Droughts

A drought is a period of below-average precipitation in a given region; resulting in prolonged shortages in the water supply, whether atmospheric, surface water or ground water. A drought can last for months or years, or may be declared after as few as 15 days. It can have a substantial impact on the ecosystem and agriculture of the affected region and harm to the local economy. Annual dry seasons in the tropics significantly increase the chances of a drought developing and subsequent bush fires. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.

Put simply, droughts are caused by a prolonged depletion of precipitation in a certain ecosystem or climate over a long period of time. Unlike normal dry spells, droughts are so severe that they can thoroughly dry out vast expanses of land, like deserts. Droughts can be extraordinarily damaging and expensive to the people who live in the environments where they occur, especially in terms of the agricultural industry.

While weather tends to follow patterns and cycles, the causes of these patterns can become disrupted over time. The Gulf Stream, for example, carries warm water near the equator north, where it warms up the western portion of the European continent. If the Gulf Stream stopped flowing, parts of England and other areas might receive less rain, which could cause droughts.

Droughts are more common than many people imagine, and there are always droughts occurring in the United States. Over the years, experts have learned which areas are most vulnerable to drought, and they have prepared infrastructure to help drought-stricken areas get the water they need until local conditions return to normal.

Parts of the developing world, however, might not have this infrastructure, and even relatively minor droughts can cause widespread crop failures and other potentially devastating problems. Experts concerned about global warming point to the possibility of more droughts in particularly vulnerable areas and the cascade effect they would have on civilization around the planet.

Droughts are characterized into four different types.

 

Hydrological droughts: impact the river systems and water reservoirs needed to produce hydroelectric power.   It refers to shortages of water resources, when for example; groundwater, reservoir, or stream levels are significantly reduced.  This is considered the drinking water type of drought. Conditions for hydrologic drought are built over extended periods of time.  It takes a longer time for reservoirs or streams to become depleted, which corresponds to longer replenishing periods.

Meteorological droughts: Meteorological drought is defined usually on the basis of the degree of dryness (in comparison to some “normal” or average amount) and the duration of the dry period. Definitions of meteorological drought must be considered as region specific since the atmospheric conditions that result in deficiencies of precipitation are highly variable from region to region.

Agricultural drought: this is a situation when rainfall and soil moisture are inadequate during the crop growing season to support healthy crop growth to maturity, causing crop stress and wilting.  Monitoring and assessment of drought condition at different scale, and timely dissemination of information constitutes the most vital part of drought management system.  Therefore, a sound, operationally feasible, objective and economically viable system of drought monitoring and decision support would enable efficient management of this hydro-meteorological disaster.  Along with robust monitoring system, a mechanism for rainfall prediction and drought brings total solution for drought management.

Socioeconomic droughts:  definitions of drought associate the supply and demand of some economic good with elements of meteorological, hydrological, and agricultural drought. It differs from the aforementioned types of drought because its occurrence depends on the time and space processes of supply and demand to identify or classify droughts. The supply of many economic goods, such as water, forage, food grains, fish, and hydroelectric power, depends on weather. Because of the natural variability of climate, water supply is ample in some years but unable to meet human and environmental needs in other years. Socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply. For example, in Uruguay in 1988–89, drought resulted in significantly reduced hydroelectric power production because power plants were dependent on streamflow rather than storage for power generation. Reducing hydroelectric power production required the government to convert to more expensive (imported) petroleum and implement stringent energy conservation measures to meet the nation’s power needs.

Drought is hard to detect and cannot be prevented. It is different from other natural hazards, such as typhoons, hurricanes and tornadoes. The impacts of drought can be mitigated through careful planning and management.  Water conservation is one of the easiest ways to mitigate the impacts of drought. Simple everyday tasks, such as turning off the water while brushing teeth or using a glass to rinse afterwards, can help save gallons of water in a month.

On a larger scale, many businesses and cities use grey water to water larger land areas, such as parks and golf courses. Grey water is used water that is treated and cleaned.

MONTHS	Long-term Average	30-Year Average	2017
January	62.1	61.7	52.3
February	34.6	36.3	28.2
March	26.8	27	22.4
April	32.2	33.9	1.2
May	50.5	48.4	58.5
June	130.1	127.5	256.4 (Wettest June since 1985_at Point Salines)
July	139.2	139	110.3
August	145.9	147.8	172.1
September	131.4	134	143.3
October	142.6	142.7	204.5
November	165.5	163.2	147.1
December	104.3	103.8	89.5

• A one month analysis, reflects short term trends and indication of soil moisture and crop stress.
• A three month analysis, reflects short to medium term moisture and conditions at the beginning of the growing
season
• A six month analysis, reflects medium term trends in rainfall showing rainfall distribution over seasons and stream flows and reservoir levels
• A twelve month analysis, reflects long term trends and indications of ground water levels