Name:
Fall 2006 Final Exam
Be sure and read each question carefully. Answer on a separate sheet of paper.
Hints: specific
details, facts, quantitative answers will receive full scores. Repeating the question, vague and minimal
responses, obvious guesses will get low scores.
If you are not sure about a question or your answer, ask! (approximate answer lengths: 20 pts = 1 page answer; 10 pts = ½ page
answer; 5 pts = ¼ page answer)
1. (5 pts) Explain how a river’s discharge rating curve is developed, and what it is used for.
2. (5 pts) Explain how a river’s flood frequency curve is developed, and what it is used for.
3. (5 pts) Describe the types and causes of uncertainty in estimating the magnitude and frequency of river floods.
4. (5 pts) Define the Mercalli Index and explain why it is useful for hazard mitigation.
5. (5 pts) Briefly
describe two common water-related hazards in
6. (5 pts) From “The
Big Uneasy” article, give 5 factors which make it difficult to produce an
acceptable rebuilding strategy for
7. (10 pts) USGS seismic hazard maps often give information on a particular region such as:
“accelerations of 8-12% g, with a 10% chance of exceedance over a 100-year time interval”. Explain what this means.
8. (10 pts) List the important lessons learned from the 1994 Northridge earthquake in developing seismic hazard mitigation plans.
9. (10 pts) List the reasons why the Parkfield “earthquake prediction experiment” is so important with respect to the USGS seismic hazard assessments?
10. (10 pts) Should
the southern
11. (10 pts) List the pros and cons of using GIS as part of an overall hazard mitigation strategy.
12. (20 pts) List the
main factors (geological and political) which contributed to the high
vulnerability of the lower
For any river, you can relate the height to the discharge over time, and from this develop a “rating curve” to allow automated, rapid evaluations of river discharge.
-you need a lot of measurements, because most flow tend to bunch around a typical flow. But it’s during the very high flows that you want to see the changes.
-the curve must be constantly revalidated, because there are constant changes in a rivers’ watershed (construction), flow patterns, channel geometry. Also, note that the curve is not a line
2. (5 pts) Explain how a river’s flood frequency curve is developed, and what it is used for.
Compare recurrence with magnitude. Used to predict high flows, or frequency of a given flow level.
3. (5 pts) Describe the types and causes of uncertainty in estimating the magnitude and frequency of river floods.
-the dataset is long enough to establish a consistent trend
-the watershed has not undergone significant changes (diversions, dams, construction)
-the river channel has not undergone significant changes (meander, scouring, levees, straightening)
-the regional climate has not changed significantly over the data period
4. (5 pts) Define the Mercalli Index and explain why it is useful for hazard mitigation.
This categorizes seismic events by their intensity, specifically how it is felt by observers or what effects it has on the environment (motion, damages). This allows long term scale of activity; focuses on damage rather than strength; can be done retrospectively, and in regions which are not instrumented; can use structural effects to help understand seismic events. This is also relatively simple for the public to be involved, and the USGS routinely uses questionnaires after events to gather information which can be used in a GIS, to help understand the spatial distribution of seismic effects.
5. (5 pts) Briefly describe two common
water-related hazards in
Lack of groundwater towards the end of the dry season. Pollution (geothermal, industrial, agricultural) of surface and drinking water.
6. (5 pts) From “The Big Uneasy” article, give 5
factors which make it difficult to produce an acceptable rebuilding strategy
for
-typically only small isolated steps taken in rebuilding; no official, master plan; severe population losses in some areas; reluctance of city officials to make difficult decisions; high risk remains; environmental degradation leaves few natural mitigation; controversy over national funding of a local problem; population density
7. (10 pts) USGS seismic hazard maps often give information on a particular region such as:
“accelerations of 8-12% g, with a 10% chance of exceedance over a 100-year time interval”. Explain what this means.
-acceleration with respect to gravitational acceleration; 10% that this level of shaking will either occur or greater over 100 years. Refers to a particular fault or set of faults. Linear, so that over 200 years it’s a 20% chance. Not based on understanding of seismic processes.
8. (10 pts) List the important lessons learned from the 1994 Northridge earthquake in developing seismic hazard mitigation plans.
Different factors which produced the patterns of damage observed about the known epicenter:
-thrust fault offset ground deformation from the epicenter
-local site amplification very important for damage severity
-soil type, topography, building type/construction affected damage levels
-sedimentary basins (old lakes) act as convex lenses to focus seismic waves
-structure, such as faults and folds
-groundwater, such as faults and folds
-landfill or unconsolidated sediments
9. (10 pts) List the reasons why the Parkfield “earthquake prediction experiment” is so important with respect to the USGS seismic hazard assessments?
This was a study by the USGS, based on the probabalistic prediction that the recurrence rate of the Parkfield fault was 22 years. They instrumented the region heavily, expecting an earthquake around 1988. It did not occur until this year, and also the style of event (size, motion, location) was unexpected. Basically this suggests that there is a lot of error in the prediction methods used, even for a location that was considered to be pretty well understood
10. (10 pts) Should the southern
Weak building codes: unsafe construction, higher risks
Overly stringent building codes: unneeded costs, promoting evasion, and diverting resources from other more pressing areas.
Stein estimates a 10% additional cost to Memphis building would cost over $200 million per year, 10 times higher than FEMA’s estimated annualized earthquake loss in Memphis ($17 million). This is likely too high, because the estimate uses the USGS hazard predictions. FEMA estimates NMHZ buildings 5-10 times less likely to be damaged by earthquakes than in California.
-uncertainties in models not publicized
-poor understanding of earthquake probability
-earthquakes occur at long time scales, so more efficient to replace buildings as they age, than to tear down functional buildings
-statistically, few people in the
-no justification that NMSZ earthquake risks are equal to
those in southern
-no consensus on code changes, so need more discussion
11. (10 pts) List the pros and cons of using GIS as part of an overall hazard mitigation strategy.
-digital, repeatable, easily modified
-cost, need to keep updated, technological difficulty
12. (20 pts) List the main factors (geological
and political) which contributed to the high vulnerability of the lower
-develop a leaky levee system, to replenish the marshes with sediment, nutrients and water.
-construct flood gates across
-close the shipping channel from
-add a new shipping outlet to the southern end of the Mississippi River, facing the west, so that the very end of the river will have a reduced current, allowing sediment deposition and westward transport. This transport will start replenishing the barrier islands and marshes along the Louisiana coast.