Hybrid modelling for urban water supply system management based on a bi-objective mathematical model and system dynamics: A case study in Guilan province

The increase in population, demand growth, limitation of water resources, and huge costs of water supply with the execution of new plans for water resources development have attracted more attention to the management of the existing resources and facilities exploitation. For this purpose, the present study uses optimization methods in urban water supply system programming and introduces state and flow variables to provide the urban water supply model and evaluate the factors affecting the urban water supply cycle in Guilan province using the system dynamics. Finally, a model is presented in line with the management status of the Guilan Water and Wastewater Company in Rasht branch. Evaluating the accuracy and validity of the model presented in the water supply system from different water resources shows that increasing the treatment capacity and water resources in the province can affect the treatment cost and reduce the shortage and wastewater. Regarding the parameters which have a positive effect on the amount of input water, it is required to consider appropriate systems to control the input water and manage such valuable resources. Eventually, forecasting the amount of shortage in the studied area during the next 100 years indicates a linear trend that the number of shortages increases in an upward manner in each period due to the increased population and decreased amount of precipitation.