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Drought is a deficiency in precipitation over a long period of time (months or even years) that results in severe water shortage. It causes adverse impacts on animals, vegetation, and people. Draught is a periodical feature of climate that happens in almost all climate zones. This article presents an overview of the causes and consequences of draught, types of draught, and drought mitigating strategies.

Causes

What causes drought? The major cause of draught is the lack of rainfall over an extended period of months or even years. In general, precipitation relates to the amount of atmospheric water vapor combined with the air mass released on the surface of the earth. Drought results if either the amount of water vapor or air mass is reduced. The following are the factors that cause drought: above average normalcy of high pressure systems; winds that carry continental air masses instead of oceanic air masses; high pressure areas that prevent rainfall or thunderstorm activity over a certain region; global warming and other atmospheric and oceanic temperature cycles; deforestation and erosion; and climate change. Human factors (poor water management and excessively high water demand) can worsen the effects of drought.

Cost

Drought can have significant impacts on the environment, agriculture, health, and economy. It can also potentially cause social strife. Examples of the consequences of drought: death of livestock, wildfire and dust storms, reduction in crop yields, famine, malnutrition and dehydration, reduced electricity production, substandard crop and limited yield productions, social unrest, and mass migration.

Drought is one of the most costly climate-related events when it comes to economy. The 1988-1989 drought that hit the eastern and central United States resulted in a loss of about $15 billion in agricultural output alone. The National Climatic Data Center reported that the drought cost the country around $39-$40 billion.

Types of drought

There are three types of drought: meteorological, agricultural, and hydrological. Meteorological drought is defined based on the length of the dry period and the degree of dryness. The onset of the event usually happens with a meteorological drought.

Hydrological drought occurs after periods of extended absence of rainfall that affect water supply (for example, ground water, lake and reservoir levels, streamflow), possibly causing major societal impacts. Because hydrologic systems interconnect regions, the impact may reach regions beyond the boundaries of the rainfall-deficient area.

Lastly, agricultural drought connects various features of hydrological drought or meteorological drought to agricultural effects, focusing on rainfall deficiency, reduced reservoir or ground water that are crucial for irrigation, soil water deficits, and so forth.

Mitigating strategies

There are many ways to mitigate the impacts of draught. One strategy is to desalinate sea water for consumption or irrigation. Accurately planned crop rotation can also help reduce erosion and enable farmers to plant crops that are less dependent on water in drier years. Another strategy in drought mitigation is transvasement. Here, redirecting rivers and building canals are gigantic efforts at irrigation in many drought-prone areas. Moreover, cloud seeding has been widely used in many countries as an artificial method in inducing precipitation.

In addition, drought can be mitigated if people make it a daily habit to regulate water use. This may involve the regulation of the use of hoses, buckets, or sprinklers on outdoor plants, topping up of pools, the washing of vehicles, and washing of outdoor hard surfaces that include paths and roofs. People can also use devices that help conserve water inside the home such as dual flush toilets, shower heads and taps).

 

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