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As the social economy is further developed, there have been increasingly severe ecological and environmental issues. For instance, rivers located in mountainous areas are often encountered with the issue of zero flow. The ecological base flow was put forward to ensure the continuous flow of rivers, to realize the minimum ecological function, and to meet the most fundamental requirements of sustaining the river ecosystem. Wulong River Basin in Yantai City of China was taken as example here. Based on the runoff data collected in the Tuanwang Hydrological Station from 1960 to 2016, the measured runoff data was restored to natural runoff sequence by adopting the item-by-item investigation method. The different ecological base flows of Wulong River were calculated by adopting the Tennant Method, the Qp90 Method, the Texas Method, the Base Flow Ratio Method, the Tessman Method, and Wetted Perimeter Method. The research findings have shown that the Base Flow Ratio Method proves to be the optimal approach for calculating the ecological base flow of Wulong River. Based on the analysis of the assurance degree of ecological base flow, the period from April to June is the period with the lowest assurance degree of ecological base flow.

Urbanization has a significant impact on the hydrological characteristics of developed areas as well as downstream regions. As a watershed is increasingly covered with impervious surfaces, it experiences decreased rainwater infiltration, increased runoff, and shortened concentration times, thereby affecting the natural cycle of urban water systems. Many natural flood control and storage mechanisms have been systematically destroyed by urban development, and water pollution has become an increasingly serious global concern. Low-impact development (LID) is an ecological rainwater runoff management method that has been identified as a promising approach to reduce runoff and improve water quality. Recent research and advances in LID are systematically introduced and reviewed in this paper, including popular models, the main LID design elements and facilities, and the mitigation that LID provides for both floods and pollutants in urban areas. Future research into LID will need to enlarge its scope to broader regions and networks, develop and refine suitable models, and explore ways to integrate LID into existing water management systems in urban areas.

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