Zhangxi Polder

Overview

Zhangxi Polder is a polder within the Lishui Economic Development Zone. On 31 July 2019 the Jiangsu Provincial Development and Reform Commission and the Jiangsu Provincial Department of Water Resources approved the preliminary design of the Sanya Polder, Zhangxi Polder and Lingzhuang Polder drainage pumping station project under Su Fa Gai Nong Jing Fa [2019] No. 667; the approval records that "the polders Sanya Polder, Zhangxi Polder and Lingzhuang Polder lie within the Lishui Economic Development Zone, where the drainage system is incomplete and the drainage standard low, so that a rainstorm very readily causes waterlogging"; the project code is 2018-320117-76-01-102854 (Jiangsu Provincial Development and Reform Commission and Jiangsu Provincial Department of Water Resources, Su Fa Gai Nong Jing Fa [2019] No. 667).

Location: the approval writes only that the polders "lie within the Lishui Economic Development Zone" and does not give the town or subdistrict. The district government's administrative divisions page gives the development zone and Zhetang Subdistrict on one row, as "Zhetang Subdistrict (Development Zone)"; this entry records Zhetang Subdistrict, as set out under Open questions.

Basin: the three stations pump the polders' floodwater into the Ergan and Yigan rivers (Su Fa Gai Nong Jing Fa [2019] No. 667); the district government's geographical position page lists the Yigan and Ergan rivers in the Qinhuai River system, and this entry records the Qinhuai for its basin.

Scale gaps: no official area or embankment length is given for Zhangxi Polder, and this entry declares gaps for both its area and its length. The scale figures in the approval are the design flow and installed capacity of the drainage pumping stations, not the polder's area or embankment length.

Formation and change

The pumping station project: the task of the works is to demolish the old stations and build three new drainage pumping stations, pumping the polders' floodwater into the Ergan and Yigan rivers respectively, raising the drainage capacity of the three polders and meeting a 20-year drainage standard. The design flows of the three stations are 13 cubic metres per second for the Sanya Polder station, 10 for the Zhangxi Polder station and 7 for the Lingzhuang Polder station, 30 cubic metres per second in all (Su Fa Gai Nong Jing Fa [2019] No. 667).

Site: the new Zhangxi Polder drainage pumping station lies behind the left dike of the Ergan River at chainage 18+400, about 70 m downstream of the Maogongdu drainage pumping station (ibid.).

Class of the works: the Sanya Polder and Zhangxi Polder pumping station works are class III, with the pump chamber, inlet pool, trash-rake bridge and other main structures of grade 3 and secondary structures of grade 4; the outlet culverts of the three stations are structures through the dike and take the same grade as the dike, grade 2; the basic seismic intensity is VII (ibid.).

Scale of the pumping station: the Zhangxi Polder pump chamber is of the wet-chamber type, 12.5 m long, with four bays 3.6 m wide each and a total width of 17.8 m; the outlet box culvert has two bays of 2.0 x 2.0 m, with two 2.0 x 2.0 m gates at the outlet. For the hydraulic machinery four submersible axial-flow pumps are used, each with a design flow of 2.59 cubic metres per second, a design net head of 4.3 m and a 250 kW motor, 1,000 kW in all (ibid.).

Investment and period: the estimated investment is 75.56 million yuan for the three stations together, with a provincial and higher subsidy of 22.67 million yuan and the rest raised by Nanjing; the total construction period is 12 months (ibid.). This investment is for the three drainage pumping stations together, not for the Zhangxi Polder station alone.

The historical basis for merging polders: the Lishui County water plan for the Eleventh Five-Year period records that by the end of the Tenth Five-Year period the county had "strengthened 300.17 km of dikes ... and merged 175 small and medium polders into 52 polders with a certain capacity for flood defence and drainage", and gives the low-lying polder area along rivers and lakes as 293.52 sq km (People's Government of Lishui County, Lu Zheng Fa [2005] No. 76). That group of figures is a cumulative county-wide basis before 2005, not a figure for Zhangxi Polder alone.

Review of the 13th Five-Year period: the 14th Five-Year water development plan lists among the achievements of the 13th Five-Year period "completing the new build or upgrading of 12 key pumping stations, namely Jinjia Polder, Dahuang Polder, Sanya Polder, Lingzhuang Polder and Zhangxi Polder, Baocheng Mingyuan in Yongyang, Changbao Polder in Honglan and Fucai Polder in Jingqiao" (General Office of the People's Government of Lishui District, Lu Zheng Ban Fa [2021] No. 87). This document is an approval, not a completion acceptance document, and this site has found no source for the actual completion of the works, as set out under Open questions.

Landscape and visiting

Zhangxi Polder is a polder, not a scenic area. This site has found no first-tier source for visitor facilities, tickets or opening times at Zhangxi Polder; the landscape of the polder consists mainly of polder dikes, canals and pumping station structures, and visits should follow the official notices of the district water department and the local town or subdistrict. This entry was checked to September 2026.

Open questions

• Area and length gaps: no official area or embankment length is given for Zhangxi Polder, and this entry declares gaps for its area and its length; the scale figures in the approval are the design flow and installed capacity of the drainage pumping stations, for which this site has no matching field, and they are not used to fill an area or a length.
• Two figures for the design flow: the 10 cubic metres per second of the Zhangxi Polder drainage pumping station is the figure in the approved preliminary design; other texts, such as the Nanjing 2020 government investment plan, give 14 cubic metres per second, a planning basis. The two figures differ, and the source and the stage must be stated when either is used; they must not be used interchangeably.
• Investment qualified: the estimated investment of 75.56 million yuan is for the three drainage pumping stations, Sanya Polder, Zhangxi Polder and Lingzhuang Polder, together, not for the Zhangxi Polder station alone.
• Location: the approval writes only that the polders "lie within the Lishui Economic Development Zone" and does not give the town or subdistrict; this entry records Zhetang Subdistrict for its towns, following the correspondence of "Zhetang Subdistrict (Development Zone)" on the district government's administrative divisions page.
• Flood-diversion ditch: this document is throughout an approval for drainage pumping station works and contains nothing on flood-diversion ditches; no official source checked this round contains the name "Zhangxi Polder flood-diversion ditch", and this entry does not write a length or a flood-diversion extent for one.
• Approval, not acceptance: this document is a preliminary design approval, not a completion acceptance document; this site has found no source for the actual completion of the works, and it is not written from this document that they are complete.
• Merging of polders and polder area: the Eleventh Five-Year water plan records that by the end of the Tenth Five-Year period the county had merged 175 small and medium polders into 52 and gives a low-lying polder area of 293.52 sq km, a cumulative county-wide basis before 2005, not a figure for Zhangxi Polder alone, and the two must not be used interchangeably.
• Drainage standard: the 20-year standard is a drainage standard and is not the same kind of standard as a river's flood defence standard, and the two must be distinguished in writing.