Conceptual Sim-Heuristic optimization algorithm to evaluate the climate impact on reservoir operations

[Display omitted] •Conceptual Sim-Heuristic reservoir optimisation operation at Klang Gate Dam.•Investigation of the climate impact on reservoir operation based on CMIP5.•Statistical GCM downscaling strategies using predictant-predictor variables.•By incorporating CMIP5 and data-driven approaches into the simulations process.•CMIP5 reservoir optimisation applied nature-inspired Harris Hawks Optimisation. This study covers the application of sim-heuristics to simulate and optimise the KLang Gate Dam (KGD) operating rule curve using the Coupled Model Intercomparison Project 5 (CMIP5) climate scenarios. This research aims to examine future climate change impacts on the KGD reservoir water resources. First, based on model institution location and data availability, a few General Circulation Models (GCMs) under the CMIP5 were chosen. Most earlier studies had solely examined the impact of climate change on future reservoir operations using a single GCM. The ensemble of GCMs for precipitation, temperature (Maximum, Minimum, and Mean), and solar radiation for the base period (1991–2005) and future climatic scenarios under the Representative Concentration Pathways, RCP 2.6, RCP 4.5, and RCP 8.5 were downscaled, trained, and tested using data-driven techniques namely; the Artificial Neural Network (ANN) and the Support Vector Regression (SVR). During the base period, the SVR (Poly function) achieved R performance values of 0.6201, 0.5743, 0.6926, and 0.6073 for the respective predictant variables. Upon addressing for rainfall-runoff, the Turc-radiation evaporation strategy was utilised at this study location since it was suitable for the tropical, humid, or sub-humid region. Few scenarios were developed to forecast water demand. Scenario 1 was based on the base period (1991–2005) of water demand, whereas Scenarios 2 and 3 were based on maximum and mean temperatures, respectively (2020–2099). The results were then evaluated in terms of storage failure, reliability, resilience, and vulnerability. Overall, Scenario 3 showed the greatest reliability in satisfying exact demand with 93.54 %, as well as the least shortage index and length of water deficit under RCP 4.5.