by Lisa Peryman

Too many dams to look after

As China continues to embrace a new era of hydropower expansion, demand for dam inspection has outpaced the country’s supply of inspectors, ramping up safety fears for thousands of small- and medium-sized dams in China’s rural areas that have been “ignored”, reports Ecns.cn.

A quirky update from China’s Ecns.cn news service — the official English-language website of the state-owned China News Service agency — entitled, “Dam inspections found lacking,” reveals the country is facing a critical shortfall of the “professionals” needed “to conduct regular inspections of thousands of small- and medium-sized dams in rural areas.”

Ni Guangheng, director of the Institute of Hydrology and Water Resources at Tsinghua University, told Ecns.cn that “heavier rainfall caused by climate change” — the latter threat Chinese authorities and the country’s dam-building industry have leveraged to revive its hydropower muscle — is posing a dam safety risk, particularly in the rural parts of southern China.

Unusually heavy rainfall in April has already caused water levels to rise several meters higher than average in some areas, causing inflow from the upper streams of the Yangtze River to hit an eight-year high, forcing the Three Gorges Dam to discharge more water. Officials warn the worst is yet to come.

Various reports highlight a growing concern China may be in for a pronounced spring flood crisis, exacerbated by an ongoing El Nino effect that began in September 2015. The strength and length of the current El Nino event has many concerned its similarity to an El Nino phenomenon that triggered China’s horrific 1998 flooding of the Yangtze could repeat itself this year.

Although one of the functions of dams is to help alleviate the impacts of flooding, dams can also heighten flood risk and the consequences of flooding through soil erosion, silt build-up (which causes water downstream of dams to flow faster), landslides caused by rising and falling reservoir levels, human error in dam operation (when spillways are opened too late from an overfilled dam, for example), dam failure and so on.

The Shanghai-based Sixth Tone news outlet reports the Three Gorges Dam, completed in 2009, with “its ability to hold a maximum of 22.15 billion cubic meters of water in its 500-kilometer-long reservoir,” is a potential flood-control advantage that wasn’t available in 1998. But Sixth Tone also reports that impact estimates forecasting the potential fallout from this year’s flood season “might not be reliable since the Three Gorges Dam has altered river channels and flood patterns” and that “the effect of other flood control infrastructure along the [Yangtze] river is also unclear.”

Meanwhile, state-owned mega-dams such as Three Gorges and the Gezhouba cascade hydropower stations continue to receive regular inspections, notes Ecns.cn, but there aren’t enough professionals to go around for aging smaller dams that are not regularly maintained. Speaking to Ecns.cn, Wu Suhua, a senior engineer at the Dam Safety Management Center under the Ministry of Water Resources, recalls dozens of small dams that collapsed or were damaged in Wenchuan County, Sichuan, as a result of a killer earthquake that struck the province in 2008 — a quake that some experts say was linked to the “mass loading and increased pore pressure” caused by the nearby Zipingpu dam reservoir, which may have either triggered the quake or contributed to the severity of it.

Wu told Ecns.cn, the number of inspectors needed to boost China’s supply of professionals was hard to calculate but that “China must fill the gap left by a lack of training and attention to the hidden trouble.” Said Wu: “We hope that with well-planned designs and regular maintenance, the dams are able to tackle any future challenges that may occur hundreds of years after the project is done.”

Patrice Droz, coordinator of a cooperative dam safety program between China and Switzerland that helped train 300 professionals in China, told Ecns.cn: “China should put more emphasis on maintenance and early identification of measures needed to address potential dangers.”

Read the Ecns.cn article, “Dam inspections found lacking” here

 

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