U.S. Drought Continues

Drat the Drought
droughtFarmers in the nation's Midwest were nervous as they started this year's spring planting. Rainfall last year was well below normal, and this year seemed drier than last. The word drought was spoken in hushed tones by those who remembered the last disastrous drought in 1988—a drought so severe that farmers took years to recover financially. Is last year's drought over, or is it continuing?

On Tuesday, the National Oceanic and Atmospheric Administration (NOAA) released its summer drought outlook. To no one's surprise, NOAA scientists announced that many parts of the United States are still experiencing the drought that started two years ago. They said that the drought is not ending soon.

Abnormally dry conditions already exist in the Midwest, the Southwest, and the Southeast. Extreme drought conditions exist in Louisiana and Texas. Severe droughts exist all along the southern tier of states from New Mexico to Florida, and in the nation's heartland from Missouri north into Iowa, Nebraska, Illinois, and Indiana. NOAA's summer forecast for below normal precipitation and above normal temperatures will only make the drought worse.

Depending on your community's source of water, it sometimes doesn't take more than a few weeks without significant rainfall for local government officials to start talking about droughts and taking strong measures to conserve water. Car washing may be banned. Homeowners may be told to water their lawns every other day or perhaps not at all. Town officials may even go door-to-door, promoting the use of low-flow showerheads—all to conserve water.

Tapped Out

The fresh water we use every day—for drinking, watering lawns, and washing dishes—can be traced back to rainfall. But unlike a prairie settler who may have caught rain in barrels as it fell off his cabin roof, we don't use rain directly. We use rain that has run off into rivers or that has filtered into the ground. We use water that is stored in artificial lakes called reservoirs and then treated and piped to our homes.

Think about where your community gets its water. Water shortages are caused by a temporary or permanently uneven demand for water. Is your community vulnerable to a water shortage? Does your water come from groundwater or from surface water such as a reservoir or river?

  • If you don't know the answer, visit Surf Your Watershed, where you can find out about the source of your water.

When Will It End?
Much of our weather in North America is linked to the cyclical warming and cooling of water in the Pacific Ocean. The warming events are known as El Niño. The cooling events are known as La Niña. And, for much of the United States, a La Niña event, such as the one we are experiencing now, means drought.

The worst drought in the United States in 50 years occurred during the last major La Niña from 1988 to 1989. For many farmers in the Corn Belt, what they are seeing this spring seems too similar to what they experienced in 1988, when crops planted in the spring never got the rain they needed to grow. Rainfall in the Midwest was as much as 85% below normal. Crops and livestock died. Millions of acres of trees were destroyed by forest fires impossible to control.

There is some hope that the present drought will have less severe consequences. Researchers believe that the current La Niña event, which began in May 1998, may have peaked in January 2000. Satellite images show that the large area of cold water in the Pacific Ocean associated with La Niña has started to disappear. Since March, the colder La Niña surface waters off the coast of South America have been replaced by water that is slightly warmer than normal. This warmer water should weaken the local trade winds, which should in turn weaken the La Niña.

Dried Up

Unfortunately, a drought is made worse by unusually warm weather. The warmer and drier the air is, the more moisture evaporates from the soil. Farmers attempt to irrigate to save their crops—except that the water can evaporate too quickly to do the crops much good.

Whether due to global warming, La Niña, or something else, temperatures in the Midwest have been much warmer and drier than usual. April was the driest month in 106 years in Missouri. If these temperature increases are being caused by global warming, then droughts could become more frequent. Even a 1 degree Fahrenheit increase in average global air temperature could cause drastic changes in weather patterns. Conservative estimates by an international group of scientists studying climate change predict an increase of 2 to 6 degrees Fahrenheit over the next 100 years, almost entirely as a result of human activity. By comparison, average air temperatures during the last Ice Age were only 5 to 9 degrees cooler than present.

However, just because La Niña is weakening does not mean that it is over. La Niña events can last up to three years, and this one has just turned two years old. NOAA has predicted La Niña will last until at least August, and that the United States will experience an unusually warm spring and summer.

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Trickle-Down Theory
Even if precipitation and temperatures in drought-stricken areas were to return to normal levels today or tomorrow, the drought might still be with us for some time. Streamflow—a measurement of the amount of water flowing in a river or stream—is at record low levels in many parts of the country. This lack of water in streams isn't only because of low rainfall. There weren't the normal heavy snows during the mild La Niña winter. With less snowpack, there was less meltwater this spring to feed rivers and streams.

groundwater schematic

Look at the illustration above. This is a cutaway view—a cross-section—showing the relationship between surface water and groundwater. The water table is the top of the underground area where water fills the pores and cracks in the soil or rock. The surface of a stream or pond is an extension of that water table. Water is free to flow from the surface underground and vice-versa.

This relationship between surface water and groundwater makes water use during droughts very tricky. If streams are lower than normal, groundwater flows out to temporarily keep the streams flowing. But soon the groundwater becomes depleted to the point where the water table drops and the stream dries up. Over pumping of groundwater from wells can cause water from streams to get sucked into the ground, drying up the streams.

Many towns and farms get their water by pumping groundwater from wells. But groundwater is almost a nonrenewable natural resource. It takes many years to replenish groundwater naturally. In a March news conference, USGS Director Charles Groat said, "Think of it as not having enough money to put into the bank. In some areas of the country, we don't have enough water now to put into our groundwater bank. This is the time of year we are supposed to be recharging our savings—our groundwater and reservoirs. That hasn't happened this winter, and so we don't have the buffer we need when we start making withdrawals in the summer. When our dry summer hits, we may not have enough in savings to get through without problems. We anticipate additional drought problems in the months ahead based on the low volumes of surface and groundwater we're seeing now."

Learn More

More Links

  • The National Drought Mitigation Center is an excellent source of information on droughts, their impact, and on how to best deal with them.

  • How do population growth, the locations we choose for our cities, technology, and the conflicting interests of individuals and countries interact when it comes to water resources and drought? Read this news analysis at CNN.com.

  • Check out these animations of monthly streamflow from the USGS. The data compares current streamflow with a 30-year historical record. What do you notice about the data for the Southeast as compared with New England and the Mid-Atlantic states?

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