River Flooding Research

Statement 1
Refers to which river, A or B
Statement 2
Refers to which river, A or B
Explanation for answer
1
There is a dam across the river
B
There is no dam across the river
A
Rainfall on River B takes a long time to get discharged downstream because it is kept back and stored in a reservoir for a period of time before being released through the dam and able to go further downstream; however, whereas on River A there is a nothing to impede the flow of the water straight down the river
2
A rural area
B
An urban area
A
Urban areas have increased impermeable surfaces increasing surface runoff and reducing lag time. Peak discharge is increased. A at an urban area while B rural

3

An area of steep slopes

A

An area of gentle slopes

B

Steep slopes have low infiltration. Runoff to rivers also streams is increased. Gentle slopes have high infiltration, slowing surface runoff therefore increasing lag time.

4

An area with low drainage density

A

An area with high drainage density

B

Areas with high drainage densities have limited infiltration promoting significant runoff. Low drainage densities area have high infiltration, therefore high runoff. High drainage densities have shorter lag time and the peak discharge is big

5

An area of sandstone

B

An area of granite

A

Areas with impermeable rocks has less infiltration also more surface runoff reducing lag time. Granite is impermeable

6

An area that experiences the precipitation in a short torrential downpour

A

An area that experiences the precipitation as a long period of steady drizzle

B

High downpour increases the amount of water over a very short time. This increases the peak discharge.

7

An area of light vegetation/scrubland in the summer

A

An area of mature deciduous woodland in the summer

B

If the area is bare, there will be limited interception increasing surface runoff. Lag time is reduced and peak discharge increased

8

An area where the soil is not saturated

B

An area where the soil is saturated

A

Saturated ground has limited infiltration and more surface runoff. Surface runoff reduces lag time and increases the peak discharge

9

An area in a mild, dry fall

A

An area in the spring after heavy snow

B

When the snow melts the discharge increases. This will be for a short time and therefore lag time increases.

10

A mature deciduous woodland in the summer with +20°C temperatures

A

A mature deciduous woodland in the winter with +5°C temperatures

B

Humid vegetation encourages extensive vegetation cover encouraging infiltration through interception explaining why River A receives less surface runoff.

(Hartanto et al., 2003)

Reference

Hartanto, H., Prabhu, R., Widayat, A. S., & Asdak, C. (2003). Factors affecting runoff and soil erosion: plot-level soil loss monitoring for assessing sustainability of forest management. Forest Ecology and Management, 180(1), 361-374.