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📌 What is SRTM?

The Shuttle Radar Topography Mission (SRTM) provides global digital elevation data at 30-meter resolution. It’s one of the most widely used elevation datasets for terrain analysis, watershed modeling, and more.

🛠️ Step-by-Step: Clipping and Downloading SRTM for Bangladesh

Let’s walk through a simple GEE script that:

1. Loads the SRTM DEM.

2. Filters the country boundary for Bangladesh.

3. Clips the DEM to this boundary.

4. Displays the map.

5. Exports the result as a GeoTIFF to your Google Drive.

📜 Google Earth Engine Code

// Load the SRTM DEM
var srtm = ee.Image("USGS/SRTMGL1_003");

// Load country boundaries from GADM (Level 0)
var countries = ee.FeatureCollection("FAO/GAUL/2015/level0");

// Filter for Bangladesh
var bangladesh = countries.filter(ee.Filter.eq('ADM0_NAME', 'Bangladesh'));

// Center the map view on Bangladesh
Map.centerObject(bangladesh, 7);

// Add the boundary layer to the map
Map.addLayer(bangladesh, {color: 'red'}, 'Bangladesh');

// Clip the SRTM image to the boundary of Bangladesh
var srtmBangladesh = srtm.clip(bangladesh);

// Define visualization parameters
var visParams = {
  min: 0,
  max: 1000,
  palette: ['0000FF', '00FFFF', '00FF00', 'FFFF00', 'FF0000', 'FFFFFF']
};

// Add the DEM to the map
Map.addLayer(srtmBangladesh, visParams, 'SRTM DEM over Bangladesh');

// Export the clipped DEM to Google Drive
Export.image.toDrive({
  image: srtmBangladesh,
  description: 'SRTM_Bangladesh_DEM',
  folder: 'EarthEngineExports', // Change to your preferred folder
  fileNamePrefix: 'SRTM_Bangladesh',
  region: bangladesh.geometry(),
  scale: 30, // 30m resolution
  crs: 'EPSG:4326',
  maxPixels: 1e13
});

📤 How to Download the DEM

1. Open the Google Earth Engine Code Editor.

2. Paste the script into a new script window.

3. Click Run to load and view the DEM.

4. Open the "Tasks" tab (top-right corner).

5. Click "Run" on the export task.

6. Once processed, the DEM will be saved to your Google Drive in the folder you specified.

🌍 What Can You Do Next?

• Open the GeoTIFF in QGIS or ArcGIS.

• Overlay it with administrative boundaries or land cover maps.

• Use it for flood mapping, terrain analysis, or watershed modeling.