Geography Theme 2 Flashcards
Characteristics of a river:
- width
-depth
-speed of flow
The hydrological cycle
-the hydrological cycle is a closed (no inputs and no outputs) system
-water is constantly recycled through the system
- within the hydrological cycle, there are stores and transfers (flows)
Go to photos and do the activity
1,precipitation
2,condensation
3,evapotranspiration
6, overland flow
7,infiltration
8,percolation
9,throughflow
10,evaporation
11,groundwater flow
Explain : Precipitation
- Any form of water, such as rain, snow, sleet, or hail, that falls to the earth’s surface
When can precipitation only happen?
-when the air is saturated
-there is a nucleus to form around =for heavy drops
-temperature below dew point
State the three types of precipitation
- cyclonic (frontal)
-orgraphic (relief)
-conventional
Evaporation
- is the process by which a liquid or a solid is changed into a gas.
-Evaporation increases under warm, dry, windy conditions
Factors of evaporation (7)
-temp= if hotter evaporation will increase
-humidity
-wind speed= the higher, the more evaporation decreases because wind blows water vapour
-water quality= the clearer and fresh the more evaporation
-depth of water = shallow+wide surface are the more evaporation
-size of water body
-vegetation cover
Interception
-water intercepted and stored by vegetation
- There are 3 main components, ways of interception; interception loss, through fall,
Explain the three main ways of intercepting
1, interception loss= water that is held by a plants surface—> later evaporated/absorbed by plant
2,throughfall= water that falls through Thais I’m vegetation/ drops from leaves
3,stemflow= water that twinkles along twigs+branched down to the trunk
Evapotranspiration
-combined effects of evaporation and transpiration
-water moves outside, plant down a concentration gradient
-most important aspect of waterloss
Infiltration
-process which water soaks into the ground, soil layer
What’s the infiltration capacity
- is the maximum rate at which rain can enter the soil/ground.
-it varies according to time raining, type of soil, how often vegetation occurs….. - infiltration capacity decreases with time through a period of rainfall
Percolation
- it happens one infiltration happened
-it’s the downwards movement of water from the soil to the rock beneath
Surface runoff- overland flow
-water moving over the surface
When does surface runoff occur?
- when soil becomes saturated
- precipitation exceeds infiltration rate
-Impermeable soil rock
-high suspended flow
Throughflow
-water flowing through the soil, on natural pipes and between soil horizons
-once infiltration happens= water flows downhill through soil
Groundwater flow
-subsurface water in soil
-once infiltration happens= water flows slowly through rock towards the sea
Characteristics of a river and drainage basin
-source
The place where a river begins
Tributary
A small river that joins the large river
Confluence
The point where the tributary joins the main river channel
Mouth
The point where the river enters the sea
Estuary
The part of the mouth that is tidal
Watershed
The high ground separating one river basin from another
Downstream characteristics of a river that increase
-discharge
-occupied channel width
-channel depth
-average velocity
-load quantity
Why does the discharge increase downstream
-as a river moves downstream, additional discharge is added to the main river by tributaries, surface flow and ground water
Why does the load quantity increase as you go downstream?
As a river moves downstream, erosion occurs along the river banks and bed, eroded particles are added to the river’s load.
Energy in a river (kinetic and potential)
1, overcome friction with the bed and banks (95% of it’s energy is used this way )
2,transport it’s load (when it loses energy, it drops/deposits it’s load)
3, erode the channel bed, banks and load
Channel shape
-The efficiency of the channel is how easily water moves along it without using energy
-efficiency is measured by hydraulic radius
-the most efficent shape is semi-circular
Channel roughness
Channel roughnesss causes friction, which slows the velocity of the water, friction might be caused by boulders, broken tress and uneven surface.
Erosion is
This is where the river or sea wears the rocks away
Transportation is
Where the river or sea carries eroded material, boulders, pebbles, sand, silt and mud eroded by the river are carried downstream
Deposition is
When a river no longer has the energy to carry the load so it gradually drops it on the river’s bed
The 4 types of erosion
-attrition
-hydraulic action
- corrasion (abrasion)
-solution (corrosion)
Attrition
-“rock on rock”
-this is where rock fragments carried by the waves hit against each other and gradually wear down to form sand and slit
Hydraulic action
“Pressuring”
- as waves break against the cliff face, the pressure of the breaking wave can compress air in cracks p. This compressed air gradually forces open the crack in the rock- as this process continues, the rock becomes increasingly weakened
Abrasion
“ rock on cliff”
- this is when rock fragments are hurled at cliffs by breaking waves, gradual at scraping away at the cliff face
Solution
“Rusting, dissolving”
- this occurs where the salt water is able to dissolve so,e of the chemicals in rocks- for example, limestone cliffs are gradually weakened as the salt water dissolves the calcium carbonate in the limestone
Factors that affect erosion (4)
-load= the heavier+sharper the load the grater the potential for erosion
-velocity and discharge= the greater the velocity and discharge the grater erosion
-gradient =increased gradient,more erosion
-PH= rates of solution are increased when the water is more acidic
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Transportation
-suspension
-solution
-traction
- saltation
Suspension
- carrying
- fine, light material is carried along by the river
Solution
- minerals are dissolved in the water, this is chemical change
Traction
Large boulders and rocks are rolled along the river bed
Saltation
Small pebbles and stones are bounced along the river bed
Deposition
Main reason= river loses energy
- as river drops it’s load when the speed or volume of river creases, the load, which is carried gets deposited
-the heavier material is deposited first and the finer material carried further.
Proccess
#depositon occurs:
# decrease in gradient
#decrease in river flow
#the river meeting the sea or lake often creating a delta
