I am working on identifying and delineating potential zones of sand rivers using Sentinel-2 in QGIS. So far the NDVI values have been helpful but is there another indicator that could spell out the differences between the sediment type(whether unconsolidated or consolidated) and sizes in the river channel, on the flood plains and adjacent to the floodplain (on the bare ground)?
Dear Felix,
there are couple of spectral indices that were suggested in context of geological/geomorphological research. The ENVI documentation offers a list on the Indices and provides additional references:
https://www.harrisgeospatial.com/docs/alphabeticallistspectralindices.html
https://www.harrisgeospatial.com/docs/backgroundgeologyindices.html
I agree with Dr. Ullmann. Furthermore, would be great if you could find some digital elevation model to check your images. Moreover, you should think about the main characteristic of the things you want to find such as low humidity, high reflectance..... and create your own index. A PCA or tasseled cap transformation could help you a lot.
I hope this will help you
Adding a digital Elevation model to the analyses is a good idea Ivan Lizaga . A free Version of the global TanDEM-X DEM was just released. "The TanDEM-X digital elevation model with 90-m horizontal sampling is now available for download for scientific applications." --> https://tandemx-90m.dlr.de
Terrain analysis in SAGAgis may help you. In addition, you could propose some new spectral indices. Becasue your objective is to distinguish sediment type and sizes in the river channel, the combination of different bands would be useful.
Dear Felix Nyarko, the use of TIN is optimum for distinguishing sediment size in the river channel