Drought: Its Causes, Stages, and Problems

An Overview of Drought

Drought. cuellar 155113496 Getty Images

Every year as summer approaches, areas around the world grow concerned about seasonal drought. Throughout the winter, many places monitor precipitation and the snow pack to prepare for what the warmer, drier months may bring. In addition, there are areas where drought is a regular year to year occurrence that lasts longer than just the summer. From hot deserts to the freezing poles, drought is something that affects plants, animals, and people worldwide.

Definition of Drought

Drought is defined as a period in which a region has a deficit in its water supply. Drought is a normal feature of climate which happens in all climate zones from time to time.

Usually, drought is talked about in one of two perspectives- meteorological and hydrological. A drought in terms of meteorology takes into account deficiencies in measured precipitation. Each year's measurements are then compared to what is determined as a "normal" amount of precipitation and drought is determined from there. For hydrologists, droughts are monitored by checking stream flow and lake, reservoir, and aquifer water levels. Precipitation is also considered here as it contributes to the water levels.

In addition, there are agricultural droughts that can impact crop production and cause changes to the natural distribution of various species. The farms themselves can also cause droughts to happen as soil is depleted and therefore cannot absorb as much water, but they can be impacted by natural droughts as well.

Causes of Drought

Because drought is defined as a deficit in water supply, it can be caused by a number of factors. The most important one though relates to the amount of water vapor in the atmosphere as this is what creates precipitation. More rain, sleet, hail, and snow can occur where there are moist, low pressure air systems.

If there is an above average presence of dry, high pressure air systems instead, less moisture is available to produce precipitation (because these systems cannot hold as much water vapor). This results in a deficit of water for the areas over which they move.

The same can also happen when winds shift air masses and warm, dry, continental air moves over an area as opposed to cooler, moist, oceanic air masses. El Nino, which affects the ocean's water temperature, also has an impact on precipitation levels because in years when the temperature cycle is present, it can shift the air masses above the ocean, often making wet places dry (drought prone) and dry places wet.

Finally, deforestation for agriculture and/or building combined with the resultant erosion can also cause drought to begin because as soil is moved away from an area it is less able to absorb moisture when it falls.

Stages of Drought

Since many areas, regardless of their climatic region, are prone to drought, different definitions of the stages of drought have developed. They are all somewhat similar however, usually ranging from a drought warning or watch, which is the least severe. This stage is declared when a drought could be approaching.

The next stages are mostly called drought emergency, disaster, or critical drought stage. This final stage begins after a drought has occurred for a long period and water sources begin to be depleted. During this stage, public water use is limited and oftentimes drought disaster plans are put into place.

Consequences of Drought: Short and Long Term

Regardless of a drought's stage, there are short and long term consequences with any drought because of nature and society's dependence on water. Problems associated with drought can have economic, environmental, and social impacts on both the areas where they occur and areas that have relations with those where the drought happens.

Most of the economic impacts of drought are associated with agriculture and the income generated from crops.

In times of drought, the lack of water can often cause a decline in crop yields, and thus a reduction in income for farmers and an increase in the market price of products since there is less to go around. In a prolonged drought, unemployment of farmers and even retailers can occur, having a significant impact on the economy of the area and those with economic ties to it.

In terms of environmental problems, drought can result in insect infestations and plant diseases, increased erosion, habitat and landscape degradation, a decrease in air quality and that of what water is present, as well as an increased risk of fire because of drier vegetation. In short-term droughts, natural environments can often rebound, but when there are long term droughts, plant and animal species can suffer tremendously, and over time desertification can happen with an extreme lack of moisture.

Finally, droughts have social impacts that can cause disputes between users of available water, inequalities in water distribution between wealthy and poor, disparities in areas in need of disaster relief, and a decline in health.

In addition, in rural developing countries population migration can begin when one area experiences drought because often people will go to areas where water and its benefits are more prevalent. This then depletes the natural resources of the new area, can create conflicts among neighboring populations, and takes workers away from the original area.

Over time, increased poverty and social unrest is likely to develop.

Drought Mitigation Measures

Because severe drought is often slow in its development, it is relatively easy to tell when one is coming and in areas that are capable, there are several mitigation measures that can be used to reduce the impacts felt by drought.

The most important steps in lessening the effects of drought though are soil and water conservation. By protecting soil, it is better able to absorb precipitation, but it can also help farmers to use less water because it is absorbed and not as much runs off. It also creates less water pollution by the pesticides and fertilizers present in most farm runoff.

In water conservation, public use is often regulated. This mostly includes watering yards, washing cars and outdoor fixtures such as patio tables, and swimming pools. Cities such as Phoenix, Arizona and Las Vegas, Nevada have also implemented the use of xeriscape landscaping to reduce the need to water outdoor plants in dry environments. In addition, Water conservation devices like low-flow toilets, shower heads, and washing machines can be required for use inside the home.

Finally, desalination of seawater, water recycling, and rainwater harvesting are all things that are currently under development to build on existing water supplies and further reduce the impacts of drought in dry climates.

Whatever method is used however, extensive monitoring of precipitation and water usage are the best way to prepare for a drought, inform the public on the problem, and implement conservation strategies.