1. When New Orleans was drained of water and levees were built to keep new water
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Question
1. When New Orleans was drained of water and levees were built to keep new water from coming in, what happened to the elevation of New Orleans over time?
a. The elevation of New Orleans moved upwards b. The elevation of New Orleans stayed the same c. The elevation of New Orleans moved downwards
2. Which two closest bodies of water does New Orleans sit between and below according to the film?
a. Mississippi River & Lake Ponchartrain
b. Mississippi River & The Gulf of Mexico
c. Lake Ponchartrain & Lake Borgne
d. Lake Ponchartrain & The Gulf of Mexico
e. Mississippi River & the Atlantic Ocean
3. What happens to soil when it has been drained of water?
a. The soil expands.
b. The soil shrinks
4. When New Orleans was drained of water and levees were built to keep new water from coming in, what happened to the elevation of New Orleans over time?
a. The elevation of New Orleans moved upwards
b. The elevation of New Orleans stayed the same
c. The elevation of New Orleans moved downwards
5. How have the wetlands where the Mississippi River enters into the Gulf of Mexico been reduced in size?
a. Sediment starvation due to construction of levees
b. Too much sediment due to destruction of levees
c. Sediment starvation due to destruction of levees
d. Too much sediment due to construction of levees
6.Why does the reduction of wetlands along the Gulf Coast put New Orleans at greater risk from storm surge? Choose the best answer:
a. Wetlands block hurricane winds
b. Wetlands soak up water, thereby lowering the surge level
c. Wetlands actually increase storm surge, so a reduction would actually benefit New Orleans in the long run
7.At what elevation does Africa Brumfield’s home in New Orleans sit at? At what elevation does Lisa Monti’s home in Bay St. Louis sit at?
a. 4 feet above sea level/20 feet below sea level
b. 12 feet above sea level/20 feet below sea level
c. 10 feet below sea level/4 feet above sea level
d. 12 feet below sea level/20 feet above sea level
8. Why did the levy’s fail at the lower 9th ward?
a. Overtopping
b. Undermining
9.Why did the levy fail at the 17th Street and London Avenue canals?
a. Overtopping
b. Undermining
10. Of the choices given below, which one is one of the proposed ideas given at the end of the film to prevent a disaster like Katrina from happening in the future in New Orleans?
a. Let the Mississippi River run wild once again – Remove the levees
b. Reduce our carbon footprint to prevent global warming from raising sea level
c. Build a large sea wall where the wetlands were once located
d. Put homes on larger foundations so that they will sit higher than any potential flood waters
Explanation / Answer
1. Levee is the mound of sediments or embankment build to prevent the inflow of water to the surrounding areas and hence prevent flooding. When the height of a levee is raised then it should also be widened since the sediment cannot hold to the steep slopes and will collapse eventually. In the case of New Orleans the poorly constructed levees result in their erosion over a period of time and result in flooding of the New Orleans. The main cause of this flooding was the subsidence caused by the compaction of the river deposited sediments. So over a period of time the elevation of the New Orleans is decreasing with the soil subsidence which increase the intensity and level of flood every time.
2. The central portion of the New Orleans is completely surrounded by water. In the north of New Orleans lies the lake Pontchartrain and the Mississippi river to the south and to the east it is surrounded by Lake Borgne and towards the west and east it is surrounded by wetlands. The two closest body of water in which New Orleans lie in between and below are the Mississippi river and the Lake Pontchartrain. The New Orleans is in constant threats of floods from these water bodies.
3. When the water is drained from the soil it will compact due to squeezing of water molecules from it and its volume its will reduce. So the soil will shrink. The shrinkage of soil will depend on how much the volume of water the soil originally contain.
5. The wetlands where the Mississippi river enters the Gulf of Mexico is reducing in size. Though there is abundance of river water sediments as well as fresh water into the Mississippian delta but the delta growth has been truncated in the past decades. This is construction of levees which have been built to protect the coastal areas from the flooding. But these have resulted in cutting the deposition of sediment in most parts of the delta. So there is sediment starvation in the delta region due to construction of levees.
6. The wetlands act as a barrier for the incoming hurricane winds towards the land. They will slow the speed of hurricane winds by 5-40 % depending upon the storm and the storm will die down quickly and will not travel much distance inland. Since the wetlands are rapidly decreasing along the Mississippian river, in the absence of the wetlands these hurricanes will make disastrous impact on the nearby coastal areas. So the wetlands block hurricane winds
8. The lower ninth ward borders the Mississippi area towards the south and the St Bernard Parish to the east and towards the west is the Industrial canal. When the hurricane Katrina breaches the levees it overtops or rises above the level of the levee and erodes the base of the embankment causing them to collapse which flooded the area. So the main cause of lower ninth yard failure was the overtopping
8 .Similarly the 17th street and London Avenue also fail during the surge of hurricane Katrina. The surge of the hurricanes breach the storm wall, it overtops the levees and erodes its base underneath. The main factor which is responsible for the failure of these levees is also the phenomenon of overtopping.
10. The construction of levees is also an important factor which increases the impact of hurricane like Katrina. The surge of storm water overtops the levees and cause flooding in the area. Also the construction of levees prevent the deposition of sediment deposition and development of marsh which act as a barrier to the hurricane winds and can considerably reduce the speed of the hurricane wind penetrating inland. In the absence of marsh due the impact of the hurricane is increased several times. So to reduce the impact remove the levees and let the Mississippi river becomes wild again.
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