Friday, April 8, 2011

Are the deserts expanding?

More than one fifth of the area of India is occupied by Thar Desert,Africa by Sahara Desert, China by Gobi  desert,South America By Atacama desert.The arid and semi arid lands constitute about two fifth of India where an estimated 200 million people are living.Deserts arid and semiarid regions of the world receive an average of less than 350 millimeter rain every year .These cover about 43 percent of earth's  land
 About 4500 years ago,the Harappan civilization flourished in regions now occupied by Thar desert.Rhinos and Elephants roamed in the forests that once grew there .large scale deforestation and climatic changes gradually converted the region into a desert. The Rajasthan desert is one of the  most densely populated deserts of  the world.The density of population is 48 persons per square kilometer. Rapid  increase in live stock population and increased cultivation  resulting in ploughing more  and more increased vulnerability of fertile soil if any  left to soil erosion

The deserts of the world show signs of expansion with time . Sahara desert is spreading southward as much as 50 km per year in some places . It has engulfed about 6500,000 square kilometers  of arable land during the last century.The situation is not different in South America ,West Asia,China and other places where desert occur.Many of the regions now occupied by deserts were once fertile.For about six centuries ,North Africa was one of the principal granaries of the ancient Roman empire.The sand dunes of Sahara covers the ruins of great cities once flourished there.

No comments:

Post a Comment