Simulation-based Optimization of Water Resource Systems: A Review of Limitations and Challenges

Integrated and sustainable river basin management requires accurate assessment and optimized allocation of available water resources, considering the impacts of climate and anthropogenic changes. It can benefit from coupled modeling frameworks combining simulation models and optimization algorithms (OAs). This article reviews simulation-based optimization (SbO) techniques developed for integrated water resources management (IWRM) classified into four distinct categories: i) coupled Simulation-only Models (SM-o) and Simulation Models with water allocation skill (SM-wa); ii) coupled Simulation Models with water allocation skill (SM-wa) and OAs; iii) coupled SM-o and OAs, and iv) simultaneous coupling of SM-o, SM-wa, and OAs. These simulation-based optimization frameworks are constructed using various coupling strategies—isolated, loose, tight, and integrated—based on the required level of data exchange and interactions between model components. The first category (SM-o—SM-wa) is predominantly based on applying offline/isolated coupling methods, whereas subsequent categories witness the adoption of loose and tight coupling approaches. The findings of this review underscore the value of SbO frameworks in promoting comprehensive and sustainable management of water resources capable of addressing single-period and multi-period allocations, as well as optimizing reservoir operation policies within a single framework. Additionally, this review can be a valuable resource for researchers, modelers, and policymakers in selecting suitable simulation models, OAs, and coupling methods for effective decision-making in IWRM.