GEE_Code.txt

var START_DATE = '2006-01-01';
var END_DATE = '2010-12-31';
var SCALE = 11000;
var DROUGHT_THRESHOLD = 0.00002;

var dataset = ee.ImageCollection("IDAHO_EPSCOR/TERRACLIMATE")
  .filterBounds(table)
  .filterDate(START_DATE, END_DATE)
  .select(['soil', 'pr', 'pet']);

var soilData = dataset.select('soil');
var months = ee.List.sequence(1, 12);
var years = ee.List.sequence(2006, 2010);

var byMonthYear = ee.FeatureCollection(
  years.map(function(y) {
    return months.map(function(m) {
      var filtered = soilData
        .filter(ee.Filter.calendarRange(y, y, 'year'))
        .filter(ee.Filter.calendarRange(m, m, 'month'))
        .mean();
      
      var stats = filtered.reduceRegion({
        reducer: ee.Reducer.mean(),
        geometry: table,
        scale: SCALE
      });
      
      var isDrought = ee.Number(stats.get('soil')).lt(DROUGHT_THRESHOLD);
      
      return ee.Feature(null, {
        'soil_value': stats.get('soil'),
        'year': ee.Number(y).format('%d'),
        'month': m,
        'date': ee.Date.fromYMD(y, m, 1).format('MMM'),
        'drought_alert': isDrought
      });
    });
  }).flatten()
);

var summaryStats = byMonthYear.reduceColumns({
  reducer: ee.Reducer.mean()
    .combine(ee.Reducer.stdDev(), '', true)
    .combine(ee.Reducer.minMax(), '', true),
  selectors: ['soil_value']
});

var calculateBandCorrelation = function(band1, band2) {
  var joined = dataset.select([band1, band2]);
  return joined.reduce(ee.Reducer.pearsonsCorrelation());
};

var soilPrecipCorr = calculateBandCorrelation('soil', 'pr');
var soilPetCorr = calculateBandCorrelation('soil', 'pet');

var advancedChart = ui.Chart.feature.groups({
  features: byMonthYear,
  xProperty: 'month',
  yProperty: 'soil_value',
  seriesProperty: 'year'
})
.setChartType('LineChart')
.setOptions({
  title: 'Monthly Soil Moisture by Year',
  titleTextStyle: {fontSize: 16, bold: true},
  hAxis: {
    title: 'Month',
    titleTextStyle: {italic: false, bold: true},
    gridlines: {count: 12},
    ticks: [1,2,3,4,5,6,7,8,9,10,11,12]
  },
  vAxis: {
    title: 'Soil Moisture',
    titleTextStyle: {italic: false, bold: true},
    gridlines: {count: 10},
    viewWindow: {min: 0}
  },
  series: {
    0: {color: '#1a237e', lineWidth: 2},
    1: {color: '#0d47a1', lineWidth: 2},
    2: {color: '#1976d2', lineWidth: 2},
    3: {color: '#039be5', lineWidth: 2},
    4: {color: '#00acc1', lineWidth: 2}
  },
  pointSize: 4,
  legend: {position: 'right'},
  curveType: 'function',
  interpolateNulls: true
});

var legend = ui.Panel({
  style: {
    position: 'bottom-right',
    padding: '8px 15px'
  }
});

var makeRow = function(color, name) {
  var colorBox = ui.Label({
    style: {
      backgroundColor: color,
      padding: '8px',
      margin: '0 8px 0 0'
    }
  });
  return ui.Panel([colorBox, ui.Label(name)], ui.Panel.Layout.Flow('horizontal'));
};

legend.add(ui.Label('Soil Moisture Levels'));
legend.add(makeRow('#1a237e', '2006'));
legend.add(makeRow('#0d47a1', '2007'));
legend.add(makeRow('#1976d2', '2008'));
legend.add(makeRow('#039be5', '2009'));
legend.add(makeRow('#00acc1', '2010'));

var panel = ui.Panel({
  style: {
    position: 'top-right',
    padding: '8px'
  }
});

var yearSelector = ui.Select({
  items: ['2006', '2007', '2008', '2009', '2010'],
  placeholder: 'Select Year',
  onChange: function(year) {
    var yearData = byMonthYear.filter(ee.Filter.eq('year', year));
    var yearChart = ui.Chart.feature.byFeature(yearData, 'month', 'soil_value')
      .setOptions({
        title: 'Soil Moisture for ' + year,
        lineWidth: 2,
        pointSize: 4
      });
    print(yearChart);
    var droughtAlerts = yearData.filter(ee.Filter.eq('drought_alert', true));
    print('Drought Alerts for ' + year + ':', droughtAlerts);
  }
});

var statsPanel = ui.Panel({
  style: {
    position: 'bottom-left',
    padding: '8px 15px'
  }
});

statsPanel.add(ui.Label('Statistical Summary:', {fontWeight: 'bold'}));
statsPanel.add(ui.Label('Mean: ' + summaryStats.get('mean').getInfo().toFixed(2)));
statsPanel.add(ui.Label('StdDev: ' + summaryStats.get('stdDev').getInfo().toFixed(2)));
statsPanel.add(ui.Label('Min: ' + summaryStats.get('min').getInfo().toFixed(2)));
statsPanel.add(ui.Label('Max: ' + summaryStats.get('max').getInfo().toFixed(2)));

panel.add(ui.Label('Filter by Year:'));
panel.add(yearSelector);

var soilViz = {
  min: 0,
  max: 0.00005,
  palette: ['#000004', '#2C115F', '#721F81', '#B63679', 
            '#F1605D', '#FEAF77', '#FCFDBF']
};

Map.centerObject(table);
Map.addLayer(soilData.mean().clip(table), soilViz, 'Mean Soil Moisture');
Map.add(panel);
Map.add(legend);
Map.add(statsPanel);

print('Soil Moisture Analysis');
print(advancedChart);
print('Soil-Precipitation Correlation:', soilPrecipCorr);
print('Soil-PET Correlation:', soilPetCorr);

Export.table.toDrive({
  collection: byMonthYear,
  description: 'soil_moisture_analysis',
  fileFormat: 'CSV'
});

Export.image.toDrive({
  image: soilData.mean().clip(table),
  description: 'soil_moisture_map',
  scale: SCALE,
  region: table,
  maxPixels: 1e9,
  fileFormat: 'GeoTIFF'
});

// For multiple years
years.getInfo().forEach(function(year) {
  var yearImage = soilData
    .filter(ee.Filter.calendarRange(year, year, 'year'))
    .mean()
    .clip(table);
    
  Export.image.toDrive({
    image: yearImage,
    description: 'soil_moisture_map_' + year,
    scale: SCALE,
    region: table,
    maxPixels: 1e9,
    fileFormat: 'GeoTIFF'
  });
});