lecture #2 Flashcards
What is drainage area?
Is the land area that is drained by all the tributary systems above a chosen point in the main channel
What is discharge?
Is the volume of water passing through a channel per unit of time
What is discharge related to?
It’s related to water velocity and stream cross sectional area
How do we classify stream orders?
Smallest streams are assigned first order and the order increases when two streams of the same order join- is the strahler classification system
What number of streams occur most often in a watershed?
low-order streams
What comprises most of the length of a watershed? Low order or high order streams?
low order streams, even though high order streams are longer, because there’s more low order streams they make up most of the length
What does perennial mean? Intermittent? Ephemeral?
Perennial means flowing all the time, excluding times of drought.
Intermittent means flowing some of the time and receiving water from groundwater.
Ephemeral means flowing rarely and not receiving input from groundwater.
What kind of organisms would do good in Ephemeral streams? What kinds would do bad?
Organisms that need consistent water won’t survive well, organisms that go through diff life stages might for example frogs
How can surrounding vegetation impact the stream?
As water drains through watershed, the water chemistry will be impacted as the water drains from surrounding vegetation.
What is a riffle?
Is little waves, happens over gravel
What is a pool?
is still water, happen over fine sediment
How does composition of bottom of shape effect stream?
Effects flow of stream and shape of stream (depth)
How does composition of stream bed effect stream?
shallow areas have ripples due to big boulders, deeper areas will have pools as we have finer sediments there
Between the riffle and the pool what do you get?
runs, these are smooth running waters over a smooth surface
What is a reach?
Is a section of river
What is thalweg?
Is the fastest moving water, usually always on the outside edge
Where is most of the erosion experienced in the stream?
At the outside bend of the river, on the other side sediments accumulate
What is a point bar?
Is where sediments collect
Meanders what over time?
exaggerate
How does meander change with drainage area? Why?
The larger the drainage area the higher the meander will be
Larger drainage leads to more discharge? T OR F?
T
Total wetted width is what?
Adding all wetted widths
What is bankful width?
Look at where there is high water marks, where there is change in vegeatation, a topographcal break from vertical to flat flood plain and from steep bank to more gentle slope, the highest elevation where there is no material below it and a change in texture of the deposited sediment
What is channel slope?
Looking at how high banks are on each side
What is maximum depth?
is highest depth of water in stream
What is drainage basin length?
Is the straight line distance of the basin
What is drainage basin land slope?
is slope of drainage basin
What is drainage basin area?
area of drainage basin
How does braiding occur?
happens over time and depends on substrate around river
How does braiding influence stability of river?
it increases stability
What is the best way to prevent flood?
a big floodplain
What is a Wrybill?
Breeds only in braided rivers of New Zealand’s South Island, needs sediments ot make nest braiding provides habitats (has deeper pools, islands)
What is a stream hydrograph?
it is a graph which shows discharge after rainfall
How does urbanization effect discharge?
They cause peak of dishcarge to ahppen faster and amount to increase do to the impervious surfaces
Why are wetlands positive?
they regulate flow of water
support important habitats
are important for biodiversity and ecosystem functioning
What is the defn of wetlands?
Land saturated with water long enough to promote wetland or aquatic processes as indicated by poorly drainied soils, water loving veg, and various kinds of biological activity that are adpated to a wet environment
Are wetlands conserved?
Are often drained, fille din or modified, 70% of wetlands were lost between 1940-80, most wetland loss is driven by agriculture with peatland being used for fuel and moss
Ecosystem function and services for wetlands are what? 8
habitats for plants, animals, and regions of high biodiversity
Carbon storage
Cyclone and hurricane mitigation
high productivity
nutrient removal from water
biofuel creation
floor control
How do wetland cover impact nitrate in water? crops?
They take up nitrate, crops increase nitrate
