Recent land use changes in north dust storm source area affecting Beijing and Tianjin II: Otindag Sandy land

Dust storm became a severe environmental problem in Beijing and Tianjin Regions at the beginning of this century, and its trajectory stretches to Korea Peninsula, Japan Archipelago, comes through Pacific Ocean and vanishes at the east of U.S.A. By means of remote sensing, ground station observation and sand samples, dust storm affecting Beijing and Tianjin Regions comes from Middle Asia and Mongolia Plateau. And dust from desert margin, plowed farmland and degraded grassland contribute more to the dust weather. The middle part of Inner Mongolia Plateau is the closest sandy land to Jing and Tianjin, and it is the path of the heaviest dust Beijing storm in 2000 that has a far-reaching, impact on China's government to manage environment. So, land use pattern and its changes in this area should be stressed on, for combating desertification. Landscape pattern is much mixed and it has long history of pasturing and tillage in the area, as a whole, three categories of land use become obvious: agro-pastoral transitional zone, Otindag sandy land, and grassland. Based on remote sensing (RS) images of Landsat in 1987, 1995 and 2000, using geographical information systems (GIS), this paper delineates the extent of Otindag sandy land. Using neighborhood processing method in GIS, it shows the distribution and area of Otindag, so that it can provide RS data to the debating area of Otindag. Fragmental sandy land distributes with various land use categories, and its area decreases in a rainier year, 1995. Fixed sand dune becomes active under heavier press of anthropogenic factors, such as over-grazing. So, pasturing prohibition should be apply to this extensive area.