Three Gorges Probe

Chapter 7 – Unresolved Issues: Perspectives from China

by Shiu-hung Luk, Ph.D., and Joseph Whitney, Ph.D.

The Chinese feasibility study for the Three Gorges Project, which was conducted under the aegis of the State Planning Commission,* remains a secret government document. From 1987 to 1989, while official studies were under way, numerous research papers1 on the feasibility of the Three Gorges Project were circulated and published in Chinese journals.

During this period, the Chinese press reported that views critical of the project were under-represented in official documents and that a vast number of critics had not been heard by decision makers in the upper echelons of China’s central government. Since then, several collections of essays such as those edited by Tian Fang and Lin Fatang, senior officials with the State Planning Commission, have been published in China as a forum for dissenting views.2

This chapter reviews the key unresolved issues that have been raised within China about the Three Gorges Project and have not been adequately addressed by the CYJV study.

Resettlement

The scale of resettlement required for the Three Gorges Project surpasses that of other major dams such as the Sanmenxia Dam on the Yellow River, the Danjiangkou Dam on the Han River, and the Wujiangdu Dam on the Wu River. China’s record on resettlement is tragic: according to China’s Ministry of Water Resources,* 30 to 40 percent of the 10 million people who have been relocated to make way for hydroelectric dams since the late 1950s are still impoverished and lacking adequate food and clothing.3 Although China has recently improved its guidelines for resettlement in accordance with the World Bank’s criteria for “successful resettlement,” the people who would be displaced or affected by the Three Gorges have no guarantee they would be spared the hardship and suffering associated with such schemes.

Proponents of the Three Gorges Project are well aware of the potential for social upheaval and conflict, so it is disturbing that none of the writings reviewed, either Chinese or foreign, present any evidence that the people who would be affected by the scheme have been consulted about the impact resettlement would have on their lives.4

The Chinese resettlement plans, as reviewed by CYJV, suggest that the displaced population could migrate uphill, so that even though they would be forced to abandon their town or village, they could remain in the same county.5 On paper this may seem reasonable, but after examining the conditions in the upland areas, it is obvious that this scheme would not be successful.

Land Availability

Fundamentally, the problem is that the best land in the area is in the valleys which would be flooded by the reservoir. This land is already 15 percent overpopulated,6 and the remaining land is further uphill, too steep to cultivate properly, and relatively infertile. In fact, Chinese soil scientists have estimated that five times the area of less productive uphill land would be needed to replace the 26,800 hectares of prime agricultural land which would be lost to the reservoir.7 This amount of land is simply unavailable in this area.

In addition to the problem of finding replacement land, Chinese critics have doubts about the plans to integrate resettlement with natural resource development as a means of creating jobs for the non-agricultural sector.8 They question not only the economic viability of some of the proposed schemes, but whether the necessary capital and resources would ever be made available.9

Development Plans

For example, the proposed salt mine development in the Three Gorges region would probably have difficulty competing with salt mines that are well established elsewhere in the province. Vague plans to develop tourist industries conflict with plans to expand polluting industries in the same region. And the proposal, endorsed by CYJV, for intensive orange and dairy production appears similarly unworkable.

Resettlement Costs

  • According to CYJV, over one-half of the land slated for rural resettlement is situated above 800 metres elevation. Because of the cost of access and the fact that cultivation is limited to a small range of crops at higher elevations, development there would be more expensive. CYJV apparently failed to include this cost in its estimates.

  • CYJV assumes the cost of relocating nearly a dozen cities and scores of towns, along with all their basic infrastructure such as roads and water supply systems, in the Three Gorges region by assuming it would cost about the same as rebuilding Tangshan, a northeastern city, with a population of 1.4 million, after it was totally devastated by an earthquake in 1976. But state planning officials, Tian and Lin, point out that this is an underestimation because Tangshan was rebuilt on level ground compared to the rugged hilly terrain in the Three Gorges region.10

The Impact of Upstream Land Use Changes on Soil Erosion, Sedimentation and Flooding

Editor’s Note: The rate of sedimentation in the proposed reservoir during its lifespan depends, in part, on land use and soil erosion patterns upstream. Quantifying the actual long-term rates and patterns of sedimentation for a number of decades is a complex issue which has long been a source of contention among scientists. Here the authors explain why proponents wrongly discount the impacts of sedimentation which could significantly shorten the useful life of the Three Gorges Dam.

Numerous Chinese authorities11 report that soil erosion, and therefore the sediment load in the Yangtze River, is increasing because of population pressure and land degradation upstream of the Three Gorges. If the Three Gorges Project is built, some scientists are predicting a 15 percent increase in expected rates of sedimentation during the reservoir’s lifespan, and others are predicting even higher increases.12 The impact of resettlement alone – due to activities such as land clearing, cutting down trees for fuel, mining, and extraction of building materials – is expected to cause an annual 2.5 percent increase in the Yangtze’s sediment loads.

CYJV, on the other hand, suggests that no obvious increases or decreases in the Yangtze’s sediment load have been observed, and it makes the overly conservative assumption that sediment would deposit in the reservoir at a fixed rate over time. In addition, CYJV’s estimate of the amount of sediment which would become trapped in the reservoir appears low for several reasons. First, it assumes that sediment which is currently building up behind dams on upstream tributaries will remain there indefinitely. But within a few decades or less, these reservoirs will become clogged with sediment, at which time the dams will have to be taken out of operation in order to flush out the accumulated sediment. From there, the sediment will eventually be flushed into the Yangtze River, causing a significant increase in the river’s total sediment load.

Yangtze Valley Planning Office reports suggest building even more dams upstream as a strategy to substantially reduce sediment input to the Three Gorges reservoir.13 Technically, this would reduce sedimentation in the reservoir for a short term but it would eventually cause sedimentation problems further upstream. Furthermore, to build more dams to control sediment would ignore upstream land degradation and soil erosion which are the cause of the high sediment load problem.*

Secondly, CYJV assumes that only 20 percent of soil eroded from land upstream of the Three Gorges ever reaches the Yangtze River. This discounts a significant amount of eroded soil, which is first transported by floodwater and deposited onto flood plains and other low-lying areas, but would eventually be flushed into the Yangtze.

Proposed Sediment Management Strategy

Based on its initial assumptions about rates and volume of sedimentation, CYJV predicts that in the early years of dam operation, 60 to 70 percent of the river’s sediment would be trapped in the reservoir. The coarser sediment would deposit in the upper end of the reservoir, known as the backwater reach, gradually forming a delta which would encroach on the dam’s useful storage capacity. Also, the river channel would become raised, thereby increasing upstream flood levels and obstructing navigation, particularly in the dry season. According to CYJV, the reservoir slope would become flatter and reach a state of equilibrium after about 100 years. CYJV claims that at that time, there would be no net additional deposition or erosion of sediment in the reservoir. Moreover, CYJV believes that “If the reservoir is operated as proposed, about 90% of its effective storage can be preserved indefinitely.”14 To prevent unwanted sediment buildup in the reservoir and thereby preserve long-term storage capacity in the reservoir, water levels would be lowered to the flood control level (FCL) of 140 metres during the flood season. At this time the flow is carrying most of its sediment load, so water is released rather than stored to avoid sediment deposition. After the flood flows when the water is relatively sediment-free, the reservoir would be raised to the normal pool level (NPL) of 160 metres and maintained at that level as required for power generation. In other words, the operating rule would be to store water when clear and release when turbid.

Critics suggest that this proposed operating procedure would not be effective for several reasons:

  • Although some of the finer sediments would be flushed out, this operation would have no effect on coarser sediments which are expected to form a delta beginning several hundreds of kilometres upstream.

  • At the reservoir backwater, 600 kilometres upstream of the dam, floodwater would continue to deposit sediment as they flow into the reservoir, quite independently of how the dam is operated. And as more sediment accumulates, the rate of build-up increases, extending deposition further and further upstream.

Proponents, on the other hand, suggest that this problem would be limited because at the end of each dry season, water levels in the reservoir would be lowered, allowing the river to erode the sand bars and shoals which are formed during each flood season (this process is known as retrogressive scouring).15 In practice, however, retrogressive scouring has been ineffective hundreds of kilometres upstream of dams such as the Sanmenxia Dam on the Yellow River.16 And in the case of the Three Gorges Project, the reservoir is nearly five times the length of the Sanmenxia reservoir, which makes it even more doubtful that the river would effectively scour sediment deposits away. To make matters worse, the narrow Tongluo Gorge, located 15 kilometres downstream of Chongqing, acts as a bottleneck in the river so that any lowering of water levels at Three Gorges to flush sediment through would have a negligible impact on the problem of sedimentation near Chongqing.

Backwater Sedimentation and Increased Flooding

Sun and Fang17 believe that the city of Chongqing would face an increased flood risk because backwater sedimentation would raise the elevation of the river channel. CYJV recognizes that significant sedimentation would occur, thereby increasing the level of flooding near Chongqing, although it appears it did not quantify the amount and cost of dredging required to reduce the flood risk.

Navigation

Editor’s Note: The Yangtze River is a major east-west artery of trade and commerce, and is strategically important to the economic development of southwest China. The 660-kilometre reach of the river between Yichang and Chongqing is characterized by numerous narrow gorges, strong currents and dangerous shoals. Because of this, navigation is treacherous, and the cost of shipping through this reach is more than double the cost below Yichang. According to proponents, the Three Gorges reservoir would transform this hazardous reach into a deep, gently flowing waterway, which would allow large ocean-going vessels access to the river port of Chongqing.18 The resultant increase in shipping would, in turn, facilitate the development of Chongqing as the largest municipality and inland port in southwestern China.

CYJV defines navigation benefits as equivalent to the reduced transportation costs of moving cargo and passengers through this reach of the Yangtze. The calculation of benefits is largely dependent on, and proportional to, the projected increases in shipping traffic.

Increased Volume of Shipping on the Yangtze

Members of the Chinese People’s Political Consultative Committee (CPPCC), an influential group of “opposition” parties, are sceptical about the Ministry of Communication’s projected five-fold increase (an annual goal of 50 million tonnes) in shipping as a result of the improved navigation. CYJV’s estimate of 41 million tonnes is equally theoretical, since no thorough study has yet been done to determine the volume of shipping traffic that could be moved through the locks under various scenarios of vessel and tow size, proportion of passenger vessels to freight vessels, and with various traffic control procedures.

Impact of Sedimentation on Navigation

CYJV expects that backwater sedimentation would obstruct navigation in the channel and access to river port facilities near Chongqing, particularly in the dry season. CYJV failed to investigate this, and also the feasibility and cost of dredging operations which could be required on a massive scale.

Another issue not yet raised by proponents is the impact of sediment releases from the Three Gorges Project on the Gezhouba Dam which is 40 kilometres downstream. These sediment releases could form a delta where the Yangtze River slows down to meet the Gezhouba reservoir. As would be the case upstream of the Three Gorges Project, sedimentation in the Gezhouba reservoir would not only reduce its limited storage capacity but, without continuous dredging, could also impede navigation.

Navigation Benefits Achievable Without the Three Gorges Project

CYJV provides preliminary evidence that without the Three Gorges Project the present volume of shipping traffic (6 to 9 million tonnes) could be roughly tripled (17 to 28 million tonnes) depending on the size and mix of vessels. They also state that better traffic control procedures, extended hours for navigation, more powerful tug boats, and improved barge design could all serve to increase channel capacity beyond present limits. If these improvements were implemented, the volume of shipping traffic could equal or possibly exceed CYJV’s projections for the Three Gorges Project.

The Multipurpose Conflict

Quite apart from the technical problem of managing the sediment that could impede navigation through this reach, and the wide range of complex factors influencing improved transportation on the Yangtze, neither CYJV nor the various Chinese sources have dealt adequately with one of the most important issues: the inherent conflict associated with operating a multipurpose dam. Intended to generate power, provide flood control, and improve navigation, the reservoir would have to be maintained at different levels to achieve optimum benefits for each function.

Generally speaking, for power generation and navigation, the higher the water levels in the reservoir the better. Conversely, for flood control – the primary purpose of the dam – water levels should be as low as possible prior to the flood season in preparation for storing peak floodwater. To complicate the matter further, the operation for controlling sediment requires that water be stored only in the dry season when it is relatively sediment-free, and released in the flood season when the river’s sediment load is highest.

Proponents claim that shipping costs for vessels proceeding upstream against the strong current would be reduced due to the slower velocities in the reservoir. But if little water is actually being stored, in order to avoid sediment buildup, then it is not clear whether velocities through the gorges would be significantly reduced. Neither is it clear what the impact of operating to serve peak electricity demands in the dry season would be on flows downstream of the Three Gorges Dam and the Gezhouba reservoir. If, for example, the flows were too low, navigation depths would be insufficient and navigation would be impeded through this section.

According to CYJV, the 160-metre recommended scheme would eliminate all but one of the 32 existing bottlenecks through the narrow gorges reach of the river and the 12 existing winching stations.* However, CYJV downplays the fact that the reservoir would, at best, be held at this level for only six months of the year (November to April). For the remainder of the year, the reservoir would either be at the flood control operating level (FCL) of 140 metres or fluctuating somewhere between FCL and normal pool level – assuming floodwater are not stored. When the reservoir is held at the FCL, anywhere from five to eight bottleneck sections would still exist in the 60-kilometre reach downstream of Chongqing. Proponents have failed to consider how the bottlenecks at low water levels would affect larger ships which are expected to travel the improved waterway.

Conclusions

Despite the major investment of time and effort on the part of CYJV in preparing the feasibility study for the Three Gorges Project, there remain serious conceptual and data shortcomings with respect to resettlement, reservoir sedimentation, upstream flooding, multi-purpose operation and navigation benefits. Because a large number of potential costs have not been evaluated by proponents, and are not included in the cost-benefit analysis, it is by no means certain that the benefits of the Three Gorges Project outweigh the costs. If a rigorous cost-benefit analysis of the Three Gorges Project were to include these costs, the proposed scheme would appear far less economical than its proponents now claim.

 

 


Sources and Further Commentary

 

*The State Planning Commission plays a central role in China’s energy and economic planning, and reports directly to the State Council.

*The Ministry of Water Resources and Electric Power has been divided into two distinct ministries, the Ministry of Water Resources and the Ministry of Energy.

*Proponents of the project also argue that there are advanced technologies available to reduce soil erosion although they tend to be too expensive. Less expensive soil erosion control measures, such as terracing, planting grass, shrubs, and trees, would be ineffective because any planted vegetation is likely to be denuded by people in desperate need of fuelwood for cooking. In any case, proponents do not include the cost of implementing soil erosion strategies, necessary for reducing sediment input to the reservoir, in the project cost estimate.

*Winching stations are situated at narrow sections of the Yangtze River. A mechanical winch and steel cable, attached to the oncoming vessel by a tugboat, is used to pull the boat through the narrow section.

Categories: Three Gorges Probe

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