Three Gorges assisted Yu the Great in controling the waters and guiding boatmen. The Xiling Gorge comprises a series of famous gorges, including Military Book and Sword Gorge, Yellow Cow Gorge, and Lantern's Shadow Gorge. In 1919, after Sun Yat-sen had put forward the concept in the Plan for Industrial Development of his (), experts investigated damming the Three Gorges, but it was not until 1994 that the Three Gorges project officially started. In 1944, the Nationalist government recruited John L. Savage, the Chief Engineer of the United States Bureau of Reclamation, who came to China and made a 10-day investigation of
Three Gorges Dam by 190 million tonnes, sulfur dioxide by 2.29 million tonnes, and nitrogen oxides by 980,000 tonnes. The dam increased the Yangtze's barge capacity sixfold, reducing carbon dioxide emission by 630,000 tonnes. From 2004 to 2007, a total of 198 million tonnes of goods passed through the ship locks. Compared to using trucking, barges reduced carbon dioxide emission by ten million tonnes and lowered costs by 25%. Two hazards are uniquely identified with the dam. One is that sedimentation projections are not agreed upon, and the other is that the dam sits on a seismic fault. At current levels, 80% of