A mountain lake in a forest park in south-west China attracts many tourists. What they may not immediately know is that its bottom is not of natural earth and stone, but stainless steel.
The bed and sides of Tianchi Lake, in Chongqing Wuling Mountain Forest Park, are lined with 660 tonnes of 3mm thick stainless steel, reports Jimu News.
A staff member told Jimu that the steel is probably to prevent water leakage from the 27,683 sq m lake. Wuling Mountain Park includes a karst landscape that is fairly permeable. In China, especially in the north, where water resources are seriously scarce and groundwater levels are constantly falling, some anti-seepage measures are applied to rivers and artificial lakes, generally using membranes or natural clay.
Zhengguan News commented that this is the first case in China of such large-scale application of metal to a natural landscape. It questioned whether stainless steel will cause damage in the long-term to the water body and the surrounding ecosystem.
The steel beneath Tianchi Lake cost more than CNY 20 million (about USD 2.8 million) and has had no impact on water quality, according to some Wuling Mountain Park staff who spoke to Xiaoxiang Morning News.
An article published in Oceans and Wetlands stated that metals are not conducive to biological attachment, microorganisms cannot survive, and the entire food chain inside the lake cannot operate stably. Moreover, metals have strong reflective and thermal conductivity, and stainless steel pool bottoms have a great impact on water temperature, which may affect the ecosystem.
China National Radio responded to the intense online interest in the story by interviewing the person in charge of Wuling Mountain Forest Park. They said that anti-seepage measures were first taken in the lake in 2014 to ensure water supply for tourism. When conventional methods were unsuccessful, the stainless steel approach was taken, the person said.
About two decades ago, the laying of anti-seepage membranes on the bottom of the artificial lake in Beijing’s Old Summer Palace caused great controversy and gave rise to China’s first state-level public environmental hearing.
Read Dialogue Earth’s previous reporting on the discussion around laying an impermeable plastic lining in the Old Summer Palace lake.