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This short test is designed to measure the users’ level of understanding of the basic process that control landform development after using WILSIM. When taken in conjunction with the PRE-TEST it will allow the WILSIM designers to determine how effective the model is as an educational tool.

1. What is the definition of “Runoff”?
A. Water flowing across the land surface (overland flow) during or after a rainfall event.
B. Water infiltrating into the soils or porous rock at the land surface during a rainfall event.
C. “Rain drop splash” that erodes the land surface.

2. What is necessary in order for Runoff to occur across the land surface?
A. Rainfall events must be slow and gentle such that all precipitation infiltrates or soaks into the land
surface or soils.
B. The duration of a rainfall event must be long enough, or produce a sufficient volume of
precipitation to saturate the soils or rock at the land surface such that the excess water will flow
overland (across the land surface).
C. Runoff is only possible if the land surface is completely impermeable to rainfall water (it won’t let
any water infiltrate downward into the soil or rock).
D. Runoff is only possible after torrential downpours of rain.

3. What is the definition of a drainage network or drainage system?
A. A single river channel that flows across the land surface.
B. A series of short unconnected stream segments or gullies that can be seen along a sloping land
C. An integrated branching arrangement of smaller streams joining together to feed larger streams
that then feed one or more main river channels.
D. A random arrangement of streams that may or may not connect and that flow in seemingly
random directions.

4. Concerning the time frame over which drainages develop, why are numerical models
such as WILSIM so valuable?

A. They can compress time so that during a brief model run you can observe the evolution of a
drainage system that would take place over long periods of geologic time.
B. They allow you to explore and appreciate the effects of different factors on landform.
C. They allow you to study the evolution of a drainage system in front of computer
thus eliminate the need to do field work.
D. Both A and B.

5. When flowing water erodes the land surface to create a drainage network, do these
drainages always develop at the same rate everywhere in nature or in a computer

A. Yes.
B. No.

6. What do you think the best definition for “erodibility” would be?
A. The degree to which a surficial material is resistant to erosion by flowing water. Some rock types
and soils are easily eroded and some are very resistant to erosion.
B. The rate at which streams transport eroded sediments down slope or down stream.
C. The degree of steepness for slopes and stream channels in a drainage system.
D. The change in slope from one portion of a drainage to another.

7. The term “Tectonics” refers to which of the following?
A. The form of an entire drainage basin.
B. The slope of the land surface.
C. The process by which drainages form.
D. Deformation of the Earth’s crust and surface which serves to create changes in land surface slope
(such as the formation of mountains and plateaus).

8. Which of the following do you think would be the primary variable that controls the rate
of drainage network development?

A. Climate; including the amount of rainfall and the vegetation cover.
B. Tectonics.
C. The durability of the surface rock or soil and how easily it can be eroded.
D. The steepness of the slope over which the streams flow and erode.
E. All of the above are primary or important variables.

9. WILSIM can also simulate the affects of climate change upon drainage form or
morphology over time (i.e., initially dry then evolving into a wetter climate or vice
versa). How do you think climate change would affect drainage morphology?

A. It would not affect the morphology, only the rate at which the drainage develops.
B. Because the rate at which material is transported downslope to the developing stream changes as
climate changes, the morphology of the drainage as well as the rate of development will change.

10. Define Cross Section in a geographic sense.
A. The statistical distribution (or histogram) of the elevation measurements for many or all points in
a land surface grid.
B. A profile of the elevation along a specific line across the land surface grid.
C. The general surface slope or change in elevation from one point on a land surface grid to another .

11. What is a Hypsometric Curve?
A. A nondimensional curve that essentially describes the relative proportion of a watershed that lies
at or above a given height relative to its total elevation range .
B. The longitudinal profile of elevation along a major stream from its source (highest elevation) to its
mouth (lowest elevation).
C. A measurement of the total volume of sediment eroded from one part of a basin and deposited in
another part.
D. A measure of the sinuosity of a stream channel (measures how curvy the stream channel is).

12. Where in the landscape do you think the deposition (accumulation of eroded and
transported sediments) would most unlikely to occur?

A. In places where the slope is very steep.
B. In places where the slope is very gentle.
C. In places where there is a change in slope from steep to gentle.
D. In places where the stream enters an open waterbody such as lake or ocean.

13. If all variables for two model runs are identical, why do dendritic drainages develop in
different locations and with slightly different morphologies across the landscape grid?

A. Because anisotropy of rock type (variations in erodibility) is an integral part of the program.
B. Because precipitation events (precipitons) occur randomly across the land surface grid through
time so no two model runs will have identical precipitation histories.

14. Can WILSIM effectively model the degree of vegetation cover?
A. Partially, by decreasing the degree of erodibility under wetter climates that would support a
greater protective vegetation cover.
B. Partially, by increasing the degree of erodibility under wetter climates that would support a
greater protective vegetation cover.
C. No, there is no variable to simulate this in the model.
D. Yes, vegetation cover is implicitly modeled within WILSIM under the climate constraints.

15. What do the hypsometric integrals as implemented in WILSIM tell you about the
drainage network and the elevation changes through time?

A. They give you an accurate hypsometry for specific drainage basins within the grid.
B. They can show the changes in elevation due to erosion through time for a specific drainage basin
within the grid that has a uniform slope.
C. They can show the changes in elevation due to erosion and deposition through time for a specific
drainage basin.
D. They supply information on elevation change for erosion and deposition across the entire grid. It
does not measure individual basins nor does it account for sediment transported off of the edge of
the grid.


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