hard vs soft enginerring rivers

Question 1

dams and reservoirs (hard)

Answer 1

reservoirs store water, preventing floods and controlling water flow
generate hydroelectric power

expensive, can flood existing settlements
material is deposited in the resovoir not downstream leading to framing downstream becoming less fertile

Question 2

channel straightening (hard)

Answer 2

meanders removed -

water leaves area more quickly rather than building up so flood risk is lower

flooding however may happen downstream instead
faster moving water may cause more erosion downstream

Question 3

embankments (hard)

Answer 3

raised walls are built - floods are less frequent as the river can hold more water

quite expensive and risk of severe flooding if they break

Question 4

flood relief channels (hard)

Answer 4

divert water around built up areas

gates mean the release of water can be controlled - reducing the flood risk

increased discharge where the relief channel re-joins the river which could cause flooding

Question 5

flood warnings and preparation

Answer 5

give people time to gather possessions or evacuate - reducing the impact of flooding

doesn’t prevent floods
some people don’t have access to warnings
modifying buildings is expensive

Question 6

flood plain zoning

Answer 6

resrictions on buildings on area of rivers that are likely to flood

risk is reduced - fewer impermeable surfaces are created

expansion of urban areas are limited if there arent other suitable building areas
cant help with areas with existing buildings

Question 7

planting trees

Answer 7

increases interception of water and lag time

discharge and flood risk decrease
vegetation reduces soil erosion

less land available for farming