Working with Hydrosheds

Investigate how and where water flows

Step 1: Download the 30sec SHAPE: Drainage Basins (Beta) for Asia

step 2: Download the administrative boundaries for Indonesia.

Step 3: Use the clip function in ArcMap or QGIS to clip the watersheds within the country.

Step 4: Make a subset of all watersheds larger than 50 Sqm2 and save it as a layer.

Step 5: save the new layer as a KML.

Step 6: Upload the kml as a fusion table.

Follow these instructions to upload and display the fusion table.

Step 7: Display the fusion table in the GEE with the code below:

var ft = ee.FeatureCollection("ft:1iSZG5gJnLKJ4VYLfnBXGO9IoFWuVPMVd79j7q8rf")

Map.addLayer(ft)

Step 8: Use the inspector to select a watershed.inspector

Step 9: Use the code below to select an watershed

// select polygon based on BASIN_ID
var myPolygon = ft.filter(ee.Filter.eq("BASIN_ID",254632));

// add single watershed
Map.addLayer(myPolygon,null,"my watershed");

Step 10: Use the code below to calculate the bounds

// get bounds of polygon
var bounds = ee.Feature(myPolygon.first()).bounds().geometry();

// add single watershed
Map.addLayer(bounds,null,"Bounds");

Step 11: Use the code below to calculate a buffer

// buffer bounds
var buffer = bounds.buffer(50000);

// add buffer
Map.addLayer(buffer,null,"Bounds with buffer");

Step 12: Import the
WWF HydroSHEDS Hydrologically Conditioned DEM, 3 arc-second.

Step 12: Import the
WWF HydroSHEDS Hydrologically Conditioned DEM, 3 arc-second.

var DEM = ee.Image("WWF/HydroSHEDS/15CONDEM");

// create the vizualization parameters
var viz = {min:0.0, max:1000, palette:"1400f7,00f4e8,f4f000,f40000,960424"};

// show DEM
Map.addLayer(DEM,viz,"DEM");

Step 13: Set the nodata values to -9999 instead of 0

// replace the mask by -9999
var mask = dem.mask()
var demMap = ee.Image(-9999).where(mask,dem)

Step 14:Export the data to the Google Driver

//Export the image, specifying scale and region.
Export.image.toDrive({
   image: demMap,
   description: 'DEMKapuas',
     scale: 1000,
    region: buffer
 });

2 thoughts on “Working with Hydrosheds”

  1. How do you isolate Map of Indonesia from the downloaded Asia basin map?

    How do you download the Administrative boundary for Indonesia?

    How to select a particular Watershed-Catchment Area with river profile and cross-section?

    Like

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