Fluvial Geomorphology 1

Question 1

fluvial geomorphology=

Answer 1

the long-form study of running water

Question 2

What are the 3 zones of running water?

Answer 2

zone 1: headwaters
zone 2: mainstream
zone 3: delta/ estuary

Question 3

How might rivers (any channel of running water) develop?

Answer 3

1. precipitation or snow melt
2. sheets of water across a plane
3. rills form (start of channels!)

eventually= gullies/ rivers

Question 4

Fluvial geomorphology focuses on the ___, ___, and ___ of sediment

Answer 4

erosion, transport, and deposition

Question 5

The amount of runoff (overland surface flow) and thus surface erosion depends on 3 things:

Answer 5

1. precipitation intensity (rate and duration)
2. infiltration rate (subsurface)
3. connectivity

Question 6

Surface water hydrology=

Answer 6

the study of the hydrological cycle involving water at the earth’s surface

Question 7

Vadose vs phreatic zone?

Answer 7

vadose= zone above the water table

phreatic zone= the part of an aquifer, below the water table, in which relatively all pores and fractures are saturated with water (saturated)

Question 8

give 7 factors affecting run-off vs infiltration?

Answer 8

1. sediment/ lithology: grain size, porosity
2. vegetation/ water bodies: evapotranspiration, root depth, leaf density
3. precipitation intensity/ durations (saturating the subsurface)
4. Climate: arid, temp, prev ground saturation
5. slope/ topography
6. land use (pavement, deforestation, mining, storm surges)
7. structures like joints, roots, permeability (eg karsts)

Question 9

T/F
average annual runoff is higher in areas where average annual precipitation is high

Answer 9

true

because ground becomes saturated, so more runoff

Question 10

Once channelized flow exists, why might you want to measure it? Give 2-4 reasons

Answer 10

1. policy (water use, agriculture, etc)
2. erosion rates
3. water quality
4. chemodynamics

Question 11

In a hydrograph:
- through flow= _____
- base flow= ____ ___

Answer 11

interflow

groundwater flow

Question 12

storm flow=

Answer 12

overland flow + through flow

Question 13

what are some key considerations for long-term use in regards to discharge rating curves?

Answer 13

shifts in bed morphology!

Question 14

Recurrence Interval (RI)=

Answer 14

the recurrence of a particular discharge over time
- measured as a mean frequency over a Q record duration

Question 15

What are the 2 types of flood frequency analysis?

Answer 15

1. annual duration
2. partial duration

Question 16

annual duration flood frequency analysis=

Answer 16

each record-year’s peak discharged is considered in the analysis as the “annual maximum flood” (AMF)

Question 17

partial duration flood frequency analysis=

Answer 17

max discharge of “n” events (peaks) over some threshold
- this timeseries analysis method may include more than one peak Q in a single year
- “Peaks-Over-Threshold” (POT)

Question 18

How do you calculate the Recurrence Interval?

Answer 18

RI= (n+1)/r

• n= # of events (length of record
• r= rank of event from largest to smallest with highest magnitude flood having r=1

Question 19

How do you calculate flood probability?

Answer 19

P= 1/RI
so you need to calculate RI first

Question 20

What are some ways you might be able to estimate RI beyond the record duration?

Answer 20

tree ring records or flood plain deposits

Question 21

Give some potential issues with a long record of floods

Answer 21

• It’s a static record, but there are land use changes/ water management changes, etc
• data quality issues can happen over long records

Question 22

Give the 6 important fluvial processes

Answer 22

• weathering
• erosion
• entrainment
• transport
• deposition
• re-suspension and deposition

Question 23

weathering=

Answer 23

physical, chemical, or biological breakdown of material (bedrock or sediment)

Question 24

erosion=

Answer 24

removal of material (sediment) from the landscape

Question 25

entrainment=

Answer 25

incorporation of sediment into the fluid column

Question 26

transport=

Answer 26

movement of particle/ sediment by the fluid (ice/ water/ wind)

Question 27

deposition=

Answer 27

loss of particle from the fluid column; its motion has stopped

Question 28

stream ____ is principally related to erosion, transport, and deposition

Answer 28

velocity

Question 29

What (4) landscape and channel characteristics might impact stream velocity?

Answer 29

• slope
• channel shape (wide or deep)
• channel roughness- cobbles veg etc
• amount of discharge

Question 30

How does Q (discharge) change downstream?

Answer 30

tributaries combine, so Q increases downstream
remember, Q= volume/ time

Question 31

as discharge increases downstream, stage ____ downstream, and the ratio of water in contact with the bed generally ____

Answer 31

increases

decreases

Question 32

As Q increases, the water in contact with the bed decreases, therefore ___ can increase

Answer 32

velocity can increase because there is less friction (with the bed)

Question 33

as gradient increases, velocity of water typically

Answer 33

increases

Question 34

what is the relationship between velocity and distance from headwaters?

Answer 34

as velocity increases, so does distance (linear/ exponential?)