Sand dune - Auroville Green Practices

Prashant Hedao & Lata Iyer
Auroville TN
SOURCE: NCGIA, UC Santa Barbara
CIESEN, Columbia University
Backwaters,
Sand Dunes &
Mangroves
Sand Dunes
Sand Dunes
PONDICHERRY
CHENNAI
Sand Dunes
Backwaters
Backwaters
Backwaters
  Mangroves
  Sand dune ecosystem
  Indigenous fringe forests
…all of these have suffered as humans move
closer to the sea
•  Grows in water by trapping silt
•  Needs right combination of salt
& fresh water
•  Roots above water level for
aeration
SOURCE: UNEP / WCMC
Sand dune may be simply defined as a mound or ridge formed by the
deposition of sand. These geologic landforms develop when an
abundance of sand combines with wind, vegetation and geography
SOURCE: Design with Nature by Ian L. Mcharg
Established primary and secondary dune
  Salt Spray is reduced by primary dune and ground level rises
  Xeric thickets replace dune grass
  Secondary dune is stabilized. Dune grass is replaced by plants not requiring
sand deposition
  Fringe forests established behind the stabilized secondary dune
In case of Tamil Nadu coast it is “Tropical Dry Evergreen Forest”
SOURCE: Conservation Science Program, World Wildlife Fund - US
SOURCE: USAMS & Survey of India, 1954
Vegetation on Sand Dunes
View of Sand Dunes from Agricultural Fields
View of Agricultural Fields from top of Sand Dunes
•  Indegenous / native species should be planted
•  High tolerance to any disturbance, have built-in defense mechanisms
•  Low and/or no maintenance once it stabilizes
•  No threat of attacks by pests
•  May take longer, but it is worth the wait
•  Species diversity is the key
•  Should plant at all levels:
(ground covers, shrubs, understory, keystone species)
•  Less chance of getting wiped out in case of a disease outbreak
… this will ensure long term survival of the ecosystem and
hence protection to communities
RED - 0 – 5 m
GREY –above 5m
BLUE – Below MSL
Characteristics
•  Very difficult conditions
•  Very little land available that
is 5m above mean sea level
(MSL); lot of land is actually
below MSL
•  Therefore ideal for growing
paddy as lot of stagnant water
is available
•  All development of residential
areas should be in north-south
direction
•  Very important that existing
drainage channels are
preserved
Road
SOURCE: Google Earth
SOURCE: Pacific Disaster Center, Hawaii / DigitalGlobe
SOURCE: Pacific Disaster Center, Hawaii / DigitalGlobe
SOURCE: Pacific Disaster Center, Hawaii / DigitalGlobe
Garbage Blocking Channels
Large Channels but Narrow Culverts
Orange Line - Watershed / Catchment Boundary
Raised roads act as watershed dividers and block the natural water flow
When roads are built in rural areas,
they are raised above the
surrounding land (to avoid flooding)
and normally cut across agricultural
fields
Over time the road gets “Pucca” .
Now because of trapped water
natural vegetation thrives there and
ground water recharge improves
Continued…
But after sometime strip
development (shops /
houses) starts on both
sides of the road.
People raise their land
above the road level. This
is to avoid water from
entering into their property.
Built-up area increases; which results in less ground water recharge and
increased surface run-off
If the culverts / bridges provided under the road for free flow of water are
not large enough or not provided at all, there will be bottle-necks and flooding
will result.
Water is trapped by the roads and has nowhere to go – hence FLOODING
• 
Higher elevations; NOT in low lying area as it will be prone
to flooding
• 
NOT in the natural or man-made drainage channel which
may flood in monsoons
• 
NOT on steep slopes that are prone to erosion
• 
NOT on aquifer/Groundwater recharge areas
• 
Should maintain & ensure linkages for livelihood needs, social
networks, caste issues and primary / secondary economic networks
… all this information should be collected and used
in the planning process
Not Much Intact Ecosystems
in Gangetic Plains
SOURCE: Conservation Science Program, WWF-US
SOURCE: Conservation Science Program, WWF-US
SOURCE: WWF-Nepal & WWF-US
Bombay Floods
SOURCE: Global Land Cover Facility, University of Maryland / NASA
(glcf.umiacs.umd.edu/index.shtml)
Thank you
prashant@auroville.org.in
lata@auroville.org.in