY OPTIMIZATION SIMULATION MODELS

Abstract

Optimization-Simulation models based on the mathematical programming algorithms are powerful tools, capable of providing solutions to the problems which engineers and planners face while planning and remodeling of complex water resources systems. Sustainability of reservoirs implies a need for the control and adjustment of reservoir design characteristics, resulting in optimal, or near optimal system performance throughout the lifetime of the reservoir. System analysis, which involves the use of the optimization and simulation techniques, is a set of powerful tools to solve reservoir planning and operation problems. In reservoir operation phase, more concentration is applied to determine more practical and user friendly initial policies for reservoir operation. In addition, some prospective realistic aspects should be incorporated in the reservoir operation in the optimization models. Therefore, looking at the above objectives existing Harabhangi irrigation project has been chosen as the study area, which is an inter basin irrigation project in Orissa state (India), where water from river Harabhangi, a tributary of river Vanshadhara in Vanshadhara basin ( an inter-state basin, between Orissa and Andhra Pradesh), is transferred to Padma river in Rushikulya basin (a basin in Orissa state) To accomplish the above mentioned objectives, for the Harabhangi project the following studies were carried out. A complete yield model has been applied to determine the optimal capacity and reservoir yield with 100 % reliability. A -simplex LP approach is-used. Also an optimal annual reservoir yield for irrigation from the Harabhangi reservoir has been determined on the basis of driest year's inflow and 75% dependable year's inflow. An implicit stochastic linear programming yield model is used for the purpose. Simulation analysis is also carried out for the both planning and operation of the reservoir. Optimal annual yield, which is obtained from yield model (YM) is verified using simulation. Continuous Hedging Rules (CHR) have been applied to check the performance of reservoir. Based on the above studies, the following are the findings in the respect of the Harabhangi project. By using the complete yield model, actual annual irrigation demand cannot be met. A smaller value of 67 MCM reservoir capacity is obtained by simulation for 25% failure probability. For the existing reservoir live capacity of 100.25 MCM, two types of annual yields have been .proposed using-YM, i.e., one on the basis of driest year's inflow(i.e., 212.68 MCM) and another on the basis of 75% dependable year's inflow(216.25 MCM). The within year and over year reservoir capacities are also'determined from the model results(i.e., 70.96 MCM. and 29.04 MCM, and 64.27 MCM and 35.73 MCM, for the within year and over year reservoir capacities, corresponding to the optimal reservoir yields in the former and later cases, respectively). A simulation is carried out to verify the YM result. A value of 200.98 MCM is obtained as reservoir. capacity with 75% reliability which is closer to the results obtained from YM. The results of reservoir yield model were used to estimate hedging fraction (Kpt) to be used with CHR application. Simulation is carried to compare the performance of the reservoir using SOP with the performance using CHR. It gives the acceptable performance especially during the months of late non-monsoon season.