script GEE Lineas de Costa Sentinal 2018 a 2024 ej Solis Chico

// ===================== 1. ÁREA DE INTERÉS ======================
var centro = ee.Geometry.Point([-55.70237, -34.78015]);
var radio_m = 2000;
var aoi = centro.buffer(radio_m);

// ===================== 2. PARÁMETROS ======================
var anios = ee.List.sequence(2017, 2024);
var cloudMax = 10;
var threshold = 0.0;
var scale = 10;
var simplTolerance = 20; // en metros
var minArea = 1000; // m²

// ===================== 3. FUNCIÓN DE PROCESAMIENTO POR AÑO ======================
var extraerLineaAnual = function(anio) {
  anio = ee.Number(anio);
  var inicio = ee.Date.fromYMD(anio, 1, 1);
  var fin = inicio.advance(1, 'year');

  var s2 = ee.ImageCollection("COPERNICUS/S2_SR")
    .filterBounds(aoi)
    .filterDate(inicio, fin)
    .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', cloudMax))
    .map(function(img) {
      var ndwi = img.normalizedDifference(['B3', 'B8']).rename('NDWI');
      return img.addBands(ndwi).copyProperties(img, ['system:time_start']);
    });

  var ndwiCollection = s2.select('NDWI');
  var conteo = ndwiCollection.size();

  return ee.Algorithms.If(
    conteo.gt(0),
    (function() {
      var ndwiMedian = ndwiCollection.median().clip(aoi);
      var waterMask = ndwiMedian.gt(threshold);

      var polygons = waterMask.reduceToVectors({
        geometry: aoi,
        geometryType: 'polygon',
        scale: scale,
        maxPixels: 1e12,
        eightConnected: false
      });

      var filtrado = polygons.map(function(f) {
        var area = f.geometry().area(1);
        return f.set('area_m2', area);
      }).filter(ee.Filter.gt('area_m2', minArea));

      var linea = filtrado.map(function(f) {
        var linea = f.geometry().simplify(simplTolerance);
        return ee.Feature(linea, {
          'anio': anio,
          'area_m2': f.get('area_m2'),
          'fuente': 'Sentinel2'
        });
      });

      return linea;
    })(),
    ee.FeatureCollection([])
  );
};

// ===================== 4. APLICAR A CADA AÑO ======================
var coleccionAnual = anios.map(function(a) {
  return extraerLineaAnual(a);
});
var lineasFinal = ee.FeatureCollection(coleccionAnual).flatten();

// ===================== 5. VISUALIZACIÓN ======================
Map.centerObject(aoi, 13);
Map.addLayer(lineasFinal, {color: 'blue'}, 'Líneas de costa por año');

// ===================== 6. EXPORTACIÓN ======================
Export.table.toDrive({
  collection: lineasFinal,
  description: 'LineasCosta_SolisChico_2017_2024',
  fileFormat: 'GeoJSON'
});