Water environment problem identification and treatment countermeasure in Jiaxing urban river network

Jiaxing is one of the important cities in the Yangtze River Delta, as a typical plain river network city, Jiaxing existed a series of problems such as low-lying flat terrain, poor water mobility, and easy siltation of pollutants. Furthermore, because of bad water quality at upstream rivers, concentrated population, increasing urban runoff pollution, and frequent disturbances from shipping, etc., the concentrations of total phosphorus and ammonia nitrogen in the urban river network could not stably reach Grade Ⅲ of Environmental Quality Standards for Surface Water (GB 3838-2002); the water transparency was low, with an average value of less than 40 cm; the aquatic vegetation was general deficient in the river network, and the area of the water with rich submerged plants accounted for only 5% of the total water area, urgent restoration of aquatic ecosystems must be concerned. In view of the existing main water environmental problems, restoring the ecological integrity and virtuous circle of the river network was taken as the core goals, and increasing water transparency, and growing submerged plants were considered as the important pathways. Specific treatment countermeasure had five aspects, including exogenous control, endogenous reduction, habitat improvement, water ecological restoration, and long-term management, in order to reconstruct grass-type clear water ecosystem in river network water system, enhance the water self-purification capacity, and finally realize the overall water quality improvement of the urban river network in Jiaxing City.