Evolution Process of Urban Spatial Pattern in Hubei Province Based on DMSP/OLS Nighttime Light Data

This paper intends to investigate the urban spatial patterns of Hubei Province and its evolution from three different perspectives: urban nodes, urban connections and urban clusters. The research adopts nighttime light imagery of cities in Hubei Province, the viewpoint of ′point-axis-area′ in the ′point-axis system′ theory, and employs light index model, gravity model and social network analysis. The findings are as follows: 1) In terms of urban nodes, the urbanization process of Hubei has been carried out mainly on the basis of external expansion rather than internal increasing. The polarization trend of urban connection network is strengthening. 2) As for urban connections, the estimation of urban connections using light index model is capable of containing various actual flow, and the connections are getting increasingly closer. 3) In regard to urban groups, seven urban groups of varying sizes have formed. On that basis, three stable and relatively independent urban groups as the centers, namely Wuchang, Yichang and Xiangyang emerge as well. But the structures of ′Wuhan Metropolitan Area′, ′Yichang-Jingzhou-Jingmen City Group′ and ′Xiangyang-Shiyen-Suizhou City Group′, which are defined by local development strategy in Hubei Province, are different from the above three urban groups.

Environmental Effects of Foreign Trade and Its Spatial Variations in Mid-eastern Provinces and Cities of China

The studies on environmental effects of foreign trade and its spatial variations are helpful to design and implement environmental protection countermeasures.In order to eliminate the adverse effects of insufficient observation values on the accuracy of regression results and dynamic information quantity of fitting equation during empirical study,panel data of the mid-eastern provinces and cities of China from 1985 to 2007 were selected based on the adjustment of classical regression model in this paper.Panel unit root test and panel cointegration analysis method were applied to investigating the environmental effects of foreign trade and its spatial variations in the mid-eastern provinces and cities of China and its three groups divided by foreign trade dependence.The results show that all scale effects are positive,while all technical effects are negative and unable to counteract positive scale effects.Foreign trade development is regarded as an important cause for outstanding eco-environmental problems in the mid-eastern provinces and cities of China.Total effects and structural effects are significantly different among different groups because of spatial variations in environmental policies,export destinations,source of FDI,etc.Following the principle of′coordinating generality and considering differences comprehensively′,it is essential to issue a series of policies and countermeasures corresponding to differences in regional environmental effect of foreign trade,in order to coordinate the relationship between foreign trade development and eco-environment in each region.

Land use change and soil erosion in the Maotiao River watershed of Guizhou Province

Due to the extremely poor soil cover, a low soil-forming rate, and inappropriate intensive land use, soil erosion is a serious problem in Guizhou Province, which is located in the centre of the karst areas of Southwest China. In order to bring soil erosion under control and restore environment, the Chinese Government has initiated a serious of ecological re- habilitation projects such as the Grain-for-Green Programme and Natural Forest Protection Program and brought about tremendous influences on land-use change and soil erosion in Guizhou Province. This paper explored the relationship between land use and soil erosion in the Maotiao River watershed, a typical agricultural area with severe soil erosion in central Guizhou Province. In this study, we analyzed the spatio-temporal dynamic change of land-use type in Maotiao River watershed from 1973 to 2007 using Landsat MSS image in 1973, Landsat TM data in 1990 and 2007. Soil erosion change characteristics from 1973 to 2007, and soil loss among different land-use types were examined by integrating the Revised Universal Soil Loss Equation （RUSLE） with a GIS environment. The results indicate that changes in land use within the watershed have significantly affected soil erosion. From 1973 to 1990, dry farmland and rocky desertified land significantly increased. In contrast, shrubby land, other forestland and grassland significantly decreased, which caused accelerated soil erosion in the study area. This trend was reversed from 1990 to 2007 with an increased area of land-use types for ecological use owing to the implementation of environmental protection programs. Soil erosion also significantly varied among land-use types. Erosion was most serious in dry farmland and the lightest in paddy field. Dry farmland with a gradient of 6°-25° was the major contributor to soil erosion, and conservation practices should be taken in these areas. The results of this study provide useful information for decision makers and planners to take sustainable land use management and soil conservation measures in the area.

Estimating single scattering albedo of winter wheat over the North China Plain using AMSR-E data

We proposed a method to estimate single scattering albedo of winter wheat over the North China Plain with AMSR-E passive microwave imagery. The relationships of single scattering albedo and optical depth between 6. 925 GHz and 10. 65 GHz were derived from simulations. To retrieve the single scattering albedo,the relationships were combined with the physical expressions of microwave vegetation indices derived from the first-order parameterized emission model. Comparisons with normalized difference vegetation index( NDVI) obtained from daily MODIS reflectance product showed that the variations in winter wheat single scattering albedo were similar to those of winter wheat NDVI. However,several differences were observed. NDVI showed saturation from the heading stage to the milky stage of winter wheat,whereas single scattering albedo remained sensitive to the growth of winter wheat. Single scattering albedo offers certain advantages in reflecting the growth status of winter wheat.