利用NDVI指数识别作物及土壤盐碱分布的应用研究

Applied Study on Identification of Crops and Salinity Distribution by NDVI Index

利用监督分类、NDVI指数等遥感影像处理方法,在黄河上游的宁夏青铜峡灌区开展识别作物及土壤盐碱分布的应用研究。基于LANDSAT卫星遥感影像,依据NDVI指数推断作物及土壤盐碱分布,得到灌区作物及土壤盐碱分布状况和相应的估算结果。研究结果表明,灌区上、下游之间在作物长势上存在着较大差异,北部地区明显低于南部,土壤盐碱分布差别是造成该差异的主要原因之一。受盐碱影响的作物面积在年度内随气候条件的改变呈现出明显的季节性变化,灌区年内受土壤盐碱危害的面积约为100000hm2,近1/3的作物面积受到程度不一的土壤盐碱化影响,且灌区下游的盐碱地面积及盐碱化程度均高于上游。

By applying remote sensing techniques to the Qingtongxia Irrigation System (QIS) in Ningxia, this paper presented the applied study on identification of crops and salinity distribution by the NDVI Index. Extensive use of various image processing methods, including the supervised classification and the NDVI index, were made to identify the crops and salinity distribution. For the QIS, based on the LANDSAT scene, the distribution of cropped area and salt affected area were deducted from NDVI computation. The results indicated that a sharp contrast in cropping intensities is showed between south and north, i.e. upstream and downstream. The phenomenon that the northern part of QIS shows less intense cropping intensities is strongly assumed to be the consequence of the salinity. During the year 1999 in QIS, it is clear that a seasonal variation in the total salt affected area is evidently observed as change of the climatic conditions, and the RS approach has shown the geographic extend of salinity, representing about 100000 hm^2, i.e. one third of the total cropped area is affected by salinity.