WEEK 4: Physiology of Streams and Lakes Flashcards
Define Stream
- is a body of flowing water in a defined channel
- Longest:nile
-largest discharge and dranage : Amazon
no clear definition between stream and river, streams slightly smaller (but not official)
How are streams formed
Thermodynamics: precip brings in water into river system gravity: adds energy that forms channel
Drainage area
the area on land where the water comes from
-Watershed area defines is the border of the basin
Define Discharge
- volume passing through river per unit time
- if +’ve then related to the drainage area, variably by climate and geology
Stream order
supposed to help figure out where the various sources of rivers that stream into the main one
- order 1 is
- streams order must add up to the tributary
- issue: really doesn’t help with any defining
Different river patterns
- variably driven by geology
(dentric - fingers coming into one) (radial&ammlus - formed on volcano/mountains) (trellis parallel ridges) (rectangular - formed by faults)
what do Hydrographs measure
measure the continues water discharge over time
- the shape of graph depended on rain/storm events
- effected by urbanization } causes river to get to normal faster, as there is less influtration into soil
Name and describe the three ways water gets to a stream
- Overland } above surface flow
- subsurface flow } infiltration, but above water table
- ground water} from bellow water table, aquafire
factors include incline, solid, moisture of soil, height of water table
Types of flow permanence
Perennial } Constant stream, gw
Intermitten} Seasonal (dry vs wet season)
Ephemeral } Stream flows from a storm event, no GW
Pool ruffle features
regular river pattern involves, shallow and fast (riffles) alternated with deep slow areas (pools)
- caused by high sloped, most common in areas that gradient, gravel bed
- less effective at higher flows
What type of Channel flows
- Meander: Bendy rivers. caused by erosion, then dropping sediment
- Braided: Common in high slopes, non-cohesive sediment and many possible channels
- Confined } Narrow confined stream due to unerodable exterior
Flood plain
is a flat area often flooded by overflow, common with low lying meandering streams
Define bed material
- this contains river flow
- more e needed to move larger sediments,,, and ones that are more cohesive
On river erosions:
Naturally, this occurs to lead to lead to equilibrium as river volume changes,
- bank-erosion involves making it steep, then dropping sediments
- Threshold of bed movement: Shear stress
-
On sediment loading
defined about amount passing through a point/time
- dissolved load: Minerals, wont fall out
- suspended load: helping normal flow, lower [] at the bottom more near top
- bed loads: large particles at the bottom, moves at a different rate then water
What is a lake?
slow/non-moving body of water in a depression & not connected to the ocean
- can be fresh or saline (esp if high evaporation is a thing)
- includes pools in river, ponds
Where are most lakes distributed?
a lot in areas where glaciers left depressions (esp in the north)
- and in the very north (low evaporation, and high precipitation) ( emphasis on the low precipitation)
- intermittent lakes are a thing, but not very common, mainly only in arid areas that fill in during the wet season
What is a reservoir?
a man-made lake, often created via damning rivers
- often shallow and it inc productivity
- changes species dynamics of the river
- changes river speed suddenly, causes large segment drops
What are the local impacts of Reservoirs
- ## done to stop flooding, but often increases the water level fluctuations } impacts littoral community
Global impacts of the reservoir?
- ## due to large sediment deposit, its stoping nutrients and minerals from going into the ocean
3 main ways lakes are formed
- Tectonic: moves earths, make deep lakes
- – (Graben lakes: full crust falling) (Horst lakes: crust tilts, one side gets really deep)
- Damning: Natural from lava flows, bevers, etc. Smaller &shallow
- Glacial formation: MOst common esp in the north
- —scour: digs out the earth (cirque) –glacial till: Huge ice deposit, then melts (kettle lakes)
Non-main lake formations
- Volcanic, karst (bedrock disovles, sinkhole)
- Fluval (a meandering river that gets cut off, oxbow lake)
Subhabitats in lake
1) Pelagic } surface, open water 2) Profundal } open h2o, deep 3)littoral }edge of lake , most productive
Lake properties. how they affect productivity?
SA: changes, light exposure
Depth: How far light can get
Volume: combines SA and D
Retention: How long a single molecule of h2o stays in the lake, controlled by in/out of water
Shoreline development: hoe mutch edge of the lake is there, changes amount of nutrence gets into lake
