Drought-water stress and adaptations, Biology

Drought

Drought refers to a condition of water shortage and it can result from many reasons. Frequently less than the normal rainfall is a common cause of drought. Less than 75% of normal rainfall may be defined as drought. We may, however, bear in mind that not only the total rainfall but its distribution in time is vitally important for crops. Small deficit (or surplus) in rain is not necessarily directly related to agricultural productivity. A severe drought reduces stream flow and recharging of aquifer. This results in lowering of water. table, loss of agricultural crops, wild life and aquatic life. Water level in lakes, streams and reservoirs drops due to failure of rains. As a result crop yield and fodder production suffer adversely resulting in food scarcity and human discomfort, and stress to livestock. The incidence of forest fue increases and overall conditions become difficult.

Due to the pressure of growing population over-exploitation of water resources has become a universal feature. Consumption of bsh water is due to rapidly growing urbanisation, industrialisation and mechanised agriculture which leads to over-exploitation of water resources. over-expioitation of fresh water resources can create severe limitation to growth and development. Excessive withdrawal of ground water in coastal areas  has resulted in salt water intrusion into the aquifers . Consequently, the ground water has become unfit for human consumption and agriculture on account of high salinity. Ponds, bogs and streams are sites where ground water appears at the land surface. Excessive withdrawal of ground water and overdrawing of ground water lower the water-table as well as the level of water in lakes and streams and may completely dry them up.

Posted Date: 12/11/2012 12:32:46 AM | Location : United States







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