Best Method to Extract the River Line from Satellite Images?

Question

What is the best method to extract the river line from satellite images?
Is the Normalized Difference Water Index (NDWI) good or not?
What the best index?

Prem Baboo · Accepted Answer

Satellite-based remote sensing imaging can provide continuous snapshots of the Earth’s surface over long periods.River extraction from remote sensing images is useful for the comprehensive study of dynamic changes of rivers over large areas.The extraction of the drainage hydrographical network is a key for various types of study such as hydrological analysis, geomorphology, environmental science, terrain analysis and still a research topic in the field of GIS. Drainage network are extracted through satellite image (e.g. Digital Elevation Model (DEM)) processing, contour map processing and raster map processing. Due to the advances in satellite imagery high resolution DEM are captured by many satellite recently
The method requires the prior generation of a geodesic mask and a marker image by applying a series of transformations to the original image. These images are then combined so as to produce a pseudo digital elevation model whose valleys match the desired networks. The performance of the methodology is demonstrated for the extraction of river networks from a single band of a Landsat image. The method is generic in the sense that it can be extended for the extraction of other types of arborescent networks such as blood vessels in medical images.
Define the outlets of the desired river network and a region of interest.Enhance potential river stretches.Generate a pseudo DEM by computing the geodesic time function with the outlets as reference set and the image with enhanced rivers as geodesic mask; Calculate the local flow directions of the pseudo DEM and the subsequent contributing drainage areas;Trim the resulting space filling network so as to obtain a network matching the target network.

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