At four in the morning one day in early July, 31 villagers living on the banks of the Yellow River in Jiaozuo county, central China, woke to find themselves trapped by rapidly rising waters. They made it to safety, but only after a major rescue effort. This was an artificially-created “flood”, designed to clear silt from China’s second longest waterway. And, once again, it drew public attention to Yellow River regulation projects.
Under the Yellow River’s management system, water levels are adjusted at five reservoirs on the river and its tributaries – at Wanjiazhai, Sanmenxia, Xiaolangdi, Guxian and Luhun. When the reservoir gates are opened, the fast-flowing water picks up silt and carries it downstream, clearing the water course and removing sediment from the reservoir.
On the morning of June 19, the Yellow River Flood Prevention Office gave the order to flush silt from the Xiaolangdi reservoir in Xin’an county, Henan province, officially marking the start of the tenth round of silt regulation on the Yellow River. Some 2,500 cubic metres of water a second rushed towards the ocean, carrying with it the silt that had built up on the floor of the reservoir over the previous year.
The Yellow River contains more sediment than any other river in the world. Each year, the river bed increases in height by 10 centimetres as a result of the accumulation of silt. This is the biggest challenge for those trying to manage the flow, and the reason the river so often breaches its banks. The communities next to the Yellow River have, in the 2,000 years for which records exist, seen this happen on average twice every three years.
According to the website of the Yellow River Conservancy Commission (YRCC), the government agency that oversees management of the river basin, careful preparations for the “artificial flood” had been made. There had been three trials and six full-scale operations, during which 380 million tonnes of silt had been moved to the Bohai Sea.
Efforts to regulate silt in the Yellow River in fact began as early as 1957, at Sanmenxia. An article published on the YRCC’s website in 2007 describes the construction of the water-control hub at the gorge as a monumental effort, made possible only by the heroic spirit of thousands of workers. But as the Soviet experts who designed the dam failed to take into account the amount of silt in the river, in the years following construction, the structure failed to function properly and had a devastating environmental impact.
In the first year of operation alone, the river bed behind the dam rose by 4.5 metres, according to a 2002 report by the Economic Observer. A build up of silt where the Wei River, the Yellow River’s largest tributary, entered the reservoir caused water to back up, threatening Xi’an and the Guanzhong plain. Dykes had to be built along the banks of the Wei, which had never before posed a flood risk. The situation persisted until changes were made to the dam. At the time, the lack of democratic policymaking mechanisms meant that a key opponent of the dam, professor Huang Wanli, a hydraulic engineer at Tsinghua University, was not only unable to influence the process, but was actually persecuted as a rightist.
Almost half a century later, in 2002, the construction of the Xiaolangdi dam and a number of key technological advances allowed the practice of silt regulation to begin, director of the hydroscience and engineering laboratory at Tsinghua University, Wang Guangqian, explained to chinadialogue.
Earlier this year, the South China Morning Post reported that these regulation efforts had raised the quality and quantity of water in the Yellow River, as well as reducing silt. By the end of 2009, it said, the river water was passing more then 70% of potability tests, compared with an 86% failure rate in 2002. Moreover, in eight straight years the river had never run dry, and the continuous flow had helped to improve its ecology. Earlier reports from chinanews.com said that 42 square kilometres of lost wetlands in the Yellow River Delta had been restored, and the bronze gudgeon – a fish not seen since the 1980s – had returned.
These results have not gone unrewarded. In March this year, the YRCC received the Lee Kwan Yew Water Prize at Singapore’s International Water Week, singled out for its use of technological innovation and a sustainable development to achieve success in river management.
Putting together the regulation project reportedly involved cooperation from water authorities in 13 provinces, almost 10 billion yuan (US$1.5 billion) of infrastructure investment and decades of research by numerous academic institutions. And yet these “artificial floods” still carry clear risks. According to the Economic Daily News, the lower reaches of the Yellow River affect the safety and livelihoods of 100 million people, in particular the 1.9 million people who live on its banks. Any errors in controlling the flow could result in a real flood, placing these people and their property in danger.
According to a local media report, the tests for the first silt regulation effort in 2002 resulted in 119 square kilometres of crops being inundated in the county of Puyang, Henan province, alone, affecting more than 125,000 people and causing 165 million yuan worth of damage. According to one Puyang resident, this was the worst flood since 1996, with complete crop failures seen across almost all of the affected land. However, the Commission’s Yellow River Report said that just 33 square kilometres of land – between the river itself and the dykes – had been submerged.
After 2002, the controversy over silt regulation was rarely mentioned in the media. According to Wang Guangqian, “This was because the outcomes were excellent and there was general approval. The project is entirely in accordance with scientific principles.” Unlike the voices that question the wisdom of man-made floods, Wang holds that the practice has lowered the riverbed downstream by more than a metre, doubling flow capacity and greatly reducing flood risk.
But the Jiaozuo incident has revived concerns. This time around, the victims were all local villagers. According to the Oriental Today, the 31 farmers had arrived two days earlier to build a shed and plant crops, and had been sleeping on the ground. While the sudden flooding did not cause any deaths, the loss of crops, seeds and tools still brought heartache. Granted, the villagers were occupying mudflats that were originally part of the Yellow River. But farmers have been making a living in this way – planting crops on the river’s banks – for many years.
Some commentators have raised additional concerns about silt regulation practices. Zhang Ren, a professor at Tsinghua University’s department of hydraulic engineering, told China Newsweek that, given the Yellow River is so short of water, the flooding practice is hugely wasteful. Wang Guangqian refutes this, saying that just a small proportion of the water flow is held back in the reservoirs, where it is stored up to create a flood peak, meaning no water is actually wasted.
Others worry about coping with shifts in flow patterns. Silting varies across different stretches of the Yellow River. On its upper and middle reaches, from the source in the Bayan Har mountains in western China to Hekou in Inner Mongolia and then from Hekou to Taohuayu in Henan province, the river flows through loess plateaus, picking up loose sediment, which gives the water its muddy appearance. That silt is then deposited in the lower reaches, from Taohuayu to the Bohai Sea, causing the river bed – and the dykes – to increase in height. But the situation is changing.
Qin Weizhi, director of Yuangang Agriculture and Forestry Development, a company in Gansu that has long worked on Yellow River siltation, told chinadialogue that there is an urgent need for protection of the wetlands at the Yellow River’s source: “Some 200,000 mu [133 square kilometres] of wetlands are turning to desert every year. There is half as much water as there was five years ago. If this carries on, then sooner or later there are going to be major problems.”
Wang Guangqian maintains that, despite this reduction, silt in the Yellow River has dropped from 800 million tonnes to 600 million tonnes in recent years – due, he says, to soil conservation measures, a reduction in rainfall and the dams built to remove silt. But he also admits that silt regulation suffers from technical limitations and the results of the process are not ideal. The silt deposits in the Xiaolangdi Reservoir are hard to shift and, over the next 20 years, some way of dealing with the accumulated sediment will need to be found. Wang is not worried: “At that point the silt will be higher and therefore easier to move, though control of water flow will be harder.”
Meng Si is managing editor in chinadialogue’s Beijing office. Additional reporting by chinadialogue intern Yang Jie.
Homepage image by Gavin
