Drought occurs when areas experience abnormally low precipitation for a long time, and this deprives water sources on the surface (such as rivers) and underground (like aquifers). Periods of drought are natural, but when human activities cause them to occur in combination with high temperatures, they can become catastrophic.
Every drought is different, and its effects on the environment, agriculture, businesses, public water supply and people will vary depending on its duration, intensity, causes and locations. But, there are some basic principles that can help us understand the nature of a drought and improve preparedness for it.
Most people are familiar with the concept of drought from a meteorological, or weather, perspective. When an area doesn’t receive its normal amount of rain or snow for a long period, people start to talk about it as being in a state of drought. This kind of drought can be caused by changes in the way wind patterns move clouds and moisture, or by astronomical events that cause extremes in temperature and precipitation.
Environmental droughts occur when natural ecosystems are pushed beyond their capacity to adapt, leading to reduced plant growth, decreased or even disappearing wildlife populations and landscape-level changes (e.g., forests being replaced by grasslands). These types of droughts can be caused by changes in the water cycle due to climate change or by the impact of human activities on a region’s ability to respond to changing conditions.
Social impacts of drought include famine, migration away from drought-stricken areas, and conflicts over scarce resources. Economic losses associated with droughts result from damage to crops and loss of drinking water supplies. They can also affect hydroelectric power production, and disrupt the natural cycles of carbon, nutrients, and water in ecological systems.