Water Cycles Flashcards
1
Q
What is the global water budget?
A
- The largest store is the Ocean with 97% of all water
- 2.5% of all water is freshwater, of which 69% is glaciers, ice caps, ice sheets and 30% is groundwater
- Surface and other freshwater is 1% of stores which is permafrost, lakes, swamps, marshes etc.
2
Q
What is the hydrology like in polar regions?
A
- 85% of solar radiation is reflected
- Permafrost creates impermeable surfaces
- Lakes and rivers freeze
- Rapid runoff in spring
- Seasonal release of biogenic gas into atmosphere
- Orographic and frontal precipitation
3
Q
What is the hydrology like in tropical regions?
A
- Dense vegetation consuming 75% of precipitation
- Limited infiltration
- Deforestation leads to less evapotranspiration and precipitation
- Very high temperatures and humidity causing convectional rainfall
4
Q
What is a drainage basin?
A
- An open subsystem operating within the closed global hydrological cycle
- An area of land drained by a river and tributaries with a boundary known as a watershed usually a hill or mountains
5
Q
What is the difference between open and closed systems?
A
- Closed systems, a system that has no inputs or outputs, only throughputs
- Open Systems, a system of inputs, outputs and throughputs
6
Q
What is precipitation and how does it act as an input to drainage basin’s?
A
- Caused by the cooling and condensation of evaporated water vapour in the atmosphere formed of clouds
- When condensed, it is released as rain, snow, hail, sleet etc.
- Primary factors influencing volume of precipitation include seasonality, variability and latitude
7
Q
What are the different fluxes within a drainage basin?
A
- Due to gravity and rely on the relief of the land
- Interception
- Infiltration
- Surface runoff
- Throughflow
- Percolation
- Groundwater flow
8
Q
What is interception?
A
- Intervention of plant’s leaves changing the direction or temporarily stopping water form reaching the ground
- Varies depending on the type of vegetation
- Water trapped on leaves is known as interception store which is the greatest at the start of storms
9
Q
What is infiltration?
A
- Movement of water from the ground into the soil
- The infiltration capacity is the max amount of infiltration that can take place which can be affected by
Soil composition - Sandy soils are more porous than clay ones
Previous Precipitation - Saturation will reduce infiltration and increase the surface runoff
Type and amount of vegetation - Deep root growth can stop infiltration
Relief of land - Sloped land will encourage
10
Q
What is surface runoff?
A
- Water flows overland rather than infiltrating the ground
- Occurs when the gradient of land is greater
- Primary transfer of water to river transfers
- Moderate/fast
11
Q
What is throughflow?
A
- Water flows through the soil into streams and rivers
- Speed is dependent on the type of soil
- Clay soils with smaller pore spaces have a slower flow rate
- Sandy soils drain faster due to larger pore spaces and natural channels due to worms etc.
- Moderate/fast
12
Q
What is percolation?
A
- Water moves from the ground and soil into porous rock and rock faults such as bedrock and aquifers
- Percolation rate depends on the fractures or the permeability of the rock
- Slow
13
Q
What is groundwater flow?
A
- Gradual transfer of water through porous rock due to gravity
- Water can become trapped long term in the deepest layers of bedrock creating water stores such as aquifers for the drainage basin
14
Q
What outputs are there for the drainage basin system?
A
- Evaporation
- Transpiration
15
Q
What is transpiration?
A
- Direct loss of water from the water source, interception storage and soil moisture into the atmosphere
- Rates increase when it’s warmer, windier or drier
Other factors influencing the rate of evaporation:
- Volume and surface area of the water body
- Vegetation cover or buildings surrounding water
- Colour of surface beneath the water, black will absorb, white will reflect
16
Q
What stores are there in a drainage basin?
A
- Soil water, used by plants ,mid term
- Groundwater, stored in the pores of water, loong term
- River channel, stored in rivers, short term
- Interception, stored on the leaves and branches of plants, short term
- Surface storage, puddles, ponds, lakes etc. Variable
17
Q
What is a water table?
A
- Upper level of pore spaces and fractures become saturated
- Used by researches to assess levels of drought, health of wetlands success of restoration programmes etc.
18
Q
What are some physical factors influencing drainage basins?
A
- Climate, Amount of rainfall and vegetation growth
- Soil composition, Amount of composition, throughflow and infiltration
- Geology, affects percolation and groundwater flow
- Relief, Steeper gradients of land influence amount of groundwater flow and infiltration
- Vegetation, Affects interception and overland flow
- Size, larger basins collect more precipitation
19
Q
What are some anthropogenic factors influencing drainage basin?
A
- Deforestation/afforestation, affects infiltration, interception, overland flow and evapotranspiration meaning more or less flooding
- Changes in land use Converting
land to farmland means less interception, increased soil compaction and more surface runoff - Urbanisation, impermeable surfaces reduce infiltration, and increases surface runoff and river discharge
- Ground water abstraction, water table drops due to water being taken out faster than its being replenished
20
Q
What is a water budget?
A
- Measures the difference between the input and output of water in an open system
- January, precipitation is greater than evaporation creating a soil moisture surplus
- June, temperature increases so does evaporation and the soil moisture surplus is used through soil moisture utilisation
- August, Maximum amount of evaporation and biggest risk of drought
- September, precipitation increases but soil moisture deficit due to amount of evaporation in August
- October-December, soil moisture recharge occurs as precipitation exceeds evaporation
21
Q
What is a river regime?
A
- Annual variation of river discharge
- Most water isn’t from precipitation but from steady groundwater flow
- Seasonality variation caused by glacial meltwater, snowmelt or monsoons causing sudden fluctuations
- Larger rivers have more complex regimes due to spanning across multiple reliefs and climactic zones such as the Mississippi river
