hydrosphere Flashcards
(12 cards)
what is a drainage basin
a drainage basin is an area of land drained by a single river
what physical factors can affect a drainage basin
the type, intensity, duration and frequency of precipitation.
how does the type of precipitation affect a drainage basin
rain will move quicker through a drainage basin than snow which could lie on the ground for a period of time before melting
how does the intensity of precipitation affect a drainage basin
heavy rain won’t immediately soak into the land as the land cannot absorb it at the rate that is falling; therefore, it is more likely to flow as overland flow and reach the river channel more quickly
how does the duration of precipitation affect a drainage basin
prolonged rainfall will cause the land to become saturated and the water will flow overland when no more water can soak in
what are the human factors that can affect a drainage basin
farming, deforestation, urbanisation, mining
how does farming affect a drainage basins
increased crop yield reduces infiltration, since more water is being intercepted whereas when the crops are harvested the water will reach the river more quickly
how does deformation affect a drainage basin?
deforestation increased surface runoff since water is no longer being intercepted or stored. this means that precipitation will reach the trunk river quicker increasing river discharge and flooding risks.
factors that affect hydrographs?
- river basin shape
- river basin area
- rock type
- soil
- land use
- river basin slope
how does river basin shape affect a hydrograph?
circular river basin shape - this will cause a steep rising limb, a short lag time and a high peak discharge
elongated river basin shape - this will cause a shallower rising limb, a longer lag time and a lower peak discharge
how does the river basin area affect the hydrograph?
large drainage basin - precipitation has a larger distance to travel to the trunk river. this means that the graph will have a shallower rising limb, longer lag time and a lower peak flow.
small drainage basin - precipitation has a smaller distance to travel to the trunk river. therefore the graph will have a steeper rising limb, a shorter lag time and a higher peak flow.
how does rock type affect the hydrograph?
impermeable rock - (doesn’t absorb water) there will be little infiltration and lots of overland flow meaning the water will reach the trunk river faster creating a steep rising limb, high peak flow time and a short lag time.
permeable rock -
