朋友们好，本次我们基于Landsat和Sentinel数据，去云计算NDWI，并导出水体提取结果的栅格数据。您只需要导入研究区table，更改时间段运行。归一化水体指数（NDWI）是遥感影像分析中常用的指数，主要用于识别和提取水体。NDWI通过比较可见光波段（绿波段）与近红外波段（NIR）的反射率差异，突出水体与非水体区域的区别。水体在近红外波段的反射率较低，而在绿波段的反射率较高，因此NDWI能够有效地识别水域。该指数在水体监测、水资源管理以及环境变化研究中有着广泛应用。![]()
var studyArea = table;
function calculateNDWI(image, bands) { var ndwi = image.normalizedDifference(bands).rename('NDWI'); return image.addBands(ndwi);}
function processSentinel2() { return ee.ImageCollection('COPERNICUS/S2_SR_HARMONIZED') .filterDate('2023-03-01', '2023-05-31') .filterBounds(studyArea) .map(function(image) { var cloudMask = image.select('QA60').bitwiseAnd(1 << 10).eq(0) .and(image.select('QA60').bitwiseAnd(1 << 11).eq(0)); return image.updateMask(cloudMask); }) .map(function(image) { return calculateNDWI(image, ['B3', 'B8']); }) .select('NDWI') .mean() .clip(studyArea);}
function processLandsat8() { return ee.ImageCollection('LANDSAT/LC08/C02/T1_L2') .filterDate('2023-03-01', '2023-05-31') .filterBounds(studyArea) .map(function(image) { var opticalBands = image.select(['SR_B.*']).multiply(0.0000275).add(-0.2); var thermalBands = image.select(['ST_B.*']).multiply(0.00341802).add(149.0); return image.addBands(opticalBands, null, true).addBands(thermalBands, null, true); }) .map(function(image) { return calculateNDWI(image, ['SR_B3', 'SR_B5']); }) .select('NDWI') .mean() .clip(studyArea);}
var sentinel2NDWI = processSentinel2();var landsatNDWI = processLandsat8();
Map.centerObject(studyArea, 10);Map.addLayer(sentinel2NDWI, {min: -1, max: 1, palette: ['green', 'white', 'blue']}, 'Sentinel-2 NDWI');Map.addLayer(landsatNDWI, {min: -1, max: 1, palette: ['green', 'white', 'blue']}, 'Landsat 8 NDWI');
Export.image.toDrive({ image: sentinel2NDWI.gt(0).selfMask(), description: "Water_Bodies_Study_Area_2023_Sentinel2", scale: 30, region: studyArea, fileFormat: 'GeoTIFF', maxPixels: 1e9});
Export.image.toDrive({ image: landsatNDWI.gt(0).selfMask(), description: "Water_Bodies_Study_Area_2023_Landsat8", scale: 30, region: studyArea, fileFormat: 'GeoTIFF', maxPixels: 1e9});
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