Dr. M.V.Ramana Murthy
&Dr. M.A.Atmanand,
Ministry of Earth Sciences
• Rivers in
spate,
Submerged
flyovers ,
Airport, Roads
and Settlements
Dec., 2015 Floods that paralyzed Chennai – Some snapshots
Coastal Flooding –information
lacunae
No data on
• Vulnerable areas
• Extent of flooding
• Low lying areas
• No warning system
Early Warning System for forecasting Coastal Floods
MoES ( NCMRWF, IMD and NCCR) has
developed Urban Flood Warning System
integrating the Numerical models of
Weather (Precipitation),
Hydrology (Catchment),
Hydraulic ( River),
Hydrodynamic (Tide and Storm
Surge )
and Urban Drainage/overland flow.
Web Based Decision Support System is
put into operation for Greater Chennai
Corporation (GCC) in association with
TN State Disaster Management Unit by
integrating Topography
(DEM)/Bathymetry,
population/infrastructure and
administrative information.
Similar System is being developed by
MoES for Mumbai with network of
observatories. It will be extended to
other cities in the country.
Water demand, Population growth, Over exploitation of resources
Climatic change and variability
Land use, Catchment areas for Refill / Reservoirs
Water quality , Pollution
Natural /Chemical / Biological Impurities
Sea Water Ingression
Contamination by Industrial / Domestic Waste
Poverty and economic policy
Water resource Management
International waters / Sociological issues
Water Scenario: Challenges
Source: 'India's Water Future to 2025-2050’,International Water Management Institute; Datamonitor; ’Dreaming With BRICs: The Path to 2050’,GoldmanSachs Global Economics Paper No:99;Population Division, Department of Economic and Social Affairs, United Nations: ’Sustainable Technology Options forReuse of Wastewater', Central Pollution Control Board; 'Urban and Rural Areas 2007’,Population Division, Department of Economic and Social Affairs,United Nations; 'India's Water Resources,Availabliity,Needs and Management:21st Century', German Coastal Engineering Research Council
Source: Sustainable technology options for Reuse of Wastewater', Central Pollution Control Board; 'Wastewater management and Reuse for Agriculture andAquaculture in India’, CSE Conference on Health and Environment 2006; Wastewater reuse and Recycling Systems: A perspective into India and Australia',International Water Management Institute
Source: 'Corporate initiatives for Water Conservation and Waste Water Management’ India Water portal; 'Higher Incomes for farmers in India’s KarnatakaWatershed', World Bank; 'Rain Water Harvesting Catches on in Chennai', The Hindu Business Line; 'Agricultural Engineering', Government of Tamil Nadu; ’SeaWater Reverse Osmosis Plant to be Established in Chennai', Andhra News; ‘BARC Builds Barge-mounted Plant to Produce Safe Drinking Water', Live Mint;'Garland of Hope: River-linking as a Solution to Water Crisis ‘,The Times of India
Source: ‘India’s Water future to 2025-2050:Business as usual Scenario and Deviations’, International Water Management Institute; India Census 2001;’WaterPoverty in Urban India: A Study of major Cities’, Jamia Millia Islamia;’ Troubled Waters', Development Alternatives;’ Dreamings with BRIC’s: The Path to2025’,Goldman Sachs,2003;’Urban and Rural Areas 2007’,United Nations; ’Water Supply-The Indian Scenario’, IEA India ;’Status Of Water Treatment Plants InIndia', Central Pollution Control Board; Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat
On 18 June 2019, the city's reservoirs ran dry, leaving the city in severe crisis
Chennai population : 8.24 million (2011 census)
As the city lacks a perennial water source, catering the water requirements of the population has remained an arduous task.
Although three rivers flow through the city,
Chennai relies on North East Monson to
replenish its water reservoirs since therivers are polluted with sewage.
With the increase in population and
depleting ground water the city often
grapples with acute water supply
shortages.
Chennai Water Crisis
Chennai is entirely dependent on ground water resources to meet its water needs.
Ground water resources in Chennai are replenished by rain water and the city's average rainfall is 1,276 mm.
Chennai receives about 985 million liters per day (mld) from various sources against the required amount of 1,200 mld. This demand is expected to rise to 2,100 mld by 2031.
Water to the city's residents is being supplied from desalination plants at Nemelliand Minjur; aquifers in Neyveli, Minjur and Panchetty;
There is a canal to tap into excess water from the Krishna basin (as part of the Telugu Ganga project) and Cauvery (Veeranam project).
There are four reservoirs in the city, namely, Red Hills, Cholavaram, Poondi and Chembarambakkam, with a combined capacity of 11,057 mcft.
Demand and Supply of Water in chennai
The failure of northeast monsoon in 2018 and pre-monsoon showers in 2019 have caused depletion of the already over-exploited lakes.
The Poondi reservoir has a capacity of 3,231 mcft
The Chembarambakkamreservoir has a capacity of 3,645 mcft.
2018 2019
2018 2019
Present Scenario : As on June 2019
The Chennai city has network of about 650water bodies including major lakes, pondsand storage tanks has been destroyed. Thecurrent number stands at around 27,according to the NIDM study.
Total area of 19 major lakes in the CMAhas nearly halved from 1, 130 hectares toabout 645 hectares.
This is the overall capacity of water bodiesin the city to contain excess rain water hasreduced.
Cause I : Disappearing water bodies
Extent of Water bodies as mapped from
Toposheet and Pre and Post flood
satellite data
SOI Toposheet(1975) : 105.5 sq.kmPre-flood Sat data (6.10.2015) : 35.4 sq.kmPost-flood Sat data (10.2.2016) : 105.7 sq.km
Cause I : Disappearing water bodies
Water bodies
Topo
sheet
[1976]
6-Oct-
15
10-Jan-
16
%
Change
Ambattur
Lake 1.68 1.41 1.3
22.62%
Chembaramba
kkam Lake 20.54 8.52 19.71
4.04%
Cholavaram
Lake 6.54 1 6.2
5.19%
Korattur Lake 1.96 1.57 1.68 14.28%
Porur Lake 1.17 0.09 0.75 35.89%
Puzhal Lake 19.54 3.94 19.06 2.45%
Retteri Lake 1.47 0.82 1.07 27.21%
Velachery
Lake 0.95 0.08 0.16
83.15%
Cause II : Tampering of recharge structures
Tampering of recharge structures like lakes, tanks , ponds and wetlands is one reason attributed to the water crisis in Chennai.
Cause III : Fractured flood sink
Pallikaranai is a freshwater marsh inthe city of Chennai and is home toseveral rare/ endangered andthreatened species.
Pallikaranai used to cover an area of50 sq km but it has now been reducedto a tenth of its size. 90% of themarshland has been lost toconstruction of IT corridors, gatedcommunities, garbage dumps andsewage treatment plants.
A survey conducted by Care EarthTrust in the early 2000s revealed thatthe marsh had shrunk by almost 90percent--from close to 6000 hectaresto barely 600 hectares--over a 50-yearperiod.
Fractured flood sink - Temporal changes in Pallikaranai marsh (1990-2016)
Dump yard
Chennai’s Water Crisis:Five-point solution
Improving storage of surface water
Efficient implementation of rainwater harvesting
Recharging groundwater
Protection of flood plains, lakes and wetlands
Desalination plants
According to the records of the Water Resources Department, only 19 of the 29 major
waterbodies in the city's periphery can be restored.
Nine lakes cannot be rejuvenated owing to encroachments, including those in
Valasaravakkam, Virugambakkam, Maduravoyal etc.
Once rejuvenated completely, the remaining lakes will have a combined storage
capacity of 1,000 million cubic feet (mcft).
In addition, if the four primary reservoirs are desilted by a metre, an additional water
volume of about 500 mcft can be stored.
It is estimated that as many as 3,600 tanks in and around the Chennai metro area
(covering the whole of Kancheepuram and Tiruvallur districts), if properly preserved
and networked, can provide five times the quantum of water that the city needs in
normal times. Water harnessed through these tanks is estimated to be about 80,000
million cubic feet (TMC).
Solution I :Improving storage of surface water
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DESALINATION TECHNOLOGIES
Thermal Desalination
1. Multi effect distillation / Multi stage flashing
2. Low Temperature Thermal Desalination
3. Solar based Desalination
Membrane Desalination
1. Sea water reverse osmosis
2. Electro dialysis
Desalination
Natural Way
LTTD Desalination at
Union Territory of Lakshadweep
LTTD ProcessVertical Temp profile across Ocean
•Temperature differences between the surface (28o– 30o) and deep sea
water(10-12o) at the Islands used
•Under vacuum condition, warm (surface) sea water is evaporated and it is condensed using the deep sea cold water resulting in pure fresh water
• Major components are Marine Structure, Plant Building and Deep sea submarine pipeline
Desalination Low Temperature Thermal Desalination uses two water
bodies where in warmer water is evaporated at low
pressures and the colder water is used in condensing
the colder water to obtain high quality drinking water.
The applicability of the technique is site specific.
Other techniques for desalination are Reverse Osmosis,
Multi Stage Flashing and Multi Effect Distillation
Islands with availability of 400m depth for cold water
within 1 km distance and Coastal Thermal Power Plants
discharging huge amounts of hot water into nearby sea
are suitable for LTTD. For mainland applications an
offshore floating plant would be required.
23
Kavaratti Island, UTL
RO plant Bitra
Parabolic Solar
Collectors
MED System
Solar Desalination
LTTD PLANTS TAKEN UP BY MOES-NIOT
Completed• 2005: Kavaratti Plant – 100 m3/day• 2007: Barge Mounted Plant - 1000 m3/day• 2009: Power Plant Based LTTD – 150 m3/day• 2013: Solar MED 35 m3/day (Cond. design by NIOT)• 2011: Agatti and Minicoy Plants – 100 m3/day
Underway• 2 x 1000m3/day: Power Plant based Plant in
Tuticorin (Design Stage, fabrication to commence)• 10000 m3/day Offshore Plant (DPR Stage)• 6 x 150m3/day: Plants in Lakshadweep Islands
(Under Progress)
Agatti-2011
NCTPS -2009 Off Chennai - 2007 Kavaratti -2005
Minicoy-2011
Coral/sand stone rock in HTL
Underwater pictures Agatti / Androth
AgattiAndroth
DESALINATION: PROCESS Ocean Thermal Gradient: The temperature of water decreases
with an increase in depth.
Low Temperature Thermal Desalination (LTTD)
The temperature difference is utilized to produce potable water by
evaporating surface sea water at low pressures and condensing the resultant fresh vapour with deep sea cold water.
26
Components: Flash Chamber, Condenser, Sea Water Pumps, Vacuum System, Cold Water Pipe, Marine structures like sump, Bridge and Plant Building.
Desalination plant
1000m
Cold water pipe
400m
LagoonReef
Typical Island profile
LTTD plant at Agatti
Minicoy LTTD plant
Completed LTTD Plants at UT LakshadweepLTTD plants each with fresh water generation capacity of 100 m3/day were established at Agatti
(July 2011), Minicoy (April 2011) and Kavaratti (May 2005). Six more plants under construction at
Amini, Androth, Chetlat, Kadamat, Kalpeni and Kiltan islands.
SumpPlant building
Approach trestleInstallation of Deep Sea
Cold Water Pipe
230m (approx.)700m (approx.)
400m (appro
x.)
Agatti Desalination plant
Major components: Marine Structures (Sump, Approach Bridge, and Plant Building) Submarine Cold Water
Pipe: ~ 1000m long HDPE pipeline with attachments;
Process Equipment (Flash Chamber, Condenser, Seawater Pumps, Vacuum System, Plant Piping )
AGATTI PLANT
Sump with Sea Water Pumps
Plant BuildingWith Equipment
Bridge for Access, Piping and Power
BreakerRegion
Shallow Water Region
Control Room
Typical conditions in the Breaker Region of the Site
Side view of the Plant
KILTENCHETLET
KADAMAT
AMINI
KALPENI
ANDROTH
A 35000 liters per day capacity is installed atRamanathpuram, TN, in 1400 m2 area with apower requirement of 26 kW.
Concentrates Solar Energy with Linear FresnelType Collectors for Heating / EvaporatingSeawater
Multistage Desalination of the sea water Features: 6 stage multi effect
desalination (MED) system forDesalination
Components: Pumps for maintaining theflows; vacuum system for maintaining therequired pressure in the system;Instrumentation for the plant
Advantages / Disadvantages for remote islands• Effective utilization of the solar heat for only
6 hours during the day• Periodical cleaning Essential to ensure
efficiency
EVAPORATOR
FLASH CHAMBER
CONDENSER
COLOUR CODE
BRINE PUMP
MAIN SEA WATER PUMP
DISTILLATE PUMP
DM RECYCLEPUMP
VACUUM SYSTEM
BRINE
SEA WATER
STEAM
DISTILLATE
DISTILLATE OUTLET
BRINE REJECT
SEA WATER INLET
SOLAR PANEL
Solar Desalination System - A Schematic
Parabolic Solar Collectors MED System
A view of the Desalination Plant a Ramanathapuram
Solar Assisted LTTD Plant Installed at Ramanathapuram, TN
Schematic of Solar desalination plant
Solar Thermal Distillation Plant of 10 m³/day capacityhas been commissioned by IIT Madras with thefunding of MoES under TRB.
Intake caisson with pumping system for supplying seawater to the MED plant has been commissioned byNIOT.
Intake seawater systemIntake caisson
Solar Desalination at Kanyakumari
Plant capacity (m3/day)
Collectorarea (m2)
Water requirement (m3/day)
Surface area condensation (m2)
0.05 10 1 0.4
1 100 20 4
10 600 200 32
100 5000 2000 400
1MLD Barge Mounted LTTD Plant
Plant Components
A View of the Barge and its mooring
Pipe Tow
For mainland applications, the necessary depth for the availability of 10 – 12o Cwater is at 40 – 50 km from shore. HDPE pipe of length 600 m was towed,upended connected at the bottom of the barge at 1000 m water depth.
Deepest SPM in Indian water and for the first time in the country synthetic ropeswere used for such a mooring.Fresh water with TDS 10 ppm was obtained through indigenously designed andfabricated flash chamber and condenser.
10 MLD OFFSHORE DESALINATION PLANT Requirements : • Depth of at least 1000 meters• Distance at least 20 – 25 km from shore• Requires a large size stable weather platform for housing plant • a large cold water conduit and station keeping / mooring for the plat form• Long and higher dia pipeline required for pumping water• Very complex and challenging
Preparation of detailed project report using an industrial partner is in advanced stage of completion. In-house activities for power optimization, and detailed analysis of offshore components are also in progress.
Configuration as in DPR
In-house design configuration
• LTTD can be adopted in coastal thermal power plants where large quantity of water is drawn from the sea for cooling the condensers and later rejected back into the sea as hot water causing extensive thermal pollution.
• Power plants need De-mineralized water that is produced from local supply through RO process
• Thus, the LTTD method in Power Plants can serve two purposes –(1) generation of fresh water, thereby reducing the load on external sources. (2) reducing temperature of reject water thereby reducing the load on the
cooling tower
• NIOT successfully Demonstrated Condenser Reject based LTTD in North Chennai Thermal Power Station.
LTTD Using Condenser Reject Water (waste heat) in Power Plants
Typical CONFIGURATION OF A DESALINATION PLANT Working with POWER PLANT Condenser Reject Water
2 x 1 MLD capacity LTTD Plant in Coastal Thermal Power Plant
Establishment of Waste Heat Recovery LTTD plant using an industrialpartner for 2 modules each of 1 MLD capacity at Tuticorin ThermalPower Station (TTPS) premises.
Out of 2 modules, 1 module to produce drinking water of TDS : 100 – 200ppm, and othermodule to produce boiler qualitywater of TDS : < 2 ppm.
RFP is in progress for the award of the Work.
Overall layout of the plant
Outfall
2 modules(Flash chamber with condenser)
Cold water pumps
Warm water pumps
Power plant reject water
pipes
Parameter Desirable limit
Permissible limit
LTTD Water at Agatti
LTTD Water at NCTPS Plant
Color 5 hazen 25 hazen OK OK
Odour Unobjec-tionable
Unobjec-tionable
OK OK
Taste Unobjec-tionable
Unobjec-tionable
OK OK
pH 6.5 8.5 7-8 6.54
TDS (PPM) 500 2000 180 24
Chloride (PPM) 250 1000 90 12
Total Hardness (PPM)
300 600 100 4
Total Coli form (MPN)
- 10 Not Detected <2
COMPARISON OF WATER QUALITY WITH DRINKING WATER
NORMS
LTTD - Advantages
No pretreatment of feed water required.
Assured consistent quality water fit for drinking as per WHO standards.
Operational simplicity and easy maintenance.
No external energy for evaporating the sea water
Assurance of constant cold water temperature source
Reduces the thermal pollution when used in the process industries
Air Conditioning if on land
Cold water which is being discharged to the sea can be used to
run an air conditioning system.
Aquaculture – Land or Offshore
Deep sea water is rich in nutrients and can be used cultivate
marine life.
LTTD - CHALLENGES
• Large volumes of water are to be handled
• Low temperature differences leading to low efficiencies makes
design of thermal components challenging with available market
components.
• Power optimization required for low operation costs
• Design of structures and cold water intake pipe complex in island
scenario.
• Design of all weather floating platform and cold water conduit
never attempted before and very complex.
• Transportation of fresh water to shore never tried before and
needs designs adapted from oil industry.
• Capital cost intensive since components have to have long life in
seawater environment.
CONCLUSIONS Water Management Techniques to be implemented
Protection of Lakes and Water Bodies
Desilting of Lakes and Water Bodies
Rain Water Harvesting
Environmentally friendly Desalination Technology
Even though LTTD plants have been established at various places, still
more research has to be conducted to meet the challenges such as
increasing the thermodynamic efficiency especially in design of higher
capacity offshore / power plant based desalination plant.
Future plans : Implementation of OTEC / other renewable energy
sources such as solar / wave to make the desalination system self
sufficient.
41
THANKS FOR KIND ATTENTION