基于NDWI的海南岛西部沙漠化信息自动提取方法研究

分析海南岛西部沙漠化土地的光谱特征，主要表现为沙漠化土地整体反射光谱率偏高，在TM3和TM5波段表现尤其突出，反射光谱曲线的波峰形态也比其他背景地物更为明显。选择能较好反映沙漠化土地的植被信息（TM4）和土壤水分信息(TM5)的波段，经波段运算得出归一化水指数（NDWI），用以自动提取沙漠化土地信息。运用海南岛西部典型沙漠化区域对该方法进行了精度检验，结果表明，利用NDWI自动提取沙漠化土地信息是可行的，正确率达到89.71％。为快速自动提取沙漠化土地信息提供了一种新思路，以期能更快捷地为沙漠化治理决策提供准确的时空变化信息和科学依据。

Method of Desertified Lands Extraction based on NDWI in Western Hainan Island

Firstly,we have analyzed the spectral value of desertified lands in the west of Hainan Island,and result shows that desertified lands,with wavier spectral curve,has higher spectral value than the other object features especially in spectral band TM3 and TM5.Secondly,we have calculated the normalized difference water index(NDWI) with TM4 that can reflect vegetation information well and TM5 that can reflect soil moisture information well to extract desertified lands from TM images.Lastly,we have chosen a typical desertified area in the west of Hainan Island to prove the method,and results show that the accuracy of extraction reaches 89.71%.This paper has provided a new method to extract desertified lands quickly from TM image,expecting to provide real-time information and scientific base for the decision-making in desertification control.