Spatio-Temporal Changes of Land Use in Jinghe Watershed

YANG Li, XIE Gao-di, ZHEN Lin, LENG Yun-fa, GUO Guang-meng(Institute of Geographical Sciences and Natural Resources Research,CAS, Beijing 100101, China)  

In the second half of the 20th century, rapid development of Northwest China caused many environmental problems, one of which is land use and land cover change. Many studies showed that land use and land cover change caused by people directly influenced form and evolvement of soil and water erosion. Based on Remote Sensing and GIS, this paper studies the land use change of Jinghe Watershed during 1986 to 2000, which locates in the northwest of Loess Plateau and is one of the areas that suffer most from soil and water erosion. The results are shown as follows: 1) in three periods, grassland and arable land are main types of land use, which occupied 85% of total area of Jinghe Watershed, area of forest is 10% and other three land use types only occupies 5% of total area, which showed land use structure changed little during 1986～2000. It also shows that at time scale within 20 years, the macrostructure of land use of a watershed doesn’t change greatly; 2) generally speaking, during 15 years between 1986 and 2000, the area of arable land, urban construction land have been increasing, which shows enlargement of cities and towns is the main reason. Results also show that the area of woodland and grassland decreased between 1986 and 1995, while increased between 1995 and 2000, which shows the implementation of policies has won initial success in some area of Jinghe Watershed in some sense; 3) During these periods, inter-transitions between different types of land use are very complex, mainly occurring among woodland, grassland and arable land. The most notable transition occurred between grassland to arable land, whose transferred area was up to 14.87×10~4 hectare. It is worthwhile to note that the transitions between subtypes of grassland are much bigger than the transitions between different types described above, and the transferred area were 53×10~4 hectare, which occupied 1/6 of total area of grassland, although these transitions didn’t change the area of grassland; it implied that the quality of grassland changed from degraded condition to recovery status; 4) The main reasons of land use change in Jinghe watershed are probably policies, the enlargement of cities and towns and the increase of population.

【Fund】： 国家973项目 农林复合景观的生态耦合关系及水土资源优化配置(编号:2002CB111506)。
【CateGory Index】： F301.24

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