When was the Yangtze River Three Gorges area mapped for major dam planning?

The idea of a major dam in the Three Gorges region of the Yangtze River was discussed in the early 20th century, with significant planning proposals appearing in the 1920s and 1930s. The site’s steep terrain and immense river flow made it attractive for flood control and electricity generation. Although the modern dam was completed much later, the planning history stretches back many decades. This makes the project one of the longest-developed river engineering ideas in modern history.