Earth from Space: Gariep Dam, South Africa
The Gariep Dam, the largest dam in South Africa, is featured in this false-colour image captured by the Copernicus Sentinel-2 mission.
The Gariep Dam, visible in the bottom right of the image, lies along the Orange River, bordering the Free State and Eastern Cape provinces. The dam’s primary purpose is for irrigation, domestic and industrial use as well as power generation. The wall of the Gariep Dam, which is around 88 m high and 900 m long, holds back the Gariep Reservoir and, when full, the reservoir covers an area of around 360 sq km.
This image has been processed in a way that highlights vegetation in shades of green and water bodies in black. The water on the east side of the Gariep Dam appears in royal blue owing to a large quantity of sediments coming from the Orange River, therefore appearing brighter than the water flowing out of the west side of the dam.
The Orange River plays an important role in the South African economy by providing water for irrigation and hydroelectric power. It rises in the Drakensberg mountains in Lesotho, flowing westwards through South Africa to the Atlantic Ocean.
The river is said to be one of the world’s most turbid, and is estimated to deliver around 60 million tonnes of sediment each year to the western margin of South Africa. A significant quantity of this sediment is believed to be from soil erosion, an increasing environmental threat to sustainability in southern Africa.
On the northern shore of the dam lies the Gariep Dam Nature Reserve, home to the largest number of Springbok in the country as well as other animals such as zebras, black wildebeest and ostrich.
The bright green circular shapes along the Orange River are an example of centre-pivot irrigation systems, where equipment rotates around a centre pivot and crops are fed with water from the centre of the arc.
In the left of the image lies the Doornkloof Nature Reserve, at the southern shore of the Vanderkloof Dam (not visible). The reserve is home to kudu, brown hyena and around 170 bird species.
The rest of the image is dominated by bare soil and rocky terrain which appear in different shades of pink and red. Straight lines in the image are roads which connect this area to other parts of South Africa.
Data from the Copernicus Sentinel-2 mission can help monitor changes in urban expansion, land-cover change and agriculture monitoring. The mission’s frequent revisits over the same area and high spatial resolution also allow changes in inland water bodies to be closely monitored.
This image, captured on 30 January 2020, is also featured on the Earth from Space video programme.
