Laoshi Kan Reservoir

Laoshi Kan Reservoir

Laoshi Kan Reservoir is a national water conservancy scenic area.

Laoshi Kan Reservoir is a national-level water conservancy scenic area, located on the Nanxi, a tributary of the Xitiao River, 10 kilometers southwest of Xiaofeng Town, Anji County, Zhejiang Province. It is one of the major backbone water conservancy projects for managing flood disasters in the Taihu Lake Basin. This large (Type II) reservoir primarily serves flood control functions while also supporting irrigation, power generation, aquaculture, and other comprehensive uses. The reservoir benefits a flood control area of 190,000 mu and irrigates 45,000 mu of farmland, making it an extremely important facility in terms of function and status.

Key Structures:

(1) The dam is a clay-core rock-fill dam with a maximum height of 36.9 meters, a crest elevation of 126.4 meters, a crest length of 560 meters, and a crest width of 6.0 meters.

(2) Flood Discharge Structures:

a. Normal spillway gate: A mid-channel type with a gate bottom elevation of 98 meters, a sill elevation of 107.0 meters, a net opening width of 18 meters, and three 6.9-meter-wide steel flat gates installed, achieving a maximum discharge capacity of 2,320 cubic meters per second.

b. Emergency spillway: A fuse plug-type structure with a weir crest elevation of 120 meters, a total width of 50×2+60=160 meters, and a maximum discharge capacity of 3,168 cubic meters per second.

c. Diversion gate: A deep-channel type with a weir crest elevation of 111.0 meters, a sill elevation of 116.8 meters, a net weir width of 77 meters, and one 7.7×5.8-meter radial gate installed, achieving a maximum discharge capacity of 400 cubic meters per second.

d. Water conveyance tunnel: With a cross-section of 7.07 square meters, an inlet bottom elevation of 100 meters, a maximum discharge capacity of 32.0 cubic meters per second, and a power station equipped with two generating units totaling 1,860 kilowatts. The reservoir is designed mainly for flood control, supplemented by irrigation and power generation. It is designed for a 50-year flood event and checked against a 500-year flood event, with PMF (Probable Maximum Flood) conditions considered for dam safety measures. The design flood level is 123.1 meters, the check flood level is 124.5 meters, and the dam safety flood level is 125.6 meters.

The total reservoir capacity is 117 million cubic meters, with a normal water level design of 114.5 meters, corresponding to a reservoir capacity of 42.5 million cubic meters, and an irrigation area of 45,000 mu.

Tourism Development:

Laoshi Kan Reservoir is the largest lake at the source of the Huangpu River system. Officially designated as a “National Water Conservancy Scenic Area” by China’s Ministry of Water Resources, it is characterized by its “greenery, coolness, clarity, and purity,” making it an excellent destination for outdoor activities.