Dr. M.V.Ramana Murthy
& Dr. M.A.Atmanand,
Ministry of Earth Sciences Dec., 2015 Floods that paralyzed Chennai – Some snapshots
Coastal Flooding – information lacunae
No data on • Vulnerable areas • Extent of flooding • Rivers in • Low lying areas spate, • No warning system Submerged flyovers , Airport, Roads and Settlements 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 Scenario: Challenges
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 Source: 'India's Water Future to 2025-2050’,International Water Management Institute; Datamonitor; ’Dreaming With BRICs: The Path to 2050’,Goldman Sachs Global Economics Paper No:99;Population Division, Department of Economic and Social Affairs, United Nations: ’Sustainable Technology Options for Reuse 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 and Aquaculture 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 Karnataka Watershed', World Bank; 'Rain Water Harvesting Catches on in Chennai', The Hindu Business Line; 'Agricultural Engineering', Government of Tamil Nadu; ’Sea Water 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;’Water Poverty in Urban India: A Study of major Cities’, Jamia Millia Islamia;’ Troubled Waters', Development Alternatives;’ Dreamings with BRIC’s: The Path to 2025’,Goldman Sachs,2003;’Urban and Rural Areas 2007’,United Nations; ’Water Supply-The Indian Scenario’, IEA India ;’Status Of Water Treatment Plants In India', Central Pollution Control Board; Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat Chennai Water 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 the rivers are polluted with sewage.
With the increase in population and depleting ground water the city often grapples with acute water supply shortages.
On 18 June 2019, the city's reservoirs ran dry, leaving the city in severe crisis Demand and Supply of Water in chennai
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 Nemelli and 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. Present Scenario : As on June 2019
The failure of northeast monsoon in 2018 and pre-monsoon showers in 2019 have caused depletion of the already over-exploited lakes.
2018 2019 The Poondi reservoir has a capacity of 3,231 mcft
2018 2019
The Chembarambakkam reservoir has a capacity of 3,645 mcft. Cause I : Disappearing water bodies
The Chennai city has network of about 650 water bodies including major lakes, ponds and storage tanks has been destroyed. The current number stands at around 27, according to the NIDM study.
Total area of 19 major lakes in the CMA has nearly halved from 1, 130 hectares to about 645 hectares.
This is the overall capacity of water bodies in the city to contain excess rain water has reduced. 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.km Pre-flood Sat data (6.10.2015) : 35.4 sq.km Post-flood Sat data (10.2.2016) : 105.7 sq.km Cause II : Tampering of recharge structures
% Topo Change sheet 6-Oct- 10-Jan- Water bodies [1976] 15 16 Ambattur 22.62% Lake 1.68 1.41 1.3 Chembaramba 4.04% kkam Lake 20.54 8.52 19.71 Cholavaram 5.19% Lake 6.54 1 6.2 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 83.15% Lake 0.95 0.08 0.16 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 in the city of Chennai and is home to several rare/ endangered and threatened species.
Pallikaranai used to cover an area of 50 sq km but it has now been reduced to a tenth of its size. 90% of the marshland has been lost to construction of IT corridors, gated communities, garbage dumps and sewage treatment plants.
A survey conducted by Care Earth Trust in the early 2000s revealed that the marsh had shrunk by almost 90 percent--from close to 6000 hectares to barely 600 hectares--over a 50-year period. 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 Solution I :Improving storage of surface water
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). 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
19 Desalination
Natural Way LTTD Desalination at Union Territory of Lakshadweep LTTD Process Vertical Temp profile across Ocean
o o •Temperature differences between the surface (28 – 30 ) 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. Kavaratti Island, UTL
Parabolic Solar MED System Collectors
Solar Desalination RO plant Bitra 23 LTTD PLANTS TAKEN UP BY MOES-NIOT
Completed Minicoy-2011 • 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 Agatti-2011 • 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)
NCTPS -2009 Off Chennai - 2007 Kavaratti -2005 Underwater pictures Agatti / Androth
Coral/sand stone rock in HTL
Androth Agatti 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. Components: Flash Chamber, Condenser, Sea Water Pumps, Vacuum System, Cold Water Pipe, Marine structures like sump, Bridge and Plant Building.
26 Completed LTTD Plants at UT Lakshadweep LTTD 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 MajorAmini,componentsAndroth, Chetlat,: MarineKadamat,StructuresKalpeni(Sump,andApproachKiltan Bridge,islands.and Plant Building) Submarine Cold Water Pipe: ~ 1000m long HDPE pipeline with attachments; Process Equipment (Flash Chamber, Condenser, Seawater Pumps, Vacuum System, Plant Piping )
Minicoy LTTD plant 1000m Lagoon Reef Desalination plant 400 Cold water m LTTD plant at Agatti pipe
Typical Island profile 230m (approx.) 700m (approx.)
400m Approach trestle Installation of Deep Sea (appro Sump Cold Water Pipe x.) Plant building Agatti Desalination plant AGATTI PLANT
Typical conditions in the Breaker Region of the Site
Plant Building With Equipment
Control Room
Bridge for Access, Piping and Power
Sump with Sea Breaker Water Pumps Region
Side view of the Plant
Shallow Water Region CHETLET KILTEN
KADAMAT ANDROTH
KALPENI
AMINI Solar Assisted LTTD Plant Installed at
COLOUR CODE
STEAM Ramanathapuram, SEATN WATER BRINE DISTILLATE A 35000 liters per day capacity is installed at VACUUM Ramanathpuram, TN, in 1400 m2 area with a SYSTEM power requirement of 26 kW. FLASH CHAMBER
Concentrates Solar Energy with Linear Fresnel EVAPORATOR CONDENSER Type Collectors for Heating / Evaporating Seawater SOLAR PANEL BRINE REJECT Multistage Desalination of the sea water DISTILLATE DM RECYCLE BRINE OUTLET PUMP PUMP
DISTILLATE Features: 6 stage multi effect MAIN SEA SEA PUMP WATER PUMP WATER desalination (MED) system for Solar Desalination System - A SchematicINLET Desalination Parabolic Solar Collectors MED System
Components: Pumps for maintaining the flows; vacuum system for maintaining the required pressure in the system; Instrumentation for the plant
A view of the Desalination Plant a Ramanathapuram Advantages / Disadvantages for remote islands • Effective utilization of the solar heat for only 6 hours during the day • Periodical cleaning Essential to ensure efficiency Solar Desalination at Kanyakumari Solar Thermal Distillation Plant of 10 m³/day capacity has been commissioned by IIT Madras with the funding of MoES under TRB.
Intake caisson with pumping system for supplying sea water to the MED plant has been commissioned by NIOT.
Plant capacity Collector Water requirement Surface area (m3/day) area (m2) (m3/day) condensation (m2) Schematic of Solar desalination plant 0.05 10 1 0.4 1 100 20 4 10 600 200 32 100 5000 2000 400
Intake seawater system Intake caisson 1MLD Barge Mounted LTTD Plant
For mainland applications, the necessary depth for the availability of 10 – 12o C water 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. Plant Components
A View of the Barge and its mooring
Pipe Tow
Deepest SPM in Indian water and for the first time in the country synthetic ropes were used for such a mooring. Fresh water with TDS 10 ppm was obtained through indigenously designed and fabricated 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
Configuration as in DPR
In-house design configuration
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. LTTD Using Condenser Reject Water (waste heat) in Power Plants
• 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. 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 industrial partner for 2 modules each of 1 MLD capacity at Tuticorin Thermal Power Station (TTPS) premises. Out of 2 modules, 1 module to produce drinking water of TDS : 100 – 200 ppm, and other module to produce boiler quality water of TDS : < 2 ppm. Power plant Warm water reject water pumps pipes Outfall
Cold water pumps
2 modules (Flash chamber with condenser)
Overall layout of the plant
RFP is in progress for the award of the Work. COMPARISON OF WATER QUALITY WITH DRINKING WATER NORMS
Desirable Permissible LTTD Water at LTTD Water at Parameter limit limit Agatti NCTPS Plant Color 5 hazen 25 hazen OK OK Odour Unobjec- Unobjec- OK OK tionable tionable Taste Unobjec- Unobjec- OK OK tionable tionable pH 6.5 8.5 7-8 6.54 TDS (PPM) 500 2000 180 24 Chloride (PPM) 250 1000 90 12 Total Hardness 300 600 100 4 (PPM) Total Coli form - 10 Not Detected <2 (MPN) 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. THANKS FOR KIND ATTENTION
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