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Flood management

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Flood management refers to the various methods used to reduce or prevent the detrimental effects of flood waters. Flooding can occur due to natural processes, such as extreme weather upstream, or human changes to waterbodies and runoff. Effective management is essential because floods can damage property and endanger human and animal lives. They can also cause soil erosion, destroy fish spawning grounds, and impair hydroelectric power or waterway navigation. Financial losses are often massive, with some floods in U.S. history costing billions of dollars.

Scientists and engineers categorize management into two primary types: structural and non-structural. Structural flood management, also called flood control, uses physical solutions to manage water movement. These include reservoirs, levees, dredging, and diversions. Non-structural management focuses on reducing risk without physical barriers. This includes land-use planning, advanced warning systems, and flood insurance. While structural methods like flood walls are effective, modern landscape engineering often prefers soft infrastructure. This involves using natural systems, such as marshes and flood plains, to handle increasing water levels.

Humber Weir
Humber Weir

A key concept in modern flood control is the idea of "slowing the flow." Very dangerous floods are often characterized by brief, sharp spikes in river levels. In these cases, the water level rises and falls very abruptly. This quick spurt of water creates a high peak flood level, which causes the most damage. To prevent this, managers try to blunt the spike by slowing the surface runoff. Methods include using vegetation, meanders, or porous materials to spread the flow over a longer time. By letting water soak into marshes or floodplains, the peak level is significantly decreased.

Natural & impervious cover diagrams EPA
Natural & impervious cover diagrams EPA

Management can be applied at three distinct levels: individual properties, small communities, and entire cities. On a private level, owners might use sandbags, waterproof important areas, or block air vents. They can also use permeable paving to improve rainwater filtration. For larger communities, the high value of infrastructure often justifies the high cost of mitigation. Engineers might channel rivers running through urban developments or build embankments to raise the water edge. In some cases, temporary flood defenses are constructed in areas prone to seasonal rising waters.

Communit1
Communit1

Large-scale protection for towns and cities often relies on flood risk maps. These maps show areas prone to flooding based on historical data. For example, the Environment Agency in the UK produces maps to identify at-risk zones. In the United States, FEMA produces flood insurance rate maps to identify future risks. These maps allow local governments to use zoning regulations to prevent development in dangerous areas. One advanced strategy is "strategic retreat." This involves removing buildings from flood-prone areas and returning the land to parks or wilderness.

Infrastructure such as dams and reservoirs plays a massive role in large-scale flood control. Many large dams include flood-control reservations. This means the reservoir level is kept below a certain elevation before the rainy or melt season begins. This creates extra space to catch incoming floodwaters. In the United States, the design of these structures is regulated by the US Army Corps of Engineers. Besides flood control, these reservoirs can also provide hydroelectric power, water conservation, and recreation.

泄洪中的新安江水电站
泄洪中的新安江水电站

As climate change progresses, flood management has become a vital part of climate change adaptation. Rising sea levels and increased storm intensity mean that coastal management must now handle both natural tides and rising oceans. Building "resilience" is a major focus of modern urban planning. Resilience means designing infrastructure so that cities can recover quickly after a flood occurs. This might include putting electrical equipment on roofs instead of basements or building homes on stilts. Such technologies help individuals and communities return to normal more rapidly.

06 2023 Thames Barrier IMG 7506
06 2023 Thames Barrier IMG 7506
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File:Humber Weir.JPG
Humber Weir.JPG
File:Natural & impervious cover diagrams EPA.jpg
Natural & impervious cover diagrams EPA.jpg
File:Environmental assessment- Rehabilitation of flood control works, Meadowhurst Levee, Benewah County, Idaho - USACE-p16021coll7-10091 (page 7 crop to flood level graph).jpg
Environmental assessment- Rehabilitation...
File:Communit1.jpg
Communit1.jpg
File:泄洪中的新安江水电站.jpg
泄洪中的新安江水电站.jpg
Influence of flood-control structures on...
File:Flood shelter suitability map of Bangladesh.jpg
Flood shelter suitability map of Bangladesh.jpg
File:Floodgate_Tokyo.jpg
Floodgate_Tokyo.jpg
File:06_2023_Thames_Barrier_IMG_7506.jpg
06_2023_Thames_Barrier_IMG_7506.jpg
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