Characteristics of combined sewer overflows in Shanghai and selection of drainage systems

• Published in: Water and environment journal : WEJ Vol. 24; no. 1; pp. 74 - 82
• Main Authors: Li, Tian, Tan, Qiong, Zhu, Shiqing
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.03.2010; Blackwell Publishing Ltd; Blackwell
• Subjects: Applied sciences; China; combined sewer overflow; combined sewer systems; Continental surface waters; drainage; drainage system; drainage systems; Exact sciences and technology; hydraulic model; Natural water pollution; nonpoint source pollution; overflow frequency; Pollution; pollution control; rain; Sewerage works: sewers, sewage treatment plants, outfalls; streams; urban nonpoint pollution; Water treatment and pollution; watersheds; China, People's Rep., Jiangsu Prov., Suzhou; Japan; China, People's Rep., Shanghai; China; Combined sewer; Hydraulic model; urban nonpoint pollution; Pollution control; Urban area; Pump; Overflow; Design; Rain; Storage; Nonpoint pollution; overflow frequency; Watershed; combined sewer overflow; Pollution abatement; Sewer network; drainage system
• ISSN: 1747-6585; 1747-6593
• DOI: 10.1111/j.1747-6593.2008.00141.x

The overflow frequencies of combined sewer systems (CSSs) along Suzhou Creek in Shanghai are definitely lower compared with low interception ratio and design expectation. This noteworthy phenomenon was analysed and the results indicate that large sewer storage capacity due to a dense interconnection between sewer systems, flat pipe slope and pump drainage pattern, as well as the spatial-temporal difference of rainfall on a large catchment that is integrated by the connected network, lead to the overflow frequencies of combined sewer overflows (CSOs) along Suzhou Creek that are much less than those of designed and of Japanese counterparts. The drainage hydraulic model was used to simulate the performance of typical CSSs in Shanghai centre area to further explain the phenomenon. Meanwhile, as separate systems have serious illicit connections and are subject to heavy wet weather pollution in Shanghai, separate systems did not show the expected advantage in nonpoint pollution control. Thus, keeping old CSSs in the Shanghai downtown area seems to be of great value with respect to the control of urban non-point pollution.