The Study On The Ancient Cities And Environmental Change In The Southwest Mu Us Desrt

Desertification caused by including climate change and human activities is the phenomenon ofland degradation occurred in arid, semi-arid and sub-humid arid areas. In China, 2 622 000 km~2 ofland area is affected by desertification and about 54 billion RMB was lost annually because of it.Thus the desertification is one of the most important factors to impact the development ofeconomics, and it affected sustainable development of our country.Mu US sandy land, however, at the northwest margin of Loess plateau, is a place in China wherehas most serious desertification, so it is of great practical and academic significance to interpretthe processes of historic desertification here.Combined analysis of ancient literature, fieldwork survey and quaternary sediment, this paperinterpreted the influence of human activities to the change of Mu US sandy land under thebackground of climate change.Based on the analysis of ancient literature, the thesis showed an approximate process ofdesertification and gave the onset time of desertification of the southwest margin of the Mu USsandy land under the background of climate change in history and, combined with the profileevidence, analyzed the causes of the desertification. Then, synthesizing the timing of change ofdesert and the time of human occupation, the timing and the causes of desertification are given inthe thesis.Desertification before the Ming dynasty is caused by climate change. However, increase ofpopulation, impact of war should be the causes of the desertification after the Ming dynasty andthe result is much apparent at the end of the Qing dynasty. In addition, three typical ancient citieswere selected as a proxy to indicate the environment change, namely Tongwan city, Sanchahe cityand Beidachi city. Experimental analysis and field survey showed that sand dunes had been set inwhen these ancient cities were founded.Field survey and interpretation of landsat image of southwest Mu Us sandy land showed thatdesertification had been enlarging in the Wushen banner, Etuoke frontier banner, Dingbian countyand Jingbian county from 1977 to 1986. The economic lose was also calculated. Direct economiclose reached 42.51 hundred million RMB and indirect economic lose 3781 hundred million RMBfrom which we can get that indirect economic lose is far more than direct lose, the result indicatesthat lose of environment deterioration caused by desertification is very serious.According to the study,As the results showing, one of the important reasons of development of desertification isexceptionally unreasonable land use in response to the continual deterioration of climate.Converse of desertification should depend on the combat action of human beings. At last, on the base of analysis of the processes and forcing of desertification happened in Wushen banner, Etuoke Frontier banner, Dingbian county and Jingbian county, in accordance of the trend of the desertification and characters of the regions, the author suggested: Limit the speed of population increase, forbid graze, keep the livestock in fence, protect and recover vegetation, change the agricultural structure and adjust the land use manner should be the way to prevent desertification.