River Series 1

Question 1

T or F. Zones of greatest turbulence tends to be away from the zone of the lowest velocity.

Answer 1

F. Highest velocity

Question 2

Turbulence appears as eddies:

Answer 2

Intermittent Vortices
Helicoidal flows
Rollers
Surge Phenomenon

Question 3

Bedrock erosion processes:

Answer 3

Corrasion
Fluid Stressing
Cavitation
Corrosion
Plucking

Question 4

Depressions may be rounded or sharp, cusped in profile, and have crests lying across the current path.

Answer 4

Erosional marks

Question 5

Enumerate the pothole types:

Answer 5

Plunge pool type
Shallow gouge holes
Eddy holes

Question 6

Maximum volume of sediments a stream can carry of a given size.

Answer 6

Capacity

Question 7

The largest particle size the stream can carry

Answer 7

Competence

Question 8

T or F. Factors such as discharge, slope may vary along the length of the channel, therefore competence will vary continuously

Answer 8

T

Question 9

Transportation of sediment occurs in three ways:

Answer 9

Suspension, Saltation, and Rolling.

Question 10

________ and _______ of particles, discharge and flow-depth variations down a river, the capacity of bedload also varies

Answer 10

Sorting and attrition

Question 11

There are two factors of open channel hydraulics:

Answer 11

Force of gravity and frictional forces

Question 12

Pulls the water downslope

Answer 12

Force of gravity

Question 13

Resistance for downslope movement

Answer 13

Frictional forces

Question 14

Roughness is controlled by:

Answer 14

• amount of vegetation
• size of bed
• bank material
• irregularity of adjacent channel cross sections

Question 15

Discharge is calculated by:

Answer 15

Q= AV
Q = Discharge
A = Cross-Sectional Area
V= Velocity of the flowing water

Question 16

_________ expressed that Natural channels however are not of a regular polygonal shape, with rough beds and walls

Answer 16

Antoine Chezy

Question 17

Antoine Chezy equation:

Answer 17

𝑉= 𝐶√𝑅𝑆
C = Coefficient based on gravity and roughness
R = Hydraulic radius
S = Stream Gradient

Question 18

Maning formula

Answer 18

𝑉=1/𝑛 𝑅^2/3 S^1/3(m/s)

Question 19

T or F. In hydrograph, it is assumed that surface waters from a drainage basin flow uniformly but will eventually reach the stream by various routes.

Answer 19

F. does not flow uniformly

Question 20

Maximum height of the stream over time

Answer 20

stage hydrograph

Question 21

Discharge over time

Answer 21

discharge hydrograph

Question 22

The application of studying hydrograph is predicting the flood recurrence interval, where each year flood heights are recorded and/or discharge is recorded.

Answer 22

Flood Frequency

Question 23

Flood frequency formula:

Answer 23

return period = number of years +1 / rank of individual flood

Question 24

Pattern of discharge varies with the following factors:

Answer 24

Climate
Heat Balance
Vegetation
Soils
Rock structures
Basin shape and size

Question 25

Only _______, _________, and ________ are independent of climate.

Answer 25

rock structure, basin shape and size

Question 26

T or F. Bedload decreases as flow velocity and discharge increases.

Answer 26

F. bedload increases

Question 27

T or F. Suspended and Solution load varies more as flow velocities and discharge varies throughout the stream

Answer 27

T

Question 28

It is clear that bedload increases as flow velocity and discharge increases. Bedload is reported to be only ________ of the overall sediment discharge of the river, however _______ in alpine areas.

Answer 28

1%; 70%