Drought is a natural phenomenon that occurs when an area of the Earth experiences abnormally low rainfall for a sustained period. Droughts can have many impacts including crop loss, water shortages and wildfires. The Intergovernmental Panel on Climate Change (IPCC) warns that droughts are increasing in frequency and intensity due to climate change.
The most significant impact of a drought is the decrease in food production and supply. This can lead to food insecurity, hunger and death. This is especially true for the developing world where droughts can cause local economic collapse and social unrest.
When a region is experiencing a drought, soil moisture is depleted, surface water supplies are diminished and deep groundwater levels drop. This is because all precipitation that falls is used up by plants and groundwater storage, evapotranspiration, runoff, and streamflows. During a drought, only a small percentage of whatever precipitation does occur can replenish this soil moisture. Consequently, most of the precipitation ends up as runoff and streams flow, which can result in water shortages in cities.
The onset and severity of a drought depends on the location, timing and duration of the dry weather. Different crops respond differently to drought conditions. Field crops like corn, soybeans and wheat are most affected. However, specialty crops like fruits, vegetables and tree nuts also suffer as farmers are forced to fallow land or destroy orchards, which reduces their revenue and the variety of foods available in stores.
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