Earth from Space: Desert growth

18 May 2012

These false-colour Landsat images from 1984, 1990, 2000 and 2011 show agricultural development in northern Saudi Arabia close to the border with Jordan, about 150 km west of the city of Sakakah.

As the years go by, land cultivation increases using fossil water that accumulated underground when the area received more rain and was covered by a lake several thousand years ago.

The fossil water used here for irrigation is up to 20 000 years old and, because of the climatic situation today, the water reserves are not being refilled.

In the early 1980s, the only vegetation in the area could be found around oases. By 2011, large-scale agriculture was providing wheat and corn for the region’s growing population.

The cropland is divided into circles due to the central-pivot irrigation system, where the long water pipe rotates around a well at the centre. Since no crops can grow in this climate without intensive irrigation, the fields are perfectly round.

The false colour makes vegetation look mostly red in this image sequence, and allows for better discrimination between different vegetation types than normal images.

This is helpful when satellite data are used in agricultural monitoring for mapping and classifying land use, crop type, crop health, change detection, irrigated landscape mapping and crop area mapping.

The Thematic Mapper on Landsat-5 is jointly managed by NASA and the US Geological Survey. ESA supports the Landsat series as a Third Party Mission, meaning it uses its ground infrastructure and expertise to acquire, process and distribute Landsat data to users.

Last year, ESA opened its Landsat data archives for use by the scientific community, free of charge.

The Image of the Week is featured on ESA Web-TV, broadcast online every Friday at 10:00 CEST.

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