Living In The Flood Zone

In early February 2008, heavy rains swelled over riverbanks in Bolivia's eastern lowlands. President Evo Morales declared the area a national disaster and toured parts of the area on Monday, February, 11. At least 60 people have been killed because of the widespread flooding, and over 40,000 people have had to flee their homes for higher ground. Emergency workers have been busy rescuing stranded residents and distributing food and tents.

This is the second year in a row such severe flooding has overtaken this region. Some officials point to climate change as the culprit.

In the United States in 2005, Hurricane Katrina's forceful winds and rain caused waters to rise and breach the levees of New Orleans and other parts of the Gulf States. Today, thousands of people remain homeless as the city continues to figure out how best to rebuild.

Climate change may be one factor contributing to worse and more frequent flooding. However, human activities have add to flood risk by interferring nature's built-in safeguards. For example, home and commercial construction replaces an area's natural landscape with asphalt and cement. Rain quickly runs off these surfaces rather than getting absorbed and transported through slow-moving aquifers. Mountaintop coal mining removes the mixed, mature forests in coal-laden regions, reducing the area's resistance to heavy rainfall. Intensive crop irrigation and new housing developments can drain flood-protecting wetlands.

Experts disagree on whether flooding is worsening due to climate change and human activities. Some believe that recent events are more likely part of natural long-term cycles, including El Niño. Many areas are known to experience 100-year and 500-year flood cycles.

During this week's lesson, you will learn about the nature of floods and discover how a few major floods affected regions of the United States.

Flood Science and Forecasting

Begin your journey at PBS with their special series InFocus: Floods, produced right after the big flood event in Grand Forks, North Dakota, in mid-April of 1997. Start with exploring The Hows and Whys of Floods. What are the two main types of floods? What factors drive each type? How can meteorologists help predict flooding?

Before continuing through the rest of the pages at InFocus, jump over to the National Ocean and Atmospheric Administration (NOAA) site, Floods Monitor, to see how scientists are using the most current technologies to help forecast floods and warn citizens of potential flood danger. Click around to different parts of the site to check out the recent flood and flash flood warnings and watches. When you click to see the Daily Rainfall Accumulation, you will go to the Advanced Hydrologic Prediction Service (AHPS) site.

Locate the cities where the government has issued a flood warning or watch. Near what rivers do these cities lie? Cross-reference these forecasts with the AHPS data and maps. With some additional research, find out how many people live in and near each city. Think about how many roads, parking lots, homes, and commercial buildings exist there. Talk with classmates and come up with a guess about what percentage of land has been urbanized (that is, is no longer in its natural state). Discuss what factors are influencing the flood prediction in each of these cities.

If you have time, browse through the Flood Summary Archive, which includes flood data as far back as 1997.

Flood Stories

Back at the InFocus: Floods site, read about the Real Life Accounts, Pet Rescues, and Flood Fighters. What were people's reactions to flooding? What were the consequences?

Now, travel down the Mississippi and through time to learn about the flood history along this might river. At the PBS site, Fatal Flood, start with the Timeline to see how people settling in the New Orleans area began building protective levees as early as 1726. In 1927, tension builds, fueled by rising flood risk and social disparity. In what ways did these events affect the town of Greenville, Arkansas?

Next, compare and contrast the Maps and statistics of the 1927 and 1993 floods in the Mississippi River Basin. Why do you think so many fewer people were displaced and less damage was done in 1993 compared to 1927?

Travel farther down the Mississippi, and forward in time, to New Orleans of 2005 to learn about the Storm That Drowned a City. Start with the Interactives, examining the Anatomy of Katrina and How New Orleans Flooded, Also, Map the Flood onto your local city area to see what the extent of the flooding would have been there.

Now, learn from The Man Who Knew, and why holding together the city of New Orleans has been a 300-Year Struggle. Why did the "Levees-Only Policy" fail, and what did the government do differently because of the 1927 flooding? Open the Flood-Proofing Cities interactive, to discover what methods New Orleans—and communities throughout the Mississippi River Basin—may consider for improving flood protection.