![]() It damages property and endangers the lives of humans and other species. ![]() Purposes Reducing the impacts of floods įlooding has many impacts. About 30 percent of all precipitation becomes runoff and that amount might be increased by water from melting snow. ![]() Water then runs off the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes, and human-made reservoirs. This has been exacerbated by human activities such as draining wetlands that naturally store large amounts of water and building paved surfaces that do not absorb any water. Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannot absorb all the water. Flooding can be exacerbated by increased amounts of impervious surface or by other natural hazards such as wildfires, which reduce the supply of vegetation that can absorb rainfall.ĭuring times of rain, some of the water is retained in ponds or soil, some is absorbed by grass and vegetation, some evaporates, and the rest travels over the land as surface runoff. Causes of flooding Relationship between impervious surfaces and surface runoffįloods are caused by many factors or a combination of any of these generally prolonged heavy rainfall (locally concentrated or throughout a catchment area), highly accelerated snowmelt, severe winds over water, unusual high tides, tsunamis, or failure of dams, levees, retention ponds, or other structures that retained the water. In the context of natural hazards and disasters, risk management involves "plans, actions, strategies or policies to reduce the likelihood and/or magnitude of adverse potential consequences, based on assessed or perceived risks". įlood management (or flood risk management) is a broader term that includes mitigating and preparing for flooding disasters, and providing risk analysis for example through the practice of flood risk assessment. Further examples for this type of flood control are: "zoning ordinances and codes, flood forecasting, flood proofing, evacuation and channel clearing, flood fight activities, and upstream land treatment or management to control flood damages without physically restraining flood waters". ![]()
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