Estuary Processes and Managment - River Dynamics and Integrated River Management - page 492

bordering the provinces of Zhejiang and Jiangsu in the west (Fig. 8.27). Rapid economic development
and increase in population has resulted in serious surface water pollution problems due to large amounts
of untreated wastewater being discharged into the rivers and other watercourses. It is estimated that the
total sewerage flow from Shanghai will be 8.5 million m 3 per day in 2010, in which more than 7.0
million m 3 per day of wastewater will be discharged into the Yangtze River estuary (YRE) and Hangzhou
Bay through outfalls after preliminary treatment; the other 1.0 million m 3 per day of wastewater or more
will be discharged to the nearby inner rivers after intensive treatment.
Fig. 8.27 Sketch map of Yangtze River estuary and the positions of the outfalls
Since the 1980s, great efforts have been devoted to improve the water environment in Shanghai by the
provision of proper sewage treatment and disposal systems. The First Shanghai Sewerage Project (SSPI)
was completed in 1993. In this project, the wastewater is conveyed and disposed to YRE at Zhuyuan
through a submerged outfall after preliminary treatment. SSPII (completed in 2000) discharges wastewater
into YRE through a submerged outfall at Bailonggang at the freshwater/saltwater interface and high
turbidity mixing zone. Bailonggang is 38.5 km downstream of Wusong where the Huangpu River enters
the Yangtze River, and 16.5 km downstream of Zhuyuan. For SSPIII (completed in 2008), a new Xinhe
outfall (discharge 1.50 m 3 per day) has been established downstream of Bailonggang. Prior to SSPIII, the
discharges of the Shidongkou, Zhuyuan and Bailonggang outfalls were 0.17, 1.45, and 0.79 million m 3
per day, respectively; for SSPIII projects, their loads are 0.8, 3.30, and 1.70 million m 3 per day.
Figure 8.27 shows a map of the YRE and the positions of existing outfalls and proposed outfall. The
Yangtze River is bifurcated by Chongming Island into the south branch and north branch from Xuliujing,
and almost all of the flow goes through the south branch while the flow in the north branch can be ignored.
The south branch is divided into the south channel and north channel by Changxing Isle and Hengsha
Isle, in which the flow distributes in close proximity to each other, and the south channel is bifurcated by