Desert agriculture based on fossile groundwater
Background
Saudi Arabia is one of the most arid countries in the world and is mostly covered by deserts. This goes hand in hand with a relatively low population density. While the economy of the country largely depends on the export of fossile fuels (oil and gas), it comes as a surprise that Saudi Arabia has been exporting wheat, too. With the exception of oases, agriculture in Saudi Arabia has been mostly based on extensive farming. Only with the exploitation of large fossile groundwater deposits for irrigation it was possible to intensify the production of wheat and other crops.
The area around the town of Ha’il is located above a large groundwater deposit that has been exploited with increasing intensity since the 1970ies. While the originally applied techniques led to the quick evaporation of a large part of the water, combined with a relatively quick salination of the soil, the methods used now are better adapted to this difficult environment. Nevertheless, the use of fossile groundwater will end once the groundwater layers are depleted.
Diagram: Wheat export of Saudi Arabia (in 1000 tons)
The satellite images show an excellent contrast between vegetation and the surrounding desert, as the numerous center-pivot irrigation fields show. Therefore, they are very well suited to monitor the development of the irrigated fields and the crops cultivated. This makes it possible to use the data for crop monitoring as well as precision farming, as the analysis of data allows to tell where the supply of water and fertilizers need to be optimised.
Exercises
- Satellite Map:
- Look at the satellite image map and deselect the all satellite images by unticking the respective boxes.
- The Open Streetmap (OSM) map remains. Which land cover classes can you identify?
- Now add the satellite images one by one, starting with 1985 (lowest in the list) and continuing with 1995, 2005, 2015, and 2023. Which land cover classes can you identify? Does the number of land cover classes change?
- Toggle between the satellite images from 2023 and 1985. Where are the changes in the land cover most prominent?
- Where can you find an increase of the cultivated area, where a decrease?
- EO Browser:
- Open the EO Browser.
- Find the most recent Sentinel-2 dataset covering the area displayed in the satellite map.
- Select a true colour visualisation.
- Can you identify additional, recent changes in the area (check e.g. agricultural land)?
- Select the false colour infrared representation. Can you identify the land-use of the most intensely vegetated areas (represented by bright red colours)?
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