2. Advantages of having natural drainage
systems
1. Support of riparian and wetland vegetation.
2. Creation of habitat for wildlife and aquatic species.
3. Slowing down and attenuating floodwater by spreading out flows over vegetated
overbanks.
4. Promotion of infiltration and groundwater recharge.
5. Enhancement of water quality.
6. Provision of corridors for trails and open space.
7. Enhancement of property values and quality of life.
3. FUNCTIONS AND BENEFITS OF HEALTHY STREAMS
Source: Douglas County Storm Drainage Design and Technical Criteria Manual
4. IMPACTS OF STREAM DEGREDATION
Source: Douglas County Storm Drainage Design and Technical Criteria Manual
5. Adverse affects of Destroying natural
drainage systems
1. Environmentally bad decision as the problem gets out of sight-out of mind-not solving
the problem!
2. The concrete slab effectively stops groundwater recharge.
3. The slab cover over the nala shall aggravate the ‘heat island’ effect.
4. The siltation in the drain shall become difficult and more expensive to manage and
would require specialised super-suction machines.
5. The sewage being carried by the drain shall be deprived of sunlight and
oxygen, creating septic conditions and effectively increase the pollution load on the
river.
6.
7. Alternatively…
1. The drains could use on-line decentralised biological wastewater treatment to treat the
waste water and reuse the same for irrigation and create a landscaped parkway like
‘OSHO PARK’ in Pune.
2. The sanitised drain then could be used for creating picnic hubs, jogger’s park, a NMT
connection to achieve interconnectivity between various residential neighbourhoods,
etc.
Before
Case example: Osho Park, Pune
After
10. Barapullah Nallah corridor - Before
http://www.greenlightdhaba.org/2011/04/wrong-turn-at-barapullah-nallah.html
11. Barapullah Nallah corridor - After
http://www.greenlightdhaba.org/2011/04/wrong-turn-at-barapullah-nallah.html
12.
13. Undo the mistakes.…
Restoration/Daylighting of Natural Drainage systems
Daylighting refers to projects that uncover and restore streams and
rivers previously buried in underground pipes and culverts, covered by
decks, or otherwise removed from view.
Source: http://www.sf-planning.org/ftp/files/Citywide/Glen_Park/PUC_Daylighting_FAQ_and_Case_Studies.pdf
21. Timeline of Cheong Gye Cheon river stream
Named Cheong gye cheon meaning
clear water stream
Construction of road/ highway/freeway
over polluted streams
1970
1300
2011
1945
Shanty towns along polluted & open
sewage channels for city
Stream restored to its ecological function
http://didacticdiscourse.wordpress.com/2012/03/29/reclaiming-nature-in-the-city-cheong-gye-cheon-restoration/
22. Timeline of Delhi water channels
Settlement along water channel
Construction of road/ highway over
polluted streams
2010
1200
1945
Slums along natural drainage channels &
open sewage channels for city
-------
?
23. Policy principles required…
Source: Urban Drainage and Flood Control District (Colorado), 2001
A natural drain policy must highlight followed principles;
1. Drainage is a regional phenomenon that does not respect the boundaries between
government jurisdictions or between properties.
2. A storm drainage system is a subsystem of the total urban water resource system.
3. Every urban area has an initial and a major drainage system, whether or not they are actually
planned and designed.
4. Runoff routing is primarily a space allocation problem.
5. Planning and design of storm water drainage systems generally should not be based on the
premise that problems can be transferred from one location to another.
6. An urban storm drainage strategy should be a multi-objective and multi-means effort.
7. Design of the storm water drainage system should consider the features and functions of the
existing drainage system.
8. In new developments, attempts should be made to reduce storm water runoff rates and
pollutant load increases after development to the maximum extent practicable.
9. The storm water management system should be designed, beginning with the outlet or point
of outflow from the project, giving full consideration to downstream effects and the effects of
off-site flows entering the system.
10. The storm water management system should receive regular maintenance.
11. Floodplains need to be preserved whenever feasible and practicable.
12. Reserve sufficient right-of-way to permit lateral channel movement whenever the floodplain
is contained within a narrow natural channel. Urban Drainage and Flood Control District
(Colorado), 2001
24. Strategy for protecting and restoring storm water channels
Create City level Watershed Management Plan (WMP) and
Urban Drainage Master Plan
Typical Watershed Map of a City, with multiple watersheds
Watershed map using Digital
Elevation Model (DSSDI)
