Urban drainage

Question 1

What is the definition of drainage basin?

Answer 1

Area of land which is drained by a river and its tributaries. The watershed divides one basin from another.

Question 2

What is the process of drainage?

Answer 2

1. Inputs- what is put in or taken in by any process
2. Storage- action and method of storing something for future use
3. Flow- moving from one place to another in a steady stream
4. Output- place where something leaves the system

Question 3

Why does drainage differ in urban areas?

Answer 3

• Less interception
• Less infiltration as impermeable ground
• More reaches the rivers as it goes through purpose built drains

Question 4

What is the definition of sustainable urban drainage systems?

Answer 4

They try to hold back surface run off in urban areas and allows natural processes to break down pollutants.

Question 5

Techniques of SuDS?

Answer 5

1. Swales- shallow channels store excess water
2. Permeable roads
3. Bio-Retention basins- gravel layers beneath reed beds, collect and filters water
4. Detention basins
5. Rain gardens- shallow depressions planted with shrubs
6. Green roofs
7. Water butts

Question 6

Benefits of SuDS?

Answer 6

• Slow surface run off, allowed to infiltrate
• Filters polluted water
• Increase habitats
• Green space improves local areas

Question 7

Drawbacks of SuDS?

Answer 7

• Not all developers are willing to install this
• Expensive
• Wastes valuable land which could be built on

Question 8

Why is flooding more common in urban areas?

Answer 8

• More precipitation
• Impermeable surfaces
• Less interception as less vegetation

Will only get worse in the future as climate change means increased water in the water cycle.

Question 9

Lambs drove, Cambridgeshire (case study of SuDS):

Answer 9

Aims:
- Showcase practical and innovative water management techniques in new developments.

Techniques used in Lambs Drove:

• Water butts
• Green roofs and swales
• Detention and retention basins
• Permeable paving

Their management train:
- Water is controlled from point at which it enters the site until it leaves, everything works in a system to mimic natural processes.

Successes:

• Cost-effective
• Better quality of life due to green spaces and attractive landscapes
• Improved water quality.

Question 10

Sheffield Blue Loop (River restoration case study):

Answer 10

What is it?
- Trail around the river and canal, includes a 13km walk and cycle route.

What was it like before?
- When coal industry started to decline the canal and surrounding area fell into disrepair and dereliction.

Aims of the scheme:

• Support local communities
• Reducing flooding and increase biodiversity
• Improve quality of surrounding areas.

Main features:

• Unique habitats
• 13km walk and cycle routes with benches and picnic areas
• Marina for boats

Successes:

• Helps restore river and encourage visitors
• Reduces car use
• Local businesses encourage to use sustainable initiatives.
• Habitats improved