Droughts in North West India Essay

1827 WordsNov 24, 20148 Pages
DROUGHTS:- A STUDY ABSTRACT: Drought is one of the major natural calamities that effect more than Drought in the most general sense is a deficiency of precipitation over an extended period of time resulting in a shortage of water for some activity, group, or environmental sector. Its impacts result from the interplay between the natural event (less precipitation than expected) and the demand people place on water supply, and human activities can exacerbate the impacts of drought. In general terms a region is said to be drought prone if it receives a rainfall lesser than the average rainfall of the region over a season. Droughts can be classified as follows:- 1. Meteorological Drought: It is a situation in which there is more than 25% decrease in the precipitation from the normal precipitation over an area. A year is called as a drought year if more than 20% area of the country is affected by drought. 2. Hydrological Drought: Hydrological drought means a below average value of stream flow in lakes, ground water etc. It has four components: i. Magnitude or amount of deficiency ii. Duration iii. Severity iv. Frequency of occurrence 3. Agricultural Drought: It is defined using aridity index. AI=(PET-AET)*100/PET Where, PET=Potential Evapotranspiration AET=Actual Transpiration Based on AI anomalies a region may be classified as AI ANOMAL | SEVERITY CLASS | ZERO OR NEGATIVE | Non-Arid | 1-25 | Mild Arid | 26-50 | Moderate Arid | >50 | Severe Arid | Causes Of Droughts: The causes of droughts may be as varied as its types. Even though the most general and prominent cause of droughts is a low rainfall, a hydrological drought may occur as an after effect of floods where in the storm water may fail to percolate into the ground water table due to

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