Integrated Planning for Water Pollution Control in Suburban Regions in South-Eastern China

Water pollution caused by agricultural runoff and domestic sewage discharge is a critical issue for surface water quality and ecosystem health in developing regions worldwide. This paper focuses on a suburban region in south-eastern China which epitomizes the challenges of agricultural nonpoint source pollution and inadequate sewage infrastructure prevalent in rapidly developing areas. An integrated planning approach combining engineering solutions for sewage collection and treatment with ecological restoration of polluted waterways is needed to address these multiple pollution sources. The watershed was zoned into key control, general control, and preventive control areas based on pollution risk levels. Two engineered treatment wetlands were designed to reduce nitrogen and phosphorus loads by averages of 33.0% and 27.2% respectively. Ecological ditches, convergent wetlands, and enhanced biofilters were proposed to intercept and retain nutrients in runoff. Five land use scenarios were evaluated via pollution load and reduction rate analysis to set water quality goals. The integrated plan is projected to reduce annual loads by 3.97 tons for ammonia-nitrogen, 0.62 tons for total phosphorus, and 5.44 tons for total nitrogen. This study provides a replicable combined ecological restoration and engineering approach to improve water quality in agricultural nonpoint source pollution regions.