SHENZHEN'S PRACTICE OF POLLUTION PREVENTION AND CONTROL OF RAINFALL OVERFLOW BASED ON WATER ENVIRONMENT GOVERNANCE IN SMALL WATERSHED

Considering the issue of inconsistent adherence to water environment quality standards due to pollution from rainfall overflow, the technical approach to managing dynamic water environments in small watersheds in Shenzhen was investigated. Firstly, by utilizing comprehensive continuous water quality data of full coverage, the rivers exceeding standard levels during the rainy season and their corresponding overflow outlets were accurately identified as treatment targets. Secondly, a holistic investigation was conducted within each small watershed where these rivers and overflow outlets were located in order to systematically identify various existing water environment problems. This facilitated the establishment of problem-measure-target relationships and rectification task ledgers aimed at promoting effective remediation efforts. Finally, based on the implementation of the measures and the results of water quality monitoring, the standard assessment and water quality inspection in rainy season are carried out in the small watershed after renovation, and dynamic management is implemented. After over one year of exploration and implementation, there has been a 7.73% annual increase in the proportion of river monitoring sections meeting or surpassing Class III standards during the rainy season; additionally, there has been a yearly reduction of more than 25% in flood season overflow pollution intensity across three major national sections. These achievements demonstrate certain results in preventing and controlling rainfall overflow pollution during the rainy season. The findings presented herein can serve as valuable references for other cities seeking to address similar issues related to rainfall overflow pollution prevention and control.