Flashcards in ✅220.127.116.11 - Urban Drainage Deck (17)
What is interception?
When precipitation lands on buildings, vegetation, concrete etc before it reaches the soil. Storage is temporary, often quickly evaporated
What is vegetation storage?
All the moisture in vegetation at one time
What is surface storage?
Total volume of water held on Earth's surface in lakes, ponds and puddles
What is groundwater storage?
Water in underground permeable rock strata
What is channel storage?
Water held in a river or stream channel
How can flooding be increased in urban areas?
If run off from roofs and paved areas is piped into waterways
What are SUDS?
Sustainable Urban Drainage Systems
What do SUDS aim to do?
Control the quality and rate of run off from a development
Improve quality of run off
Enhance the nature conservation, landscape and value of site and surroundings
What are permeable pavements?
Pavements made of porous material such as concrete blocks, porous asphalt and crushed stone
Where does water go from a permeable pavement?
It may infiltrate directly into the subsoil or be stored in an underground reservoir before soaking into the ground
What are swales?
Shallow ditches with gently sloping sides that can be built into the landscape
What are the advantages of swales?
They provide temporary storage for storm water
Reduce peak flows
Facilitate filtration of pollutants
Encourage microbial decomposition
How can green roofs act as SUDS?
They reduce flow rates and improve water quality, as well as improving insulation
What are infiltration trenches?
Stone filled reservoirs to which stormwater run off is redirected
How are pollutants removed from infiltration trenches?
By absorption, filtering and microbial decomposition in the surrounding soil
What does the type of SUDS in place depend on?
The pollutants present in run off
The size of and drainage strategy for the catchment area
The hydrology of the area and infiltration rate of soil
The presence of Groundwater Source Protection Zones or contaminated land