The study of spatio-temporal variation of impervious surfaces for Dianci Basin using TM imagery from 2002 to 2009

Impervious surface area (ISA) extraction is important for many planning and management applications because of the impacts that impervious surfaces have on a range of environmental resources such as groundwater, hydrological cycle simulation, water management and area pollution assessment. The Dianci Basin is the most developed economic district of the Yunnan province. In recent years, with the rapid urbanization especially surrounding the Dianchi water body, the impervious surface coverage rate has also grown rapidly and has resulted in severe degradation of basin water environment within the Dianci watershed. Extracting the dynamic expansion of impervious surfaces for the Dianci basin in both space and time is essential for analyzing the impacts on the environment. Landsat and other medium-resolution satellites provided the necessary spatial details and temporal frequency for mapping impervious surface expansion of Dianci Basin in the past decade. In this paper, we extracted the ISA informations based on Landsat images of 2002, 2006 and 2009 by using artificial neural network and monitored impervious surface change in the Dianci Basin by analyzing the multi-temporal impervious surfaces. Results of this study were as follows: (1) the area of ISA in the Dianci Basin increased 47 square km from 2002 to 2006 and 73 square km from 2006 to 2009 separately. (2) The spatial distribution of ISA was described according to the 2002/2006 percentage respectively. Most of middle and high percentage ISA was mainly located in the city interior of Kunming. (3) High percentage of ISA moved from the inner city to southeastern and south portions of Kunming and surrounding the Dianci Lake during 2006-2009.(4) Combining the change of ISA with social condition, the driving relationship was analyzed in detail. It was evident that ISA change has a deep relationship with the economic development of this basin in the past eight years. Because of the government of Yunnan province has proposed a “Building new developed Kunming city” and a “Strategy about surrounding Dianci lake development,” the new Chenggong city, some industrial parks and a new international airport have been building since 2003. The results were important and valuable for land use management, ecological protection and Dianci lake pollution treatment.