# Water consumption by land-use class

How much water is consumed by all these forests?

Step 1: Import the chirps dataset

Step 2:  Set the time and date variable.

```// variables for start and end year
var startyear = 2006;
var endyear = 2006;

// create a list with months
var months = ee.List.sequence(1,12);

// define start and end date
var startdate = ee.Date.fromYMD(startyear,1,1);
var enddate = ee.Date.fromYMD(endyear,12,1);

// create list for years
var years = ee.List.sequence(startyear,endyear);
```

Step 3: Import the ET dataseries

```// import actual ET data
var aET = ee.ImageCollection(&quot;users/atepoortinga/etdata&quot;);
```

Step 4: Import the landuse map you create in this exercise.

```// landuse map
var luse = ee.FeatureCollection('ft:1Hgt_gN4R7opnaFxamqJsJnkic_WWunxgbBtHsT5J','geometry');
```

Step 5: Filter on date and location.

```// select P for time range
var P = chirps.filterDate(startdate, enddate)
// Sort chronologically in descending order.
.sort('system:time_start', false)
.filterBounds(luse);

// select aET for time range
var aET = aET.filterDate(startdate, enddate)
// Sort chronologically in descending order.
.sort('system:time_start', false)
.filterBounds(luse);
```

Step 6: Calculate the monthly Precipitation

```// calculate the P for each month
var allP =  ee.ImageCollection.fromImages(
years.map(function (y) {
return months.map(function(m){
var w = P.filter(ee.Filter.calendarRange(y, y, 'year'))
.filter(ee.Filter.calendarRange(m, m, 'month'))
.sum();
return w.set('year', y)
.set('month', m)
.set('date', ee.Date.fromYMD(y,m,1))
.set('system:time_start',ee.Date.fromYMD(y,m,1));

});
}).flatten());
```

Step 7: Create a chart with the Monthly rainfall for each landuse class.

```// Predefine the chart titles.
var title = {
title: 'Rainfall',
hAxis: {title: 'Time'},
vAxis: {title: 'P (mm)'},
};

// setup the chart for P
var chart = ui.Chart.image.seriesByRegion(allP, luse, ee.Reducer.mean(), 'precipitation', 2500, 'system:time_start', '??')
.setOptions(title)
.setChartType('ColumnChart');

print(chart);
```

Step 9: Do the same for ET.

Step 10: Do the same for incremental ET you created in this exercise.

## One comment

1. Sean says:

How did you filter the data by land use category? I ran the code and it only extracted monthly precipitation for the entire region.