Water Flashcards
stream flow
amount of surface water flowing downhill through creeks, streams, and rivers toward the oceans
mesasure at gauging station
integrates surplus runoff and waters upstream within a catchment basin
streamflow that is composed entirely of groundwater is termed base flow, or fair-weather runoff
= occurs where a stream channel intersects the water table
discharge
amount of water flowing past a certain point in given time
measure: use channel width, channel depth and velocity
runoff
starts off a sheet flow
= quantity of water discharged in surface streams.
includes:
- waters that travel over the land surface and through channels to reach a stream
- interflow = water that infiltrates soil surface and travels by means of gravity toward a stream channel (always above the main groundwater level) and eventually empties into the channel.
- groundwater = discharged into a stream
velocity of water
dependant on slope of the land
steeper slope = faster water
shape of river channel = dependant on geology of area (hardness of rock)
all factors: velocity + geological and geomorphological shapes crteated
determine maturity of hydrological landscape
water supply
- oceans (96%)
- fresh water (2.5%)
= glaciers and ice caps (68%)
= ground water (30%)
= surface/ fresh water
===permafrost and ground ice (69%)
===lakes
=== atmosphere, rivers, swamps, soil moisture
water cycle
Water returns to Earth from precipitation falling on the land, where gravity either takes it into the ground as infiltration or it begins running downhill as surface runoff.
following sheet flow –>
rills
streams
channels
creeks
streams and rivers
rivers
help keep the aquifers underground full of water by discharging water downward through their streambeds.
oceans stay full of water because rivers and runoff continually refreshes them.
watershed
the area of land where all of the water that falls in it and drains off of it goes to the same place.
Watersheds can be as small as a footprint or large enough to encompass all the land that drains water into rivers
Larger watersheds contain many smaller watersheds
The size of a river is highly dependent on the size of its watershed
erosion and deposition
constantly changing
- changes in river channel
- composition of channel bed and banks
- vegetation cover
- variations of weather and climate pattern
- human activities = land use changes
PROCESS:
stream erosion = caused by loosening particles from the stream bed or by abrasion
==== this will create sediments = make up the load of the stream
River sediments:
- bed load = coarse particules moving along the bottom of river channel
- suspended load = muddy river + 90% of total load
- dissolved load = carried in chemical solutions ( Ca2+; Na+; Mg+ )
from upstream do downstream
- capacity
- competence
capacity = max amount of particules
competence = max size of particules
the slower a stream is flowing, the lower its competence becomes = deposition or sedimentation occurs
stream = seperate solid particles in different sizes
surface water –> rivers
rivers = network of streams
watershed = drainage basin
== where the river receives its discharge
base level (sea level)
= through erosion, they make their way down to base level
gradient = determinate speed at which the water flows = force of erosion
when change conditions of river = flow changes
base level
lowest elevation to which a stream can erode
= end destination of a stream
ultimate base level and local base level
profile of stream adjusted to base level
= building a dam === block, filter and contain sediments = new stream profile formed by deposition of sediment
= new base level
waterfalls and other topographic features depending on the resistance of the rock beds
Combining geology of area and base level
low base level
= Narrow V shaped valley
approaching base level
= erosion and deposition
= starts to expand
at or close to base level
= floodplain well developped