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土壤盐渍化严重威胁着干旱区绿洲的稳定与可持续发展,因此借助遥感手段快速提取盐渍地信息并及时掌握其空间分布有着重要的现实意义。以塔里木盆地北缘盐渍地普遍发育区域库车绿洲为例,探讨了干旱区以盐生植被红柳为主要覆盖的盐渍地信息的提取方法。综合利用TM卫星图像数据以及Radarsat雷达数据,分析了研究区主要地物的光谱特征及其波段间的相互运算,从而分析盐渍地与其它地物之间的可分性。着重分析了雷达波段作为一个波段加入ETM的6波段中一起参与主成分变换后对盐渍地信息的提取。研究表明:K-L-5(第五主成分)是提取重度盐渍地信息的最佳波段,TM1是区分红柳覆盖区(轻、中度)盐渍地信息的最佳波段,提取盐渍地信息时混分的水体信息可以通过MNDWI(改进归一化差异水体指数)设定一定的阈值予以剔除,混分的植被信息可以通过NDVI设定一定的阈值予以剔除。根据以上分析,建立决策树模型进行盐渍地信息的提取。结果表明,该方法的总体提取效果较好,是干旱区监测盐渍地变化的有效手段。同时也说明由于雷达波段的参与增加了盐渍地与其它地物之间的可分性,为雷达影像在提取盐渍地信息方面提供了一条有效途径。
Soil salinization is a serious threat to the stability and sustainable development of the oasis in the arid area. Therefore, it is of great practical significance to quickly extract salty soil information and grasp its spatial distribution by means of remote sensing. Taking Kuqa Oasis, a saline-saline-endemic area in northern margin of Tarim Basin, as an example, the extraction method of salinized soil information, which is mainly covered by Salix psammophila, is discussed. Based on the comprehensive use of TM satellite image data and Radarsat radar data, the spectral features of main features in the study area and the inter-band operation are analyzed to analyze the separability between salted land and other features. The analysis of the radar band as a band join ETM in 6 band together after the principal component transformation of the salty ground information extraction. The results show that KL-5 (the fifth principal component) is the best band for extracting salty ground information, TM1 is the best band for salinization of the area covered by Salix The mixed water information can be removed by setting a certain threshold by MNDWI (Improved Normalized Difference Water Index), and the mixed vegetation information can be removed by setting a certain threshold by NDVI. Based on the above analysis, a decision tree model is established to extract salty ground information. The results show that the overall extraction of this method is effective, which is an effective method to monitor the change of saline land in arid areas. At the same time, it also shows that due to the participation of radar band, the separability between saline land and other landmarks is increased, which provides an effective way for radar image to extract salty land information.