Deck 14: Viewshed and Watershed Analysis

Question 1

The basis for viewshed analysis is called the line of sight operation:

Answer 1

True

Question 2

Which of the following can affect the result of watershed analysis?

A) Flow accumulation threshold
B) both DEM resolution and Flow accumulation threshold
C) Flow direction method
D) DEM resolution
E) all of these are correct

Answer 2

all of these are correct

Question 3

A higher resolution DEM will result in a ______ stream network:

A) denser
B) less dense

Answer 3

denser

Question 4

List three parameters, which one can experiment in viewshed analysis.

Question 5

The D8 method for deriving flow directions is most effective in steep terrain with well-defined channels.

Question 6

A cell value of zero in a flow accumulation raster indicates that the cell is located on a:

A) flat area
B) stream
C) ridge

Question 7

A stream link raster has a unique ID value for:

A) each stream outlet
B) each stream junction
C) each named stream
D) each stream segment between two junctions

Question 8

To generate area-wide watersheds from a DEM, we must create several intermediate rasters. Draw a flow chart that starts with the DEM, followed by the intermediate rasters, and ends with the watershed raster.

Question 9

Viewshed analysis can be performed using:

A) a TIN
B) an elevation raster
C) both an elevation raster and a TIN

Question 10

A larger viewing radius will result in a larger viewing area.

Question 11

A threshold value is needed for converting a flow accumulation raster to a stream network raster. How should one choose the threshold value?

Question 12

Define a flow accumulation raster.

Question 13

Define "cumulative viewshed."

Question 14

What input data do you need for viewshed analysis?

Question 15

In ArcGIS, the parameters for viewshed analysis such as viewing azimuth are set up as attributes in the viewpoint data set.

Question 16

You are recommended to fill sinks in the input DEM before performing watershed analysis on it. What are sinks?

Question 17

Explain the D8 method for deriving a flow direction raster.

Question 18

Define "watershed analysis."

Question 19

Define a reverse viewshed analysis.

Question 20

A higher threshold value applied to a flow accumulation raster typically result in a ______ stream network:

A) less dense
B) denser

Question 21

A filled DEM means that:

A) None of these is correct
B) An elevation value has been filled for each cell in the raster.
C) Sinks have been removed from the raster.
D) Cells with 'no data' have been removed from the raster.

Question 22

How can the viewing azimuth affect the result of a viewshed analysis?

Question 23

If you have 2 observation points for a viewshed analysis, the output raster from ArcGIS will have ____different cell values:

A) 4
B) 1
C) 3
D) 2

Question 24

Which of the following statements is true about watershed analysis?

A) All of these are correct.
B) Watersheds may be truncated along the study area boundary.
C) Watershed analysis can take place at different spatial scales.
D) Delineation of watersheds can be area-based or point-based.
E) Both watershed analysis can take place at different spatial scales and watersheds may be truncated alond the study area boundary.

Question 25

A viewing azimuth of 180°will cover a larger viewing area than a viewing azimuth of 45°.

Question 26

Describe an application example of viewshed analysis.

Question 27

How can the viewing radius affect the result of a viewshed analysis?

Question 28

ArcGIS offers different algorithms for calculating flow direction including D8 and D?.

Question 29

How is viewshed analysis run along a linear feature (e.g., a scenic highway)?