Tang Dynasty, Yellow River, Yangtze River Basin Flooding And Locust

China is a big country in agriculture from time immemorial. The agricultural economy is an important pillar of the feudalistic economy. The natural disaster is an natural enemy of agriculture. But not all of the disasters were sheer natural disasters.As a matter of fact, a lot of disasters ever happened were due to the fact that humankind had disobeyd the order of nature time and again in living and production.In a sense, historical natural disasters in the past were all artificial disasters.Almost all the floods ever happened in the valleys of the the Yellow river and the Yangtse river in Tang Dynasty as well as Wu-Dai Dynasties bore the argument mentioned above. The Yellow river and the Yangtse river conceived Chinese civilization.But natural disaster were growing severe. The irrational exploitation should undertook the main duty. Regarding the eco-systematical environmental problems as the clues, this thesis intends to study the causes and effects between the agricultural cultivation and river floods.I found that there were some certain inevitable contacts between the locust pest and flood disasters when I studied the flood disasters in Tang dynasty systematically. But for a long time, the common knowledge on the causes of the locust pest have been limited to the drought. I absorb some of the results of the ecological research on locust. At the same time, I enumerated nearly all the the historical data bearing on the floods and locust pests in Tang dynasty. Thereby,I proved the feasibility of the conclusion that floods is really the important inducement of the locust pest.So this thesis expounded the locust pest as well as the floods in the valleys of the the Yellow river and the Yangtse river in Tang Dynasty.