Lecture 1; Rivers and lakes Flashcards
what does density vary with in water?
temperature and salinity
what is velocity?
the resistance of a fluid to something moving thorugh it
what is roughness?
property of an organism or bed of a stream in contact with the fluid of water flowing over it
what does roughness increase with?
size and velocity
which freshwater system is depth more important in?
lakes
What forces impact larger objects?
pressure > drag
what forces impact medium objects?
pressure and drag both important
what forces impact small objects?
drag and viscosity
Reynolds number equation
density x velocity x length / viscocity
what is Reynolds number?
ratio of pressure forces to drag forces
does flow increase downstream and why?
yes due to more inputs pf water form the catch,ent
lotic?
rivers as flowing systems
lentic?
lakes as standing waters
name 3 sources of energy to the stream
- sunlight (SW radiation)
- LW radiation
- connection from river to air above
Hyporheic
below river bay
what is more variable, air or water temperature?
Air is more variable
when does relationship between air and water temperature not exist?
when water freezes
Frazil ice
small mobile ice
Anchor ice
solid ice which can’t move
coldest form of streams?
glacier fed stream
most variable streams?
streasms receiving snowmelt as runoff
average temperature tends to increase as we go downstream?
TRUE
why small streams more stable?
dominate by one type of source
riparian vegetation?
vegetation growing alongside of river (30m)
effect of riparian veg on stream?
- creates more shade
- decrease temp as blocks out sunlight
what increases DO in freshwaters?
- photosynthesis
- turbulence
- more surface are
DO and water temp relationship?
- inverse relationship
- cold water can hold more DO
polar and covalent compounds relationship with temperature?
- polar; positive
- covalent; negative
When is DO less soluble n water?
in warmer temperatures
DO levels for egg development?
> 0.5mg/l
co2 + H2o =
H2CO3 (carbonic acid)
when does co2 dissolve more?
when temp increases
rainwater pH?
5.64
buffering is…
effect of small changes that inputs of acids will have on a small river or lake
buffering is caused by
natural carbonates and bicarbonates
source of phosphorous?
weathering of phosphate bearing rocks
phosphorus cycle?
- sourced from p rocks
- becomes lake sediment
- dissolves into imorganic phosphate
- plant and bacteria convert it into organic posphate
in natural waters, what is the N;P ratio?
6:1
allochotonous carbon
from outside the system
autochtonous carcbon
from within the system
