Chapter 17 (GEOL107)

Identify the true statement. Choose one: A. A 200-year flood has a recurrence interval of, on the average, once every 200 years. B. Two 100-year floods cannot occur in the same year (or in consecutive years). C. An annual probability of 4% means that there's a 1 in 4 chance that a flood of some given size will happen in any given year. D. The size of a flood and its recurrence interval are inversely related; the larger the flood, the shorter its recurrence interval.

A. A 200-year flood has a recurrence interval of, on the average, once every 200 years.

Which of the following statements is true? Choose one: A. A stream is any channelized body of running water. B. A stream that swings back and forth in snake-like curves is called a braided stream. C. The efficiency of downcutting depends on the velocity of stream flow, not the strength of the substrate. D. A meander bend that gets cut off from the stream is called a point bar lake.

A. A stream is any channelized body of running water.

Which of the following was the location of a flash flood caused by over 19 cm of rain in about an hour's time? Choose one: A. Big Thompson River, Colorado, 1976 B. Indonesia, 2007 C. Bangladesh, 1990 D. Yangtze River, China, 1931

A. Big Thompson River, Colorado, 1976

Identify the statement that is true about an ephemeral stream. Choose one: A. In dry climates, it can become a dry wash (also called wadi or arroyo). B. It is replenished by both precipitation and groundwater. C. It flows year-round. D. Its bed lies below the water table.

A. In dry climates, it can become a dry wash (also called wadi or arroyo).

Which of the following would be a poor choice for land use in a floodplain? A. a sewage treatment facility B. agricultural lands C. a golf course D. public soccer fields and recreational lands E. a forest preserve

A. a sewage treatment facility

Waterfalls Choose one: A. may form where movement along a fault has produced an escarpment. B. form when water gently spills over a gradual ledge, hugging the rock wall. C. may be found where a stream crosses an easily eroded ledge of rock. D. last for millions of years.

A. may form where movement along a fault has produced an escarpment.

Fluvial landscapes that are early in their evolutionary progression have Choose one: A. narrow, deep valleys. B. broad floodplains. C. natural levees. D. oxbow lakes.

A. narrow, deep valleys.

Which of the following statements is true? Choose one: A. Water from trunk streams flows into tributaries. B. Stream flow is fastest in the center of the channel near the surface. C. A shallow stream is less turbulent than a deep stream. D. The slowest-moving part of a stream is called the thalweg.

B. Stream flow is fastest in the center of the channel near the surface.

Which of the following statements about the hydrologic cycle is true? Choose one: A. Headward erosion causes sheetwash. B. There is an exchange of water among oceans, land, and atmosphere. C. Water that manages to infiltrate the land is lost to the cycle. D. Surface snow and ice are not part of this cycle.

B. There is an exchange of water among oceans, land, and atmosphere.

Streams come down out of steep areas (like mountains) onto much flatter land, lose velocity, and drop material in triangular-shaped structures called Choose one: A. levees. B. alluvial fans. C. deltas. D. point bars.

B. alluvial fans.

The total load that a stream can carry is called its Choose one: A. course. B. capacity. C. reach. D. competence.

B. capacity.

A typical longitudinal profile of a stream Choose one: A. is roughly a convex-up curve. B. illustrates that a stream's gradient is steeper near its headwaters than near its mouth. C. shows a cross section of the stream from bank to bank at one particular site. D. shows almost horizontal plains near the stream's headwaters and deep valleys near its mouth.

B. illustrates that a stream's gradient is steeper near its headwaters than near its mouth.

Deltas Choose one: A. make poor farmland because they flood regularly, and flooding leaches out the minerals. B. received their name because some have a triangular shape, but many don't. C. may form where a stream empties into a valley bottom at the base of a mountain range. D. are likely to slowly sink and become swampland called a bird's-foot delta.

B. received their name because some have a triangular shape, but many don't.

If a flood has a five-year recurrence interval, what are the odds of it occurring in an one year? A. 5% B. 50% C. 20% D. 10% E. 0.5%

C. 20%

Which of the following statements is true? Choose one: A. Floodplains are hazardous areas and should be avoided when considering where to put farmlands. B. If a dam is constructed properly, it will not change the ecosystem of the area it's in. C. Early civilizations of Egypt, India, and China were established in river valleys and on floodplains. D. Use of the waters of major rivers, like the Colorado River, has not affected their size or discharge.

C. Early civilizations of Egypt, India, and China were established in river valleys and on floodplains.

Incised meanders Choose one: A. form when base level remains stable for long periods of time. B. are demonstrating a feature of stream immaturity (meanders) in a mature setting (steep walls). C. can result from either superposed or antecedent stream activity. D. develop when the stream gradient is steepened or discharge decreases.

C. can result from either superposed or antecedent stream activity.

The total sediment load of a stream includes Choose one: A. surface load. B. rolling load. C. dissolved load. D. saltation load.

C. dissolved load.

A drainage network Choose one: A. drains water directly into the ocean. B. is a trunk stream that cuts across a resistant ridge. C. is an interconnected group of streams that collects water over a large area. D. is considered a trellis network when rivers flow over uniform substrate with a gentle slope.

C. is an interconnected group of streams that collects water over a large area.

Identify the true statement about drainage divides. Choose one: A. Precipitation that falls on the west side of the continental divide flows to the Gulf of Mexico and the Atlantic Ocean. B. The divide that runs along the crest of the Appalachians separates the Atlantic Ocean drainage from the Arctic Ocean drainage. C. The ultimate base level for streams on the east side of the continental divide is the Pacific Ocean. D. A drainage divide is a ridge that separates one watershed from another.

D. A drainage divide is a ridge that separates one watershed from another.

The largest river in the world, on the basis of discharge, is the Choose one: A. Mississippi River. B. Congo River. C. Yangtze River. D. Amazon River.

D. Amazon River.

The Mississippi Delta Choose one: A. is a recent landform, since it formed within the last 1,000 years. B. developed its shape because the ocean current there was stronger than the river current. C. exhibits the traditional delta (Δ) shape. D. is the product of several avulsions.

D. is the product of several avulsions.

The discharge of a stream is Choose one: A. constant for the length of the stream. B. calculated by dividing its cross-sectional area by its velocity. C. typically lower in spring than during the summer. D. likely to decrease downstream in arid regions and increase downstream in temperate regions.

D. likely to decrease downstream in arid regions and increase downstream in temperate regions.