The frequency of extreme weather events in China has been increasing due to global warming. The variety of soil types makes for varying levels of water retention capacity across Southwest China. However, spatially detailed information about soil water retention capacity is often difficult to obtain on a large scale. It has been hypothesized that agricultural drought is directly related to evapotranspiration fluxes and soil water retention capacity. This paper presents the relative water supply capacity index (RWSI), which is based on the integrated standardized precipitation evapotranspiration index (SPEI) and vegetation condition index (VCI) to explore the potential of using the temporal moderate resolution imaging spectroradiometer archive and meteorological data collected from stations in Southwest China to estimate the soil water retention capacity. The results showed that the spatial pattern of RWSI correlated well with that of the soil clay content in Southwest China, which suggests that RWSI could reflect the variations in relative soil water retention capacity in the research region. The RWSI was significantly correlated with relative soil moisture at depths of 0 to 10 cm and 10 to 20 cm. These data showed that RWSI could be used to examine and distinguish the relative differences in soil water retention capacity with an integrated implication of VCI and SPEI in Southwest China.
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.
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.
Terrestrial eco-system in coastal zones is unstable and land-use and Land-cover of its land resource are crucial for its
sustainability. Therefore it is necessary to understand distribution of land use/cover changes in those tender areas. This
paper was to analyze changes of land use/cover in Yellow River Delta in China during recent ten years, which was its
fast development period, by remote sensing monitoring. Two Landsat TM images in October of 1995 and 2004 were
processed using ERDAS software and supervised classification method in study for the land use and land cover of those
two years. The two land use/cover maps were overlaid to discover the changes. It was showed that lots of land use/cover
changes in the Yellow River Delta had taken place in past ten years. Because abundant sand that carried by river water
filled up at estuary of the Yellow River, new land increased fleetly. The rates that foreshore were turned into fishery land
was high for aquaculture with salt water had been developed quickly. Another important effect of human activity was
that part of waste land and grassland had been cultivated for crops. With industry and economy development, land for
urbanization had been outspreaded. Although fast exploitation had been carried out in Yellow River Delta going though
those years, some human activities on land use were inharmonious for sustainable development of land resource in this
area. This must be pay attention to by local government and people.