Quiz 19 Flashcards
Give 4 physical factors that increase the chance of river flooding
Heavy rainfall
prolonged rainfall
geology(rock type)
relief(changes in land height)
GIve 2 human factor that can increase the chances of river flooding
urban land use and deforestation
How does heavy rainfall increase the chance of a flood?
heavy rainfall means that water arrives too quickly to infiltrate,so theres a lot of surface run-off,which increases discharge
How does prolonged rainfall increase chances of river flooding?
prolonged rainfall can saturate the soil. any further rainfall cant infiltrate increasing surface run-off into river channels
How does geology(rock type) increase chance of a flood?
impermeable rock dont allow infiltration so surface run-off is increased, increasing discharge
How does deforestation increase chance of flood?
less trees to do interception, increasing infiltration which leads to overstauration, so more surface run-off then increasing discharge
How does urban land use increase chance of flood?
bulidings are made of impermeable rock which dont allow infiltration, increasing surface run-off so more discharge
What are dams and reservoirs?
Dams is a barrier built across rivers in the upper course. A reserviour is a artifical lake formed behind a dam
What are 2 advantages of dams and reservoirs?
1.reservoirs store water controlling the water flow
2. preventing floods downstream
What are disadvanatges of dams and reservoirs?
Dams are very expensive to build
What is channel straightening?
meanders are removed by building straighter artifical channels
What are 2 advanatages of channel straightening?
1.water leaves the area more quickly rather than building up
2. so flood risk is lower
What is a disadvantage of channel straightening?
flooding may happen downstream instead
What are embankments?
raised walls that are built along river banks
what are 2 advanatges of embankments?
- the river can hold more water
- so floods are less frequent
What is a disadvanatge of embankments?
They are quite expensive
What is flood plain zoning?
restrictions prevent buliding on parts of a flood plain that are likely to be affected by a flood
What are 2 advanatages of flood plain zoning?
- fewer impermeable surfaces are created
- reducing flood risk
what is afforestation?
planting trees in river valley increases interception
what are 2 advantages of planting trees for flood prevention?
decreases discharge and reduces flood risk
What is a disadvanatge of planting trees for flood prevention
less land is available for farming
What is river restoration?
making the river more natural by removing man-made levees
What are 2 advantages of river restoration?
discharge is reduced,so there is less risk of flooding downstream
what is a disadvantage of river restoration?
local flood risk can increase
