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
slow meandering rivers
flat terrain that reduces the flow speed of water, allowing the river to curve
very mature river
longitudinal profile is not as steep
velocity not as high
- deposition of point bar ( = where sediment is deposited)
= deposition of sediment occurs on the inner edge because the river, moving slowly, cannot carry its sediment load, creating a slip-off slope - erosion of cut bank
= velocity of the water is highest along the outer part of the channel = erode and transport sediment from the bank
alluvial fans + Deltas
Mississipi river
delta
= has moved locations several times over the last years.
suspended material
prone to frequent flooding.
The Niagara Escarpment
Late Ordovician age (approximately 450 million years ago).
Those that comprise the major part of the Escarpment proper belong in the Early and Middle Silurian age
(approximately 400 million years ago).
area lay under a shallow warm sea.
== following the ice age the sea lay in a depression of the earth’s crust, the centre of
Michigan Basin
outer rim of this massive saucer-shaped feature defines the Niagara Escarpment.
Weathering and erosive forces
= chemical weathering of porous dolostones = dissolved and karst features
Frost action is continually loosening large blocks of rock from the face creating a talus slope below. Sometimes a huge chunk of the Escarpment breaks off.
components:
-erosion resistant dolostone
- shale
- erosion-resistant limestone
- sandstone
Richelieu River
source = Lake Champlain
continued rain in Vermont kept increasing the water from Lake Champlain.
High winds going in the North Easternly direction, also kept on pushing lake water into the River
The Earth’s Water Budget
The total amount of water on Planet Earth is constant.
= No water is being added or removed from the system.
The Hydrosphere
The Hydrological Cycle
one of the four geographical spheres on Planet Earth
– will interact with the other spheres (atmosphere, biosphere, lithosphere).
Water on the Planet will therefore recycle
and rejuvenate itself.
Sources of clean water
Groundwater
= found all over the planet, no
matter how dry the surface is.
the water table
boundary between water-saturated ground and unsaturated ground.
follow the same shape as the surface topography
=soil moisture
== unsaturated zone
===water table
==saturated zone
=ground water
depends on permeability of porosity
of underlying rock structures.
When rain water seeps into the ground by gravity, it percolates through the gaps or openings in soil and rock.
Water then accumulates underground = the surface of this underground collection of water is called the water table.
Below water table: rocks + soil are full of water.
+ Pockets of water existing below the water table = aquifers.
An area’s water table can fluctuate as water seeps downward from the surface.
The level of the water table will also influence
whether a stream is gaining or loosing water
– this is usually a seasonal cycle.
How can groundwater be polluted? Explain
groundwater movement
Leakage from septic tanks and/or waste-disposal sites = introduce bacteria to the water
pesticides and fertilizers that seep into farmed soil end up in water drawn from a well.
a well might have been placed in land that was once used for something: chemical dump site.
aquifers
underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt).
Groundwater from aquifers can be extracted using a water well.
KARST TOPOGRAPHY
landscape created due to the presence of limestone
Slightly acidic water will dilute the calcite = reducing the structural integrity of the rock.
sinkholes
Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form.
cavities or pits in the ground that forms when water erodes an underlying rock layer
- the rock is limestone, salt beds, or carbonate rock, which can naturally dissolve by groundwater circulating through them.
two types of sinkholes:
- forms when the roof of a cave collapses and exposes the underground cavern.
- forms when water dissolves the rock beneath the soil and creates an underground chasm.
Without rock to support it, the layer of soil eventually collapses and creates a hole on the surface
ex: Guatemala, Montreal
springs
formed when the water reaches the surface through a fracture or porous layer.
= occur along faults (a fracture in the earth), or in areas of great topographic relief such as cliffs or valleys.
= result of water flowing along an impermeable surface within the lithosphere
Another form of Spring = Hot Spring.
–water from a hot spring is between 6 and 9 degrees C.
Hot springs are heated by the Earth’s internal heat
—Hot Spot and Caldera at Yellowstone National Park.
Geysers are something different to regular hot springs
aquitard
layer
localized zones of saturation can also result when the groundwater percolates down to an
impermeable layer, and a localized well results.
geysers
= intermittent springs that shoot water up
in the air
= water within underground caverns
will heat up until it becomes steam
= As the pressure increases the
steam will be ejected into the atmosphere.
wells
natural or artificial.
recharge area
pressure surface
ARTESIAN wells run along impermeable layers.
+ non flowing artesian well = water mjust be pumped from pressure surface to surface
When digging a well into the water table, it is important to determine how the new flow
will affect the area around the well, and the water quality of the well itself.
SCHEMA:
well
former water table
= cone of depression
== lowered water table = dry well
you can dry up your neighbor’s well
= heavy pumping
The Ogallala Aquifer
largest aquifer in the world
its use or misuse - water levels are decreasing
rapidly.
= Groundwater Mining – where the resource is “permanently taken” from the ground.
Transcanada wanted to build its oil pipeline over the Ogalala.
The newest threat of contamination:
Hydraulic Fracturing – or fracking.
hydraulic fracking = injection of water + sand + chemicals at high pressure into wells
= shale layer cracks
= fissures held open by sand so natural gas from rock can flow up the well
// water, sand, chemicals forced in = fracturing fluid is pumped into well
// gas forced out = natural gas escape
= groundwater contamination + air quality degradation
oxbow lake
a meander in adjacent river = got cut off because neck of land between river banks got more and more narrow
