Available online at www.CivileJournal.org Civil Engineering Journal (E-ISSN: 2476-3055; ISSN: 2676-6957) Vol. 9, No. 04, April, 2023 860 Optimization of Integrated Reservoir for Supporting the Raw Water Supply Shafur Bachtiar 1 , Lily M. Limantara 1* , Moh. Sholichin 1 , Widandi Soetopo 1 1 Department of Water Resources Engineering, Faculty of Engineering, University of Brawijaya, Malang, Indonesia. Received 26 November 2022; Revised 08 March 2023; Accepted 11 March 2023; Published 01 April 2023 Abstract This research intends to analyze the optimal operation pattern for fulfilling the raw water demand, and it is conducted in the integrated cascade reservoir of Duriangkang-Muka Kuning, Batam City, Indonesia. However, Batam City is the economic center of the Riau Islands and absolutely needs enough raw water supplies to support its development. The need for raw water in Batam City is predicted to reach about 6,630.29 l/s in 2025. Due to the population growth that is estimated to reach about 1.8 million people in 2025 and the plan of Batam City development as an industry and tourism center, Batam City is faced with the condition that reservoir management becomes a very important thing for supporting the continuity of water supply. The methodology consists of collecting the supporting data, such as inflow, reservoir capacity curve, and data on water needs; then building the optimization model by determining the objective function and constraints of the integrated reservoir; and carrying out the optimization model by using linear programming and simulation models for the integrated reservoir operation. The result presents optimal reservoir operation of the integrated Duriangkang-Muka Kuning reservoirs. The reservoir operation consists of the boundary curve of upper and lower normal operation, the outflow for fulfilling the water need, and the rule of supply pumping from Duriangkang reservoir to Muka Kuning reservoir. It is hoped that the result can be used as a reference in operating the two reservoirs to fulfill the water needs of the Batam City population. Keywords: Optimization; Duriangkang; Muka Kuning; Reservoir Operation; Water Supply. 1. Introduction The important tasks that are faced by the decision-makers and the water resource managers are to find and assess effective solutions for some water problems. The general systems approach to the problems has been to optimize [1], simulate [2], or choose an alternative solution based on the trade-offs among the conflicting objectives [3]. The population growth in income implies the growth of water and food demand [4], but it is also reflected in the contamination of water bodies. Water resources have a direct relationship with the system approach due to both the system and non-linear relations [5]. A system is mentioned as a set of elements with connections among each other. Any system is composed of many sub-systems, each of which is open and autonomous, directly integrated with and interrelated with its environment [6]. In drafting the multi-reservoir operation pattern, the water transfer from the spillway reservoir has to consider the available capacity from the acceptor reservoir. A set of new release rules in every reservoir has to be analytic by considering the optimum condition of water balance and reservoir capacity of each reservoir [7]. Therefore, the management of multi-reservoir systems needs comprehensive consideration because between the reservoirs there is a relationship like a separate reservoir [5]. * Corresponding author: lilymont2001@gmail.com http://dx.doi.org/10.28991/CEJ-2023-09-04-07 © 2023 by the authors. Licensee C.E.J, Tehran, Iran. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).