Droughts are a type of natural disaster that involves below-average precipitation or a severe water supply shortage over a sustained period of time. Droughts often give rise to famines that can lead to the loss of millions of lives. Here is a list of the factors that trigger a drought:
Low Levels of Precipitation
Little or no precipitation is one of the major causes of a drought. Lower than average levels of rainfall over a sustained period of time can dry the soil and and lead to crop failures. Meteorological disturbances like extremely high temperatures and changes in wind patterns can lead to lower than normal rainfall in an area. Droughts are usually common in places where normal levels of rainfall are generally low, making them more susceptible to changes in precipitation patterns.
El Niño events affecting several parts of the world are often associated with hotter and drier weather conditions. These events are thus linked to droughts in different parts of the world at different times depending on the strength of the events. El Niño events influence weather patterns in the Amazon basin, parts of the U.S. and Central America, and even parts of Africa and Southeast Asia.
Droughts are common in areas experiencing long, dry seasons. Since humidity levels are low during these seasons, water evaporation rates are high. As a result, water bodies like lakes and rivers dry up nearly completely. Vegetation cover and agricultural crops dependent on these water bodies also die due to the absence of water. Higher temperatures during the dry season further promote the evaporation of water and thus worsen the drought.
Global warming induced climate change is believed to be one of the more recent causes of drought. While climate change can bring more precipitation to some areas due to the melting of glaciers and higher rates of evaporation from water bodies, it will lead to droughts in other areas where higher temperatures will dry up the remaining water bodies.
Irresponsible agricultural practices like the over-irrigation (depleting water resources) and over-farming (adversely impacting the soil quality) of land can often lead to droughts. Deforestation can also cause a drought since the absence of tree cover makes soil more susceptible to the erosional forces of wind and water. Thus, human activities can also trigger drought or worsen the impact of a drought caused by meteorological alterations.