A drought is
an extended period of months or years when a region notes a deficiency in its
water supply. Generally, this occurs when a region receives consistently below
average precipitation. It can have a substantial impact on the ecosystem and
agriculture of the affected region. Although droughts can persist for several
years, even a short, intense drought can cause significant damage and harm the
Types of Drought
Meteorological drought is the amount of dryness and the duration of the dry
period. Atmospheric conditions that result in deficiencies of precipitation
change from area to area.
2. Agricultural Drought
Agricultural drought mainly effects food production and farming. Agricultural
drought and precipitation shortages bring soil water deficits, reduced ground
water or reservoir levels, and so on. Deficient topsoil moisture at planting may
stop germination, leading to low plant populations.
3. Hydrological Drought
Hydrological drought is associated with the effects of periods of precipitation
shortages on water supply. Water in hydrologic storage systems such as
reservoirs and rivers are often used for multiple purposes such as flood
control, irrigation, recreation, navigation, hydropower, and wildlife habitat.
Competition for water in these storage systems escalates during drought and
conflicts between water users increase significantly.
4. Socioeconomic Drought
Socioeconomic drought occurs when the demand for an economic good exceeds supply
as a result of a weather-related shortfall in water supply.
Causes of Drought
rainfall is related to the amount of water vapour in the atmosphere, combined
with the upward forcing of the air mass containing that water vapour. If either
of these are reduced, the result is drought.
· Above average prevalence of
high pressure systems
· Winds carrying continental,
rather than oceanic air masses (ie. reduced water content)
· El Nino (and other oceanic
· Some speculate that global
warming will have a substantial impact on agriculture throughout the world, and
especially in developing nations.
Drought Mitigation Strategies
1. Desalination of
sea water for irrigation or consumption.
monitoring - Continuous observation of
rainfall levels and comparisons with current usage levels can help prevent
man-made drought. For instance, analysis of water usage in Yemen has revealed
that their water table (underground water level) is put at grave risk by
over-use to fertilize their Khat crop. Careful monitoring of moisture levels can
also help predict increased risk for wildfires, using such metrics as the
Keetch-Byram Drought Index or Palmer Drought Index.
use - Carefully planned crop
rotation can help to minimize erosion and allow farmers to plant less
water-dependant crops in drier years.
harvesting - Collection and storage of
rainwater from roofs or other suitable catchments.
water - Former wastewater (sewage)
that has been treated and purified for reuse.
6. Transvasement - Building
canals or redirecting rivers as massive attempts at irrigation in drought-prone
restrictions - Water use may be regulated
(particularly outdoors). This may involve regulating the use of sprinklers,
hoses or buckets on outdoor plants, the washing of motor vehicles or other
outdoor hard surfaces (including roofs and paths), topping up of swimming pools,
and also the fitting of water conservation devices inside the home (including
shower heads, taps and dual flush toilets).
8. Reduction of
Human population and animal pressure.
seeding - an artificial technique to