民勤绿洲荒漠化遥感评价研究

利用3个年份TM数据,研究荒漠化遥感评价方法,并对民勤绿洲荒漠化进行了初步研究。建立起以遥感光谱特征、组合派生特征和空间结构特征为评价因素,用最大似然方法和景观格局分析进行荒漠化评价的方法,以及在此基础上区域荒漠化评价指数的计算方法。研究表明,3个年份的荒漠化评价总精度都在0.8以上;引入模式识别技术,将是荒漠化评价的主要发展趋势。1988到1997年间,民勤绿洲荒漠化面积没有扩大,基本保持稳定,但各荒漠类型和等级内部间发生转化。从民勤区域荒漠化指数看,1988年为0.71,1992年是0.69,1997年为0.76。1988到1992年期间,荒漠化以水蚀、风蚀过程为主,荒漠化严重程度有所下降,速率为0.5%;1992到1997年间,盐渍化荒漠化过程加剧,荒漠化严重程度加剧,速率为1.4%。作为水蚀荒漠化过程则在整个评价期内减弱。在景观格局上,1992年的整体景观破碎化程度下降,景观格局最为稳定;而1997年破碎化程度最大,景观格局复杂、最不稳定。因此景观格局也反映出两个评价时段内荒漠化演化过程不同,从1988到1992年,土地退化减弱;而1992到1997年间,土地退化进一步加剧

Evaluation Method on Minqin Oasis Desertification with Remote Sensing

The paper studies the land desertification evaluation method by remote sensing techniques and its application on the Minqin Oasis desertification research. This includes the maximum likelihood decision rule and landscape pattern analysis based on the remote sensing spectrum, derived combination character and spatial structure characters. The experiment results showed that the method achieved satisfactory evaluation results since the overall accuracy of the desertification evaluation for Minqin county were over 0.8 in 3 different years. It will be the main method for desertification evaluation based on quantity remote sensing techniques in the future. From 1988 to 1997, the total desertification area of Minqin Oasis was not expanded. The change occurred between the desertification types and grades. During the period of 1988 to 1992, the water and wind erosion desertification process played the main role, the severity of regional desertification decreased, the reduced rate was 0.5%. From 1992 to 1997, the salinization erosion desertification process took the main role and land degradation increased, the deterioration rate was 1.4%. The water erosion process was less important in this region during the study period. The total landscape was most fragmentary and complex in 1997, by contrast, it was less fragmentary and more stable on the landscape structure in 1992. The landscape pattern index for each desertification class had changed differently. The landscape pattern change during the study period also indicated the different processes in the evoluation of land desertification in the study area.