Discrepancy of Extraction of Standing Water between Index Methods and TM5 Thresholding

Standing water extent is important information for the management of water resources. In the past, this information was collected by using aerial photos and ground surveys. These traditional methods are time-and cost-consuming. At present, satellite imagery is used for this purpose more and more extensively. In this paper, the western part of Hongze Lake and its adjacent upland were taken as test area. Several methods such as Normalized Difference Water Index (NDWI), Normalized Difference Vegetation Index (NDVI) and single band density slicing were used for the extraction of standing water extent and the results were compared and analyzed. The experiment showed that different methods have different advantages. The results from NDWI and TM5 threshold are nearly similar and reliable. The results from NDVI method were associated with the plants distribution and open water extent can be described by this method. NDWI can suppress the mixed pixels of water and vegetation and wet vegetation. Moreover, the linear water bodies can be delineated continuously. The results from TM5 include more mixed pixels of water and other objects.