遥感监测下鄂尔多斯市地物类型动态分析

Analysis of features change in Ordos based on remote sensing monitor

鄂尔多斯市是农牧交错带中段的典型地段,生态环境十分脆弱,土地沙化问题严重。对鄂尔多斯市地物类型近13年的遥感监测结果表明,1990-2003年鄂尔多斯市发生变化的地物类型面积占总面积的8.60%,变化过程突出表现为土地沙化过程和草地退化过程。气候朝干旱化与温暖化方向发展的趋势是生态环境退化的背景因素,人为活动的影响加剧了这种退化过程。

Ordos City （37°35′24＂--40°51′40＂N, 106°42′40＂-111°27′ 20＂E, 1 000-1 500 m a. s. l. ） is located in the hinterland of the Ordos Plateau, its east - west length and south - north wid h are 400 km and 340 km, its total area and population are 8.7 × 10^4 km^2 and 1.27 × 10^6, respectively, and its eastern, western and northern sides are surrounded by the Yellow River. In the study area it belongs to the typical temperate semiarid desert steppe climate, winter is long and cold, spring drought and strong winds occur frequently, and summer is short, The annual sunshine duration, temperature, precipitation, evaporation and frost - free period vary in ranges of 2 716-3 194 hours, 5. 3 -- 8. 7℃ , 170-350 mm, 2 000-3 000 mm and 130-160 days respectively. The central part of the study area rises and slopes towards its peripheral regions, gullies are densely distributed, and the Mu Us Sandland and Kubuky Desert are distributed; its western part is a typical desert steppe; its eastern part is dominated by hills and valleys with serious soil erosion; and its northern part is a alluvial plain of the Yellow River and teems with primary products because of the fertile soils. Ordos City is a typical region in the farming- pasturing ecotone, the ecological environment is extremely vulnerable, and the land desertification is serious. In this paper, the dynamic change of the ground object types in Ordos City is analyzed based on the RS-based monitoring data. The results show that the proportion of area of the changed ground objects dominated by land desertification and steppe degeneration in Ordos City during the period of 1990 - 2003 occupies 8.60% of the total land area, the warming - drying climatic change is the background factor of resulting in the ecological environment degeneration, and human activities accelerated such degeneration.