Assessing Transferability of Landsat-derived NDWI Values across Space and Time

Normalized Difference Water Index (NDWI) derived from the reflectance values of green and infrared bands is a widely used index for the delineation of water bodies in remotely sensed images. While attempting to identify water bodies in a remotely sensed image the analyst has to determine the threshold for NDWI values that correspond to lakes, reservoirs and ponds. However the reflectance values of water bodies in a region will vary widely because of factors such as water depth, presence of biological materials, and turbidity among others. First we tested the transferability of the range of NDWI values derived for a water body in one Landsat image to other water bodies in the same image. Next we tested the transferability of those NDWI values to the same water body in Landsat images acquired in different years. Results from this study will provide insights for automatic extraction of water bodies in Landsat images.