Flooding Flashcards
1
Q
- A stream may overflow its banks when the its ability to carry water is overwhelmed by the sheer volume of water flowing off the landscape and create what is known as a?
A
Flood
2
Q
- Provides information about a river or stream by simply plotting the discharge versus time.
A
Stream hydrographs
2
Q
- Its a process where water flows through stream channels
A
Run off
2
Q
- This is the amount of time for water to move across the landscape and into channels
A
Lag time
2
Q
- This is the discharge of groundwater into the surface environment
A
Groundwater Baseflow
2
Q
- Precipitation reaching the land surface moves downslope in thin sheets
A
Overland flow
3
Q
- This term is often applied to the larger stream that serves as the principal channel within a drainage system.
A
River
3
Q
- Continuous input of groundwater baseflow allows streams in many areas to keep flowing at some minimum level, often called ________.
A
Baseflow Condition
3
Q
- These are a result of less deep infiltration in arid areas resulting in a water table that is below the level of most stream channels.
A
Losing Streams
3
Q
- High precipitation allows more water to infiltrate to the water table which causes the water table in humid regions to be higher than the streams channel, thereby forcing groundwater to flow into streams. Such streams are often referred as ?
A
Gaining Streams
4
Q
- In a losing stream, where do water flows into?
A
Groundwater system
5
Q
- It is a network of stream channels where merging tributaries (smaller of any two merging channels) form progressively larger streams.
A
Drainage system
6
Q
- Individual systems are separated from one another by a topographic high or crest in the landscape called a?
A
Drainage divide
7
Q
- The upper portion of the drainage system is called the __________ , whereas the ____________ is found in the lower part of the system where a river empties into an ocean, lake, or another river.
A
headwaters;
mouth
8
Q
- Based on discharge, what is the largest river in the world?
A
Amazon River
9
Q
- What is the 2nd largest water basin in the Philippines? what is its total land area?
A
Mindanao River Basin;
21, 503 km2
10
Q
- These are any smaller streams that feed larger streams within a drainage basin.
A
Tributaries
11
Q
- A method of classifying or ordering the hierarchy of natural channels.
A
Strahler Stream Order
12
Q
- ____________ correlates well with drainage area, but is also regionally controlled by topography & geology.
A
Stream Order
13
Q
- Reflects downstream trade off between discharge and slope in setting transport capacity (and thus ability to move sediment and incise rock).
A
Longitudinal Stream Profile
14
Q
- The level below which a river or stream cannot incise.
A
Base level
15
Q
- What is the formula for Drainage density?
A
Total stream channel length (l) OVER the area of the drainage system(A)
16
Q
- Steep terrain tends to be highly
dissected and thus have ______________________.
A
high drainage density
17
Q
- High drainage density but
small source areas. Location: ____________________
A
Mancos Shale Badlands, Utah
18
Q
- High drainage density, small source areas in the PH. Location:
A
Rill field, Mt. Pinatubo, Philippines
19
Q
- types of DRAINAGE PATTERNS
A
Dendritic;
Parallel;
Trellis;
Rectangular;
Radial;
Annular;
Multibasinal;
Contorted;
20
Q
- Most commonly formed on horizontally bedded and uniform sediments or on uniformly resistant crystalline rocks.
A
Dendritic
21
Q
- Usually develops on moderate to steep slopes, but also where regional structure, such as outcropping resistant rock bands, are elongated and parallel.
A
Parallel
22
Q
- Patterns most commonly on dipping or folded sedimentary or weakly metamorphosed sedimentary rocks; also areas of joints and faults which intersect with right angles and old sand dunes with parallel alignment
A
Trellis
23
Q
- Usually have a more or less perpendicular turns mainly caused by criss-crossing fractures.
A
Rectangular
24
Q
- Occurs around domes or cones, and particularly common on volcanic areas
A
Radial
25
Q
- Patterns also develop around domes, where there exists alternating resistant and weak beds, so that the major channels cut through the strike and the low order streams follow the dip of the rocks.
A
Annular
26
Q
- Are loose rock particles/sediments deposited on a stream.
A
Alluvium
27
Q
- One of the key factors in a stream’s ability to erode the landscape is the?
A
Velocity of the water
28
Q
- Are unstable overhang located at the outer bank which is produced by the velocity increase on the outer bank which subsequently enhances the ability of the water to cut (erode) into the bank.
A
Cutbanks
29
Q
- On the inner bank where velocity decreases, sediment tends to accumulate and form a deposit known as a ____________.
A
Point bar
30
Q
- Downcutting by streams is not performed by the water
itself, but rather by the sediment that physically scrapes
or wears away rock in a process called _____________.
A
Abrasion
31
Q
- Sea level is often referred to as the?
A
Ultimate base level
32
Q
- The process whereby water separates sediment grains based
on their size, shape, and density is called?
A
Hydraulic Sorting
33
Q
- Describes the fraction of solid particles that is in a suspended state and moving at the same velocity as the water— suspended material is what makes streams appear muddy.
A
Suspended Load
34
Q
- Consists of sediment particles that roll, bounce, or remain stationary on the streambed.
A
Bedload
35
Q
- These are mound-shaped channel deposits consisting of sorted material ranging in size from boulders to coarse gravel to fine sand.
A
Bar
36
Q
- Are large fan-shaped deposits that form where steep mountain streams empty out onto valley floors at the mouth of rivers.
A
Alluvial fan
37
Q
- Streams also transport considerable amounts of dissolved ions (charged atoms) in what scientists refer to as the
A
Dissolved Load
38
Q
- Are formed when a river enters a lake or ocean and splits into smaller channels and begins to deposit sediment due to a decrease in velocity.
A
Delta
39
Q
- Based on the maximum yearly discharge, a _______________ can be calculated for each value, which represents the frequency a particular discharge value can be expected to repeat itself.
A
recurrence interval
40
Q
- The ability of the ground to absorb water, referred to as ______________, plays a critical role in flooding because water that is unable to infiltrate is generally forced to move as overland flow.
A
infiltration capacity
41
Q
- Because small channels are more abundant in the upper parts of a basin, flash floods are also referred to as ________________.
A
upstream floods
42
Q
49.
A
43
Q
50.
A
44
Q
51.
A
45
Q
52.
A
46
Q
53.
A
47
Q
54.
A
48
Q
55.
A
