How Can Floods Be Controlled?
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Every year, floods damage lands and property around the world. Structures such as levees and dams help to prevent and control floods. Flooding is a natural event in many ecosystems. Controlling floods has both benefits and drawbacks. Heavy rain over many days, overflowing rivers, and severe storms all cause floods. How much damage can water do? A flood occurs when water flows or collects over land that is normally dry. Flood waters can destroy property, ruin farm crops , or drown people and animals. As you might guess a heavy rainfall over a short period of time can cause a flood. In Georgia and much of the southeastern United States, such rains often come from hurricanes and other tropical storms. A hurricane can dump twenty inches of rain or more in only a few hours! Days of repeated rain can also cause floods. Water from these rains slowly fill up the ground and soil. Any additional rain is forced to flow across the surface. This flow is called runoff. Excess runoff can collect to form a flood. Rapid melting of winter snow-pack also can cause s flood in this way. Floods can also form when rivers or lakes overflow. Heavy or repeated rains can cause such floods, even when the rain falls far away. For example in 1993 rainfall was unusually heavy throughout the mid west. The runoff drained into many streets and small rivers. They in turn flowed into the Mississippi River. This great volume of water swelled the Mississippi River beyond its banks. Many river communities were flooded. Every year floods cause the United States over a billion dollars in damage. In 1993, the damage totaled a record-setting 17 billion dollars worth of damage.
Why do floods cause so much damage? One reason is the materials that the flood waters carry with them. Flood waters can pick up rocks and dirt, fertilizers and other chemicals, and even wastes from a sewage system. When these waters recede they leave behind a terrible mess. In many cases flooded buildings require major repairs before people can return to them. Yet sometimes the damage is too severe to fix. After hurricane Katrina whole neighborhoods of New Orleans were torn down. Peoples lives were forever changed. To a degree nature provides its own system of flood control. Swamps, estuaries and other wetlands are covered by water at least part of the year. In rainy weather wetlands soak up water that otherwise would flow as runoff. Forest lands also act in this way. Laws protect many wetlands and forests from development. Even so such lands continue to be lost every year to advancing cities and suburbs. Water cannot soak through parking lots, roads, or highways. These structures increase runoff and can make flooding more severe. Things that can stop floods from happening are: storm drains, levees, dams and reservoirs, and floodways.
Why do floods cause so much damage? One reason is the materials that the flood waters carry with them. Flood waters can pick up rocks and dirt, fertilizers and other chemicals, and even wastes from a sewage system. When these waters recede they leave behind a terrible mess. In many cases flooded buildings require major repairs before people can return to them. Yet sometimes the damage is too severe to fix. After hurricane Katrina whole neighborhoods of New Orleans were torn down. Peoples lives were forever changed. To a degree nature provides its own system of flood control. Swamps, estuaries and other wetlands are covered by water at least part of the year. In rainy weather wetlands soak up water that otherwise would flow as runoff. Forest lands also act in this way. Laws protect many wetlands and forests from development. Even so such lands continue to be lost every year to advancing cities and suburbs. Water cannot soak through parking lots, roads, or highways. These structures increase runoff and can make flooding more severe. Things that can stop floods from happening are: storm drains, levees, dams and reservoirs, and floodways.