The Disappearing Aral Sea

1
The Disappearing Aral Sea
In the 1960s, planners in the former Soviet
Union gave Central Asia the role of supplier of
raw cotton. Irrigation was imperative, and the
Aral Sea and its tributaries seemed a limitless
source of water. Irrigated land was expanded from
about 4.5 million hectares in 1960 to almost 7
million hectares in 1980. The local population
also grew rapidly, from 14 million to about 27
million in the same period. Water withdrawal
almost doubled to an annual 120 cubic kilometres,
more than 90 percent of it for agriculture. The
result was the collage of the prevailing water
balance in the basin. Waterlogging and
salinization eventually affected about 40 percent
of irrigated land. Overuse of pesticides and
fertilizer polluted surface water and
groundwater, and the delta ecosystems
disappeared by 1990 more than 95 percent of the
marshes and wetlands had given way to sand
deserts and more than 50 delta lakes, covering
60,000 hectares, had dried up.
2
Satellite Images
The brightness of a cloud in the visible image is
determined by its height, thickness, and amount
of water droplets. High clouds that drape over
the Earth like blankets have lots of particles
and scatter a lot of sun light. They appear white
in a visible image. Fog is also very easy to see
on visible satellite images.
In water vapor images, black indicates low
amounts of water vapor and milky white indicates
high concentrations. Bright white corresponds to
high clouds. Water vapor images provide
information in all regions, even those that lack
clouds.
IR imagery can be used to distinguish low clouds
from high clouds. Low clouds are relatively warm
and appear gray in satellite IR images. Thick
cold clouds, like the tops of thunderstorms,
appear bright white. An of IR satellite images
over visible images is that IR images are
available day and night.
Color composite images are made from the
combination of visible, IR, and water vapor
satellites. The green colors are seen in warm dry
areas, while the blues are in warm humid areas.
3
Land Use/Land Cover Change
By using the LANDSAT satellite we can see the
change in the land cover between 1988 (top) and
1996 (bottom) in Shenzhen, China. On the right
are the true color images and on the left are the
false color composites. In the false color
composites the red represents vegetation while
the white represents developed areas.
4
Yellow River Change
Looking at the satellite images of the Yellow
River in China, we can see how the development
along the coast has changed the river delta. The
light white colors seen in the water are sediment
and pollution.
5
Typhoon Fitow
Typhoon Fitow as a tropical depression in the
western Pacific on August 28th. After just two
days, it intensified into a typhoon. The storm
struck Japan near Tokyo on September 6th and
killed two people.
These are two different images of the typhoon
taken on the morning on September 4th. The water
vapor image (above) shows lots of moisture around
the storm, while the colorized infrared images
shows cold high cloud tops.
6
Shiveluch Volcano
On March 29, 2007, the Shiveluch Volcano on the
Russian Federation's Kamchatka Peninsula erupted,
sending an ash cloud skyward roughly 32,000 feet.
The image on the right taken by NASAs MODIS
satellite captured the eruption and the ash
plume.