Estimation of water demand of urban rivers and lakes in northern China based on multi-objectives and its ecological benefit assessment — II. Application of the method in the central urban area of Beijing

This paper applied the water demand estimation method developed in the previous section to the central urban area of Beijing, and estimates the water demand for rivers and lakes under the "basic demand scenario" and "ideal demand scenario". The results show that: (1) Under the "ideal demand scenario", increasing both the velocity of the river flow and water depth will significantly increase the river water demand. Adopting a reasonable still water supply or lowering the flowing water depth is one of the effective ways to balance water use efficiency and large river water demand. (2) The total water demand for the main rivers and lakes in the central urban area of Beijing under the "basic demand scenario" and "ideal demand scenario" are 200 million cubic meters per year and 1.08 billion cubic meters per year, respectively. The monthly water demand under the "ideal demand scenario" shows a significant seasonal variation, with more in summer and less in spring, autumn, and winter. (3) Water supply will increase the surface area of rivers and lakes, which will help improve the ecological quality of rivers and lakes and their surrounding areas.