Cue 7 Urban Drainage

Question 1

What are urban areas usually covered in

Answer 1

Impermeable materials like concrete or tarmac

Question 2

Urban structures are designed to shed water quickly what does this result in

Answer 2

Low infiltration and so replenishment of groundwater stores is low

Question 3

What does ground water feed and what happens during dry periods

Answer 3

Groundwater feeds rivers so during drier periods river discharge in urban areas is low

Question 4

Precipitation and more intense storms is higher in urban areas what does this cause

Answer 4

Increased surface run off

Question 5

What happens to surface run off

Answer 5

It is channeled through man made pipes which transports water to rivers and streams

Question 6

What is the result of low infiltration rates, high surface run off and channeling of water

Answer 6

It enters rivers quickly and gives a short lag time and high peak discharge with a fast return to base flow

Question 7

What is catchment management

Answer 7

A way of managing rivers and improving drainage by looking at the whole river catchment and the interaction between water and land

Question 8

What is the aim of catchment management

Answer 8

To minimize issues like flooding, drought water pollution and erosion and to improve river ecosystems

Question 9

What are the 2 methods to manage river catchments

Answer 9

1 hard engineering and soft engineering

Question 10

Describe hard engineering

Answer 10

These involve man made structures like dams, flood walls and reservoirs to prevent flooding and ensure a constant water supply

Question 11

What are the disadvantages of hard engineering

Answer 11

Expensive
Disrupt natural systems
Alter wildlife and habitats

Question 12

Describe soft engineering

Answer 12

Uses the knowledge of the river basin and its processes to try to work with nature
Uses land management and involves river restoration and conservation
It is cheaper and can improve the environment

Question 13

Disadvantages of soft engineering

Answer 13

Planning restrictions can limit the construction of new homes and businesses

Question 14

Who makes the decision about which method of land management to use and why

Answer 14

Experts and not residents as they look at what is best for the catchment as a whole - residents and communities often feel ignored

Question 15

Give an example of how catchment management systems can be disruptive

Answer 15

3 Gorges Dam in China flooded 13 cities and 140 towns forcing 1.2 million people to move

Question 16

What is th aim of sustainable urban Drainage systems (SUDS)

Answer 16

To limit natural drainage systems rather than channeling through pipes or drains

Question 17

What methods do SUDS use to decrease flooding, water pollution and drought in urban areas

Answer 17

1 vegetate trenches increase interception of rainfall and retention basins store water. They help to increase infiltration and water storage- this decreases runoff and channel flow which lowers flood risk. Increased infiltration decreases the amount of pollutants entering watercourses
2vegetate roofs intercept rainfall and increase evapotranspiration which reduces flood risk
3containers on the roofs of buildings catch and store rainwater for refuse helping to reduce drought risk

Question 18

Why are SUDS more sustainable than traditional urban drainage methods

Answer 18

They work with the natural environments to improve drainage and water quality- vegetate trenches and roofs provide new habitats and increase biodiversity