Quiz 7 Flashcards
What is one problem with relying on levees and/or flood walls for protection from flooding?
One problem with relying on levees/flood walls is that eventually they will all fail, and that currently most of the levees/flood walls are not up to current building standards
How/why does channelization work to reduce flooding in urban areas?
Channelization is the process of straightning, deepening, and possibly widening the channel of the river. This is done some more water can flow through the river before flooding starts. The problems with this is that it can create really fast currents that can be deadly, like with the Los Angeles River.
Discuss two sensible land uses that floodplains should be zone for, and explain why these land uses are “sensible”?
One sensible land use is for parks, this is because parks have very little infrastructure to them and can be easily abandoned during a flood. A second possible land use is for grazing, because when it floods you just don’t let the animals graze in that location.
Although costly, why is the Federal Emergency Management Agency’s (FEMA) buyout program better than federally-funded structural protections (dams, levees, flood walls) to flooding?
FEMA’s buyout program is better the federally-funded structural protections because the area is just abandoned and they won’t incur future costs due to floods.
How does FEMA’s buyout program work?
The buyout program is a completely voluntary program where the owner’s house is appraised at it’s preflood value and the owner is given that value for their home. Then the owner has to agree to not purchase another home on the floodplain again, and that place hast to remain open forever.
Why are detention basins now required in new subdivisions in Cedar Falls?
Detention basins are required in new subdivisions, because they slow the amount of water coming out of a river/creek after periods of intense rainfall. This helps to reduce downstream flooding.
Why are stream terraces better sites than floodplains for locating cities, railroads, and highways?
Stream terraces are safer places to live because they are relatively flat and higher above the river than the floodplain. So most high terraces don’t get flooded
What are two reasons why floodplains are ideal sites for agriculture?
They are excellent for agriculture because they are relatively flat, and have silt rich stream deposits that are good for growing crops.
Describe two ways that Lake Mead behind Hoover Dam is useful to people in the southwestern U.S.
Lake Mead is useful to people in the southwester part of the US because it provides recreatioal activities for the people in the area, and it also provides their drinking water.
Why did Des Moines go without a drinkable water supply for almost a full month in 1993? How could it have been prevented?
The building flooded and the pumps stopped working. The my could have prevented this by not building the water treatment facility on a flood plain
Detail the steps involved in forming glacial ice.
To form glacial ice, it must be in an area where snow falls faster then it melts. Then as the snow accumulates on the glacier it compacts and turns into ice.
List where are two continental ice sheets are present today.
Greenland, Antartica
How do glacial kettles form? List a place in the Upper Midwest where kettles are found.
As a glacier retreats it leaves behind blocks of ice, Then that block of ice gets buried in glacial out wash, and as the ice melts it creates a small depression called a kettle. These can be found in Story county Iowa
List a landform (not a place where it is found) created by a continental ice sheet that is mined. Describe how the glacial landform you have listed above naturally formed. How do humans make use of the glacial deposits mined from the landform?
A valley train carries glaciofluvia sediment away from resessional or terminal morraines and deposit them further away and confined to a valley. These are mined for their gravel which can be used to help build roads.
How did the Loess Hills in western Iowa form? Be sure to include all the steps related to the formation of loess, not just the depositional stage.
During the Ice Age, glaciers advanced down into the mid-continent of North America, grinding underlying rock into a fine powder like sediment called “glacial flour.” As temperatures warmed, the glaciers melted and enormous amounts of water and sediment rushed down the Missouri River valley. The sediment was eventually deposited on flood plains downstream, creating huge mud flats.During the winters the melt waters would recede, leaving the mud flats exposed. As they dried, fine-grained mud material called silt was picked up and carried by strong winds. These large dust clouds were moved eastward by prevailing westerly winds and were redeposited over broad areas. Heavier, coarser silt, deposited closest to its Missouri River flood plain source, formed sharp, high bluffs on the western margin of the Loess Hills. Finer, lighter silt, deposited farther east, created gently sloping hills on the eastern margin. This process repeated for thousands of years, building layer upon layer until the loess reached thicknesses of 60 feet or more and became the dominant feature of the terrain.
