Evaluation of landscape changes and ecological degradation by GIS in arid regions: a case study of the terminal oasis of the Shiyang River,northwest China |
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| Authors: | Xiaoyu Li Duning Xiao Xingyuan He Wei Chen Dongmei Song |
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| Institution: | 1.Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang,China;2.Cold and Arid Regions Environmental and Engineering Institute,Lanzhou,China;3.International Association of Landscape Ecology,Cold and Arid Regions Environmental and Engineering Institute,Lanzhou,China;4.College of Earth Resources and Information,China University of Petroleum,Dongying,China |
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| Abstract: | The development and utilization of water and land resources in the Shiyang River basin are the highest among the inland rivers
in northwestern China. Using GIS and the landscape structure analysis program FRAGSTATS, landscape metrics of a study area
in the lake-district in Minqin Oasis in the lower reaches of Shiyang River basin were calculated and analyzed based on TM
images from 1987 to 2001 at class level and landscape level, respectively. Transformation matrix of the landscape mosaics
was also examined. The driving forces of landscape changes were analyzed, including the dynamics of runoff and groundwater
resources and their exploitation, and influences of policies and market economy. The results showed that: (1) Patch number
of farmland and desert decreased, but their mean patch area increased, indicating that reclamation and desertification was
very serious in the study area. Contagion index for oasis increased and edge density and landscape diversity were reduced.
(2) Farmland and desert areas have enlarged by 1,520.46 and 4,941.27 hm2, respectively. This increase was at the cost of woodland and grassland, which shrank by 1,520.46 and 4,941.27 hm2, respectively. (3) The net utilization of surface water decreased by 50% in the last 10 years, and dropped to 22.3 × 106 m3 in the later 1990s. Exploitation of groundwater increased remarkably, up to 80 × 106 m3 per year in the last 5 years. (4) The capability of the economic structure to withstand pressures of the market economy has
depressed distinctly because of the simplified planting pattern, which is dominated by salinity-enduring cash crops, such
as cotton. Based on the above analysis, strategies of ecological reconstruction in the lake-district were suggested. |
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| Keywords: | Landscape changes Ecological degradation Water resource GIS |
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