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Welcome to CoreFacts, where we're always short on time, but big on science. I'm Steve Sobieszczyk. Let's get right to it, today's question is:
What causes drought?
A drought is a period of drier-than-normal conditions that results in water-related problems. Precipitation (either rain or snow) falls in uneven patterns across the country. The amount of precipitation at a particular location varies from year to year, but over a period of years, the average amount is fairly constant. In the deserts of the Southwest, the average precipitation is less than 3 inches per year. In contrast, the average yearly precipitation in the Northwest is more than 150 inches.
When no rain or only a very small amount of rain falls, soils can dry out and plants can die. When rainfall is less than normal for several weeks, months, or years, the flow of streams and rivers declines, water levels in lakes and reservoirs fall; also, the depth to water in wells increases. If dry weather persists and water-supply problems develop, the dry period can become a drought.
And now you know. Join us every weekday for a new CoreFact. If you're looking for more in-depth science coverage, please check out the USGS CoreCast at usgs.gov/corecast. If you think you have a question that's worth answering on the air, send it to us either via email at email@example.com [that's C-O-R-E-F-A-C-T-S at USGS dot GOV] or give us a call and leave a voicemail at 703-648-5600; and that is a long distance number, unless you're in the 703 area code, so long distance fees do apply.
The USGS CoreFacts is a product of the U.S. Geological Survey, Department of the Interior.
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Title: What causes drought?
Description: Listen to hear the answer.
Date Recorded: 2/5/2008
Usage: This audio file is public domain/of free use unless otherwise stated. Please refer to the USGS Copyright section for how to credit this audio.
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