Sangan River

Overview

The Sangan River is a main watercourse of the Qinhuai system, flowing from south to north into the Lishui River, and is an important municipal watercourse of Nanjing (Shiqiu Subdistrict environmental report, September 2018). The district government's geographical position page lists the Sangan River in the Qinhuai system alongside the Lishui, Yigan and Ergan rivers, and gives its length as 11.19 km.

Two figures for the length: 11.19 km (district government geographical position page; the Master Plan for the Wuxiang Mountain National Forest Park gives the Sangan River as 11.19 km within Lishui District; the Eleventh Five-Year water plan gives 11.19 km in all) and 20.7 km (Shiqiu Subdistrict environmental report). This entry's length takes 11.19 km.

Two figures for the basin: the Eleventh Five-Year water plan gives a catchment of 64.74 sq km; the Shiqiu Subdistrict environmental report gives a basin of 117.50 sq km, of which 72.66 sq km lies in Lishui District, in the middle and upper reaches. The two are on different statistical footings and are shown side by side.

The subdistrict is Shiqiu: the reach covered by the Shiqiu Subdistrict environmental report is the Sangan River from the Shijiazhuang Sluice to the Shiqiuba Sluice-Pump Station, in Shiqiu Subdistrict; the 2018 annual implementation scheme for water pollution prevention records the assessment unit for the Shigang Bridge cross-section on the Lishui and Sangan rivers as Shiqiu Town, now Shiqiu Subdistrict.

Confluence: the Yigan River joins the Sangan River at the Wangjiawei ferry and the two then flow into the Lishui River (Jiangsu Provincial Department of Water Resources, 3 July 2023).

Formation and change

The Sangan River is one of the district's seven main watercourses (Measures for the Management and Protection of Water Conservancy Works in Lishui District, Lu Zheng Gui [2022] No. 2).

Channel improvement: the water environment improvement project on the Sangan River in Shiqiu Subdistrict, from the Shijiazhuang Sluice to the Shiqiuba Sluice-Pump Station, covers 1.5 km, with a design flood standard of P=5 per cent, a 20-year event, and a 20-year embankment; the works comprise desilting, ecological revetment improvement and landscape enhancement, and rebuilding of the Mazhuang irrigation station, at a total cost of 2.9239 million yuan (Shiqiu Subdistrict environmental report, September 2018). The Nangang River lies west of Shiqiu Polder, about 3.46 km long, and joins the Sangan River below the Shijiazhuang Sluice.

Flood defence: the flood works in the Ecological Rivers and Lakes Action Plan (2019-2020) include strengthening the Sangan River embankment (Lu Zheng Ban Fa [2019] No. 92).

No first-tier source has been found for when the Sangan River was cut, for the two ends of the whole river or for its final alignment, so nothing is written here.

Landscape and visiting

Ecological corridor: the pre-approval public notice of the Territorial Spatial Ecological Protection and Restoration Plan of Lishui District (2021-2035) lists the Sangan River among the waterway corridors of its multiple-corridor pattern (pre-approval notice, July 2026, not an instrument in force).

Water quality cross-section: Shigang Bridge on the Sangan River is a municipal-level assessment cross-section (Lishui Ecological Environment Bureau, published on the district government website in January 2022). The table gives the name and level of the cross-section only, not a water quality class.

No first-tier source has been found for footpaths, waterside platforms, viewing facilities or opening information along the Sangan River, so no visiting detail is given; readers who need it should go to the official notices of the district water department, the district culture and tourism department and the local subdistricts. Information is current to September 2026.

Open questions

• Two figures for the length: 11.19 km (district government geographical position page, Wuxiang Mountain forest park plan and Eleventh Five-Year water plan, the value used here) and 20.7 km (Shiqiu Subdistrict environmental report). Both are shown and neither is chosen.
• Two figures for the basin: a catchment of 64.74 sq km (Eleventh Five-Year water plan) and a basin of 117.50 sq km with 72.66 sq km within Lishui District (Shiqiu Subdistrict environmental report). The statistical footings differ and neither may stand in for the other.
• The two ends of the whole river have not been found: the official sources give only the reach covered by the works, from the Shijiazhuang Sluice to the Shiqiuba Sluice-Pump Station, and no first-tier source for the whole river has been read, so the gap is recorded as it stands.
• The description as a second-order tributary of the Qinhuai appears only in the Shiqiu Subdistrict environmental report, and can stand alongside the Eleventh Five-Year water plan's description of it as in the Qinhuai system; it is cited with its source.
• The Shijiazhuang Sluice and the Shiqiuba Sluice-Pump Station are named by the Shiqiu Subdistrict environmental report, which gives no class for either; the three medium-sized sluices listed in the Measures for the Management and Protection of Water Conservancy Works are Tiansheng Bridge, Zhongshan River and Zhoujiashan sluices, which do not include these two, and they are not inferred to be medium-sized.
• Standard and monitored class: the Shiqiu Subdistrict environmental report records that the Sangan River is subject to class IV of the Environmental Quality Standards for Surface Water (GB3838-2002). That is the standard applied, not a monitored class, and it is not written as the river being class IV.
• Names in use: the Shiqiu Subdistrict environmental report is stamped by the People's Government of Shiqiu Town, Lishui District, Nanjing, while its title uses Shiqiu Subdistrict; the wording is repeated as it stands and this entry's subdistrict follows the present division.