EVIDENCE FROM SATELLITE IMAGES OF HUMAN-RELATED ENVIRONMENTAL CHANGE IN GUIZHOU PROVINCE, CHINA 1991–1998

Abstract

Karst area accounts for about 15% of the total land area in the world, where over I billion people live. There are many environmental problems caused by human's activities in the karst area. These environmental problems are serious, unique, and need to be dealt with urgently. Although much research has been done on land use (LU) and land cover (LC) change detection using satellite images and GIS, little has focused on the karst area. This paper takes Guizhou Province, a typical karst area in China, as an example and studies the impact of land use and land cover on the environment for the period of 1991 to 1998. Three Landsat TM scenes, acquired in November 1991, December 1994 and December 1998 respectively, were used in the study. Land use/cover is classified into five categories: water, natural vegetation, agricultural, urban or built-up, and barren land. A hybrid unsupervised/supervised method is used in the classification. To achieve a higher accuracy, 120 classes are assigned in the original unsupervised classification, and then they are combined into 5 classes. Based on the information obtained from unsupervised classification, 400 sites, or about 3 from each of the 120 unsupervised classes, were carefully chosen as training sites in the supervised classification. The study suggests that Guizhou had experienced significant changes in land use and land cover due to human's activities. Agricultural land continued to decrease from 1991 to 1998; urban area expanded dramatically in that period; the area of forest increased slightly; the area of barren land increased from 1991 to 1994, but it decreased again from 1994 to 1998. The study indicates that the driving forces for the changes were the result of strong economy, governmental policies, poor planning, low educational level, and the nature of the fragile ecosystem in the karst area. Some recommendations are proposed for better land use planning and ecosystem protection there.