Water harvesting from roads: options for semi-arid areas

Written by Rainwater Harvesting Association of Malawi  |  Added on January 17, 2017   |   Filed under Publications

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Component Design options

  • Road alignments – Location within the catchment determines water harvesting opportunities from roads
  • Road surfaces – Harvest water directly from road surface from lead-off drains and rolling dips
  • In flat areas use low filtrating stone bunds
  • Storages and enhanced recharge structures on runoff paths
  • Ability to flush away contaminated first floods from roads
  • Roadside vegetation to intercept some contaminants

Cross-drainage and Culverts   

  • Divide the road runoff into smaller flows
  • Use grade reversal and in- and out-sloping to keep runoff manageable
  • Prevent gullying of drainage stream with check-dams and armouring
  • Direct the runoff to storage and recharge areas
  • Storages and enhanced recharge structures on runoff paths

 

Roadside drains – Selecting road template so as to collect runoff in drains

Storages and enhanced recharge structures on lead-off drains

Borrow pits – Use borrow pits for storage, recharge or as seepage ponds

Access ramps and landscaping of borrow pits

Road foundation – Especially on tarmac roads use permeable substrata or lateral or transversal drains

 

Newly opened Springs  

Collect newly opened spring flows in cisterns or storage reservoirs that are adequately dimensioned and have spillways facilities

Fords (Irish bridges) and flood water spreading weirs

  • Combine fords/Irish bridges with sand dams
  • Use fords to stabilize dry river beds
  • Use access roads to create flood water spreading weirs

 

Roadside vegetation     

  • Use vegetation (combined with filtrating bunds) to slow down runoff, control erosion, and increase infiltration
  • Use vegetation to fix contaminants

 

Managing and harvesting sediment

Controlled sand harvesting from fords cum sand dams and from sand traps

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