Lecture #3 Flashcards
What does flow give us?
The Force and Energy for sediment transfer
-Helps determine what the river channel looks like and how it works
Is discharge dependant or indépendant of the channel?
Independant, it is imported from the watershed
Can he river channel decide how much water its going to get?
No, it can determine the flow characteristics only,
-River channel its self doesn’t determine the discharge at any particular time
3 Characteristics of discharge?
- Independant
- Varies over time at any given location
- Varies along the river system at anytime
What is Continuity?
Cant gain or lose mass over a short distance of the channel
-the discharge at one place is the same as the discharge a couple meters up the channel
What happens to velocity of the cross section changes?!
-Velocity has to change as well
Where is velocity measured?
Continuously measured at gauging stations
What is Day Variation?
Daily inputs (they vary) and the river changes everyday
If the same rainstorm occurs on 2 different rivers, are the characteristics observed going to be the same?
No, can expect different catchments to show different characteristics and discharges
What is Annual Variation based on?
Climate and Vegetation in surrounding area
What are the peaks in hydrographs?
Rainstorms
What are the 3 main stages in the Hydrographs?
- Rising
- Peak
- Returning to base flow
Why is peak flow important?
It does a lot of geomorphic work on the channels
What happens to discharge as you urbanize rivers?
Discharge increases, because of the bigger basin areas
What is flood frequency?
The probability of occurrence
-Highest flows have the lowest probability
Discharge=flood
Which modifies the channel more; big floods or littler ones?
- Big floods can modify the channel a lot but they are rare
- Littler ones happen more often and might be more important because it could do work just over a longer period of time
What is a flood duration curve?
Frequency distribution of daily flow values over a given time
-Takes all the values for everyday.
What is a flood record?
The highest flow every recorded for the period of time
What is Hydraulic Geometry?
Describes the way in which the discharge is distributed within the channel, what it does to the flow characteristic of a channel
What 3 variables are dependant on Q?
w v d
- Dependant on one another
- Relationship between the 3 is the hydraulic geometry and are responsible for the characteristics of the channel
Who are the fathers of fluvial geomorphology?
Leopold & Maddock
Out of w v d, which are the highest values?
v > d > w
-they all vary within a narrow range
What is bed shear stress?
Flowing water exudes a force not he ned and river channel which does most of the work to move sediments
What does the calculation for bed shear stress depend on?
flow depth and water surface
-other # are constants
