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.
The monitoring and assessment of land cover in Three gorges area, one of the main ecological flimsy
zones in China, is helpful for better understanding the function of natural and human factors on
ecosystems. With the construction of Three gorges project, the concerns on the land cover change in
Three gorges area by policy makers are raising. In this paper, Landsat TM images in 1986, 1996, 2000
and CBERS images in 2006 are used to detect the change of land cover in Three gorges area, which
include the main regions and land cover types. A series of models are built to assess these changes.
Land use intension index model and land use comprehensive benefit model are used to assess the use
effect of land. Land use dynamic degree model is built to detect the intension of change for each land
cover type in each county of this area. Land use centroid model is used to detect the spatial shift,
which shows the human activities become more and more near the bank of Three gorges reservoir in
recent 20 years. At last, this paper analyzes the temporal-spatial change of land-use and land-cover of
Chongqing and discusses the main driving forces of land cover change in Three gorges area with the
method of correlation analysis, and constructs a Markov matrix model to forecast the land cover
change in the future 10 years.
The selection of urbanization patterns and its determinants are hot issues in China nowadays. Based on land-use remote
sensing data estimated from Landsat Thematic Mapper/Enhanced Thematic Mapper digital images of Chinese Academy
of Sciences and a unique set of socioeconomic data collected by the authors, according to the build-up area (BUA), we
classified the patterns of urbanization into five scales (rural "villages", small townships, small and medium cities, large,
and super large cities). Then an econometric model is developed to empirically estimate the determinants of urbanization
patterns. Results indicate that BUA expanded rapidly from late 1980s and the patterns of urbanization are associated with
policy factors. At the same time, population and economy growth also help affect the development of urbanization
patterns. Two important policy implications can be drawn from this study. First, the process of urbanization could be
predictable and to some extent controlled through various government policies as the urbanization is strongly related to
policy choices. Second, further study is necessary to evaluate China's past and current urbanization strategy that have
been focused on the development of both small townships and super large cities since the middle 1990s. The rapid
growth of super large cities is an issue that needs more concerns by policy makers.
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.
The assessment of food provisioning services of ecosystems in Three-gorge areas is helpful for better understanding the function of ecosystems in local human well-beings. In this paper, process-based models are used to assess the potential food provisioning services derived from agriculture ecosystems and grassland ecosystems, a modifying model along with normal woodlands and a set of modifying coefficients is built to assess the potential food from woodland ecosystems. A set of power regression models based on environment factors are built to estimate the potential fish production from water ecosystems. Land cover data stemmed from Landsat TM images, as well as other natural and social-economic data in 1km resolution such as temperature, precipitation, and DEM, are used to support these assessment models. It shows that the four ecosystems in Three-gorge areas can provide 85.98×1012 calories heat, 2.49 billion kilograms protein and 823.4 million kilograms fat. Human carrying capacity model under the balance nutrition pattern is built in this paper, which results in two key findings: ecosystems in Three-gorge areas can feed 45.92 million people under wealthy living standard which is 1.53 times of the current population, and the sustainable population is from 9.69 to 36.23 million under that living standard. Multi-scale population pressure model is built to calculate the population pressure index in Three-gorge areas. The grain for green pressure index, a multivariate linear weighed model, is used to determine the spatial distribution of farmland fit for grain for green and fit for protecting.
With the rapid socio-conomic development and urbanization acceleration, obvious changes of land use have happened every year in Chongqing. The concerns on the land use dynamic monitoring and assessment by policy makers are rising. The overall objectives of this study are to monitor and examine the major determinants of land use changes of core urban districts in Chongqing. Based on the land use survey information derived from airscapes in 2005, as well as that in 1996 and the land use update data from 1997 to 2004, the land use dynamic database of core urban districts in Chongqing is built, then the land use dynamic analysis is carried out. It shows that the built up area has risen 27.6 percent and cultivated land has decreased 27.5 percent from 1996 to 2005. In this study, a system of econometric model on the changes of built up area and cultivated land has been developed, it was empirically estimated based on remote sensing data of land use and a unique set of data collected by authors on economic development and policies that have driven land use pattern changes of core urban districts in Chongqing. The results of this study indicate that economy growth, urbanization acceleration, the regional development and functional zone policy are key factors that have been driving land use changes of core urban districts in Chongqing. The paper concludes with a set of policy recommendations on harmonizing Chongqing's urban development and cultivated land protection.
With a subtropical climate, Guangxi has a typical karst landscape. Land degradation has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings in geology, topography, rainfall, and vegetative cover, as well as human activities such as deforestation. Its eco-environment has deteriorated over recent years while cultivated land is disappearing quickly. This, in turn, has exacerbated the poverty level in rural areas. In this study we monitored the spatial distribution of land degradation and its temporal evolution using Landsat TM/ETM images of the late 1980s, mid-1990s and late 2000 (for simplicity, we identified them as 1985, 1995 and 2000). We also explored the causes of its initiation and expansion. Through constructing regression models using all the relevant variables and considering the lagged effects as well as fixed effects, we quantified the exact role of different factors in causing land degradation in the study area with new findings. Based on these results we further analyzed the hazard of land degradation and proposed a few practical rehabilitation measures, including forestation, infrastructure projects, and ecological projects. The findings in this study are invaluable in preserving, restoring, and reconstructing the degraded environment in Guangxi and other karst areas in Southwest China while alleviating poverty in rural areas.
Continental aquatic ecosystems are important sources of the protein for human needs. Assessments of potential food provisioned by aquatic ecosystems can help people better understand how aquatic ecosystems can support human well-beings. In this paper, four power regression models based on environment factors, which affect fishery productivity on basal level, are built to estimate the potential productivity of natural fish in fishable paddy fields, rivers and creeks, lakes, reservoirs and ponds respectively. The data for the assessment include the raster data of solar radiation, vegetation, terrain, temperature, precipitation, soil in 1 km resolution. Population density in 1 km resolution is used to detect the possible fishery investment of aquatic ecosystems. Increasing productivity coefficients, which show the ratios of fishery productivity under investment condition to that of natural condition, are estimated according to fishery investigation of different investment. With the natural fishery productivity and the increasing productivity coefficients, potential food provisioning services of continental aquatic ecosystems are estimated. The outcome of the assessment shows that 35.59 million tons of potential fish per year can be obtained from aquatic ecosystems, which includes 16.27 million tons from fishable paddy fields, 2.09 million tons from rivers and trenches, 4.97 million tons from lakes, and 15.25 tons from reservoirs and ponds.
Debates have persisted on the precise nature and consequence of urbanization on cultivated land in China. The primary goal of this paper is to provide empirical-based evidence on the impacts of urbanization and industrialization on cultivated land. Based on cultivate land data estimated from Landsat Thematic Mapper/Enhanced Thematic Mapper digital images for 1987, 1995 and 2000 and a unique set of county-level socio-economic data, an econometric model on cultivated land change is empirically estimated. The results produce findings that are both expected and those that are fairly surprising. Because of offsetting effects of land expansion in China's northeast and northwest regions, overall there was a small net increase in cultivated land between 1987 and 2000. Although cultivated area decline between 1995 and 2000, the net decline was about 1.2% only. Industrialization and population growth were largely responsible for the fall in 1995-2000. Moreover, contrary to the conventional opinion, after holding constant the effect of industrialization and population growth, regardless of whether urban area expansion occurs in large, medium or small cities or towns, such urbanization is land-saving when compared to leaving rural residents in rural areas. Two of major implications of our analysis are: 1) although the loss of cultivated land imposes a cost on the nation, it appears to be associated with those processes that will lead to the ultimate modernization of China; 2) the nation's policies of town and small city development are not necessarily inefficient in terms of their impact on cultivated land use.