Extracting Water Content Using NDWI

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a week ago
PrudhviCharanMallampati
New Contributor

Hi. I want to extract water area from an image using NDWI. I have lots of images (Not necessarily LANDSAT). I'm not sure how to use ArcGIS Pro to extract water area. Can you please help me? (I'm new to ArcGIS Pro).

By extract water area, I mean, in the output image, water should be indicated in one color and all other parts of the image should be indicated in any other color.

Please refer to the sample input and output images.

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JayantaPoddar
MVP Esteemed Contributor

I have used a Sentinel 2A L2A 10 meters data (with Atmospheric correction).

1. Using Band3 (Green) and Band8 (NIR), I calculated the NDWI in Raster Calculator. Choose appropriate bands based on the input Sensor.

Float("Band3"-"Band8")/Float("Band3"+"Band8")

2. Used Iso Cluster Unsupervised Classification (Spatial Analyst) to classify the image into 6 classes (No. of classes could vary for you). The highest value class is the waterbody.

3. From Symbology of the classified raster, I changed the color of other classes to "No Color". You might want to define a different color for other classes.

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Another workaround could be 

1. Execute NDWI using Raster Calculator, as mentioned in Step 1 above.

2. Selecting the NDWI layer in Content, in Symbology pane, change the symbology type to "Classify". 

For Method, change it to "Manual Interval" to make finer adjustments to the range values as per your need.

 



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