River Series 1 Flashcards
T or F. Zones of greatest turbulence tends to be away from the zone of the lowest velocity.
F. Highest velocity
Turbulence appears as eddies:
Intermittent Vortices
Helicoidal flows
Rollers
Surge Phenomenon
Bedrock erosion processes:
Corrasion
Fluid Stressing
Cavitation
Corrosion
Plucking
Depressions may be rounded or sharp, cusped in profile, and have crests lying across the current path.
Erosional marks
Enumerate the pothole types:
Plunge pool type
Shallow gouge holes
Eddy holes
Maximum volume of sediments a stream can carry of a given size.
Capacity
The largest particle size the stream can carry
Competence
T or F. Factors such as discharge, slope may vary along the length of the channel, therefore competence will vary continuously
T
Transportation of sediment occurs in three ways:
Suspension, Saltation, and Rolling.
________ and _______ of particles, discharge and flow-depth variations down a river, the capacity of bedload also varies
Sorting and attrition
There are two factors of open channel hydraulics:
Force of gravity and frictional forces
Pulls the water downslope
Force of gravity
Resistance for downslope movement
Frictional forces
Roughness is controlled by:
- amount of vegetation
- size of bed
- bank material
- irregularity of adjacent channel cross sections
Discharge is calculated by:
Q= AV
Q = Discharge
A = Cross-Sectional Area
V= Velocity of the flowing water
_________ expressed that Natural channels however are not of a regular polygonal shape, with rough beds and walls
Antoine Chezy
Antoine Chezy equation:
π= πΆβπ
π
C = Coefficient based on gravity and roughness
R = Hydraulic radius
S = Stream Gradient
Maning formula
π=1/π π ^2/3 S^1/3(m/s)
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.
F. does not flow uniformly
Maximum height of the stream over time
stage hydrograph
Discharge over time
discharge hydrograph
The application of studying hydrograph is predicting the flood recurrence interval, where each year flood heights are recorded and/or discharge is recorded.
Flood Frequency
Flood frequency formula:
return period = number of years +1 / rank of individual flood
Pattern of discharge varies with the following factors:
Climate
Heat Balance
Vegetation
Soils
Rock structures
Basin shape and size
Only _______, _________, and ________ are independent of climate.
rock structure, basin shape and size
T or F. Bedload decreases as flow velocity and discharge increases.
F. bedload increases
T or F. Suspended and Solution load varies more as flow velocities and discharge varies throughout the stream
T
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.
1%; 70%
