Chennai's water woes and the way forward · 2019-08-08 · Chennai Floods –December 2015 9 Pics:...
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Chennai's water woes and the way forward L. Elango Professor Department of Geology Anna University, Chennai www.elango.net.in Brain Storming Meet on Chennai Water Management, 3 August 2019
Transcript of Chennai's water woes and the way forward · 2019-08-08 · Chennai Floods –December 2015 9 Pics:...
Chennai's water woes and
the way forward
L. ElangoProfessor
Department of Geology Anna University, Chennai
www.elango.net.in
Brain Storming Meet on Chennai Water Management, 3 August 2019
Geology of Chennai and surroundings
2
Geology of
Chennai
Groundwater occur
in
weathered/fractured
rocks and
unconsolidated
formations
3www.rainwaterharvesting.org
Water supply - Location of
reservoirs & well fields
L.Elango
Water requirement
• 8.2 millionPopulation
• 8.2 x 135 liters = 1107 MLDWater
requirement
• About 800 MLD? Now 500Water
supplied
Private sources
• The remaining?
• Private wells
Major sources
• Reservoirs – 400MLD
• Krishna – 50 MLD
• Veeranam/NLC – 200 MLD
• North/South Chennai Groundwater – 100
MLD
• Desalination – 180 MLD
• Private wells
6
Today
• Quarries about 50 MLD
7
https://www.thehindu.com/news/cities/chennai/water-supply-in-city-cut-to-525-
from-830-mld-hc-told/article28023481.ece
http://www.newindianexpress.com/cities/ch
ennai/2019/jun/25/prached-chennai-to-get-
water-from-11-more-kancheepuram-
quarries--1994856.html
•Rainfall dependent
•Extreme rainfall events – flooding
•Seawater intrusion and groundwater quality
•Urbanisation and loss of water bodies
•Reduction in groundwater recharge
•Demand supply gap – recycling of water
What are the concerns?
8
Chennai Floods – December 2015
9
Pics: Senthilkumar
Sampling wells
Sampling wells
10
Groundwater chemical quality
after floods
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Nature Sci Data (2017)
Affected Vs Not affected wells
Nature Sci Data (2017)
12
Seawater intrusion
Envi. Ear. Sci (2013) 13
Extent of seawater intrusion
1969
2015
14
Impact of a check dam
15Parimalarenganayaki et al (2015)
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MAR through Ponds
Before After
Raicy & Elango (2017)
Expected regions benefited by check dams
Approximate area of
impact from MAR
17
Integrated Modelling Approach
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1. Construction of additional check dams
(existing 9, suggested 6 more)
2. 1 + 1 m increase in crest level of all
existing check dams
3. 2 + rehabilitation of defunct water bodies
4. 3 + Interlinking of A and K rivers
5. 4 + 10% increase in recharge and SL rise
Model prediction under
different scenarios
19
Extent of seawater intrusion
1969
1990
2000
2004
2010
2015
2030-recharge
structures20
Water demand for the Chennai
city with growth in population
21Paul & Elango (2018)
Water Evaluation And Planning System
www.weap21.org
Coverage of demand with the
proposed third desalination
22
Madras
Demand Site Coverage (% of requirement met)
Scenario: Reference, All months (12)
Jan
1991
Dec
1991
Nov
1992
Nov
1993
Oct
1994
Oct
1995
Sep
1996
Sep
1997
Sep
1998
Aug
1999
Aug
2000
Jul
2001
Jul
2002
Jun
2003
Jun
2004
Jun
2005
May
2006
May
2007
Apr
2008
Apr
2009
Apr
2010
Mar
2011
Mar
2012
Feb
2013
Feb
2014
Jan
2015
Jan
2016
Jan
2017
Dec
2017
Dec
2018
Nov
2019
Nov
2020
Oct
2021
Oct
2022
Oct
2023
Sep
2024
Sep
2025
Aug
2026
Aug
2027
Aug
2028
Jul
2029
Jul
2030
Perc
ent
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Paul & Elango (2018)
Coverage with the proposed
new reservoir
23
Madras
Demand Site Coverage (% of requirement met)
Scenario: Reference, All months (12)
Jan
1991
Dec
1991
Nov
1992
Nov
1993
Oct
1994
Oct
1995
Sep
1996
Sep
1997
Sep
1998
Aug
1999
Aug
2000
Jul
2001
Jul
2002
Jun
2003
Jun
2004
Jun
2005
May
2006
May
2007
Apr
2008
Apr
2009
Apr
2010
Mar
2011
Mar
2012
Feb
2013
Feb
2014
Jan
2015
Jan
2016
Jan
2017
Dec
2017
Dec
2018
Nov
2019
Nov
2020
Oct
2021
Oct
2022
Oct
2023
Sep
2024
Sep
2025
Aug
2026
Aug
2027
Aug
2028
Jul
2029
Jul
2030
Perc
ent
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Paul & Elango (2018)
Coverage with reuse of treated
waste water
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Madras
Demand Site Coverage (% of requirement met)
Scenario: Reference, All months (12)
Jan
1991
Dec
1991
Nov
1992
Nov
1993
Oct
1994
Oct
1995
Sep
1996
Sep
1997
Sep
1998
Aug
1999
Aug
2000
Jul
2001
Jul
2002
Jun
2003
Jun
2004
Jun
2005
May
2006
May
2007
Apr
2008
Apr
2009
Apr
2010
Mar
2011
Mar
2012
Feb
2013
Feb
2014
Jan
2015
Jan
2016
Jan
2017
Dec
2017
Dec
2018
Nov
2019
Nov
2020
Oct
2021
Oct
2022
Oct
2023
Sep
2024
Sep
2025
Aug
2026
Aug
2027
Aug
2028
Jul
2029
Jul
2030
Perc
ent
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Paul & Elango (2018)
Even with the various
augmentation steps?
Demand supply gap by 2050!
25
Madras
Demand Site Coverage (% of requirement met)
Scenario: Reference, All months (12)
Jan
1991
May
1992
Oct
1993
Mar
1995
Aug
1996
Jan
1998
Jun
1999
Nov
2000
Apr
2002
Sep
2003
Feb
2005
Jul
2006
Dec
2007
May
2009
Oct
2010
Mar
2012
Aug
2013
Jan
2015
Jun
2016
Nov
2017
Apr
2019
Sep
2020
Feb
2022
Jul
2023
Dec
2024
May
2026
Oct
2027
Mar
2029
Aug
2030
Jan
2032
Jun
2033
Nov
2034
Apr
2036
Sep
2037
Feb
2039
Jul
2040
Dec
2041
May
2043
Oct
2044
Mar
2046
Aug
2047
Jan
2049
Jun
2050
Perc
ent
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Paul & Elango (2018)
Way forward
• Urban planning - need to protect
groundwater recharge areas
• Water bodies to be rejuvenated
• Supply reservoirs to be deepened
• Periodical maintenance - to be ensured
• Direct storage of rainwater in sumps
• RWH structures – annual maintenance
• Recycling of waste water
Our research in media
L.Elango
