Land use change analysis in the northeastern Qinghai Province, China by Remote Sensing and GIS

摘要

In this paper, land use maps in the two dates, 1986 and 2000, were acquired by visual interpretation from digital Landsat TM images with the help of MGE and ARC/INFO 7.1. Based on spatial analysis and statistical analysis in GIS, the spatial-temporal changes of land use from 1986 to 2000 in the region were obtained and analyzed. Firstly, the transition matrix of land use change was calculated. Secondly, the relative change rate, the indices of frequency degree and importance degree were introduced and calculated. Our objectives were to investigate transition rates of land use and flow direction rates among land use types, the regional differences and the spatial distribution of land use change. The results show that the grassland area decreased while that of urban and built-up, water area, cultivated land and forestland increased in the 14 years. Furthermore, the study indicated that the grassland decreased by 3736.84ha, 42.54% of which was converted to cultivated land, 20.77% to water area and 16.95% to woodland. Most of the losses of cultivated land were converted to urban or built-up land. Relative change rate revealed that there were significant regional differences in quantitative change of land use in every county. Frequency degree index indicated that two land use conversions were distributed widely: the conversion of cultivated land into urban and built-up land and the conversion of grassland into cultivated land. The main directions of land use change were that urban and construction land had been enlarged, cultivated land had been encroached and grassland had been continuously reclaimed as cultivated land.