drainage management

Question 1

hard engineering

Answer 1

river straightening
natural levees, embankments
flood relief channels
river channelisation

Question 2

river straightening

Answer 2

cutting through meanders to create a straight channel, increasing the gradient and speed of flow and increasing flood risk downstream

Question 3

natural levees, embankments

Answer 3

levees can be made higher so increasing capacity
embankments are raised riverbanks using concrete walls, blocks of stone or material dredged from the river bed (more environmentally friendly)

Question 4

flood relief channels

Answer 4

by-pass the main channel, can be for emergency use only when high flow levels threaten flooding or as a permanent feature enhancing the environment by creating wetlands and recreational opportunities

Question 5

river channelisation

Answer 5

lining straightened channels with concrete, reduces friction, improves the rate of flow and reduces the build up of silt as it prevents banks from collapsing, but looks unsightly and damages local ecosystems

Question 6

soft engineering

Answer 6

afforestation
riverbank conservation
floodplain zoning
river restoration

Question 7

afforestation

Answer 7

planting trees to increase interception and reduce through flow and surface run off because they take up water to grow. evapotranspiration from leaves and branches dissipates water that would otherwise end up in the river channel

Question 8

riverbank conservation

Answer 8

planting bushes and trees reduces lateral erosion, bank collapse and silting up of the channel. roots stabilise banks by binding material/sediments together

Question 9

floodplain zoning

Answer 9

restricts different land uses to certain locations on the floodplain (eg nearest to the channel only used for pasture or recreational use) natural floodplains act as a natural soakway, so protecting them from development and reducing surface run off into the channel

Question 10

river restoration

Answer 10

a return of the channel to its natural course and so reversal of artificial drainage management solutions in the past

Question 11

SUDS techniques

Answer 11

swales
permeable road and pavement surfaces
infiltration trenches
biorentation basins
detention basins 
rain-gardens
green roofs

Question 12

benefits of SUDS

Answer 12

slowing down water runoff and reducing risk of flooding
reducing the risk of sewer flooding during heavy rain
preventing water pollution
recharging groundwater to help prevent drought
providing valuable habitats for wildlife in urban areas
creating green spaces for people in urban areas