Shi Pei-ji

Characteristics and driving forces of spatial expansion of oasis cities and towns in Hexi Corridor, Gansu Province, China

This paper presents an integrated study of urban spatial expansion in the Hexi Corridor, Gansu Province, China based on TM, ETM remote sensing data in 1987, 1990, 1995, 2000, 2006 and 2011. The study explores the characteristics of urban spatial expansion and dynamic mechanism by using expansion speed index, expansion intensity index, compact index, fractal dimension, and extended flexibility index. We built the index system of influencing factors of urban spatial expansion by using the grey incidence model. The results showed that urban spatial expansion rate in the Hexi Corridor has been on the upward trend since 1987. Expansion intensity showed an obvious upward trend, however, the upward trend varied in different urban areas. In addition, the urban structure was loose relatively, but the urban compactness was more obvious. The urban spatial form tended to be simple, and the urban land use tended to become more intensive. Urban spatial expansion experienced several stages: padding internally, external expansion and padding internally. The main driving factors of urban spatial expansion are not the urban water resources and the oasis scale, but one or several factors such as economy, traffic, population, resource and national policy.

Land use structure optimization based on carbon balance: A case study in Lanzhou of Gansu Province

Land use structure optimization is the core of land use planning, which has significant influence to the carbon cycle in terrestrial ecosystems. In this paper, we put Lanzhou as case study, to realize the land ecosystem carbon balance is the breakthrough point, using the method of fuzzy linear programming, constructing model from carbon source and carbon sink, trying to put forward a new approach to optimize the land use structure. Contrast with the former planning with the optimization scheme based on carbon balance, carbon stock volume and carbon emissions of the year 2005 and 2020 are evaluated .We got a low carbon optimization scheme of land use planning finally. The results of the study show that the objective to make carbon storage maximization and to make carbon emissions minimization is consistent and the two optimizing schemes have dramatically beneficial effect on increase carbon sink and reduce carbon source, which can slow down carbon emissions in terrestrial ecosystems and realize the rational utilization of land resources and the sustainable development.