Analysis of water eco-environmental problems and related countermeasures for cities in Sichuan region of the Yangtze River Basin

Taking 18 cities in Sichuan region of the Yangtze River Basin as research objects, the water environment quality change trend and the main pollution indexes of the urban built-up areas at the main stream of the Yangtze River as well as the Minjiang-Tuojiang River and Jialing River tributary streams in Sichuan region of the Yangtze River Basin from 2016 to 2020 were investigated. The pollution discharge load of chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), total nitrogen (TN) and total phosphorus (TP) from the urban domestic sources, industrial sources and urban non-point sources of the typical cities were also estimated, to analyze the problems and causes of urban water eco-environmental problems. The results showed that water quality of urban water bodies in Sichuan region of the Yangtze River Basin had improved year by year in the recent five years, and TP, NH₃-N, TN and COD were the main pollution indexes of water bodies in the region. In addition, the domestic source was the main pollution source of the cities in the region. The insufficient urban infrastructure construction , the prominent industrial pollution problems of some cities, large urban non-point source load in wet season and the coexistence of water resources and water quality shortage were the main reasons which led to the water eco-environmental problems in the cities. On this basis, countermeasures and suggestions on further improving the quality of urban water ecological environment in Sichuan region of the Yangtze River Basin were put forward, including strengthening the construction of urban sewage collection and treatment facilities, treating typical industrial wastewater specially, strengthening the construction of rainwater and wastewater diversion pipelines and rainwater collection devices, and repairing polluted surface water with ecological methods.