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How Droughts Form

Houston, TX

As global temperatures rise, droughts are becoming an ever-present sight. Although we often hear about it on the news, what is it? Droughts are characterized as when a region or area experiences a lack of precipitation–including rain, snow, or sleet–for an extended period, which usually results in a water shortage, crop damage, and reduced soil moisture. Most droughts occur naturally, but human activity, such as overactive water use, can worsen dry conditions. The threshold for drought varies from region to region. For instance, rainfall below seven inches in the Libyan desert would be considered drought, but for the tropical island of Bali, six rainless days is already considered a drought. These droughts cannot be overlooked. In fact, due to drought's widespread effects, it is the second-most costly weather event after hurricanes.

There are several natural causes of drought, including fluctuating ocean and land temperatures. According to research, extreme weather patterns on land, such as prolonged droughts in the eastern Mediterranean and North America—the latter of which has been dubbed the region's worst drought in 900 years—correspond directly to dramatic and prolonged temperature changes in the North Pacific and North Atlantic oceans. El Niño and La Niña weather occurrences are likewise caused by variations in ocean temperatures, with La Niña being mainly well known for drying out the southern United States. Conversely, hotter land surface temperatures cause more moisture to evaporate from the soil, exacerbating drought effects.

While droughts have existed throughout human history, their frequency has increased due to unnatural causes. For instance, climate change, which causes increased sea levels and global temperatures, ice mass loss, and extreme weather events, has made dry regions drier due to warmer temperatures evaporating water faster. This phenomenon is why it is predicted that the Southwestern United States and the Mediterranean are predicted to get drier. In addition, due to high population growth, there has been an exceedingly increased demand for water. From 1960 to 2010, human water consumption increased the drought frequency in North America by 25 percent. The formation of irrigation and hydroelectric dams has also dried out downstream water sources, which may contribute to drought in other regions.

With this knowledge in mind, how can citizens prevent and prepare for droughts? One is to conserve water in agriculture. With 70% of all withdrawals worldwide going to agriculture, it is the biggest consumer of fresh water on the planet. Increasing water efficiency and reducing consumption are the main strategies for better water management in agriculture. Improvements in irrigation methods, such as converting from flood to drip irrigation, which alone can reduce water use by around 20%, as well as more exact irrigation scheduling to control the quantity of water used at various stages of crop growth, are some examples of these. Another way is to use recycled water, highly treated wastewater that can be used for landscape irrigation, industrial processes, and replenishing groundwater supplies. Lastly, there are two ways to conserve urban water. It is estimated that leaky faucets and house supplies have contributed to wasting more than 100 gallons of water per year. Thus, it is crucial to check and repair all leaky infrastructure and utilize energy-efficient technologies and appliances. And, of course, make sure you turn off your sink when you are not using it! Whether brushing your teeth or washing the dishes, do not use more water than you need.


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