I am interested in mapping surface water bodies in a desert. I have used Tasseled Cap Wetness (TCW) in GEE. After running my code, I found that water bodies (locally called tobas) were not marked. I guess my choice of data may not be correct, my visualisation parameters may be wrong, may be it did not set threshold, or I chose a bad index.

var tobas = ee.FeatureCollection("users/tariqabbas/tobasId"),
    roi = /* color: #98ff00 */ee.Geometry.Point([71.46225179238947, 28.783863923754982]);

var TCAP = function(image) 
var wetness = image.expression(
'(blue * 0.1511) + (green * 0.1973) + (red * 0.3283) + (nir *0.3407) + (swir1 * -0.7117) + (swir2 * -0.4559)',
  blue : image.select('B2'),
  green : image.select('B3'),
  red : image.select('B4'),
  nir : image.select('B5'),
  swir1 : image.select('B6'),
  swir2 : image.select('B7')
image = image.addBands(wetness.rename('wet'));
return image ;

var OLI = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR')
.filterDate('2019-06-01', '2019-06-30')

  • 1
    Hi @Tariq Abbas, I ran your code but it's not clear to me what output you expect. You will likely need to play with your parameters to capture the waterbodies you're missing (at the expense of probably over-estimating total surface water). One thing to take a look at is the Global Surface Water dataset--I don't know if it will capture your tobas, but it could save you a lot of headache if so. developers.google.com/earth-engine/datasets/catalog/…
    – Jon
    Apr 16 '20 at 16:12
  • It did not map full extent of water bodies, missed some water bodies , the results of mndwi were better but I couldn't find way to select range which should select water and mask rest of pixels. In other words , I want to search a water body in satellite view and want to see range of mndwi values , thanks for your reply Apr 16 '20 at 16:29

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