砂石

You may consider the discussion in that USSR university irrelevant. After all, there are always sands and stones and mud and debris and scum in the river of history of a great country.

That may be true. In fact, one of our senior government official was obviously thinking of the same.

But, it is all these unwanted precipitates that fill up our lakes. Have you heard of the recent stories of Poyang Lake (鄱陽湖), Dongting Lake (洞庭湖), Hong Lake (洪湖), and many others? Well, you may say that's not new. The theory of geology states that lakes are short lived because the incoming river brings along sands and stones and mud, all of which would gradually fill up the space.

And, even gigantic lakes are not spared. For example, who would now remember Yunmeng Pond (雲夢澤), which was at a time close to 40,000 square kilometers - 12 times the size of Poyang Lake?

(By the way, both Donting Lake and Hong Lake are small residuals of the legendary Yunmeng Pond.)

Nonetheless, there are reasons for modern people to worry. Lakes, at least those along the course of the Yangtze River (長江), seem to be disappearing much faster in the recent years.

Maybe for the Dam. (Don't be paranoid - there's no n to follow.)

Alas, the traditional Chinese saying is: It is more difficult to shut up people's mouth than lock up the water in a big river (防民之口，甚于防川). With the advance in technology, we can now stop both. But, the logical paradox (it is self contradicting, I know) is, the more water you lock up, the more sands and stones fill up the bottom of our lakes, as well as the bottom of our mind.