Optimization of Multi-reservoir Operation with a Hedging Rule: Case Study of the Han River Basin

Abstract

The major reason to construct large dams is to store surplus water during rainy seasons and utilize it for water supply in dry seasons. Reservoir storage has to meet a pre-defined target to satisfy water demands and cope with a dry season when the availability of water resources are limited temporally as well as spatially. In this study, a Hedging rule that reduces total reservoir outflow as drought starts is applied to alleviate severe water shortages. Five stages for reducing outflow based on the current reservoir storage are proposed as the Hedging rule. The objective function is to minimize the total discrepancies between the target and actual reservoir storage, water supply and demand, and required minimum river discharge and actual river flow. Mixed Integer Linear Programming (MILP) is used to develop a multi-reservoir operation system with the Hedging rule. The developed system is applied for the Han River basin that includes four multi-purpose dams and one water supplying reservoir. One of the fours dams is primarily for power generation. Ten-day-based runoff from subbasins and water demand in 2003 and water supply plan to water users from the reservoirs are used from "Long Term Comprehensive Plan for Water Resources in Korea" and "Practical Handbook of Dam Operation in Korea", respectively. The model was optimized by GAMS/CPLEX which is LP/MIP solver using a branch-and-cut algorithm. As results, 99.99% of municipal demand, 99.91% of agricultural demand and 100.00% of minimum river discharge were satisfied and, at the same time, dam storage compared to the storage efficiency increased 10.04% which is a real operation data in 2003.

Development of an Optimal Water Allocation Model for Reservoir System Operation

“…Another study focused on the coordinated operation of multipurpose reservoirs (Soyanggang, Chungju, and Hoengseong), a water supply-only reservoir (Gwangdong), and a large-scale hydropower reservoir (Hwacheon) within the Han River Basin [49]. The paper employed a five-level Hedging Rule and used mixed integer linear programming (MILP) to develop a reservoir operation model.…”

Improving Reservoir Operation Criteria to Stabilize Water Supplies in a Multipurpose Dam: Focused on Nakdong River Basin in Korea

“…Similar to the results of the single dam, the dam water volume using the improved operation criteria was different from that found using the past dam operation criteria. For 1994For -1995For , 2001For , 2009, and 2014-2015, which were the representative drought years in the past, the water volumes on 1 April (i.e., when agricultural water is required for paddy farming) were compared, and additionally secured water volumes were calculated ( Table 4).…”

“…For multipurpose dams, effective dam operation is essential to overcome the water supply conditions caused by changes in climate as well as the uncertainties of future water management. Many studies have assessed the performances of the water resource systems of multipurpose dams, and most have applied decision-making methods to establish water supply plans [4] or assessed the water supply capacities and reliability of multipurpose dams using operation methods [5][6][7][8][9][10][11][12] or assessment indices [13][14][15][16] for multipurpose dams. No et al [17], Choi [18], and Nam et al [19] assessed the water supply capacity of a prospective multipurpose dam using future climate change scenarios.…”

Assessing the Coordinated Operation of Reservoirs and Weirs for Sustainable Water Management in the Geum River Basin under Climate Change

“…In addition, Kim et al [29] used flow duration curve behavior characteristics to evaluate the applicability of the SSARR model, which is a basin management model. Ryu et al [30] performed research into optimizing the coordinated operation of dams using a hedging rule on the Han River water system. Ko et al [31] applied flow duration change analysis to evaluate ecological and hydrological changes.…”