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Water resources are important natural resources and play a key role in economic development and social life. China is one of the countries with the most serious water shortage in the world. In the next few decades, the contradiction between supply and demand of water resources will always plague China. Increasing the use of unconventional water resources to mitigate the water crisis is necessary way to achieve a sustainable development. There has been no effective standard yet in China to evaluate the exploitation level and potential of unconventional water resources. This study describes the current status of the exploitation and aims at establishing an evaluation system incorporating the three relevant factors, namely, driving, restrictive, and risk factors respectively, and provides a theoretical basis for the management of unconventional water resources in China. In order to mine the relationship between data and evaluation indexes, the rough set theory is adopted to determine the weight and objectively reflect the importance of each evaluation index. On the basis of the evaluation system, relevant data from 2006 to 2017 in Beijing were selected, and the results show that the urgency of unconventional water resources development in Beijing was generally on the rise with a small fluctuation range.

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%.