Test 3 Flashcards
Transpiration
Process by which moisture is carried through plants from roots to small pores on the other side of leaves where pit changes to vapor and is released in the atmosphere
Hydrologic cycle
Precipitation Infiltration Run off Subsurface flow Transpiration Evaporation (from rivers, lakes, ocean)
Rivers
Water contained within a channel
Hydrology
The science of try and streams and rivers in the hydroloc cycle
Drain basin
Area drained by a single river (or system)
-where water will flow after rain, into what river
-based on the biggest river all other rivers flow into
—we ar cape fear river basin
Basins are separated by
Ridges called divides
Continental divide
Separation of water flowing to the Pacific Ocean vs the Atlantic Ocean
Pacific west
Atlantic east
Watersheds
The smaller areas river basins are divided into
-specific river that will eventually flow into the bigger river which is what the river basin is based off of
Riparian
Areas around and affected by river including habitat
-a minimum width of riparian habitat (including vegetation) is crucial to provide ecosystem services
—for the river to provide everything it should it needs a minimum width of riparian habitat so you can’t developed too close to a river
—-varies depending on type of stream but generally minimum of 100 feet
Floodplain
Area by a river that periodically floods
-can have more than one
—ie water street downtown
*not on the coast, inland
Alluvium
Sediments deposited by rivers
—finer size sediment particles
Formation of drainage networks
Stream flow begins as water is added to the surface (snow melt, precipitation, etc)
- steam flow begins as moving “sheetwash”
- sheetwash erosion creates tiny rills (channels)
- tributaries form
Sheetwash
Thin surface layer of water that moves down slope, eroding
Rills
Rills coalesce and deepen into tributary
How/when rivers/channels flow based on location
Ephemeral-above water table: don’t flow all year
Permanent- at or below the water table: flow all year
How is river flow based on geology
Bedrock: straight, found closer to the head (source) or steeper elevations
Alluvial:
-braided: broad, gravel, shallow, weave in and out of each other; often associated w glaciers
-meandering: deep, piedmont, squiggly like, found in coastal areas
*some streams can be more than one if it for example flows from the mountains to the coast
Straight (bedrock) river
Associated with mountainous river portions - closer to the head
— “young” stream stage
Braided (alluvial)
Form where channels are choked by sediment
- gravel bars are unstable, rapidly forming, and being eroded away
- flow occupies multiple channels across a valley
- often sssociated w glaciers (but not always)
Meandering rivers (braided rivers)
Head-source of stream
Mouth-outlet of the river (where it empties)
Cut bank-where erosion occurs (higher velocity)
Point bars-deposition occurs (lower velocity)
Natural levees-bank deposition
Oxbow lakes-abandoned loops (former remnants of the river)
River components (in most rivers)
Pools-deep pools beneath banks (usually higher velocity w large rocks or something surrounding it)
Riffles-shallow, course gravel (higher in oxygen than pool, higher number of organisms because of this)
-important habitats
River process controls
- Discharge
- Gradient
- Geology
- Sediment load
Discharge in a river
Volume of water that’s passing by a certain point in a given unit of time
-mostly cubic ft per second or cubic meters per second
Equation=(depth x width) x velocity
—velocity is not uniform throughout steam (highest in the center, lowest towards the banks bc as the water is coming into contact w sediment along side the stream it’s creating friction and slowing down the flow)
—wider and shallower more friction, narrow and deep less friction)
Gradient in rivers
Slope=rise/run
Longitudinal profile = change in evolution
Thalweg- profile that connects points of highest stream velocity
Gradient decreases w distance, works towards base level (flat area)
Sediment load
Materials moved by steams in the sediment loads: three types
- Dissolved load: ions that have been dissolved into the water from wether of minerals (smallest)
- Suspended load: fine particles like clay and silt that are carried in the flow of water but not dissolved, just light enough to be carried
- Bed load: large particles roll. Slide and bounce along (largest) ie boulders