BIOGRAPHY OF A RIVER

9-12 FLOODSOBJECTIVESThe student will do the following:1. Explain some causes of flooding.2. Describe methods of flood control.3. List some disadvantages of flood control methods.SUBJECTS:Science (Physical Science,Earth Science), SocialStudies (History, Geography)TIME:2 class periods4. Locate areas in danger of flooding.5. Demonstrate use of topography maps.BACKGROUND INFORMATIONFlooding is a natural phenomenon that occurs when a watershedreceives so much water that the stream channel cannot containthe water, and the water overflows the stream banks. Causesmay include excess rain, melting snow, human-made channelsMATERIALS:large sheets of plastic (tarp orpoly)garden hose and watersweater boxes (6)PVC pipe, rain gutter, or½” or ¾” poly tubingdirt, clay, or sodbricksLegos ®, clay, or plasterand diversions, overloaded storm sewers, or failures of dams or levees. Because many cities are locatedon or near rivers and streams to take advantage of transportation, fresh water, good soil, hydroelectricpower, recreation, and aesthetic factors, floods can be expensive in terms of property damage and loss oflife.We can minimize flooding damages by not developing floodplains. Lakes, levees, and dams, have beenconstructed for the purpose of controlling floodwaters; however, often these “solutions” help one city andcause problems for another city downstream. They also usually cause changes in ecosystems.Episodic flooding, such as the Johnstown floods in Pennsylvania (3 times), the Midwest Flood of 1993, andthe Southeast Floods of 1994, are known to most Americans. Elsewhere in the world, seasonal floodingis a way of life. These annual floods carry in huge amounts of silt and topsoil that provide fertile ground fornext year’s crops. Rainfall and river monitoring systems can now alert forecasters to warn people in dangerzones to take emergency action.3-38