Drought

We explain what drought is, the types that exist and what its causes are. Also, its characteristics and the consequences it presents.

What is drought?

Drought is understood as a temporary and prolonged meteorological anomaly, in which the levels of circulating water in a region fall below the minimum limits to sustain the life of plants, animals and humans.

Water is not only essential to nourish life in all its facets (plant, animal), but it is also necessary for the enrichment of soils, the flow of organic matter (for example, that which occurs in the cycle of carbon) and the thermal regulation of our planet.

The causes and consequences of droughts are very complex. They are related to both natural factors and human action. The decrease in precipitation over time significantly alters natural dynamics and affects economic activities and the population's water supply.

To take into account: Droughts do not always occur in summer. A drought happens when there is a lack of rain, a phenomenon that can occur in any season.

For example, the Mediterranean region experiences droughts in winter and spring, and not in summer. In Mediterranean climates, summer is the dry season and, therefore, no rain is expected in this season. Drought occurs when the season begins when it is supposed to start raining and that does not happen, or it happens with values ​​well below the averages.

Types of drought

Depending on its causes, there are three types of drought:

• meteorological drought. It occurs when the level of rainfall over a prolonged period of time is much lower than the expected average. During a meteorological drought the water available in the soil, in lakes and in streams decreases, which contributes to producing the other forms of drought.
• Agricultural drought. It is associated with agroindustrial activities, since it is usually the product of the combination of a meteorological drought with the overexploitation of soils and water, which can lead to the loss of fertility and productivity of the fields.
• Hydrological drought. It occurs when water levels in a region's natural reservoirs, such as lakes, rivers, aquifers and dams, fall below the expected average, causing stored water to be used faster than it can be replenished. This can occur when meteorological drought phenomena extend for prolonged periods of time.

According to the environmental impacts they cause, droughts can be classified as:

• dry. Causes minor impacts.
• Drought regular. It causes some damage to crops and generates a certain risk of fires. Rivers, lakes and lagoons lower their water level.
• Severe drought. It causes losses in crops and pastures, and generates a high risk of fires. It usually generates water shortages.
• extreme drought. It causes serious crop losses and increases the risk of fires. It usually causes widespread restrictions on access to water.
• Exceptional drought. It causes extensive losses of crops and pastures, and an extreme risk of large-scale fires. The scarcity of water in rivers, lakes, lagoons and reservoirs is absolute.

Causes of drought

The main cause of all forms of drought is the decrease in precipitation in a region, which can be due to various and complex climatic factors, such as global warming or the La Niña or El Niño phenomena.

However, the increasing consumption of water by humanity is also a possible cause of the decrease in available water in regions, especially when humans intervene in river basins, alter soil properties or intensively use their resources. water resources.

Currently, 70% of water is used by agricultural activities, 20% by the industrial sector, and only 10% corresponds to domestic use. For this reason, and beyond the natural reasons that may explain droughts, it is important that the sectors that most intensively use this resource do so in a responsible and rational manner.

Consequences of drought

Depending on their location, duration and degree of intensity, droughts can be mild or catastrophic for life. This can have consequences for human needs and for the entire affected environment.

Among the main consequences of droughts, the following stand out:

• The quality of the soil decreases, becoming arid and infertile.
• The abundance of plant and animal life is affected, because many species do not survive.
• The living conditions of human beings deteriorate, so people suffer from diseases related to dehydration, the consumption of unsafe water and poor nutrition, and respiratory diseases as a result of the increase in dust in the air.
• There are migrations of people who decide to go live in other places.
• The price of food increases due to lower production and crop failure, which contributes to increased poverty and famine.
• Forest fires abound, which aggravates the consequences of the drought itself since the loss of vegetation cover (such as deforestation) produces an increase in soil temperature, reduces its absorption capacity and exposes it to a greater extent to erosion. .

Drought in the world

There are regions of the world in which drought has had a great impact on a social level. For example, the northwestern region of the so-called Horn of Africa and the Darfur regions of Sudan and Chad have been affected by decades of drought, which has put very strong pressures on the inhabitants of the region, leading to diplomatic clashes. between countries and, on some occasions, wars.

In Asia, the melting of the perpetual glaciers of the Himalayas, as a consequence of climate change, faces this region with increasing difficulties in obtaining water. This is because there is less ice on the summits, so the meltwater rivers that originate in the Himalayas have increasingly less water flow.

Several countries in the Himalayan region depend heavily on water from these rivers to supply drinking water to their populations and for agricultural, industrial and energy purposes. The main ones are India, Bangladesh, Nepal, Bhutan and Pakistan, and it is estimated that the drought in this region could affect more than 1.5 billion people.

Drought protection

The management of water resources consists of the implementation of public policies that seek to prevent drought and mitigate its effects. This includes:

• Planning and evaluation. Hydrological studies are carried out to evaluate the availability and demands of the population's water, and to develop short, medium and long-term management plans.
• Water conservation. States can promote water conservation practices such as promoting the use of low-water consumption devices in homes, or controlling and monitoring water use in industry and agricultural activities.
• Diversification of water sources. States often invest in the construction of plants for obtaining, purifying, storing and distributing water from different sources to diversify their supply. They can also promote the treatment and reuse of wastewater.
• Water demand management. States can implement restrictions on use when water is scarce, especially in those sectors that use the greatest amounts.
• Monitoring and alert. The behavior of the water system can be monitored to predict medium and long-term periods of drought. This allows States to implement preventive measures to mitigate its effects.

Differences between drought and aridity

The difference between drought and aridity is that drought is transitory, a consequence of the lack of rain over a period of time, while aridity is a climatic characteristic in which there is very little precipitation (up to 250 millimeters of annual precipitation).

Deserts are ecosystems found in regions with arid climates.. They are characterized by a large daily thermal amplitude, which implies very high temperatures during the day and very cold temperatures at night. In them, both Plants and animals develop adaptations to survive these conditions.which is reflected in the presence of plants with very deep roots and scaly leaves, as well as animals that can reduce their need for water and store it in their body.

Climate change

Climate change is one of the biggest challenges facing humanity today. This is a series of significant changes in the global climate, which occurs as a consequence of the accumulation of greenhouse gases in the atmosphere.

One of the main effects of climate change is the increase in global temperature. This has a direct impact on the distribution of rainfall: increased evaporation, as a consequence of rising global temperatures, evaporates soil moisture and causes drought in some regions, while causing flooding in others.

For this reason, more extreme and long-lasting droughts are being recorded at the same time as more frequent and intense storms. Additionally, climate change may increase the frequency and intensity of extreme weather events such as tropical cyclones or hurricanes.

Future water scarcity

Numerous institutions have warned about the need to foresee a future in which water will be much scarcer than at present and, therefore, living conditions will be much more difficult for human beings and other forms of life in the world. planet.

The implementation of public water management policies is imposed as a necessity, as well as the regulation, monitoring and sanitation of contaminated waters from lakes, rivers and streams.. In this sense, in 1994 the United Nations Organization declared the date of June 17 as the World Day to Combat Desertification and Drought.

This day aims to raise awareness about the importance of caring for natural resources, especially water and soil, to promote the adoption of sustainable practices for the management of these resources.

References

• ECLAC. (2019). Water and climate change in Latin America and the Caribbean: Scenarios and challenges for the integrated management of water resources. Economic Commission for Latin America and the Caribbean
• Valiente, O. (2001) Drought: definitions, typologies and quantification methods. Geographic Research Magazine26. https://www.investigacionesgegraficas.com/