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ninemsn Encarta - Flood Control (1266 words) |
 | Floods occur when soil and vegetation cannot absorb all the water; water then runs off the land in quantities that cannot be carried in river channels or retained in natural ponds and constructed reservoirs held behind dams. |
| These river floods often result from heavy rain, sometimes combined with melting snow, which causes the rivers to overflow their banks; a flood that rises and falls rapidly with little or no advance warning is called a flash flood. |
| Flood control in these areas has been directed to restoring vegetation and instituting efficient methods of soil management and conservation, such as crop rotation and contour ploughing. |
| MSN Encarta - Flood Control (1142 words) |
| Floods occur when soil and vegetation cannot absorb all the water; water then runs off the land in quantities that cannot be carried in stream channels or retained in natural ponds and constructed reservoirs (see Dam). |
| Floods in the Mississippi Valley have demonstrated that levees alone do not provide sufficient protection against flooding on a large river, and other methods of flood control, including dams and floodways, are now in use on the Mississippi River (see Levee). |
| Flood control in these areas has been directed to restoring vegetation and instituting efficient methods of soil management, such as crop rotation and contour plowing. |
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