Hydrological cycle - hydrosphere Flashcards
Baseflow
the ground water flow that feeds into rivers through river banks and beds.
Channel flow
the water flowing in a river, also known as river discharge
Condensation
the change in atmosphere when droplets of water vapour cool and change back into liquid water
Evaporation
the process by which liquid water is transformed into water vapour
considerable solar energy is needed
varies with temperature, wind speed, humidity
evapotranspiration
2 components of evaporation and transpiration
ground water
water stored within rocks, rock pores and joints
groundwater flow
water flowing slowly below the water table through permeable rock
infiltration
water socks into and moves through the soil;
this process is influenced by the permeability and porosity of soil.
percolation
as the water moves through and seeps down the soil, it may continue to move deeper (percolate) into the rocks
precipitation
MAIN OUTPUT
the variables include type or form of precipitation (rain or snow), the total amount and seasonality
runoff or overland flow
the total of all the water that flows over the surface of the river basin, mainly flowing away within rivers.
transpiration
the biological process by which water is lost from a plant through the stomata in the leaves
rates depend on the time of year, type and amount of vegetation.
Humans influencing the hydrological cycle
- urbanisation: tarmac reduces infiltration and groundwater flow. Also increases surface run off as drains will carry water faster to rivers. Reduces evapotranspiration,
- water supply and use: dams are created to increase storage for supplying water to homes, reducing water within rivers
- mining and river siltation: results in the silting up of lakes, rivers and reservoir, leading to reduced storage capacity. Reduces vegetation cover, leading to increased run-off.
- Agricultural: increase of irrigation increases infiltration and run-off. Water can be polluted by pesticides and fertilisers.
Physical influences on the hydrological cycle
- vegetation: intercepts precipitation and slow movements of water into river channels, increasing lag time; water is lost through evaporation and transpiration reducing peak discharge
- temperature: lower temperatures ( water stored as ice/snow reducing run off); melting when temperatures rise increase run-off;
- drainage density: basins with many streams drain more quickly, so have a shorter lag time