The Characteristic Analysis on the Flood Disaster of Yulin Area in the Ming Dynasty

On the basis of arranging and analyzing the history materials,the frequency,rank series,year change,seasonal change,cause disaster degree and causes of the flood disaster of the Ming Dynasty in Yulin area were discussed.The results showed that Yulin area had suffered totally 118 flood disasters in this period,once every 2.34 years on average.The frequency showed obvious increase tendency from early time to the later time of the Ming Dynasty.According to the rank series of flood disasters,the second grade of the flood disasters was 70 times and accounted for 59.32% of all;the first grade of the flood disasters was 43 times and shared 36.44%;the third grade of flood disasters was 5 times and accounted for 4.24%;but the fourth grade has not occurred.The flood disasters in the Ming Dynasty Yulin area showed obvious seasonal difference,concentrated in the July,August and September.In addition,the Yulin area is located at the southeast of Mao Wusu desert and connected to the hilly-gully region of Loess where the surface vegetation was scarce,soil erosion was serious,therefore the small rainfall was easier to bring about a flood and water logging disaster in the Yulin area.