The Water Cycle Flashcards
Major stores of water
Oceans hold 97% of all earths water
Freshwater is at 3%
Change in magnitude of water stores
- Evaporation
Evaporation occurs when energy from the sun hits the surface of water or land and causes a change in state from liquid to gas.
Rates of evaporation depends on the amount of solar energy, availability of water, humidity of the air, etc.
Changes in magnitude of water stores
- Condensation
As air cools it is able to hold less vapor.
Water condenses when it reaches dew point. Excess water in the air will be converted to liquid water + condensation
Drainage basins
The area that supplies a river with its supply of water
Drainage basin key terms (1)
- Condensation
- Cryosphereic processes
- Drainage basin
- Evaporation
- Evapotranspiration
6 .Groundwater flow - Infiltration
- Interception store
- The process by which water vapor changes to liquid
- Processes that effect the mass office at any scale
- An area of land drained by a river and its tributaries.
- Process of liquid water changes to gas. Requires energy from the sun aided by wind
- the total output of water from drainage basin directly back into the atmosphere
- the slow movement of water through underlying rocks and soil
- the downward movement of water from surface into the soil
8 precipitation falling onto vegetation surfaces or manmade cover, and is temporarily stored on the surfaces
Drainage basin key terms (2)
1. Overland flow
2. percolation
3. Run-off
4. Saturated
5. Stem flow
6. Storm and rainfall event
7. Through flow
8. Transpiration
9. Water balance
- Water flowing across land surface when rain has exceeded the infiltration capacity of the soil.
- The downward movement of water within the rock under soil moisture
- All the water that enters a river channel and eventually flows out of the drainage basin
- Any water store hat has reached max capacity
- The proportion of precipitation intercepted by the canopy, and reaches the ground by flowing down
- A storm event, rain then at least no rain for 24hrs. rainfall event, rain then at least 4hrs of no rain
- When precipitation directly falls through gaps in the canopy, reaching the ground
- The loss of water from vegetation through pores of the surface
- The balance between inputs and outputs in a drainage basin
Concept of water balance
The balance between inputs (precipitation) and outputs (run-off, evapotranspiration) is the Water balance or the Water Budget
River regime and how does it vary?
A river regime is the variation in river discharge throughout a year.
Climate, vegetation, geology and soils, land use, water abstraction and dams all influence the regime of a river.
River regime
Discharge levels fall and rise, often showing an annual pattern
How is run-off studied?
Measuring the discharge of the river. In cumecs.
Flood hydrographs
A graph of river discharge against time
How vegetation effects hydrograph shape
Thick vegetation cover in drainage basins will have a significant effect on a storm hydrograph.
Vegetation intercepts the precipitation, holding the water on its leaves, slowing down the movement of rainwater to the ground and to the river channels. This Increases lag time and reduces peak discharge.
How precipitation effects hydrograph shape?
How does relief cause
Changes in the water cycle - natural
Relief
Geology
Precipitation intensity
Vegetation
Size of basin
Changes in the water cycle - human
Deforestation
Agriculture
Water abstraction
Urbanization
How small scale deforestation effects the water cycle + hydrograph shape
On small scale deforestation
- evapotranspiration decreases
- through flow increases
- overland flow increases
Therefore the river height increases.
How large scale deforestation effects the water cycle + hydrograph shape
On a large scale of deforestation
- increases overland flow
- reduces evaporation
- decrease in precipitation
Overtime, less precipitation means less throughflow and les overland flow. This changes the water cycle.
How does agriculture effect the water cycle + hydrograph shape
Soil drainage increases river regime variability because the water reaches the river channel faster, so the river reacts more quickly to storms events.
Wind erosion of drier top soil is higher so there is a loss in nutrients and plants loose protection. farmers use fertilizer to compensate but too much fertilizer causes eutrophication.
How does water abstraction effect the water cycle + hydrograph shape
Taking water out of the river directly and out from the ground water (aquifer). If water is abstracted at a faster rate than it can be replenished, the water table will decrease.
Problems with water abstraction
Risk of salinisation
Flooding
Drying up parts
How does urbanization effect the water cycle + hydrograph shape
- Less vegetation, means less interception casuing more urface run off
- Impermible surfaes mean rain cannot filtrate, overland flow occurs more
- Drains upon sides of the roads cause water to quickly run off straight into the river
Management of the River Exe
Exmoor mires project
Peatland restoration
What? Why? Impact
Exmoor, River Exe
What? Restoring peatland, filling up drainage ditches
Why? To have a slower run off so better water quality and helps to retain carbon emissions
Impact? A slower time for water to drain to the main river (Exe)
Management of the River Exe
Wimbleball reservoir
Where? Why?
Where? Uppercourse of River Exe
Why? To store and supply water for nearby rivers
Causes a slower time for water to reach the main river (Exe)
