Reference no: EM133663071

Assignment:

MyTown has experienced an extended drought that has resulted in significantly less than average rainfall (and winter snowpack in nearby mountains) for 8 out of the last 10 years. As a result, MyReservoir has dropped more than 20 feet (6 m) below its full level a decade ago and MyMayor's office has announced plans to institute water-rationing measures (no car washing at home, no watering of lawns except on every other Tuesday, etc.).

However, MyTown residents have recently heard about record rainfall in California after a decade-long drought there, which rapidly filled a very large reservoir and threatened its dam with overflowing and possible collapse. Such a collapse would have resulted in catastrophic flooding downstream. Residents are now worried about such a future event happening to MyDam. They ask you to consult with the local hydrological engineering firm of Chavez, Washington and Stein (CW&S) to determine which areas around MyTown are at risk if the dam were to collapse.

By evaluating the volume of water in MyReservoir, and assuming the worst-case total collapse of MyDam, you and the CW&S team have determined a maximum floodwater depth of approximately 40 feet (12 m) above the streambed would occur in MyCreek south of MyTown.

Based on your studies in GLG 101, using the map and diagram provided, answer these questions:

1. What is the elevation of the bed of MyCreek immediately south of MyTown? What is the elevation of downtown MyTown? Hint: Use the elevation lines (contours) on the map, which give elevations in feet.
2. If MyDam totally collapses and floodwaters reach a maximum of 40 feet (12 m) above the bed of MyCreek, would flooding be expected in downtown? Explain.
3. Where on the map would be safe from this flooding?
4. MyDam is constructed of reinforced concrete. The dam in California that was recently threatened by flood waters is earthen (made of dirt and rocks packed together). Would MyDam be easier or harder to erode when overtopped with floodwaters? Why?
5. If planners knew several days in advance that a very large storm (that might overfill MyReservoir) was on its way, what is one thing they could do with MyDam and MyReservoir to make overtopping of the dam by waters from the upcoming storm LESS LIKELY? Hint: Think about the water level in the reservoir prior to the storm.
6. If the reservoir (full, before it drained) had a length of 2 km, an average width of 1 km, and an average depth of 15 m, what was the total volume of water (in m3) that drained out? Hints: Assume the entire reservoir emptied. Volume = length x width x depth. Be sure to convert all units to meters (m) before you multiply. 1 kilometer (km) = 1000 meters (m).
7. If it took 41 mins and 40 seconds for the entire reservoir to empty, what was the average discharge/flow rate (in m3/s) during the flood? Hint: It's the total volume (in m3) divided by the time (in s). Be sure to convert your total time into seconds (s) before you divide! 1 minute = 60 seconds.
8. Extra credit/bonus (+1 pt): How does this discharge/flow rate compare (expressed both as a % and as a reduced fraction) to the average discharge/flow rate of the Mississippi River through St. Louis (approximately 4300 m3/s)? Please round to the nearest whole percentage point (no decimals).