Surface Water
Consider all the advantages of living close to a large stream—ample moisture for crops, rich soil, easy transportation, recreation, and, most importantly, water to sustain life. Throughout history,
people have built communities near large streams to enjoy the many benefits rivers offer. There is a downside to this arrangement, however. It can be summed up in one word—floods.
Flood Control
Economically speaking, floods are one of the most devastating natural hazards that can strike a community. In an effort to reduce flood damage, people have, over the years, developed ways of taming
the raging waters of a swollen river. A levee, for example, is an artificial elevated bank that holds water within a stream’s channel. The construction of levees to contain floodwater is an ancient practice—the
Egyptians used them centuries ago along the Nile River. Levees are located along the banks of many flood-prone rivers today, including the Mississippi. Although levees do allow a stream to hold more water,
they are hard to maintain. During the Mississippi River flood of 1993, for example, 80 percent of the privately built levees along the river failed.
Dams
Flood control can also be accomplished by constructing dams along a stream. Dams hold back floodwaters and control the rate at which water travels downstream. In addition, dams provide water for hydroelectric
power, irrigation, and recreational purposes. These advantages must be weighed against the problems dams create. Dams restrict stream navigation and displace people and wildlife. They also change the
base level of tributary streams and result in a build-up of sediment in the reservoir behind the dam. Dredging, a costly procedure, is sometimes necessary to remove the accumulated sediment. In contrast,
the water released from the dam contains little sediment and may cause high rates of erosion downstream.
Redirecting the Water’s Flow
Other methods of flood control involve redirecting the path of the water. Floodways, for example, direct excess water to large, empty retention ponds in old quarries or open fields. These makeshift
ponds serve as temporary storage areas for the water. Diversion channels and spillways direct water from a flooding stream into another body of water. For example, the Bonnet Carre spillway was built
to divert floodwater away from New Orleans and into Lake Pontchartrain.
Stream Channelization
In channelization, a stream channel is widened and deepened. This allows the stream to move more water downstream at a higher velocity and thus reduces the likelihood of flooding. Channelization does
have some drawbacks, however—it can increase bank erosion and flooding downstream. In addition, channelization is expensive to maintain and, because it involves the removal of vegetation, can adversely
affect wildlife habitats.
Floodplain Regulations
Flood damage can also be reduced by restricting the construction of buildings and other permanent structures on floodplains. Communities that have floodplain regulations often rely on topographic
maps and flood-frequency records to determine which areas should be off limits to development. While floodplain regulations are important land-use planning tools, they sometimes face heated opposition
from homeowners and business people who want to develop floodplains. To balance the rights and safety of residents, it is important for community planners to educate the public about flood risks and to
ask for public input in the design of land-use regulations.
LINK UP: Find out more information about floodplain regulations.
Community Relocation
In part because of the problems associated with floodplain development, the U.S. government has instituted programs to encourage residents of floodplains to relocate to new areas. People are, however,
understandably reluctant to leave a place they consider home. It often takes a disaster—or repeated disasters—to persuade them to move. For example, the town of Pattonsburg, Missouri, experienced 33 floods
within 100 years before its residents decided enough was enough. The Federal Emergency Management Agency (FEMA) helped the 400 townspeople to plan, finance, and build New Pattonsburg at a higher elevation.
Although such a move is expensive, in the long run it saves money, and most importantly, it saves lives.
Activity
Use the Internet and other reference materials to research the relocation of communities such as Pattonsburg, Missouri, or Valmeyer, Illinois. Working as a group, develop a plan to relocate a community
of your choice along the Mississippi River.
