[GRASS-user] Sentinel2- flooding

[Stefan Blumentrath]

Hi Shane,

Following up on robertos answer:
You could try the Normalized Difference Water Index (NDWI) which is computed for S-2 as:
ndwi = (B08-B11)/(B08+B11)
or alternatively
ndwi = (B03 - B08) / (B03 + B08)
See e.g.: https://github.com/sentinel-hub/custom-scripts/blob/master/sentinel-2/ndwi/script.js

You could also take a look at Sentinel-1 for flooding / water bodies. However, Sentinel-1 would have to be pre-processed in SNAP/gpt.

Cheers
Stefan

From: grass-user <grass-user-bounces at lists.osgeo.org> On Behalf Of Shane Carey
Sent: fredag 7. desember 2018 17:35
To: roberto.marzocchi at gmail.com
Cc: grass-user grass-user <grass-user at lists.osgeo.org>
Subject: Re: [GRASS-user] Sentinel2- flooding

Ok, thanks.
Le gach dea ghui,
Shane Carey
GIS and Data Solutions Consultant


On Fri, Dec 7, 2018 at 2:45 PM Roberto Marzocchi <roberto.marzocchi at gmail.com<mailto:roberto.marzocchi at gmail.com>> wrote:
I Think there isn't any tool pre-configured. You need to find an index to calculate "flooded" cells and then you can simply use r.mapcalc

R

Il giorno ven 7 dic 2018 alle ore 14:45 Shane Carey <careyshan at gmail.com<mailto:careyshan at gmail.com>> ha scritto:
Hi,

I've obtained an image from sentinel2 where it shows flooding. Just wondering are there tools in Grass to classify an image in order to pull out these "flooded" pixels?

Thanks
--
Le gach dea ghui,
Shane Carey
GIS and Data Solutions Consultant
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