Urban Drainage

Question 1

Why is urban precipitation a problem?

Answer 1

• You get more rain in urban areas due to the warmer air in cities holding more moisture and the pollution making more condensation nuclei.
• less vegetation in urban areas so less evapotranspiration and interception.
• high surface run off
• reduced infiltration due to impermeable surfaces

Question 2

What is the urban water cycle?

Answer 2

1. Source
2. Water treatment
3. Water distribution
4. Use
5. wastewater collection
6. Wastewater treatment (links back to source in a cycle)

Question 3

How can urban areas affect rivers through pollution?

Answer 3

• sediment from building sites, river bank erosion
• oil and chemicals from cars
• heavy metals from car exhausts
• pesticides and nutrients from parks and gardens
  Viruses from pet waste

Question 4

What are SUDS?

Answer 4

They are a sequence of water management practises and facilities that are designed to drain surface water through a more sustainable approach.

Question 5

What are Swales?

Answer 5

They provide temporary storage for water, reduce peak flows and also water filtration directly into the ground.

Question 6

What are wetlands like?

Answer 6

Can accommodate varied water levels in storms, algae and plants act as filters and nutrient removal. Silt traps to manage sediment.

Question 7

What are permeable pavements like?

Answer 7

Reduces the need for sewers. The water could go through concrete block into subsoil or be stored in the underground reservoir.

Question 8

What are infiltration trenches like?

Answer 8

They are stone fixed reservoirs to which storm water run off is directed to and infiltrated into the ground. Their longevity can be extended through a filter strip or gully.