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The author:(作者)aaapublished in(发表于) 2013/12/16 0:51:05 The three gorges project eight focal point perspective
Xinhuanet, Beijing, December 15 (reporters Liu Ziling and and Li Bin and and and and Lin Hui)-from demonstration phase to run for 10 years, the three gorges project has always been the focus of public opinion.
Sedimentation plan? A severe drought in Southwest China, and the three gorges project really matter? …… Built 20, and hub success run 10 annual, cum continuous 4 years success achieved 175 m impoundment Zhiji, Xinhua News Agency reporter walked into State TGP Office, and water, and Yangtze River water Committee, and China engineering homes, and China Yangtze River Three Gorges group, units, to authority expert ask, and visits has site, and library district and the downstream multiple place, master has large first-hand information, tries to Combs interpretation shrouded in "TGP engineering" Shang of you of focus problem.
Focus: buried sediment dam?
Sedimentation is one of the main technical problems of TGP.
Sediment problem, the three Gorges reservoir, "storing clear water and releasing the muddy" method, that is, greater displacement make muddy water out when the flood season, large volume water in the dry season, thereby reducing the deposition of sediment in the reservoir.
In recent years, studies have shown that sediment of three Gorges reservoir inflow showed a declining trend. According to the Chinese Academy of engineering, in 2013, the impoundment of three gorges project pilot phase assessment synthesis report, since the beginning of the three Gorges reservoir since impoundment (2003), little change in average annual water quantity reported as finished, but average annual sediment load for the library at 203 million tons, five years ago mean value 1990. Pilot water 175 meters since the upstream of the three Gorges reservoir and sediment reduction trend is continuing, 2009 average annual inflow of suspended load sediment to 183 million tons, only five years ago mean value 1990.
Impoundment of the three gorges project pilot phase assessment project team leader, former Vice President of the Chinese Academy of engineering academician Shen Guofang appraised believes that storage of three gorges project reduces the amount of sediment, partly because of continued implementation of soil and water conservation project in the upper reaches, much improvement in the situation of soil erosion, on the other, built a series of reservoirs in the upper reaches of the three gorges, the sediment must be intercepted. He said: "the future, as new major reservoirs in the upper reaches of the three Gorges Dam joint on water storage and silt detention and scheduling, overall sediment of three Gorges reservoir will be further eased, can be maintained within 100 years of three Gorges reservoir capacity of 20 billion. ”
At present, the impoundment of three Gorges reservoir has been used for 10 years. Since 2009, the three Gorges reservoir before impoundment, and flood control, flood limit water level float after the optimization measures, average annual sedimentation and sediment 45% to forecast values only for the demonstration phase, siltation of the reservoir capacity for flood control forecast was better than the preliminary design stages. In 2012, took the deposition reduction schedule of the three Gorges reservoir, Sha Feng movement control measures, further reducing tail and silting in the reservoir area, in favour of reservoir active storage for extended periods.
Focus II: geological hazards in water?
Historically prone to geological disasters in three Gorges area, documenting large-scale landslides more than more than more than 10. After impoundment of the three gorges, how is the geological disasters in the reservoir area?
According to Zhang Cheng, Deputy General Manager of the three gorges group introduction, since 2003 since the initial filling, reservoir Bank near dam, tributary of the natural and artificial protective good stacked Bank were not found larger-scale deformation phenomena such as sliding, Bank slope stability as a whole; there have been small-scale localized deformation phenomenon of reservoir Bank reconstruction and adjustment of normal. Conclusions overall, in line with the initial design.
Statistics show that since September 2008 m pilot water until August 31, 2012, recorded new geological disasters in the reservoir area of the three gorges project disaster risk 401, Hubei area 112, 289 in the Chongqing area.
In this 401 geological disaster hazards, the vast majority occur in experimental water storage for the first year (2008), 83% per cent of the total. Since then, with the Bank gradually stabilized, incidence of geological disasters have dwindled, and began to moderate.
Surrounding area geological hazards may occur, the relevant departments to conduct focused on migrants from three Gorges area counties, districts of geological disaster control, strengthening the geological environment of the new immigrant community safety, ensure the area 2008 m experimental reservoir geological hazards since "zero casualty".
Professor-level senior engineer, Chen Houqun, academician of Chinese Academy of water resources and hydropower research, given the invisibility of geological disasters and sudden, the reservoir was high on both sides after the steep slope unstable rock avalanche danger forecast is difficult to find, and area size and population of the town expanded in recent years, land development and construction of disaster risks should not be overlooked, of geological disaster prevention and control remains to be high priority.
Focus three: reservoir-induced earthquakes?
In recent years, the once strong earthquakes in Western China, people point the finger at the three gorges project. Whether this is in line with the objective facts?
Monitoring data show that, during the impoundment of the three gorges project reservoir-induced earthquake activity dominated by tremors and tremors, mainly raised by Karst, caves soak. After impoundment of records of M4.1 earthquake in early November 2008 (equivalent to ML4.6) is the largest, far less than the initial design verification report gives "M5.5 can be considered" forecast.
Current academic recognition, the stereotype of reservoir-induced earthquake, closer to the reservoir can only be triggered from the area and is close to the limit of the seismogenic fault, deep penetration water along the fault led to the lower shear strength, is the main reason trigger earthquakes. According to hydrogeological conditions, kushui distance out no more than bank first watershed, about 3 per cent from the Bank, will not be greater than 10-kilometer.
For Wenchuan earthquake, earthquake in Lushan, southwest of earthquake induced by TGP reservoir, experts give a negative answer.
2008 "5·12" Wenchuan earthquake occurred in Longmen mountain seismic belt, northern edge of Qinghai-Tibet plateau, is an underground deep result of plate collision. Huangling Anticline, where the three Gorges Dam belonging to the Central Yangtze platform of Yangzi quasi platform fold belt, two regional tectonic conditions in which entirely different, there is no regional structural links. Cao Guangjing, Chairman of China three gorges Corporation said: "Three Gorges reservoir is not triggering the Wenchuan earthquake. ”
Focus four: dam blocking the circulation path?
Since the three Gorges reservoir, coincides with the area and its surrounding areas of frequent extreme weather and climate events, such as the 2006 drought in Sichuan and Chongqing, April winter and spring drought in 2011 and the middle and lower reaches of the Yangtze River in Southwest China, such as severe drought. "Three Gorges Dam blocked circulation affected climate around" credence to claims. In this view, the three gorges was a gap in the Sichuan basin, construction of the three Gorges Dam blocked natural water vapor loop, leading to all kinds of extreme weather events occur.
"Atmospheric circulation the vertical height of 3,000 meters, the three Gorges Dam height more than 180 meters, the three Gorges Dam have no chance of blocking or blocked circulation. "Chen Fei, General Manager of China three gorges group said.
Assessment report that Chinese Academy of engineering, near the three Gorges reservoir on local weather and climate have a certain influence, especially for temperatures above the surface is significantly lower, but the temperature has little effect on library week, reach no more than 20-kilometer.
Based on comprehensive benefit of the three gorges project this year, CMA climate assessment report, after impoundment of three Gorges reservoir (2004-2011), temperatures in most areas before impoundment of the reservoir area (1996-2003) has increased, with an average annual temperature of 17.9 to 18.9 degrees Celsius and an average increase of about 0.2 degrees Celsius.
CMA experts said that in recent years in three Gorges reservoir area and the surrounding areas of extreme weather, and atmospheric circulation and sea surface temperature changes in East Asia and closely related factors such as thermal anomaly in Qinghai-Tibet plateau, but direct contact with the reservoir was not found.
Focus five: two lakes called thirsty v crisis?
In recent years, Dongting Lake and Poyang Lake appeared at the middle and lower reaches of the Yangtze River areas, such as severe drought, some argue that with the three Gorges Dam has a lot to do. While in Hunan and Jiangxi provinces, want to set brakes stop the water in Dongting Lake and Poyang Lake at Hukou are also becoming increasingly louder. Three Gorges reservoir water to Dongting, Poyang two lakes have caused what effect?
Dongting Lake is Lake important regulation of the Yangtze River, has "accommodated four water" effect. Long time, carrying large amounts of water and sediment of the Yangtze River into the Lake, causing constant of sediment siltation of Dongting Lake, the Lake is shrinking. "Part after impoundment of three gorges project impoundment and sediment, to discharge the water cleaner, this is beneficial for mitigation of Dongting Lake's sedimentation conditions. "Shen Guofang appraised that," in the meantime, water down the Yangtze River, Dongting Lake into the river's rushing role at Sentosa is also more obvious. ”
Poyang Lake's situation is slightly different. Shen Guofang appraised introduction, is a mutual exchange of water of Dongting Lake and the Yangtze River, Poyang Lake more leaks. Annually during the water storage of the three Gorges reservoir reduced discharge than the natural flow, downstream of the dam of the lower water levels, enable Poyang Lake at Hukou traffic increases.
China engineering homes of assessment report on this do has more detailed of analysis: "TGP reservoir scheduling on hole Chamber, and Poyang commentary water resources uses of effects main performance in flood Hou impoundment during, Yangtze River River water level declined, by Jingjiang three mouth entered Dongting Lake of water reduced, commentary out Lake volume increased, dry season ahead of, LW reduced, on irrigation, and water and the ecological environment water produces must effects. ”
Focus six: rare species today?
Effect of TGP on biodiversity has been the hot topics of public concern. Before the approved the construction of three gorges project, researchers went on to explore on the ground, and on the impact of three-Gorge project on the local flora and fauna there may be a rigorous proof.
From terrestrial ecosystems, the three Gorges reservoir area of terrestrial vertebrates not only on its own to move out of the reservoir area, and outside the reservoir area has widely distributed, there is no risk of extinction. For rare terrestrial plant, relevant departments have taken conservation, wild germplasm resources conservation, Botanical Garden conservation, in situ conservation ex situ measures.
Seen from the aquatic life, the project will affect the coexistence in the region in 6 species of rare and endangered aquatic creatures, including Baiji, white sturgeon, Chinese sturgeon, sturgeon, finless porpoises and Rouge fish. In order to protect the rare species, China has set up the estuary and the white sturgeon Acipenser sinensis larvae, gezhouba dam the Chinese sturgeon protected areas, rare and endemic fish nature reserve in the upper reaches of the Yangtze River and other, and the implementation of artificial propagation of the Chinese sturgeon and Larval release.
Impoundment of the pilot phase assessment of Chinese Academy of engineering report, unique to the Yangtze River upstream of the Yangtze River fishery resources has undergone large changes, mainly for the kinds of reductions, changes in population distribution, population size changes. Fish adaptability to environmental changes also have differences, such as the Chinese sturgeon after the damming of gezhouba dam quickly adapted to the environment, under the dam formed a new spawning grounds. Chinese sturgeon Research Institute in 2009 breakthrough in artificial propagation of Acipenser sinensis technical difficulties, made the species protection work to get rid of the dependence on wild resources, have the capacity to long-term preservation of species under artificial conditions.
Seven focus: Golden water cut off?
In recent years, the dam of the three Gorges Dam ship locks often have large numbers of ships to be gates, many people begin to doubt the impact of three gorges project on the Yangtze River Golden waterway.
Before the construction of the three gorges project, Yangtze River waterway low grades, poor navigation conditions, restricting the development of Yangtze shipping. Within the Yangtze River waterway from Chongqing to Yichang, 660 kilometers, with Rapids shoal, shoals, Rapids 139, jiaotan station 24, line 46 for control sector. After impoundment of the three gorges project, channelization, the Chongqing waterway, eliminating the dam between Chongqing and all river rapids, line control, navigating across the Board to meet the annual navigation day and night.
Statistics show that in 1949, the Yangtze river cargo only 1.91 million tons; after the gezhouba navigation in 2002, 18 million tons of cargo from that section of the highest value. Yangtze navigable waterway of sanxia one-way years through increased capacity by 10 million tons to 50 million tons. In recent years, the lock freight volume increased steadily in 2011 through the lock's 100.33 million tonnes cargo volumes, 19 years before reaching the lock one-way design capacity of 50 million tons of targets.
Group companies in recent years, strengthen the management of shiplock operation of the three gorges, has taken the lock's four-level operation to expand under the 156 metre water level lock capacity measures, gradually increase the brake efficiency. Navigation in 2008 pilot during the impoundment with an average annual rate of 96.25%, above the design target of 84.13%, running for more than 1000 hours per year.
Experts say that as a response to the rapid development of the Yangtze River shipping to the new situation, meet the growing demand for lock, to promote and popularize ship type of large scale, standardization, serialization, shorten the brake interval increased gate utilization, increasing the average DWT of ships of every gate, thereby increasing capacity, expanding the shipping benefits of the three gorges project.
Eight focus: dam River regime under "sports"?
After the operation of three gorges project, water discharge, sediment-carrying capacity increase, stability of the riverbed of the middle and lower reaches of the Yangtze River, revetment works "collapse" problem is manageable, well received by the community.
Expert pointed out that, this problem in TGP engineering demonstration stage has made forecast, think TGP engineering built Hou, dam downstream will occurred long time, and long-distance of scour, with flow water level has declined, and pointed out that "TGP engineering built Hou, will according to downstream river potential adjustment of total trend and existing revetment engineering situation, continues to perfect revetment engineering, and on has built engineering for necessary of reinforcement".
Field data indicate that, since 2003, of three Gorges reservoir since impoundment dam downstream river erosion occurs mainly to chenglingji in Yichang reach of express, scour has grown to Hukou unexpectedly faster and broader than the demonstration phase was expected, but River, in General, have not changed. In General, the conclusions of the validation phase is essentially correct.
That nearshore Riverbed apparent scour depth, revetment works the lower slope steepening, "collapse" before impoundment increased, but most occurred prior to impoundment of the original Bank collapse and dangerous segments. Due to revetment engineering in 1998 after the deluge building and reinforcement, coupled with the Bank collapse occurred when Rob nurse, impoundment of three gorges project's middle and lower reaches of the Yangtze River embankment since no major danger. Future by strengthening the river monitoring, implementation of Jingjiang River control emergency project ensures safety of levees.
新华网北京12月15日电 (记者 刘紫凌、李斌、高亢、林晖)从论证阶段到运行10年，三峡工程始终是舆论的焦点。
泥沙淤积情况怎样？西南大旱和三峡工程真有关系吗？……兴建20年、枢纽成功运行10周年，暨连续4年成功实现175米蓄水之际，新华社记者走进国务院三峡办、水利部、长江水利委员会、中国工程院、中国长江三峡集团公司等单位，向权威专家请教，并走访了三峡坝区、库区及下游多个地方，掌握了大量第一手资料，试图梳理解读笼罩在“三峡工程”上的是是非非的焦点问题。
焦点一：泥沙淤积埋大坝？
泥沙淤积问题是三峡工程最主要的技术问题之一。
面对泥沙问题，三峡水库采用“蓄清排浑”的方法，即在汛期时加大排水量使浑水出库，在枯水季节大量蓄积清水，以此减少泥沙在水库内的淤积。
近年研究表明，三峡水库泥沙入库量呈现不断减少的趋势。根据中国工程院2013年《三峡工程试验性蓄水阶段评估综合报告》，自三峡水库开始蓄水以来(2003年至2012年)，入库年均水量变化不大，但入库年均沙量为2.03亿吨，为1990年前均值的42%。175米试验性蓄水以来，三峡水库上游来沙减少趋势仍然持续，2009年至2012年的年均入库悬移质输沙量为1.83亿吨，仅为1990年前均值的38%。
三峡工程试验性蓄水阶段性评估项目组组长、原中国工程院副院长沈国舫院士认为，三峡入库泥沙量减少，一方面是因为上游不断实施水土保护工程，水土流失局面得到很大改善；另一方面，三峡上游新建了一系列水库，对泥沙有一定拦截作用。他表示：“今后，随着三峡上游新建各大水库的蓄水拦沙和上下游水库的联合调度，三峡水库的泥沙淤积总体会进一步缓解，三峡水库可以在100年内维持200个亿的库容量。”
目前，三峡水库已蓄水运用10年。2009年以来三峡水库采取提前蓄水、中小洪水调度、汛限水位上浮等优化调度措施后，年均淤积沙量仅为论证阶段预测值的45%，防洪库容的淤积好于初步设计阶段预测水平。2012年，三峡水库采取了库尾减淤调度、沙峰调度措施，进一步减少了库尾及库区泥沙淤积，有利于水库更长时间保持有效库容。
焦点二：地质灾害因水起？
三峡地区历史上就是地质灾害多发区，记载的大型崩塌滑坡就有10余处之多。三峡蓄水以后，库区地质灾害情况如何？
据三峡集团副总经理张诚介绍，自2003年开始初期蓄水以来，近坝段干、支流的天然库岸和已防护好的人工堆积库岸均未发现较大规模的滑塌等变形现象，岸坡整体稳定性较好；局部出现了小范围变形与调整等正常的库岸再造现象。总体情况符合初步设计结论。
统计数据显示，2008年9月175米试验性蓄水以来至2012年8月31日，三峡工程库区共发生新生地质灾害灾险情401起，其中湖北库区112起，重庆库区289起。
在这401起地质灾害险情中，绝大部分发生在试验性蓄水第一年(2008年)，占总数的83%。此后，随着库岸逐步趋于稳定，地质灾害发生率锐减，并渐趋平缓。
围绕着库区可能发生的地质灾害，有关部门全力开展以三峡移民县、区为重点的地质灾害综合防治，强化新建移民小区的地质环境安全，保证了库区2008年175米试验性蓄水以来地质灾害“零伤亡”。
中国水利水电科学研究院教授级高工陈厚群院士表示，鉴于地质灾害具有隐蔽性和突发性，水库蓄水后两岸高陡岸坡危岩崩塌险情难以发现预测，同时库区近年来城镇规模和人口的扩展，土地开发建设致灾危险性不容忽视，对地质灾害防治仍需高度重视。
焦点三：蓄水诱发大地震？
近年来，一旦我国西部地区发生强震，就有人把矛头指向三峡工程。这种说法是否符合客观事实？
监测数据表明，三峡工程蓄水期间水库地震活动以微震和极微震为主，主要由岩溶、矿洞浸水引发。蓄水后记录到的地震以初期2008年11月的M4.1级(相当于ML4.6级)为最大，远小于初步设计论证报告中给出的“可按M5.5级考虑”的预测值。
目前学术界公认，对构造型水库诱发地震来说，水库蓄水只可能触发距离库区较近且已接近极限状态的发震断层，库水沿断层深层渗透导致其抗剪断强度降低，是触发地震的主要原因。根据水文地质条件，库水向外渗透距离不会超过库岸第一分水岭，一般距库岸边约3到5千米，不会大于10千米。
对于汶川地震、芦山地震等西南强震是否由三峡水库诱发，专家给出了否定的答案。
2008年“5·12”汶川地震发生在青藏高原北部边缘的龙门山地震带，属地下深层次板块碰撞的结果。而三峡大坝所在的黄陵背斜属于扬子准地台中部的上扬子台褶带，两者所处的区域构造条件截然不同，完全没有区域构造上的联系。中国长江三峡集团公司董事长曹广晶说：“三峡水库蓄水是不可能触发汶川地震的。”
焦点四：高坝阻断环流路？
三峡水库蓄水以来，正好是库区及其周边地区极端天气气候事件频繁发生的时期，如2006年川渝大旱、2009至2010年西南地区干旱以及2011年长江中下游冬春严重干旱等。“三峡大坝阻断大气环流影响周边气候”的说法甚嚣尘上。这种观点认为，三峡原本是四川盆地的一个缺口，三峡大坝的修建阻断了原本自然形成的水汽循环，导致各类极端天气事件的发生。
“大气环流的垂直高度为3000米，三峡大坝高度仅180多米，三峡大坝根本不可能阻挡或阻断大气环流。”中国三峡集团总经理陈飞说。
中国工程院的评估报告认为，三峡水库对附近局地天气气候有一定影响，特别是对水面上方的气温有较为明显降低作用，但对库周的气温影响不大，影响范围不超过20千米。
根据中国气象局今年发布的《三峡工程综合效益气候评估报告》，三峡水库蓄水后(2004至2011年)，库区大部分地区气温较蓄水前(1996至2003年)有所升高，年均气温17.9至18.9摄氏度，平均增加0.2摄氏度左右。
中国气象局专家表示，近年来三峡库区及周边地区的极端天气气候，与东亚大气环流、海表温度变化以及青藏高原热力异常等因素的关系密切，但与水库蓄水未发现直接联系。
焦点五：两湖喊渴伏危机？
近年来，洞庭湖、鄱阳湖等长江中下游地区出现了数次严重旱情，一些观点认为这与三峡蓄水有很大关系。而在湖南、江西省内，希望在洞庭湖和鄱阳湖湖口设闸拦水的呼声也日益高涨。三峡蓄水到底对洞庭、鄱阳两湖造成了怎样的影响？
洞庭湖是长江重要的调蓄湖泊，有“容纳四水”的调节作用。长期以来，长江水携带大量泥沙入湖，导致洞庭湖泥沙不断淤积，湖面不断缩小。“三峡蓄水后拦蓄了部分泥沙，使下泄的水更清了，这对缓解洞庭湖的泥沙淤积情况十分有利。”沈国舫说，“与此同时，清水下切长江河道，对洞庭湖入江口的冲淘作用也更加明显。”
鄱阳湖的情况略有不同。沈国舫介绍，洞庭湖和长江是互相换水的关系，但鄱阳湖更多是湖水外泄。三峡每年蓄水期间，水库下泄流量较天然流量减少，大坝下游干流水位降低，使得鄱阳湖湖口出流量增加。
中国工程院的评估报告对此做了更详细的分析：“三峡水库调度对洞庭、鄱阳两湖水资源利用的影响主要表现在汛后蓄水期间，长江干流水位下降，经荆南三口进入洞庭湖的水量减少，两湖出湖水量增加，枯水期提前，枯水位降低，对灌溉、供水及生态环境用水产生一定影响。”
焦点六：珍稀物种今安在？
三峡工程对生物多样性的影响一直是社会关注的热点话题。在三峡工程批准建设之前，科研工作者曾赴实地进行全面考察，并就三峡工程对当地动植物可能存在的影响进行了严格论证。
从陆生生态系统来看，三峡库区陆生脊椎动物不仅可以主动迁离库区，而且在库区以外有广泛分布，不存在灭绝的危险。对于珍稀陆生植物，有关部门采取了种质资源保存、植物园保存、野外迁地保存、就地保护等措施。
从水生生物看，三峡工程影响区内共存在6种珍稀濒危水生生物，包括白鳍豚、白鲟、中华鲟、达氏鲟、江豚和胭脂鱼。为了保护这些珍稀物种，我国先后设立了河口中华鲟和白鲟幼鱼保护区、葛洲坝坝下中华鲟保护区、长江上游珍稀特有鱼类自然保护区等，并实施中华鲟的人工繁殖和幼鱼放流。
中国工程院的试验性蓄水阶段性评估报告显示，长江上游干流江段的特有鱼类资源发生了较大变化，主要表现为种类减少、种群空间分布改变、种群数量变动。鱼类对环境变化的适应性也有差异，如中华鲟在葛洲坝截流后迅速适应环境，在坝下形成了新的产卵场。中华鲟研究所于2009年突破了中华鲟全人工繁殖技术难关，使该物种保护工作摆脱了对野生资源的依赖，具备了人工条件下物种长期保存的能力。
焦点七：黄金水道拦腰断？
近年来，三峡大坝船闸时常出现大批过坝船舶待闸的现象，不少人开始怀疑三峡工程对长江黄金水道的影响。
在三峡工程建设前，川江航道等级低、通航条件差，制约了长江航运的发展。重庆至宜昌660公里的川江航道内，有激流滩、浅滩、险滩139处，绞滩站24处，单行控制航段46处。三峡工程蓄水后，渠化了重庆以下航道，消除了坝址至重庆之间所有滩险、单行控制河段，川江全线实现全年昼夜通航。
统计数据显示，1949年，长江干线货运量仅191万吨；葛洲坝枢纽通航后，2002年该区段的货运量达到最高值1800万吨。三峡船闸通航使得长江航道单向年通过能力由一千万吨提高到五千万吨以上。近年来，过闸货运量稳步增长，2011年通过船闸货运总量达到10033万吨，提前19年实现船闸年单向5000万吨的设计通过能力指标。
三峡集团公司近年来加强船闸运行管理，先后采取了156米水位下船闸四级运行等拓展船闸通过能力措施，逐步提高过闸效率。2008年至2012年试验性蓄水期间的年均通航率为96.25%，高于84.13%的设计指标，相当于每年多运行了1000余小时。
专家表示，为应对长江航运快速发展的新形势，满足日益增长的过闸需求，要推广和普及船型大型化、标准化、系列化，缩短闸次间隔时间，提高闸次利用率，增加平均每闸次船舶载重吨，进而提高通过能力，拓展三峡工程航运效益。
焦点八：坝下河势会“巨变”？
三峡工程运用后，因清水下泄，水流挟沙能力增大，长江中下游的河势是否稳定，护岸工程的“崩岸”问题是否可控，广受社会关注。
专家指出，这个问题在三峡工程论证阶段已经作出预测，认为三峡工程修建后，坝下游将发生长时间、长距离的冲刷，同流量水位有所下降，并指出“三峡工程兴建后，将根据下游河势调整的总趋势以及现有护岸工程情况，继续完善护岸工程，并对已建工程进行必要的加固”。
实测资料表明，三峡水库自2003年蓄水以来，坝下游河道冲刷主要发生在宜昌至城陵矶河段，全程冲刷已发展到湖口以下，冲刷的速度和范围大于论证阶段的预计，但河势总体上尚未发生巨大变化。总的来说，论证阶段的结论基本上是正确的。
由于近岸河床明显冲深，护岸工程下部的岸坡变陡，故“崩岸”现象较蓄水前有所增多，但大部分仍发生在蓄水前的原崩岸段和险工段。由于护岸工程在1998年大洪水以后不断兴建和加固，加之在发生崩岸时及时抢护，故三峡工程蓄水以来长江的中下游堤防未发生重大险情。今后通过加强河道监测，实施荆江河段河势控制应急工程，可以保证堤防安全。
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