Rivers - Floods Flashcards
Flooding
where land that is normally not underwater becomes submerged
infiltration
Water sinking into the soil from the ground surface
discharge
amount of water than passes a given point on a stream or river bank within a given period of time
interception
water prevented from reaching the surface by trees and grass
physical causes
precipitation
- continuous heavy rainfall + prolonged light rainfall - saturates the soil (aka fills pores w/ water)
- sudden bursts/snow - (snow melts), infiltrates quickly, surface runoff increases, water will reach river quicker so the discharge increases
physical causes
geology
- impermeable rock - doesnt allow water to infiltrate = more surface runoff = increase in discharge
- permeable rock - allows water to infiltrate, so waters store = decrease chance of flood
physical causes
relief
- steep slopes - more likely for surface runoff bc water doesnt have time to infiltrate bc its going down = higher discharge
- flat + flood plains - lower risk bc water has time to infiltrate the soil
human causes
urban land use
- new infrastructure/new housing/disappearing gardens: increases area covered by impermeable surfaces = more surface runoff
- new housing: rainwater will flow into gutters and into drains, can be built in place w/ high flood risk
human causes
rural land use
- deforestation: reduces interception = saturated soil = increased runoff = increased discharge
- farming technique: removal of hedges, arable results in soil being bare
- urbanisation: greenfield sites getting built on
- climate change: extreme weather events, increased temp = more evap = more rainfall
effects
social
- Injury
- Death
- Loss of home
- Loss of belongings
- Damage to property
- Stressful
- Isolate – loss of roads
- Loss of recreational facilities
effects
economic
- Rebuild/fixing damage
- High insurance claims
- Loss of work/employment
- Loss of revenue for local area
- House value could decline
effects
enviornmental
- Habitats lost
- Loss of land
- Disrupts breeding areas
- Spread of pollution
- Spread of disease
- Large deposits of mud left behind
- Unsanitary conditions if sewage/grains flood
Flashy Response
when a drainage basin responds quickly
flashy hydrogaphy
basin size
small basins often lead to rapid water transfer
flashy hydrogaphy
drainage density
high density speeds up water transfer
flashy hydrographs
rock type
impermeable rocks helprapid overland flow
flashy hydrogaphy
land use
urbanisation = rapid water transfer
flashy hydrogaphy
relief
steep slopes = rapid water transfer
flashy hydrogaphy
soil moisture
saturated soil= rapid overland flow
flashy hydrogaphy
rainfall intensity
heavy rain may be more than vol that can be intercepted = rapid overland flow
flat hydrograph
basin size
large basin = slow water transfer
flat hydrograph
drainage density
low density = slow water transfer
flat hydrograph
rock type
permeable rock = slow water transfer bc it mves in groundwater flow
flat hydrograph
land use
forest = slower water transfer bc interception