EQ1 Flashcards
Global water stores + total stored water
Hydrosphere (all of the water on the earths surface - rivers, sea) = 96.5%
Atmosphere (water stores in the air) = 0.001%
Cryosphere (frozen water) = 1.7%
Lithosphere (rocky outer layer of earths crust) = 1.7%
Total global water
Accessible water to humans only exists on the hydrosphere
96.5% of that is ocean water
Earths freshwater supply
Only makes up 2.5% of the earths total water store
Surface water + other freshwater
Only 1.2% of earths freshwater supply - v small amount
Accessible freshwater
Amount of this that is actually accessible = 1%
Hydrological cycle: inputs, flows, fluxes, outputs
Fluxes (type of movement) = hydrological cycle: precipitation, surface run-off, evapotranspiration
Main input = HC = precipitation
Main output = HC = evaporation, transpiration, discharge
Relief rainfall
Rainfall that occurs because of landscape shape/topography
Occurs due to the change in temp of the air that rises alongside = hill/mountain
Air cools + condenses as it moves up in the atmosphere + forms clouds + rainfall
Creates drier conditions = rain shadow
Conventional rainfall
Usually occurs during = summer = UK when the sun heats the land
Creates rising pockets of warm air = convection currents
Warm air rises rapidly where it starts 2 cool + condense 2 form clouds
Clouds can be large cumulonimbus clouds
Clouds can produce heavy rainfall + thunderstorms
Frontal rainfall
Occurs when a warm front meets a cold front. Heavier cold air sinks = ground + warm air rises above it
When warm air rises it cools
Cooler air condenses + forms clouds
Clouds bring heavy rain
Flows seen = HC - 7 main categories
INTERCEPTION - through the retention of water by plants + soil
INFILTRATION - water soaking into plants + soil
PERCOLATION - deep transfer of water into bedrock
THROUGHFLOW - lateral transfer of water downslope
GROUNDWATER FLOW - v slow transfer of percolated water
SURFACE RUN-OFF - movement of water over land
RIVER/CHANNEL FLOW - water entering river/stream
Physical factors that affect drainage basin
Climate
Soil
Geology
Relief
Vegetation
Climate affecting DB
mainly impacts inputs/outputs
Changes the amount + type of precipitation + amount of evaporation
Soil affecting DB
Affects the importance of different flows in the system -e.g, surface run-off
Geology affecting DB
Affects surface run-off
Impacts percolation + groundwater flow rates
Affects soil formation
Relief affecting DB
Affects surface run-off
Impacts the amount of precipitation
Slopes affect run-off
Vegetation
Affects surface run-off
Presence of plants has major impact on interception, infiltration, transpiration
Human factors affecting DB
River management
Deforestation
Changing land use (agriculture)
Changing land use (urbanisation)
River management- DB
Construction of reservoirs
Use for domestic supply + irrigation of crops
All of this removes water from its natural place - disrupts the general flow of the HC
Deforestation - DB
Reduced evapotranspiration but Inc infiltration + surface run-off
Less rainfall put into the atmosphere + potentially less rainfall over time
Soil has a surplus of water as there is no vegetation to absorb it
Changing land use (agriculture) - DB
Arable to pastoral farming: compacts soil + Inc run-off
Pastoral to arable farming: ploughing Inc infiltration rates (loosening the soil allowing it to take more water in from precipitation)
Changing land use (urbanisation) - DB
Tarmac, tiles, concrete = speed up surface run-off, Inc flooding
Impermeable surfaces means no absorption
Example = human factors: Amazonia
Amazon basin contains the worlds largest area of tropical rainforest. Deforestation has disrupted the drainage basin cycle. Number of ways;
- lowering of humidity (less evapotranspiration taking place + less water vapour in the atmosphere)
- less precipitation
- more surface runoff + infiltration (compacting soil from removing trees)
- more soil erosion + slit being fed into rivers
Water budgets
Annual balance b/ precipitation, evapotranspiration, run-off
Annual balance b/ inputs + outputs
Can be calculated globally/locally
Useful for calculating the amount of water available for human use + available soil water
Polar: low budget, low availability etc
Water regimes
River regimes = annual variation in discharge/flow of a river at a particular point + usually measured in cumecs. Influenced by;
-size of the river + where discharge measurements are taken along it’s course
- amount seasonality + intensity of the precipitation
- temps with possible meltwater + high rates = evaporation in the summer
- geology + soils particularly their permeability + porosity: groundwater notes in permeable rocks is gradually released into the river = base flow
- type of vegetation cover: wetlands can hold water + release slowly into the river
- human activities aimed at regulating a river’s discharge
The Amazon - rivers discharge
High flow Dec-May
Dry season Jun-Nov
Moderate variability in seasons
Human influence increasing w/ urbanisation + deforestation
Alaska - rivers discharge
High flow apr-aug due 2 snowmelt
Low flow sep-mar as ice is forming
Large flow variability
Relatively few human influences
