Eco-system in karst regions is unstable, and karst-desertificaton induced by soil erosion is an important threat in southwest China. Evaluation of soil erosion is necessary for planning of soil and water conservation for sustainability of land resources and eco-system in those regions. This paper was to estimate risk of soil erosion and understand its spatial distribution in karst regions in Chongqing where are typical area with crisp eco-system in the southwest China. Land use/land cover data was deduced from remote sensing data of TM images of study area in 2000. Soil erodiable K values were estimated from soil texture and organic matter. The data of erosivity of precipitation, terrain, land use/land cover, soil erodible K values was used in this study with rectified USLE model and grid calculation of ArcGIS9 software to evaluate the soil erosion risk and analyze its spatial distribution in this region. The results showed that the risk of soil erosion was severe in the mass and its spatial difference was obvious due to integrative effect of rainstorms, Soil erodibility, topography, and land use/land cover in karst regions in Chongqing. The distribution of soil erosion risk class was closely related to the terrain, land use/land cover in those Karst regions. The large risk rate happened in areas where the terrain is steeper and the human activities were frequent for the agriculture was intensified. This must be paid more attention to by local government and people to take measures for regional soil and water conservation and sustainable development of eco-environment in karst regions in Chongqing.
Spatial pattern of urban thermal environment has an important impact on urban microclimate ecology and human living environment. Because of the limitation of current research methods and techniques, spatial patterns and dynamic characteristics of the urban heat island were not well understood. This paper took the core urban area of Chongqing as the research object, used Landsat TM images in 1988,2001 and 2006, coupled with the ground meteorological data, to detect the hot field thermodynamic landscape heterogeneity. Supported with RS, GIS and the basic theory of "landscape ecology", this paper quantitatively explored the change patterns of several basic landscape metrics and the indexes of grain autocorrelation at different scales, such as Landscape Shape Index (LSI), Fractal Dimension-Mean Nearest (FRAC-MN), Shannon-Weaver Landscape Diversity Index (SHDI), Moran I index, and Geary C index and so on. The result showed that the urban thermodynamic landscape heterogeneity in Chongqing urban area was very obvious; landscape metrics were sensitive to grain variance; urban thermodynamic landscape pattern was spatially dependent on the scale; different metrics responded to the different scale; the resolution of 150 meters was an intrinsic scale for the heterogeneity in Chongqing core city. This research also indicated that decreasing consumption of heat energy and enlarging the area of greenbelt and water are effective ways to weaken urban heat effect.
With the globe climate warming and the extension of urban area, urban heat island has become a serious problem of
urban environment. How to effectively monitor the structure and the change of urban heart island is becoming the focus
of research on urban environment. Taking the urban core area of Chongqing as the research object, this paper uses
Landsat TM/ETM+ imageries in 1988, 2001 and 2006, as well as the observing data of climate station, to study the urban
ground temperature. The retrieve method of ground temperature is discussed, including mono-window algorithm, and the
process how to get the four parameters of the algorithm. The retrieved ground temperature is standardized with
extremum and classified into five temperature zones. The buffer analysis is carried out to detect the spatial structure and
its change of urban heart island. The study shows that the character of heart island in Chongqing is great different from
that in plain cities. Owing to the effect of special terrain of Chongqing, the heart island has clear hierarchy. The study
also shows that the intension and extension of hear island is greatly enlarged from 1988 to 2006 due to the outspread of urban area.
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