This might be of interest to some? From the article THREE THOUSAND YEARS OF UNSUSTAINABLE GROWTH: CHINA'S ENVIRONMENT FROM ARCHAIC TIMES TO THE PRESENT in the journal East Asian History On page 33 and 34: Clearly, though, the historical balance-sheet of tl1e pluses and minuses of north-western agricultural expansion in imperial China has to take into account these hydrological consequences. Simply as an illustration of the kind of costs directly involved-an example chosen simply because there are some figures for it, and not because it was of any special importanceconsider the dredging of deposited sediments and the new dyking that had to be done in 1606 at Xurzhou, where the Grand Canal-supply artery for the capital--crossed the Yellow River, to keep the crossing workable. Half a million men had to be conscripted to work for six months, and the state had to pay 0.8 million ounces of silver. This was not routine, but it was not exceptional for large-scale intermittent maintenance.
