Terrestrial Tour: Water in the Desert

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As Earth's climate warms, our management of freshwater resources becomes critical if we are to preserve these resources, and therefore life, in the desert. 

Credits


Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory.

All images, illustrations, and videos courtesy of NASA
 
except:
·       Image of Antarctic snow dunes courtesy of Mark Fahnestock, University of Maryland, College Park
·       Sea creature illustration copyright The National Library of Israel, Shapell Family Digitization Project _and The Hebrew University of Jerusalem, Department of Geography – Historic Cities Research Project
·       Image of clouds off Namibian coast courtesy of Chelys
·       Image of dunes in the Namib Desert courtesy of the USGS EROS Data Center Satellite Systems Branch
·       Namibian dune photo courtesy of Wikimedia user Alcazarfr
·       Photo of the Mandara Oasis in Libya courtesy of Rudolph Baumann
·       Photo of Astrophytum ornatum cactus courtesy of Wikimedia user Stan Shebs
·       Photos of desert plants courtesy of Wikimedia user Halfalah and Dr. Eric Christian (NASA)
·       Photo of fishhook barrel cactus courtesy of Susan Lynn Peterson
·       Photo of Ubari Oasis in Libya courtesy of Wikimedia user Sfivat
·       Image of alluvial fan in Takla Makan Desert courtesy of the USGS EROS Data Center Satellite Systems Branch
·       Photos of salt-covered croplands courtesy of the USDA Natural Resources Conservation Service
 
Music courtesy of Associated Production Music
Written by Andrea Gianopoulos
Designed by Marc Lussier

Transcript


(SPEECH)
[MUSIC PLAYING]
 
(DESCRIPTION)
Text, Water in the Desert
 
The Earth spins.
 
Text, water is a necessity for life on Earth.
 
Nowhere is this more apparent than in the desert.
 
Nearly one-third of Earth's land surface is desert.
 
A world map shows coastal, hot, and cold deserts.
 
Text, true deserts receive less than 10 inches of rain annually.
 
Semi-arid regions receive between 10 and 20 inches of rain per year.
 
A pin drops on the map in an area of hot desert in Northern Africa. We zoom in to the Sahara Desert in Niger, Africa, 2009.
 
Text, because all life on Earth requires water, most deserts support only meager vegetation and very few people and animals.
 
The desert in 2007 shows more green.
 
Text, when significant rain does fall, the desert springs to life.
 
Water in the desert usually comes from underground rivers or aquifers that flow to the surface, forming isolated oases of vegetation in the desert.
 
An aerial view of the Ouargla Oasis in Algeria, Africa.
 
Text, this false-color image of Ouargla Oasis in southern Algeria reveals healthy vegetation (bright red) surrounding the oasis.
 
People often tap desert aquifers so they can plant and irrigate crops.
 
Water is the most precious commodity in the desert.
 
A pin drops on the map on Saudi Arabia.
 
Text, for more than three decades, Saudi Arabia has been drilling for water, not oil, in the Wadi As-Sirhan Basin.
 
We zoom in to the Wadi As-Sirhan Basin in Saudi Arabia, 1987.
 
Text, aquifers here hold water that fell as rain during the last ice age, when this region's climate was much more temperate.
 
The following series of false-color images reveals the growth of farms that tap the aquifers.
 
Farms appear on the image as small green circles. In 1991, farms are sparse. By 2012, most of the area is covered with farms.
 
Text, hydrologists estimate that the Wadi As-Sirhan Basin receives less than 8 inches of rain per year on average.
 
This is not enough to recharge the aquifers.
 
The Wadi As-Sirhan Basin could run dry in 50 years.
 
The Hamoun Wetlands in Afghanistan and Iran, 1976.
 
Text, for more than 5,000 years the Hamoun wetlands served as a primary source of food and shelter.
 
Two large blue-green lakes and an expansive wetland were fed by the Helmand River.
 
The dry wetlands in 2001.
 
Text, but in less than five years, drought and the overuse of irrigation cut off the Helmand River's flow and desiccated the Hamoun wetlands.
 
Dry reeds and white salt flats mark the landscape that once held a diverse and thriving wetland ecosystem.
 
In the desert, water means life.
 
Seasonal rains are followed by an explosion of desert blooms and aquifers bubbling up to the surface to form lush oases of green.
 
Water shapes desert landscapes both naturally and through human exploitation.
 
We divert rivers and drain aquifers to water crops ill-suited to grow in desert environments to feed an ever-growing population.
 
As Earth's climate warms, our management of freshwater resources becomes critical if we are to preserve these resources, and therefore life, in the desert.