A-Level Geography - Human - Urban Drainage
- Created by: Noah_S
- Created on: 16-02-22 10:46
View mindmap
- Urban Drainage
- Urban Precipitation & Drainage
- Characteristics
- Cities have warmer air, holding more moisture
- Cities have 5-15% more precipitation
- Dust and pollution make more condensation nuclei
- Cities have 5-15% more precipitation
- Less vegetation reduces evapotranspiration and humidity in urban areas
- Less vegetation reduces interception causing precipitation to land on impermeable urban surfaces
- Infiltration is reduced so drains are needed to remove surface water quickly
- Cities have warmer air, holding more moisture
- Impacts on drainage basin storage areas
- Urban rivers are important stores, as they are the exit for water transferred through the basin
- Dredging, embanking and channelisation will increase their capacity
- Reservoirs, lakes, ponds & swimming pools are permanent stores, but may suffer evaporation
- Interception storage is reduced due to the replacement of vegetation
- Replaced with impermeable surfaces engineered to drain water rapidly into the river
- Soil moisture will vary according to ground conditions, but generally less soil storage capacity
- Due to less exposed surfaces and vegetated areas
- Urban rivers are important stores, as they are the exit for water transferred through the basin
- Characteristics
- Drainage Management
- Soft Engineering
- Afforestation
- Plants trees to establish a woodland or forest
- Trees increase interception & evapotranspiration and reduce throughflow & surface runoff, less water received by rivers
- Floodplain zoning
- Restricts different land use to certain locations on the floodplain
- Natural floodplains act as a natural soakaway, so protecting them reduces surface runoff into the channel
- Afforestation
- Hard Engineering
- River Straightening
- Involves cutting through meanders to create a straight channel
- Increases flow which could increase flood risk further down
- River Channelisation
- Involves lining straightened channels with concrete
- Reduces friction, increasing flow but looks unsightly & damages local ecosystem
- River Straightening
- Sustainable Urban Drainage Systems
- Represent the environmentally friendly replication of natural drainage systems
- They hold back and slow surface runoff from any development & allow natural breakdown of pollutants
- Techniques include swales and permeable surfaces
- Swales are wide, shallow drainage channels that are normally dry
- Permeable roads/surfaces allow water through
- Slows down surface water, reducing risk of sewer flooding & recharges groundwater
- Soft Engineering
- Case Study - Lamb Drove, Cambourne
- Aims
- Cambridgeshire is a low-lying county, at risk from flooding in river valleys & urban watercourses
- Demonstrate that SUDS are a viable and attractive alternative to traditional forms of drainage
- Usage of SUDS
- Water butts are used to collect roof water for garden irrigation
- Permeable paving allows water to enter porous storage zones to filter out pollutants
- Detention basins and wetlands in open spaces slow down the runoff rate and store water on a short term basis
- A retention pond for final storage of water before being released into a drainage ditch beyond the site
- Impacts
- Construction and ongoing maintenance costs have been 10% less than conventional pipe drainage systems
- Improvement of biodiversity, ecology and quality of life at the site
- Has created a visually enhanced & attractive landscape providing social value
- Improved quality of water leaving the site
- Aims
- Urban Precipitation & Drainage
Comments
No comments have yet been made