(1) Levees in the United States
(a) A levee is a man-made earthen structure constructed along a river or coastline.
(i) They are designed to control the flow of water during times of flood or tidal storm.
(ii) The presence of a levee theoretically protects adjacent lands from flooding.
(b) All 50 states of the nation utilize levees to some degree.
(i) 22 percent of the 3,147 counties in the United States contain levees.
(ii) They are more commonly found in states with long coastlines and/or large rivers.
(2) Levee design
(a) The location of a levee requires analysis of both existing conditions and future plans for an area.
(i) Decisions need to be made regarding whether the levee will be located on river frontage or private land, and how far back from the river the levee will be located.
(ii) The levee should provide adequate waterway area to accommodate the design flood, without restricting the flow so that the impact of the flood is worsened.
(b) The location and associated costs usually dictate the type of levee chosen.
(i) The conventional earthen bank levee is by far the most common.
(ii) Full or part crib walls may be built when there is limited room.
(iii) Concrete retaining walls (floodwalls) are a viable alternative in urban areas where land space available is limited.
(iv) A roadway may be scaled upward to create a levee, if no other suitable alternative location exists.
(c) Access requirements for a levee must be considered during the design phase of a flood control project.
(i) If there is demand for public access, the design must account for this.
(ii) At the very least, the crest of the levee must be wide enough to accommodate a vehicle for maintenance purposes—this includes signage and on/off ramps.
(iii) Access po...
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(5) Community awareness
(a) The current regulations communicate flawed messages to community members.
(i) No protective measures are necessary to build on land that will not be inundated by the 100-year flood.
(ii) Flood protection is deemed unnecessary in communities protected by levees—there is no financial protection against levee failure.
(b) The universal 100-year flood protection requirement may not be satisfactory.
(i) Construction of new buildings should protect beyond this standard.
(ii) Levee heights built to protect heavily-populated areas should most definitely provide extra protection.
(c) Cost-benefit analysis of levee failure and alternatives should be conducted; benefits for reducing the probability of failure should be included.
(d) A public educated about levees will be more likely to act on evacuation orders during times of extreme flood.
The primary purpose of Friend dam is to help regulate the flow of San Joaquin into available uses of its environmental, wildlife, and farmer’s impacts. The dam controls the flow of water delivery where it needs authorization first before the schedule can release any delivery waters into canals, steam, and wild life habitats. There will be agreements and many protocols to do with it first to avoid unnecessary spilling. There are 5 release schedules which include quantity of water available, time water, flood control requirements, release schedules from storage reservoir above Millerton Lake, and water user requirements. These benefits of flood control, storage management, modification into Madera and Friant-Kern Canals, to stop salty water from abolishing thousands of lands in Sacramento and throughout San Joaquin Delta, as well as deliver masses of water into agricultural lands in 5other counties in the San Joaquin Valley.
New Orleans, Louisiana lies at the second lowest elevation among major cities in the United States. It is a city surrounded by water, making it almost like an island. To counter this dangerous combination of the low elevation along with the lakes, rivers and swamps surrounding it, the Army Corps of Engineers built a series of levees around the city to foster its protection. It is these very same levees however that might doom the city should a Category 3 hurricane ever hit. Our statistical analyses examined the current belief that there is a 39% probability that New Orleans will be hit by a major hurricane and based on the resulting Z-score, rejected that belief. We did find however that the probability, while not 39%, was still in the 30th percentile range, which should still be a major cause for concern among the leaders and residences of the city of New Orleans.
In December 1936 the United States Department of the Interior authorized the Lower Colorado River Authority to construct a low dam at the site of an old crossing on the river known as Marshall Ford. Marshall Ford Dam was completed in 1941 through the collaboration of the United States Bureau of Reclamation (USBR) and the Lower Colorado River Authority (LCRA) of Texas. The original purpose of the dam was to prevent floods from devastating Austin, TX. The capital city had substandard heavy damage from previous floods since its establishment in 1846. Soon bureaucrats came together to create the Colorado River Project, wanting to create a series of dams along the Colorado River to create hydroelectric power and serve to control floods and droughts. With Buchanan dam well under way with a total of six planned Marshall Ford was the only dam designed primarily for flood control and the only dam in which USBR oversaw construction. With money scarce there was debate over the final height dam and it reservoir capacity. This issue resolves itself with the flood of 1938. Once completed Marshall Ford Dam would flood 65 miles of the Colorado to form Lake Travis, creating the largest of the seven reservoirs known as the Highland Lakes.
Rather than working with nature through multi-tiered flood control with spillways and reservoirs, levees disallowed the river to naturally flood, deteriorated the natural ecosystem, and ultimately weakened the city’s defenses against the hurricane (Kelman). Culture and society further interacted, as beliefs in man’s power over nature and racial discrimination promoted levee expansion and racial segregation, creating a city of racially differentiated risk (Spreyer 4). As a result, inundation mostly impacted the lower land neighborhoods that housed poor people of color. Society and nature interfaced in the application of levees that contained nature’s forces. Ultimately, nature won out: the hurricane overpowered the levees and breached the Industrial Canal, disproportionally flooding the mostly black, low-elevation neighborhoods of New Orleans (Campanella
How is the Mississippi controlled ? How & why used ? Benefits Problems Levees Mounds of earth are built parallel to the river, along its banks. These contain the rising river in flood times and protect buildings along the valley on the flood plain behind. · Known & successful technology which follows nature (rivers deposit silt to build natural levees anyway) · Protect settlements ·
Yet this is not the only example of the failure of Mississippi river management. Only 10 years ago, New Orleans’ levies failed, an example of the inability to control the flooding.
They found that various socio-demographic predictors of flood risk impact the difference across flood zone categories. The main residents in inland flood zones are non-Hispanic Black and Hispanic, while coastal flood zones have more higher median income and housing value residents. I considered the study a valuable reference for future flood hazard research and comprehensive public policy making. Social groups with higher vulnerability also tends to stay instead of moving away, for they do not have the affordability for moving to other neighborhood, giving up what they have and almost start from scratch. Thus, they are actually the group of people that suffers the most and paying the most towards natural events. It is also important for the government to create a official help system to improve their resilience.
Van Heerden, Ivor Ll. "The Failure of the New Orleans Levee System Following Hurricane Katrina and the Pathway Forward." Public Administration Review, 67.6 (2007): 24-35.
The fallout of the 1927 flood demonstrates the one of many continuing struggle in dominating the Mississippi River despite understanding the true nature of the river. For example, “The average gauge readings through the last three months of 1926… of the three largest rivers… was the highest ever known… no one at the Weather Bureau or the Mississippi River Commission correlated or even compiled this information” (pg 175). The failure in understand the nature of the river prelude to more elaborate control schemes by expanding the federal government’s responsibility in seizing full control of the Mississippi River from states jurisdiction. The U.S Army Corps of Engineers is fully responsible in constructing va...
By August 28, evacuations were underway across the region. That day, the National Weather Service predicted that after the storm hit, “most of the [Gulf Coast] area will be uninhabitable for weeks…perhaps longer.” New Orleans was at particular risk. Though about half the city actually lies above sea level, its average elevation is about six feet below sea level–and it is completely surrounded by water. Over the course of the 20th century, the Army Corps of Engineers had built a system of levees and seawalls to keep the city from flooding. The levees along the Mississippi River were strong and sturdy, but the ones built to hold back Lake Pontchartrain, Lake Borgne and the waterlogged swamps and marshes to the city’s east and west were much less reliable. Even before the storm, officials worried that those levees, jerry-built atop sandy, porous, erodible soil, might not withstand a massive storm surge. Neighborhoods that sat below sea level, many of which housed the city’s poorest and most vulnerable people, were at great risk of
...e this engineers could have a back up system that would be able to pump out the liguid, one that could use the water as a power source. The engineers could try to make the walls near the water line stronger to prevent flooding. There also should have been a way to detach the drill string that would be more convenient
On August 29, 2005 Hurricane Katrina made landfall on the Gulf Coast of the United States. The storm was measured as a category three hurricane which had reached winds of approximately one hundred and forty miles per hour. The storm had initially measured almost four hundred miles across affecting the areas of Alabama, Mississippi and Louisiana. Of these three affected areas, Louisiana contained the largest amount of damage; however, one city in particular suffered the greatest damage and was the primary focus of this disaster. That was the city of New Orleans. The city of New Orleans was at an incredibly high risk for a few reasons. One reason was that New Orleans was surrounded by significant bodies of water. Each of these bodies of water had contained levees that were built in the twentieth century, where some were stronger than others. Those levees that were not built properly held the greatest risk of being breached and causing treacherous flooding as well. Another factor included New Orleans being located below sea level, which had included the “city’s poorest and most vulnerable pe...
Upon the development of the levees, the lower class (mainly consisting of colored people) was forced to live on low land which was more prone to flooding. These black communities did not have the resources or funds to prevent damage, or repair what had been damaged as a result of the structural racism which forced chronic poverty upon them. This is only one way in which the events of Hurricane Katrina was shaped by structural
Some of the damage done by Hurricane Katrina could have potentially been avoided if protection systems were installed to the proper extents. In Louisiana, “some parts of the metro area continue to lack hurricane protection built to federal standards” (Webster). Had the greater Louisiana area been better protected, it is very likely that more people would have survived and the total cost of the storm been less. Even in areas where levees...
The working document includes repeated references to gravel pit reclamation, including repeated requirements for plans, security de...