Study of reclaimed water system in downtown Los Angeles based on system dynamics theory

The shortage of water resources has seriously restricted the development of cities. Unconventional water resources is of great significance for sustainable development. As a city lack of water, Los Angeles plans to develop reclaimed water as an important component of urban water supply under the conditions of drought and over exploitation of groundwater. In order to provide a basis for urban reclaimed water construction planning, this paper developed a system dynamic model to provide scientific suggestions for the planning of reclaimed water. According to the analysis of Los Angeles water system, the model divides the system into reclaimed water system, urban water consumption system, urban water supply system and water supply cost system. The degree of water shortage, urban water supply, water supply cost, and reclaimed water production were chosen as the model index for the requirement of plan design. The historical data was employed to verify the model, indicating that the model is reliable. Then the plans under different rates of growth of reclaimed water were designed. According to the comprehensive analysis of the model index, the second plan was considered to be the optimal one: increase the local water supply in Los Angeles to 50 percent of the total by 2035 and reduce purchases by 50 percent. Finally, Reclaimed water accounts for 30% of the city’s water supply, meanwhile, water supply costs decline 10%.