By Bo Ning, Huang Zhengping & Wang Pu

金沙江，蕴含着无穷力量，蜿蜒于横断山的深山峡谷。（黄正平 摄）Jinsha River, with great power, wanders its way in the deep valley of the Hengduan Mountains. (Photo by Huang Zhengping)

大体积混凝土的温控防裂一直是工程界的难题。为了从源头上解决大坝的温度裂缝问题，白鹤滩水电站工程全坝采用低热水泥混凝土，总量达803万立方米，在国际上属首例。图为业主、设计、监理、施工各方共同检查入仓混凝土的各项品质。（黄正平 摄）Temperature control and crack prevention has long been a challenge in dam construction.In order to prevent temperature cracks from its origin, a total amount of 8.03 million cubic meters of low-heat concrete was applied to the construction of the dam of Baihetan Hydropower Station, the first of its kind in the world. In this photo, representatives from the designing,construction, supervising companies and the proprietor are inspecting the quality of the concrete. (Photo by Huang Zhengping)

“The paths on Hengduan Mountains are bumpy and hazardous, the sky is red like fire and the waters are as white as silver...” This is how the Red Army soldiers portrayed the steep mountains, deep ravines and the surging river in the Hengduan Mountains during the Long March. Today, the hydropower construction in this remote land has tamed the surging waters in the mountains and transformed the deep ravines into smooth lakes.

It was a hot midsummer day with snowy clouds curling and spreading over the mountaintops in the far distance. On the riverbanks of the Jinsha River,flowing across Sichuan Province and Yunnan Province, we witnessed the busy and on-going construction scene on the site of the Baihetan Hydropower Station and the Wudongde Hydropower Station.

After decades of on-thespot investigations, scientific experimentation, careful design and 8-years of preparation, these two massive 10-GW hydropower stations built by Three Gorges Corporation have both entered large-scale construction of dams. They are regarded as milestone projects in the history of hydropower stations both at home and abroad, following the completion of the Xiluodu Hydropower Station and the Xiangjiaba Hydropower Station on the Jinsha River. The total installed capacity of the four stations is 46.46 GW, equivalent to that of two Three Gorges Projects.

Together with the Three Gorges Dam and Gezhouba Dam, the Three Gorges Group has initiated the world's first largest clean energy corridor on the Yangtze River.

The Baihetan Hydropower Station has taken on unprecedented challenges and overcome a series of the world's toughest problems, making itself the most difficult hydropower project under construction in the world. It has broken six world records, namely, the first singleunit capacity of 1 GW under construction, the largest size of underground caverns, the largest scale of cylindrical tail water surge tanks, the highest degree of seismic resilience among 300-meter-grade arch dams, the first use of low-heat concrete for the whole 300-meter-grade arch dam, and the largest scale of nonpressure spillway tunnels, hence attracting worldwide attention.

白鹤滩水电站工程拦河坝最大坝高289米。正常蓄水位825米，防洪限制水位785米。地下厂房装有16台机组，装机容量1600万千瓦，多年平均发电量624.43亿千瓦时，相当于每年可节约标准煤约1968万吨，减少排放二氧化碳5160万吨。图为建设中的白鹤滩大坝。（肖佳法 摄）The largest dam of Baihetan Hydropower Station is 289 meters high. The reservoir has a normal water storage level of 825 meters,restricted water level in fiood control of 785 meters. The underground powerhouse is equipped with 16 machine sets with an installed capacity of 16 GW. Its average annual power generation will be 62.443 TWh, an amount equal to that generated by 19.86 million tons of coal. Thus 51.6 million tons of carbon dioxide emissions will be reduced per year because of this project. This is a photo of the dam under construction. (Photo by Xiao Jiafa)

建设中的白鹤滩大坝（肖佳法 摄）Baihetan Dam under construction (Photo by Xiao Jiafa)

烈日炎炎，工人们正忙着布设坝体廊道钢筋网体。（李亚隆 摄）Under the scorching sun, workers are busy laying reinforcing mesh for the dam tunnel. (Photo by Li Yalong)

乌东德水电站安装12台单机容量85万千瓦的水轮发电机组，总装机容量1020万千瓦，年发电量389.1亿千瓦时。最大坝高270米。乌东德水电站工程于2015年12月开工建设，预计2020年首批机组投产发电，2021年全部机组投产发电。图为乌东德水电站工程建设夜景。（黄正平 摄）Wudongde Hydropower Station is designed to be equipped with 12 hydroelectric turbine sets, each with a generating capacity of 850 MW, to reach a total installed capacity of 10.2 GW and an estimated annual output of 38.91 TWh. Its dam is 270 meters high.This station commenced construction in December, 2015. The first turbine generators are expected to be commissioned in August 2020, and all of the 12 generators will be put into service by December, 2021. This is a night scene of the Wudongde Hydropower Station under construction. (Photo by Huang Zhengping)

100万千瓦水轮发电机组，单机高50多米、重达7000多吨，是目前世界上最大的水轮发电机组。图为水轮发电机转轮出厂。（黄正平 摄）With a height of over 50 meters and a weight of over 7,000 tons, the 1-GW hydroelectric turbine generators used in the Baihetan Project are the largest in the world at present.In this photo, workers are preparing to transport one of the turbine runners from the manufacturer, Dongfang Electric Machinery. (Photo by Huang Zhengping)

乌东德水电站的蜗壳（黄正平 摄）The spiral case of Wudongde Hydropower Station (Photo by Huang Zhengping)

机组蜗壳焊接施工（肖佳法 摄）Welding of a metal spiral case (Photo by Xiao Jiafa)

乌东德水电站的右岸地下厂房，一个个机窝已浇筑成型，正转入机电安装阶段。（黄正平 摄）Hydroelectric turbines to be installed in the underground plant on the right bank of Wudongde Hydropower Station(Photo by Huang Zhengping)

白鹤滩水电站工程各类洞室总长度达217千米，洞室开挖量达2500万立方米，是国内外水电工程中规模最大的地下洞室群。这些洞室和通道就像一个巨大的“地下迷宫”。白鹤滩水电站工程泄洪建筑物由大坝坝身6个表孔、7个深孔和左岸3条无压泄洪洞组成，无压泄洪洞群规模居世界第一。图为建设中的泄洪洞，洞壁光滑如镜。（李亚隆 摄）The total length of all caverns and caves of Baihetan Project amounts to 217 kilometers, and the excavation volumes have reached 25 million cubic meters. It is the largest underground cavern system in hydropower projects both at home and abroad. These caves and passages form a huge web-like “underground world.”Its fiood-discharge system, consisting of six surface outlets and seven mid-level orifices on the arch dam, and three non-pressure spillway tunnels on the left bank, is the largest one in the world. This photo shows the mirror-like surface of a spillway tunnel. (Photo by Li Yalong)

乌东德水电站工程泄洪洞（黄正平 摄）A spillway tunnel of Wudongde Project (Photo by Huang Zhengping)

在白鹤滩和乌东德两座水电站施工现场，有这样一群特殊的工人，他们每天工作在悬梯上。（黄正平 摄）Workers at both Baihetan and Wudongde sites work on suspended ladders every day. (Photo by Huang Zhengping)

张福琼（前），四川凉山彝族工人，以前在新疆打工，因家乡附近修建白鹤滩水电站，便与老乡一起来到工地。（李亚隆 摄）Zhang Fuqiong (front) of Yi nationality from Liangshan of Sichuan Province returned home from Xinjiang Uygur Autonomous Region and came to work at the construction site of Baihetan Project with her country fellows. (Photo by Li Yalong)

乌东德水电站水垫塘边坡混凝土施工现场，这样的悬梯是工人们上下班的通道。（黄正平 摄）At the construction site of Wudongde Project, workers climb to their working spots via the cliff ladder. (Photo by Huang Zhengping)

一名女工工作之余通过微信问候家人。（黄正平 摄）A female worker sending WeChat messages to her family during a break(Photo by Huang Zhengping)