The Flood Control method is used to reduce or prevent the adverse effects of flood waters. Flood relief method is used to reduce the effects of flood water or high water levels.
Video Flood control
Causes of flooding
Floods are caused by many factors or combinations of all these prolonged large precipitation (concentrated locally or throughout the catchment area), very fast snow melts, high winds over water, unusually high tides, tsunamis, or dam failures , embankment, retention. ponds, or other structures that hold water. Floods can be exacerbated by an increase in the number of watertight surface or by other natural hazards such as forest fires, which reduce the supply of rain-absorbing vegetation.
Periodic floods occur in many rivers, forming the surrounding area known as floodplains.
During the rainy season, some water is retained in ponds or soils, partially absorbed by grass and plants, some evaporate, and others move on the ground as surface runoff. Flooding occurs when ponds, lakes, riverbeds, land, and vegetation can not absorb all water. Water then runs off the ground in an amount that can not be carried in a river channel or stored in natural ponds, lakes, and man-made reservoirs. Approximately 30 percent of all rainfall becomes runoff and that number may increase due to water from melting snow. River floods are often caused by heavy rains, sometimes increased due to melting of snow. The rapidly rising flood, with little or no warning, is called banjir bandang. Flash floods are usually caused by intense rainfall in relatively small areas, or if the area is already saturated from the previous rain.
Strong winds over water
Even when relatively light rainfall, the shoreline of lakes and bays can be flooded by severe winds - like during a hurricane - that blows water into the coastal area.
Unusual high current
Coastal areas are sometimes flooded with very high tides, like tidal springs, especially when compounded by strong winds and storm surges.
Maps Flood control
Flood impact
Floods have many impacts. It destroys property and endangers the lives of humans and other species. Rapid water runoff causes soil erosion and sediment deposition elsewhere (such as downstream or further beaches). Spawning grounds for fish and other wildlife habitats can become polluted or completely destroyed. Several high prolonged floods can slow traffic in areas with no overpass. Floods can disrupt drainage and land use economically, such as disrupting agriculture. Structural damage may occur in bridge abutments, bank lines, drains, and other structures in the flood. Waterway navigation and hydroelectric power are often disrupted. Financial losses due to floods are usually millions of dollars each year, with the worst floods in recent US history at billions of dollars.
Flood benefits
There are many disturbing effects of flooding in human settlements and economic activity. However, flooding can bring benefits, such as making the soil more fertile and providing less nutrients. Periodic floods are essential for the welfare of ancient peoples along the Tigris-Euphrates River, Nile River, Indus River, Ganges River and Yellow River, among others. The viability of hydrological-based renewable energy sources is higher in flood prone areas.
Detect
This is the method used for remote sensing disaster. Disaster detection such as floods, earthquakes, and explosions is quite complex in previous days and the range of detection is not appropriate. However, it is possible to use Multi Temporal visualization of the Synthetic Aperture Radar (SAR) image. But to get a good SAR image, perfect spatial registration and excellent calibration are needed to determine the changes that have occurred. SAR calibration is very complex and also a sensitive issue. Possible errors can occur after calibration involving the process of data fusion and visualization. Traditional pre-processing images can not be used here because of on-Gaussian from radar scattering, but a processing method called "cross-calibration/normalization" is used to solve this problem. This application generates a single disaster image called "alert map of disaster" from multitemporal SAR images. These maps are generated without user interaction and help in giving first aid directly to people. This process also provides improved image and comparison between multiple images using data fusion and visualization process. The proposed process includes filtering, histogram cutting and equity measures. The process also helps identify permanent waters and other classes by combining the compositions of pre-disaster and post-disaster images into color images for better identities.
Flood control method
Several methods of flood control have been practiced since ancient times. These methods include planting vegetation to retain additional water, drowning hillsides to slow down flow, and construction of flood channels (artificial channels to divert flood waters). Other techniques include the construction of embankments, lakes, dams, reservoirs, retention ponds to accommodate additional water during times of flooding.
Dams
Many of the dams and associated reservoirs are fully or partially designed to assist in the protection and control of floods. Many large dams have flood control reserves where the level of the reservoir must be kept below a certain height before the start of the wet/summer season is melting to allow some space where the floodwater can be filled. Other useful uses of dams created by dams include hydroelectric power, water conservation, and recreation. Construction and design of reservoirs and dams is based on standards, usually set by the government. In the United States, dams and reservoir designs are regulated by the US Army Engineers Corps (USACE). The design of dams and reservoirs follows the guidelines set by USACE and covers such topics as design flow rates in consideration for meteorology, topography, flow, and soil data for watersheds above the structure.
Dry dams refer to dams that work purely for flood control without any conservation storage (eg Mount Morris Dam, Seven Oaks Dam).
Redirect channel
Floods can be controlled by redirecting excess water into specially constructed canals or floods, which in turn divert water to temporary ponds or other water bodies where there is a lower risk or impact on flooding. Examples of flood control channels include the Red River Flood protecting the City of Winnipeg (Canada) and the Manggahan Flood that protects the city of Manila (Philippines).
floodplain and groundwater replenishment
Excess water can be used for groundwater filling with diversion to soil that can absorb water. This technique can reduce the impact of drought later by using soil as a natural reservoir. It is used in California, where vineyards and vineyards can be flooded without destroying crops, or in other places, wilderness has been reengineered to act as a floodplain.
River defense
In many countries, rivers are vulnerable to flooding and are often managed with caution. Defenses such as embankments, dikes, reservoirs, and weirs are used to prevent rivers from overflowing from the edges.
The dam, also known as the lowhead dam, is most commonly used to make millponds, but at the Humber River in Toronto, weirs are built near Raymore Drive to prevent a repeat of flood damage caused by Hurricane Hazel in October 1954.
Coastal Defense
Coastal floods have been overcome with coastal defense, such as sea walls, beach food, and barrier islands.
Tidal gates are used along with embankments and culverts. They can be placed at the mouth of a stream or a small river, where the estuary begins or where the stream, or drainage gutters are connected to the slough. Place the gate close when the tide comes in to prevent tidal water from moving into the highlands, and open during the tidal water to allow water to flow out through the sewers and to the side of the embankment. The opening and closing of the gate is driven by the difference in water level on both sides of the gate.
Floodgates that close themselves
The self-closing flood guard (SCFB) is a flood defense system designed to protect people and property from terrestrial flooding caused by heavy rain, strong winds or melting snow. SCFB can be built to protect residential property and entire communities, as well as industrial or other strategic areas. The barrier system is constantly ready for use in flood situations, can be installed in the long run and use increased flood water to use.
Temporary perimeter barriers
When permanent defenses fail, emergency measures such as sandbags, hydrosacks, flood barriers or portable inflatable tubes are used.
In 1988, a method of using water to control was discovered. This is achieved by containing 2 parallel tubes in the third external tube. When filled, this structure forms a non-rotating water wall that can control 80 percent of the height in the external water depth, with the dry ground behind it. The height of eight meters of water filled obstacles is used to circle Fort Calhoun Nuclear Generating Station during 2011 Missouri River Flooding. Instead of transporting sandbag material for flooding, piled it up, then transporting it to a hazmat disposal site, flood control can be completed by using on-site water. However, this is not fool proof. An 8 foot (2.4 m) tall 2,000 feet (610 m) long water filled rubber flood dike surrounding the parts of the plant was punctured by a skid-steer loader and collapsed flooded part of the facility.
In 1999, a group of Norwegian engineers established and patented AquaFence, a removable, removable, and reusable flood barrier that used the weight of water against itself. AquaFence removable flood panels protect cities and public facilities.
A similar technology is the Water-Gate Flood barrier, a fast-launch response retarder within minutes of self-use using the weight of water to hold it.
Hazard reduction
Strategic retreat
One way to reduce the damage caused by floods is to move buildings from flood-prone areas, leaving them as parks or returning them to the desert. The floodland purchase program has been operated in places like New Jersey (both before and after Hurricane Sandy), Charlotte, North Carolina, and Missouri.
In the United States, FEMA produces a flood insurance rate map that identifies future risk areas, enabling local governments to implement zoning regulations to prevent or minimize property damage.
Endurance
Buildings and other urban infrastructure can be designed so that even if floods occur, the city can recover quickly and costs are minimized. For example, houses can be put on stilts, electrical appliances and HVAC can be put on the roof instead of in the basement, and subway entrances and tunnels can have a moving water barrier that can be built. New York City embarked on a substantial effort to plan and build flood resistance after Hurricane Sandy.
Flood control by continent
In North America
An elaborate flood road defense system can be found in Canada's Manitoba province. The Red River flows north from the United States, through the city of Winnipeg (where it meets the Assiniboine River) and to Lake Winnipeg. As with all the rivers that flow north in the Northern Hemisphere climate zone, the melting snow in the south can cause the river's surface to rise before the north has a chance to completely melt. This could lead to devastating flooding, as happened in Winnipeg in the spring of 1950. To protect the city from future floods, the Manitoba government undertook the construction of massive diversion, embankment and flood systems (including Red River floods and floods). Portage Redirects). The system keeps Winnipeg safe during the 1997 floods that destroyed many upstream communities from Winnipeg, including Grand Forks, North Dakota and Ste. Agathe, Manitoba.
In the United States, the US Army Corps of Engineers is the leading flood control institution. After Hurricane Sandy, New York City's Metropolitan Transport Authority (MTA) started several flood-prevention projects to protect transit assets in Manhattan. In one case, the New York City Transit Authority (NYCT) MTA closed the subway entrance in Manhattan using a cloth cover system called Flex-Gate, a system that protects the subway entrance at 14 feet (4.3 m) water. The extent of extreme storm protection has been revised based on the guidelines of the new Federal Emergency Management Agency for 100 years and 500 years design flood improvement.
In the New Orleans Metropolitan Region, 35 percent of them are below sea level, protected by hundreds of miles of embankments and flood gates. This system failed in disaster, with many breaks, during Hurricane Katrina (2005) in the right city and in the eastern Metro Area, resulting in a pool of about 50 percent of the metropolitan area, ranging from a few inches to twenty feet in coastal communities.
Morganza Spillway provides a method of draining water from the Mississippi River when river floods threaten New Orleans, Baton Rouge and other larger cities in lower Mississippi. It is the largest of spillways and flood systems along the Mississippi. Completed in 1954, the spillway has been opened twice, in 1973 and in 2011.
In a successful flood prevention action, the federal government offered to buy flood-prone properties in the United States to prevent recurrent disasters after the 1993 floods throughout the Midwest. Some communities are accepted and the government, in partnership with the state, buys 25,000 properties they convert into wetlands. This wetland acts as a sponge in a storm and in 1995, when the flood came back, the government did not need to spend resources in the area.
Asia
In Kyoto, Japan, the Hata clan manages to control floods in the Katsura River around 500 A.D and also builds a floodgate on the Kazuno River.
In India, Bangladesh, and China, flood transit areas are rural areas that are deliberately flooded in an emergency to protect the city.
The consequences of deforestation and land use change on flood risk and severity are the subject of discussion. In assessing the impact of Himalayan deforestation on the Ganges-Brahmaputra Plateau, it was found that forests would not prevent or significantly reduce flooding in case of extreme weather events. However, more general studies or overview agree on the negative impacts of deforestation on flood safety - and the positive effects of wise land use and reforestation.
Many have suggested that the loss of vegetation (deforestation) will lead to an increased risk of flooding. With natural forest cover, the duration of the flood should decrease. Reducing the rate of deforestation should increase the incidence and severity of floods.
Africa
In Egypt, both Aswan Dam (1902) and Aswan High Dam (1976) have controlled the various floods along the Nile.
Europe
After the misery and destruction caused by the Great Flood of 1910 in Paris, the French government built a series of reservoirs called Les Grands Lacs de Seine (or Great Lakes) that helped relieve the pressure of the Seine during floods, especially the usual winter floods.
London is protected from floods by a large mechanical barrier across the Thames River, which is raised when the water surface reaches a certain point (see: Thames Barrier).
Venice has a similar arrangement, although it is not able to cope with very high waves. The defense of both London and Venice will be inadequate if sea levels continue to rise.
The largest and most complex flood defenses can be found in the Netherlands, where they are referred to as Delta Works with the Oosterschelde dam as its peak achievement. These works were built in response to the 1953 North Sea flood, in the southwestern part of the Netherlands. The Netherlands has built one of the world's largest dams in the northern part of the country. The closure of Afsluitdijk occurred in 1932.
The Saint Petersburg Flood Prevention Complex Complex was completed in 2008, in Russia, to protect Saint Petersburg from a storm surge. It also has a major traffic function, as it completes the ring road around Saint Petersburg. Eleven dams stretch 25.4 kilometers (15.8 mi) and stand 8 meters (26 feet) above the water level.
Flood-cleaning policy
After-flood cleaning activities often pose a danger to workers and volunteers involved in the effort. Potential hazards include electrical hazards, exposure to carbon monoxide, musculoskeletal hazards, heat or cold stress, hazards associated with motor vehicles, fires, drowning, and exposure to hazardous materials. Because the flood disaster site is unstable, hygiene workers may face sharp jagged debris, biological hazards in flood waters, open power lines, blood or other body fluids, and animal and human remains. In planning and reacting to flood disasters, managers provide workers with hard hats, goggles, heavy work gloves, life jackets, and waterproof shoes with steel fingers and soles.
Technology development
Europe is at the forefront of flood control technology, with lowland countries such as the Netherlands and Belgium developing techniques that can serve as examples for other countries facing similar problems.
After Hurricane Katrina, the state of Louisiana sent politicians to the Netherlands to tour the flood control system that is complex and highly developed in the Netherlands. With a BBC article citing experts saying 70 percent more people will stay in a delta city by 2050, the number of people affected by sea level rise will greatly increase. The Netherlands has one of the best flood control systems in the world and new ways to handle water continue to be developed and tested, such as underground water storage, storing water in reservoirs in large parking garages or at playgrounds, Rotterdam embarked on projects to build floating housing developments covering an area of ​​120 hectares (0.49 km 2 ) to cope with rising sea levels. Several approaches, ranging from high-tech sensors that detect imminent embankment failures to a moveable half-circle structure that covers the entire river, are being developed or used around the world. Regular maintenance of hydraulic structures, however, is an important part of flood control.
See also
References
Note
Further reading
External links
- Integrated Flood Management - Flood Management Program, Geneva
- Flood article - BBC News
- Flood defense works in Wiltshire - BBC
- The flood defenses work at Carlisle - BBC
- Flood management and habitat recovery - BBC
Source of the article : Wikipedia
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