JOURNAL OF NATURAL RESOURCES ›› 2013, Vol. 28 ›› Issue (6): 944-956.doi: 10.11849/zrzyxb.2013.06.006

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Ecological Risk Assessment of Small Watershed of the Three Gorges Reservoir Area Based on Land Use Change—A Case Study of Caotang River

ZHAO Yan-jie1,2, LI Yang-bing1,2, SHAO Jing-an1,2   

  1. 1. College of Geography and Tourism, Chongqing Normal University, Chongqing 400047, China;
    2. The Key Laboratory of GIS Application Research, Chongqing Normal University, Chongqing 400047, China
  • Received:2012-06-25 Revised:2012-11-25 Online:2013-06-20 Published:2013-06-20

Abstract:

To reveal the impact of ecological risk of land use change in the small watershed of the Three Gorges Reservoir Area, Caotang River watershed is chosen as the study area. Land use information was obtained from satellite remote sensing TM images of 1990, 2000, 2004 and CBERS data of 2010. The grid by 500 m×500 m was created as the auxiliary evaluation unit, and the GIS technology was employed as the data integration analysis platform. In order to generate the map of land ecological risk in 1990, 2000, 2004 and 2010, the system sampling method and block Kriging were used to make the index a spatial variable. The results indicated that land use reasonable index in the study area increased from 0.78 to 0.81, a rise of 0.03 from 1990 to 2010, appearing first a deteriorating trend and then improved trend, land use structure is reasonable along with contiguous distribution of five ecological risk levels of the study area. Edge of the study area is at low risk, the closer the distance, the higher the level of risk of the center of the study area. Regional ecological risk distribution patterns have obvious space correlation with arable land and water distribution area. Five types of ecological risk are mainly concentrated on the slopes of 15°-25° and >25° and at elevations of 500-1000 m and 1000-1500 m. Ecological risk appears first a deteriorating trend and then improved trend. The largest area of ecological risk is at lower level risk in 1990 and 2010 of the study area, accounting for 28.23% and 37.41% of the total area; in 2000 and 2004, the largest area of ecological risk is at high level risk, accounting for 26.29% and 35.54% respectively. The study revealed the main reason for the temporal and spatial variation of the Caotang River Small Watershed Ecological Risk is the constraint of natural conditions and control of human factors. The natural conditions are the incentives and human factors control is the main reason. Type of land use changes is the most important impact of changes on ecological risk factors. Finally we put forward some countermeasures for temporal and spatial variation of regional ecological risk. Specific measures include to find out the optimal combination of land-use types with improved unreasonable land-use types, to improve the stand structure, vigorously transformation of coniferous forest and shrub replanting made mixed coniferous forest; we should undertake unitive reasonable planning and management for land use which was closed with Hydro-Fluctuation Belt area while considering the water environmental pollution and soil erosion problems as a whole.

Key words: land use, ecological risk assessment, Three Gorges Reservoir Area, Caotang River

CLC Number: 

  • X826