Chapter 8 Runoff Discharge Flashcards

1
Q

Rain and snowmelt water take various paths to streams. Each path contributes differently to;

A
  • peak and timing of storm runoff
  • erosion
  • transport of chemicals into streams
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Planners need to understand runoff processes to;

A
  • identify the area contributing to runoff generation
  • assess the impact of deforestation, road construction, and other landuse change on runoff characteristics
  • evaluate the risk of stream pollution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Path 1:

A

Horton overland flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Path 2:

A

groundwater flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Path 3

A

shallow subsurface storm flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Path 4:

A

Saturation overland flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Infiltration capacity decreases as

A

the soil gets wet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Overland flow occurs when

A

rainfall intensity exceeds infiltration capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Infiltration capacity …………………considerably within a ………………depending on ………………………… and ………………………………

A

varies

catchment

soil types and vegetation cover

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Horton overland flow may occur in

A

localized areas within the catchment; partial-area concept.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Horton overland flow is rare in

A

vegetated humid region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

. Horton overland flow is rare in vegetated humid region. It is common in areas

A

devoid of vegetation such as;

  • semi-arid rangelands
  • compacted soil, e.g. logging roads
  • paved urban area, e.g. parking lots
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

subsurface storm flow (SSSF)

A

During the storm, the water table near the stream rises rapidly and increases the volume of groundwater flow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If a low permeability layer exists at some depth,

A

water accumulates above this layer and flows horizontally toward the stream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Subsurface storm flow generates …………………….. than ………………………..

A

lower volume of runoff than Horton overland flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Runoff to rainfall ratio is usually

A

less than 20%

17
Q

Most of the rain is stored in ……………………and is …………………..to ……………………………..

A

the sediments

released slowly

supply steady base flow

18
Q

If the rainstorm is large enough, the water table near the stream

A

rises to the ground surface

19
Q

return flow (RF).

A

Groundwater seeps out from the ground surface and generates overland flow.

20
Q

This Groundwater seeps ………..from the ground surface and generates …………………………is called return flow (RF)

A

out

overland flow

21
Q

The rain falling on the saturated area cannot infiltrate because

A

groundwater flow direction is upward under the area.

22
Q

Direct precipitation onto ………………………..also generates overland flow.

A

saturated areas (DPS)

23
Q

The combination of RF and DPS is called

A

saturation overland flow.

24
Q

Before a storm, saturated areas are limited to

A

the close vicinity of the stream.

25
Before a storm, saturated areas are limited to the close vicinity of the stream. They ................during the storm resulting in ..............................................
expand larger rate of runoff generation
26
Before a storm, saturated areas are limited to the close vicinity of the stream. They expand during the storm resulting in larger rate of runoff generation some areas also ................ and ....................................
expand and contract seasonally
27
In arid and semi-arid regions with ...........................and those disturbed by .................................
scarce vegetation humans (urbanization, logging, etc.)
28
In arid and semi-arid regions with scarce vegetation and those disturbed by humans (urbanization, logging, etc.), infiltration capacity is ............................ and .............................. is a dominant process
a limiting factor Horton overland flow
29
infiltration capacity is a limiting factor and Horton overland flow is a dominant process. This also happens when the top soil is
frozen
30
In most humid regions, ..................................... and .......................................are dominant processes.
subsurface storm flow and saturation overland flow
31
Where the soils are .................., ...............and ..............................., the water table is deep and the saturated zone is confined to the...........................
well-drained deep very permeable valley floor
32
Where the soils are well-drained, deep and very permeable, the water table is deep and the saturated zone is confined to the valley floor. ..................................is less important than .................................in this situation.
Saturation overland flow subsurface storm flow
33
Where the soils ...................................................................., and slope is ...................................................................,the water table is shallow and the saturated zone expand readily.
are thin and only moderately permeable gentle and concave shaped
34
Where the soils are thin and only moderately permeable, and slope is gentle and concave shaped, the water table is shallow and the saturated zone expand readily. ........................................dominates in this situation.
Saturation overland flow
35
Modification of the land surface during urbanization changes
the type and magnitude of runoff processes.
36
Modification of the land surface during urbanization changes the type and magnitude of runoff processes. Covering parts of.................................. increase .........................................................
the catchment with impervious roofs and concrete lots increases the volume and rate of Horton overland flow.
37
Planners have to design............................to accommodate increased runoff.
detention ponds
38
.......................... and.........................convey runoff rapidly to stream channels.
Gutters and storm sewers
39
The channels are ..............................and......................... to increase the efficiency, so that they transmit the flood wave .............................more quickly.
straightened lined with concrete downstream