Coastal sand dunes protect structures built behind them and help slow down coastal erosion and also the immediate impact of rising storm surge. Floodways built to relieve flood pressure can also provide ecosystem benefits. These natural systems can be effective in reducing flooding behind levees with interior drainage problems Galloway et al. Use of natural systems typically requires some form of real estate acquisition fee simple, easement, payment for use, etc. In some cases, there will be a need for construction of appropriate inlet and outlet works to permit the entry and exit of stored waters.
Accurate mapping of risks provides those living or working in flood-prone areas, in front of or behind levees, with the information necessary to make rational decisions in developing their personal or corporate flood risk management strategies. Risk mapping is discussed further in Chapter 7. Combining the natural hazard risk assessment with quantitative consideration of mitigation measures yields expected outcomes that can be graphically portrayed in a manner that facilitates public understanding of the risk and its implications for them.
Detailed weather forecasts of the path and severity of a tropical storm, and accurate predictions of stages heights of flooding rivers enable government officials and the public to make decisions to evacuate or move valuable property from high-hazard areas. Advance information about potential failures of levees or dams can significantly reduce the consequences should failures occur. Preparation of emergency action and evacuation plans can similarly reduce or eliminate casualties and property losses.
Damage to structures in the SFHA and behind levees can be greatly reduced through effective dry and wet floodproofing. Dry floodproofing seals structures to prevent floodwaters from entering; wet floodproofing makes uninhabited portions of a structure resistant to floods by allowing water to enter and flow through the structure during a flood. FEMA defines floodproofing as.
Examples of such adjustments and additions include anchoring of the building to resist flotation, collapse, and lateral movement; installation of watertight closures for doors and windows; reinforcement of walls to withstand floodwater pressures and impact forces generated by floating debris; use of membranes and other sealants to reduce seepage of floodwater through walls and wall penetrations; installation of pumps to control interior water levels; installation of check valves to prevent the entrance of floodwater or sewage flows through utilities; and the location of electrical, mechanical, utility, and other valuable damageable equipment and contents above the expected flood level FEMA, n.
Wet floodproofing includes construction of veneers to seal potential water entry into or under a structure, installation of vents to allow water to move through crawl spaces under homes avoiding different water levels outside and under a home. There is an increasing demand for products and techniques that can be used in existing properties to reduce the potential damage when flooding occurs.
To ensure that floodproofing products are well designed and manufac-. Wise land use is at the center of nonstructural flood mitigation activity and is an effective tool for reducing risk at the community level. Land-use planning implements public policy to direct how land in a given area is used.
It is executed through zoning ordinances and takes place on multiple levels of government, from national policy to local policy where there may be designation of parcels for a specific use at the local level.
When appropriate, wise land use may mean a lack of investment in a particular area Box Few issues have gained attention and controversy like land-use planning. The tension between promoting development in order to foster growth in the community and the potential long-term liabilities i. Unfortunately, when individuals or businesses develop an area that may be subject to flooding and are unaware of the potential risk, these individuals suffer when a flood event occurs.
Although the NFIP requires regulation of the land within the SFHA, it does not require flood-prone communities to regulate areas beyond the one percent annual chance flood level or areas behind levees even though both areas face flood risks. Construction standards and building codes can be developed at any level of government but they are enforced at the local level. While codes provide for public safety, they also prescribe practices and measures that directly address known causes of disaster damages.
Damages can be significantly reduced by attention to modern construction standards and building codes. Kunreuther found that one-third of the damages associated with the Hurricane Andrew could have been avoided had Florida enforced its building codes. Coastal barriers possess many characteristics that make them attractive building sites. These include their rich biological diversity, their status as popular vacation destinations, and their role as large drivers to local economies.
However, these areas pose substantial risks to both developers and homeowners. They are often the location of first landfall by tropical storms, bearing the full force of storm surges and hurricane winds, and are the victim of a constantly fluctuating landscape due to chronic coastal erosion FWS, The federal government historically subsidized and encouraged development in these coastal areas until the late s and early s, when it was realized that this subsidization and encouragement had been resulting in the loss of natural resources; presented a threat to human life, health, and property; and cost American taxpayers millions of dollars each year FWS, Virgin Islands as part of the newly created John H.
Chafee Coastal Barrier Resources System. This designation renders these coastal barriers ineligible for most new federal expenditures and financial assistance, including, most significantly, access to federal flood insurance through the NFIP FWS, Although no longer encouraged by the federal government, development in these hazardprone areas is not prohibited, provided any work and investment is made by private developers and other nonfederal parties.
In return for a lack of restrictions on development, any individual or developer choosing to live and invest in these areas agrees that they will bear the full cost of development and rebuilding in the case of a flooding event or other natural disaster instead of relying upon federal funding for roads, wastewater systems, potable water supply, and disaster relief FWS, Acquisition or relocation of properties that are repetitively flooded, substantially damaged, or need flood-related project construction have been supported by FEMA and USACE, allowing many communities to deal with the challenges of these frequent flood losses.
When land is not suitable or only marginally suitable for development or agricultural activity, that land can be acquired and placed into public use for either environmental or recreational purposes to enhance the overall quality of life in the community. Buyouts of properties that are repetitively flooded have been supported by FEMA and have allowed many communities to deal with frequent flood losses.
Although a few sections of communities have been relocated, more relocations or removals usually take place where specific parcels are identified as being at risk. When property is acquired for environmental purposes. This flood storage reduces the downstream impact of the flood and the area is restored after the flood to its previous condition.
During the Mississippi River floods, over , acres of land in the lower Mississippi Valley was used for flood storage, which dramatically reduced river stages that otherwise would have affected large communities such as New Orleans and smaller ones such as Cairo, Illinois. Through the purchase of insurance, some of the financial risk of living on a floodplain in or outside the SFHA or behind a levee is transferred, for a premium, from the individual to the entities that provide insurance.
Floodplain managers tend to consider this a mitigation technique, when in fact unlike physical measures that reduce damages,. In most floodprone areas in the United States, this insurance is provided to residential properties and small businesses through the NFIP. However, unlike the NFIP, commercial insurance rates and rates for homeowner coverage in excess of the NFIP cap are based on more detailed analysis of properties as they apply for coverage and may reflect more sophisticated risk analysis and requirements for mitigation measures Chapter 5.
When property owners take steps to mitigate potential losses through use of mitigation measures, commercial insurers typically will reduce the premiums to reflect the risk mitigation.
However, the NFIP does not provide premium reductions in areas behind levees preferred risk policies. When risk-based pricing is implemented, discounts for mitigation measures behind levees need to be considered because it is likely that, in many cases over the life of a mortgage, the premium discounts could exceed the costs of the mitigation and would be beneficial to the mortgage holder and the mortgagee.
The perception exists that flood insurance is unnecessary for individual homeowners in the floodplain because, after a flood event, government and private agencies assist the property owners in getting back on their feet. Media statements and political rhetoric regarding disaster aid imply generous aid to repair and replace property. Analysis has indicated that this is not necessarily the case Kousky and Shabman, Possession of an insurance policy provides rapid payment to the owner of claims for property damage and gives those with insurance the ability to recover much faster than those seeking to piece together other forms of assistance, which, in the long run, will not make up the entirety of losses.
Circumstances produce a variety of flood risk scenarios behind levees. These circumstances can include anything from proximity to the coast or river, local weather patterns, existing infrastructure, and community preparedness. Some risk scenarios are associated with long time horizons, such as flooding associated with climate change, and might be less perceptible to the at-risk community compared with, for example, a design deficiency in a levee discovered during the Map Modernization process.
Complicated scenarios arise as communities grapple with unique situations Box A mix of flood risk management measures tailored to the risk of a particular. Living in an area that is vulnerable to flooding, the community of Norfolk, Virginia, has spent years wrestling with flood risk. Challenging issues such as the combination of sea level rise and subsidence dramatically changing the level of the ocean in Norfolk face this community Figure ; Boon et al.
The current flood management system of Norfolk consists of pumping stations and floodwalls. Each year, the city invests in improving drainage and elevating roads. Norfolk has taken additional steps to prepare for flooding, including hiring a Dutch coastal engineering firm to conduct a vulnerability analysis to enhance mitigation and inform development.
To successfully develop a flood risk management strategy, a community, in collaboration with those entities that may be called upon to assist in the implementation of the strategy, needs to first establish the goals of the strategy. This collaboration requires the community to synchronize planning with relevant regional bodies and ensure its conformance with state and federal guidelines and regulations when they exist. A critical part of the goals of the strategy is to define the relative levels of protection both in front of and behind levees and then to lay out the appropriate combination of mitigation measures structural, nonstructural, or insurance to achieve those levels.
Today, there is no national standard for level or degree of protection for flood-prone communities, except for those choosing to participate in the NFIP. Those behind levees must ensure that the levees protect against the one percent flood. However, this criterion is a standard for participation in the insurance program, not a life-safety or property protection standard. Since the decision was made in the s to use this one percent standard for NFIP accreditation, the predominance of the written reports concerning levees have argued for a minimum standard of 0.
As indicated in Chapter 2 , when the federal government began to build levees under its flood control authorities, it began with relatively high standards. Urban area levees and those protecting the Lower Mississippi Valley were to be built to pass a standard project flood or higher level flood.
Agricultural areas were typically protected to near the percent annual chance level. Executive Order , March , directed federal agencies supporting activity in the floodplain to require critical facilities to be located outside the 0. In , the U. Water Resources Council issued Principles and Standards WRC, , which established national and regional economic development, environmental quality, and other social effects as criteria for evaluation of federal water resource projects.
These standards permitted a variety of justifications for level of protection to be considered. Life safety was not a consideration in the calculus. In , the State of California legislated that new urban levees would have to be constructed at the 0.
This represents a critical evolution in thinking—that it is appropriate to tailor flood risk management strategies to individual communities, geographic areas, or watersheds by carefully selecting a level of protection that reflects the life safety and economic assets in a given area. This includes recognition that the one percent annual chance flood standard of the NFIP might not serve as an appropriate life safety or property protection standard. Also critical to evaluating flood risk management strategies at the local level is the ability to acquire the resources it will need to carry out the floodplain management strategy.
Development of a flood risk management strategy focused solely on protection of areas behind levees would be neglecting the comprehensive nature of the flood risk challenge. It is critical to coordinate efforts to deal with one part of the floodplain with planning and other areas. Also critical is the consideration of all types of development and activity in local land-use plans, including residential, commercial, industrial, and agricultural needs of the community, placement of these components in a community, and an economic analysis of the costs and benefits of the flood risk management strategies being examined.
Do the benefits to be gained merit the commitment of the. However, approval of community participation in the NFIP and accreditation of levees in these communities is not dependent on the cost-effectiveness of the levee or other mitigation measures incorporated in the community flood risk management strategy.
Economic decisions are more closely tied to the analyses conducted by federal or state agencies to meet the criteria for participation in or construction of flood-related infrastructure under other government programs. Actions to shape flooding in one location can have impacts on flood stages i.
At the time, ad hoc levee construction generated significant, unintended hydrologic impacts at both the local and regional levels, driving the state to eventually implement statewide flood control measures through a State Reclamation Board. This plan promotes integrated, systemwide wise flood management, a key implication of which is that flood management investments e. Community flood risk scenarios will continue to evolve as change occurs.
Climate change will have a variety of regional impacts, and the geographic location of a community will affect how changing conditions affect risk. Some areas will have more droughts, some will have more frequent floods, and others will have more intense floods.
Research to understand these hydrologic changes is ongoing NRC, , a. A recent special report of the Intergovernmental Panel on Climate Change IPCC, indicates a likely increase in many regions of the frequency of heavy precipitation events, and when coupled with increasing vulnerability presents a myriad of challenges for coping with climate-related disastersIPCC.
Galloway cites 11 major international studies conducted from to that all predict significant climate change-induced hazards, including increased flooding, higher mean atmospheric temperatures, higher global mean sea levels, increased precipitation, increased strength of storms, more energetic waves, storm surges that reach further inland, undercapacity of urban sewerage and drainage systems, increased vulnerability of port cities, and disproportionate impacts on disadvantaged population segments Galloway, The rise in sea level and the increase in storm surge due to climate change puts many coastal areas at risk from intensified flooding NRC, Hirsch and Ryberg , in examining trends in annual floods at stream-gauge sites in the United States, found that, while there appeared to be no strong statistical evidence for flood magnitudes increasing with increasing global mean carbon dioxide concentration, there were differences in flood magnitudes among the four quadrants of the conterminous United States Figure Climate change is already affecting the American people.
The largest increases have occurred in the Northeast, Midwest, and Great Plains, where heavy downpours have exceeded the capacity of infrastructure such as storm drains, and have led to flooding events and accelerated erosion.
The report goes on to point out the increasing vulnerability to flooding of those in floodplains and coastal areas Figure ; NOAA, When Hurricane Sandy hit New York, FEMA accelerated the release of information about the BFEs that would be seen on the new maps so that individuals and community officials could plan the recovery and reconstruction accordingly.
These advisory BFEs for A and V zones, now in the hands of officials and the public, reflect the anthropogenic and physical changes that have taken place in the.
This is equivalent to 1. Geological Survey stream gauge stations. Upward pointing triangles represent increases in the magnitude; downward pointing triangles, decreases.
The light blue area represents a depiction of the one percent annual chance floodplain of Lower Manhattan, New York City. With sea-level rise, a far larger area would be flooded in the event of a one percent annual chance flood event. Note that flooding during Hurricane Sandy exceeded the one percent annual chance flood. With sea-level rise, the one percent annual chance flood will inundate a larger area of New York City not pictured here.
Attention to these new elevations will ensure that those who were damaged by Sandy will be able to rebuild or relocate knowing more about the hazard they face FEMA, ; Jeffrey Woodward, FEMA, personal communication, February 27, The Biggert-Waters Act established a Technical Mapping Advisory Council to serve as an advisory body dealing with map modernization issues.
The Biggert-Waters Act further charges the Administrator to review and update NFIP rate maps and to incorporate any future risk assessment submitted by the Technical Mapping Advisory Council in any such revision or update.
Flood risk management strategies are represented by portfolios of mitigation measures. A structural approach—that is, construction of a levee—is immediately visible and for many flood events provides adequate mitigation of the effects of rising waters. Contact your city or county water or sewer department for more severe blockages.
Regularly check and clean downspouts and gutters. Check and clean the gutters and downspouts at least once a year, more frequently if you have lots of trees near your home. To ensure the downspouts are clear, you can use a leaf blower or gloves to clean the gutters and a flexible water hose with a high-pressure attachment.
You can also hire a lawn or landscape pro to take care of this. Improve grading and drainage around your home. When it rains, take note of any rain or flood water that accumulates near your home.
Pay attention to areas near the foundation. The ground should slope away from the foundation of your home or business. You may need to bring in dirt and sod to improve the grading. In some cases, you may need to install drainage where water accumulates to give the water a place to go during heavy storms. Check for and seal openings and cracks in your foundation. As part of your yearly home maintenance, seal openings, such as doors, windows, utility, and exhaust penetrations, regularly inspect your foundation and seal foundation cracks with masonry or mortar caulk.
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We are a global company who provide advanced products, services and expertise to help municipal, industrial and construction customers to improve the way they process, treat and manage water. This can lead to devastating floods, as occurred in Winnipeg during the spring of To protect the city from future floods, the Manitoba government undertook the construction of a huge levee system. The system kept Winnipeg safe during the flood which devastated many communities north of Winnipeg, including Grand Forks, North Dakota and Ste.
Agathe, Manitoba. In a flood prevention act, the United States government offered to buy flood-prone properties in order to prevent repeated post-flood disasters in throughout the Midwest. Several communities accepted this proposal and the government, in partnership with the state, bought 25, properties which were converted into wetlands.
These wetlands act like a sponge in storms, and in , when the floods returned, the government did not need to allocate resources in those areas. Data on floods in Asia and in the World [4]. Victor [16] states that floods are the most common natural disasters in both developed and developing nations, accounting for almost 40 percent of natural disasters.
The Southeast Asian region is especially prone to floods, which, according to the United Nations Office for the Coordination of Humanitarian Affairs, it is estimated that 9. Victor [16] reports that Southeast Asia is particularly susceptible to the effects of climate change due to its fast growing population - the majority of which are still living in poverty - as well as poor food security and diminishing natural resources, that climate change is a result of increasing temperatures which is linked to more intense downpours, heat waves, extreme weather events, greater climate variability and rising sea levels, all of which contribute to the increased frequency and intensity of flooding in Southeast Asia.
In Malaysia, over half of the historical state of Penang was submerged in flood waters after hours of torrential rain. Other countries in the region have also been making headlines when it comes to floods particularly, Philippines and Thailand.
Victor [16] states that capacity building in priority concerns such as human resources should be strengthened. Community preparedness is another example of an intervention that can be improved in Southeast Asia. Both governmental and non-governmental operations are often unsustainable, due to lack of funding and community engagement.
There is a strong need for governmental organizations to continue developing flood planning strategies beyond mitigation and adaptation. Khinmaung-Moore [17] states that heavy monsoon rains are continuing to trigger severe flooding across Bangladesh, Nepal and India, that current floods are the worst in decades and are happening during the monsoon.
Khinmaung-Moore [17] reported that he can't say if this specific flooding is directly caused by climate change. However, there is a clear relationship between climate change and severe, erratic weather patterns like the ones he is seeing. There have been four floods in Bangladesh in which were bigger and more intense than in previous decades. Poverty reduces their options and forces them to live in and grow food in riskier areas.
Below-standard drainage, some deforestation and poor infrastructure planning are also compounding the situation. Khinmaung-Moore states that the climate is changing fast and people living in poverty, who are the least responsible for it, are often the most vulnerable to their impacts, including disasters and flooding.
Millions of lives and livelihoods are at risk. Up to this date, the flood of August 5, in Thailand was the most economically damaging flood between and , causing roughly 40 billion U. Thailand's floods of August reportedly killed 42 people and occurred in the North and North-Eastern areas of the country. Heavy storm and tropical storm Nock Ten were to blame for the flooding. Nock Ten killed 75 people in Philippines.
It also made landfall in China, Vietnam and Laos, where more damage was done and more people died. An estimated 1. Due to flooding, roughly , individuals were evacuated from low-lying areas in Thailand and 6, acres of rice and other crop fields were submerged by flowing water.
In one historic event in , over 3. In , in China, over million people were affected by major flooding. In , over million people were affected by major flood disasters in China. A flood in China in caused damage estimated to be worth 30 billion U.
In China, deviation areas are rural areas deliberately flooded in emergencies to protect cities. With natural forest cover, the duration of floods should decrease.
Deforestation amplifies the incidents and severity of floods. Figure 2 presents data about economic damage in Thailand, China, India, Germany and United States caused by significant floods worldwide from to in billion U. Figure 2 : Economic damage caused by significant floods worldwide from to in billion U. Thailand, China and India have all been hit by devastating floods during torrential monsoon rains in recent history. In this article, World Atlas demonstrates the incredible damage that floods can inflict.
Between and , disastrous floods have seriously impacted local economies around the world. Some of the most devastating of these floods occurred in the Southern and Central regions of Asia — specifically in the populous nations China, Thailand, Korea and India. Statistically speaking, only two countries outside of Asia have suffered consequences from massive floods which are severe enough in nature to make it on the list of the 10 most economically devastating floods ever recorded.
The other non-Asian country to make our list, suffering damages from two separate floods as well, is the United States. After a major U. Another U. Measures adopted for post-flood cleaning safety [5]. Clean-up activities after floods often pose risks to the workers and volunteers involved in such effort.
Potential hazards include electrical hazards, carbon monoxide exposure, musculoskeletal hazards, heat or cold, hazards related to motor vehicles, fire, drowning, and exposure to hazardous materials. As flooded disaster sites are unstable, cleaners may encounter sharp fragments, biological hazards in the water, exposed electrical lines, blood or other body fluids, and animal and human remains.
When planning and responding to flood disasters, managers should provide workers with safety helmets, goggles, heavy duty gloves, lifejackets, and waterproof boots to toes and with steel insoles.
After the flood waters recede and the cleanup has been done, most folks want to get back into their homes or businesses and start rebuilding. After the floods, the Canadian Department of Public Safety and Emergency Preparedness [20] considers necessary to restore homes to good order as soon as possible to protect health and prevent further damage to the house and its contents. The Canadian Department of Public Safety and Emergency Preparedness has established measures to be taken after floods related to the topics which are as follows: 1 Re-entering your home; 2 Ensure building safety; 3 Water contaminated; 4 Documentation; 5 Cleanup; 6 Recommended flood cleanup equipment; 7 Additional equipment; 8 Water withdrawal; 9 Heating and appliances; 10 Dirt and debris; 11 Floor drains; 12 Structures; 13 Carpets and furniture; 14 Mould; 15 Food and medicine; 16 What to discard; 17 What is salvageable; and, 18 Before moving back in.
Preservation Assistance Division from U. National Park Service [21] informs that after the flood waters begin to recede, the focus of relief efforts becomes returning things to normal. During this phase, many historic structures and properties are needlessly lost and damaged through hasty clean-up procedures. The best way to help a historic district, property, or structure prevent additional damage and maintain its integrity and character during these times of duress is with the use of proper caution and concern.
Preservation Assistance Division recommends that while the water is receding, one should plan the future steps to rehabilitation and restoration carefully. Each decision made today affects future decisions, which will need to be made tomorrow. Kerr [22] reports that "Storm cleanup is different from regular and even heavy duty cleaning. There are hazards, health concerns and other issues that go beyond normal cleaning that require specialty products, tools and cleaning techniques, as well as protective gear and safety measures not required in regular cleaning.
After a large storm and flooding, many holdings will be full, but often there are unexpected treasures that survive that can be restored. Here are guidelines to follow what can be salvaged. After a flood, removing water and drying everything out can be daunting. For spot cleaning, a good wet mop, like these suggested by Wire cutter, a New York Times company, will split the difference. Safety is a concern when handling any electric tools in a flooded area, and you should avoid using machines like the Rug Doctor if there is more than a half inch of standing water.
Do not enter a flooded space unless you are sure the electricity is turned off. After standing water has drained or been removed, dampness will persist, and along with that moisture will come mold, mildew and smells. Dehumidifiers, once the water is gone, can help keep the air at a comfortable humidity until you can make bigger repairs.
Portable air-conditioning units but not outdoor or ground-mounted central air units, which can be contaminated with silt can also help reduce humidity and moisture levels in your home. Carpet and upholstery cleaners can be used with a pre-mixed odor-eliminating solution or diluted white vinegar if allowed by manufacturer instructions to remove those damp, mildewy smells from your floors.
A bleach solution and scrub brush can be used to remove mold from hard surfaces. When cleaning mold, it is important to wear protective gloves and mask, particularly if you suffer from respiratory issues or have a weakened immune system.
To treat moderate dampness and mustiness, desiccants and odor absorbers such as Damp rid, silica, the Bad Air Sponge and activated charcoal-based products are all good choices. After Katrina, for example, some people needed expensive antimicrobial spraying equipment for their whole home.
Do your best to clean up, then keep an eye, ear and nose out for spots on walls, smells, or inexplicable coughs.
Heavily soiled laundry requires special handling, and this is especially true in the case of heavy soiling caused by floodwater.
Before doing any wash, ensure that the water supply is clean and uncontaminated, and that your laundry machines are safe to use. If they are not, head to your closest laundromat or dry cleaners. Start by taking the heavily soiled laundry outside to rinse wet or muddy items off using a hose, or place them into a utility sink for pre-rinsing if outdoor space is not available. Allow the items to dry, ideally in the sun, to help prevent mildew from developing, then shake out and brush off any dirt and mud that remains after the initial rinse.
The C. Multiple wash cycles may be needed to fully remove soil and other contaminants. For disinfecting clothes or other laundry, use the hottest water setting that is safe for the fabric type.
Once your items are thoroughly cleaned, they may go into a dryer — but not before, as the heat will set stains into soiled textiles. For your safety when working in wet conditions, wear rubber or insulated footwear, and again, do not enter a flooded space unless you are sure the electricity is turned off.
If your home has natural gas service, check for gas leaks before using electrical equipment in your home, including lights. If you have a gas grill, have your canisters checked by a professional before you try using them again. The Environmental Protection Agency recommends wearing gloves and other protective equipment in post-flood conditions, including respirators and goggles. Similarly, the U.
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