京、津、唐地区沙漠化灾害及发展趋势

DESERTIFICATION DISASTER AND ITS DEVELOPING TENDENCY IN JING-JIN-TANG REGION

京、津、唐地区的沙漠化问题作为一种鲜为人知的地质灾害正在区内某些地段发展和蔓延.沙漠化土地主要分布在永定河和滦河冲积扇区,潮白河故道区亦有零星分布.沙漠化在本区是近期出现的现象,是人为过度经济活动造成生态环境质量退化的结果.

Jing-Jin-Tang Region is a general geographic expression referring to Beijing and Tianjin cities and Tangshan and Langfang areas and their adjacent area, which is situated in the northern part of North China Plain It is a very important economic open zone. The desertification as an unknown geological disaster is developing and extending over some area in this region.Desertification refers to the fact that due to human activities beyond the limn of utili zation of natural resources in arid and semiarid districts, original non-desert regions have been transformed into a region with an environment similar to desert These effected region arc so-called desertification land.The desertification lands are mainly distributed in the area of alluvial tans of Yongdinghe River and Luanhe River, as well as in the old course of Chaobaihe River. It is the largest desertificated area in Luanhe fan, the area in Yongdinghe fan ranks the second, the last is in the old course of Chaobaihe River. It is the most serious for desertification degree in the area of Luanhe fan, the second is in the area of Yongdinghe fan.One of the landscape marks for the desertification in this region is that the wind erosional and coarsened phenomena are widespread over the surface. The second landscape mark is the shifting sand well developed as tracts. The shifting sand is mainly distributed in the old courses of rivers occasionally developed over the fans and in several modern river courses. The third landscape mark is that the concentrated shifting sand dunes are appearing. The shifting sand dunes can be found everywhere in the desertification area, they are always scattered over the farmland. The shifting dunes are very developed on the modern flood land along Luanhe River, they have the typical characteristics of barchan dune.The desertification disaster is expressed as the damage caused by wind-and-sand flow, losing organic substance from the soil, making the planting soil impoverished or the original farmland covered by shifting sand. Finaly, it causes the output of crop reduce in large area. For instance, the output of peanut is getting less and less in Luanxian County in these years.Desertification occured in the last hundred years in this region. The desertification is mainly owing to being influenced by human activities. With the intensifying human activities, natural vegetation has disappeared, this caused the changing in ecological environment. The ecological environment, which becomes worse and worse, caused the desertification.If we take no effective methods to control desertification, with the developing of economy and the increasing of population in the future, desertification land will expend larger and larger itself, and this region would be transformed into desert.