Abstract:To overcome the governance bottlenecks of urban rivers, such as "difficulty in cleaning stagnant water" and "ecological decline", Jianye District, Nanjing City, has selected three river courses, namely Tianbaoxi River, Shuanglong River, and Shangyuan River, as experimental river sections to explore the impact mechanism of the "low-cost, low-carbon, sustainable" "low-water operation" mode on the water environment and ecology of urban rivers. After isolating the experimental river sections as independent water systems, the water level of the river systems is controlled at a low water level (water depth of 0.3-0.5 meters), and clean water sources are regularly supplemented to maintain a flowing state. Multi-point water quality and sediment indicators are continuously monitored, as well as habitat changes of aquatic biological communities. After half a year of low-water operation, the water quality and sediment pollution degradation in the experimental sections have significantly improved, the biological communities have gradually evolved and become richer, and the "algae-shellfish-fish-bird" food chain has gradually improved, forming a virtuous cycle of "natural restoration". It also revealed that after the reduction of river water volume, the buffering capacity against sudden environmental conditions such as high-temperature water blooms in summer and sudden pollution discharge from outlets has weakened. In the next step, the low-water operation experimental plan will continue to be improved, ultimately forming a replicable and promotable "water governance plan" to provide reference for similar urban river governance.
