Transcript Document

Sea level changes impact on saltwater intrusion into
the Gauthami-Godavari River Estuary
Thota V. Narasimha Rao
Scientist F,
National Institute of Oceanography,
Regional Centre,
176, Lawson’s Bay Colony,
Visakhapatnam-530 017.
OBJECTIVE
Characterize salinity intrusion extent in the
Gauthami-Godavari River Estuary
INTRODUCTION
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The impacts of sea level changes on coastal areas
may cover many aspects including:
Impacts on water resources,
agricultural and
health resources in the coastal areas.
Usually impacts are exacerbated by other phenomena:
such as subsidence,
presence of ground water aquifers and
coastal agriculture.
We shall consider the saltwater intrusion impacts in some
detail.
INTRODUCTION
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Saltwater intrusion is a direct impact on:
Groundwater resources,
Soil salinity,
Agricultural productivity and
Quality in the coastal zone.
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The Godavari delta and its deterioration due to saltwater intrusion is an
example.
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Impacts of saltwater intrusion include:
Increase of soil salinity,
Deterioration of land productivity,
Socioeconomic &
Health implications.
It may lead to group migration of farmers looking for jobs else where.
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INTRODUCTION

Sea level is rising more rapidly as a result of climate change,
 Posing risks to estuaries,
 Aaquifers, Wetlands, Lowlands, Beaches, and Infrastructure.

Assess the potential impacts of sea level rise on Gauthami-Godavari
drinking water systems .

To identify systems whose intakes are vulnerable to sea level rise.
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Sea level rise could increase the salinity of an estuary
by altering the balance between fresh water and salt water.
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The implications of sea level rise for increasing salinity
have been examined in the Gauthami-Godavari River estuary.
INTRODUCTION

By correlative analysis of
 Salinity,
 Discharge,
 Tidal level &
 Calculation of two-dimensional salinity distribution of the GauthamiGodavari River estuary,
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The changes of the intensity
 Lasting hours of saltwater intrusion at Stas 1-4 &
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Changes of salinity distribution in the Gauthami-Godavar River
estuary observed during 1989-1990
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Estimations to be made for future sea level rises of 50–100 cm.
INTRODUCTION

Major concern for drinking-water utilities from sea-level rise is:
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The migration of saltwater upstream into fresh waters where
drinking-water intakes are located.
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In India, water available for agriculture has fallen nearly 10% during
the last decade.
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Sea-level rise scenarios:

To evaluate the effects of potential sea-level rise on Gauthami-
Godavari River estuary
INTRODUCTION
 Future
sea-level rise scenarios for the Indian region
for the 21st century:
1) 30 to 40 centimeters (cm) total by the year 2100;
2) up to 50 cm total by 2100; &
3) up to 100 cm total by 2100.
 We
refer to these scenarios as
1) 30- cm rise,
2) 50- cm rise, &
3)100- cm rise, respectively.
INTRODUCTION

Linear Mean Sea level (MSL) trends and 95% confidence intervals in feet/century

Vizag
1st year Last year Year Range
1937
1996
60

Chennai
1916
2003
88
0.10
0.14

Mumbai
1878
1994
117
0.24
0.08
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Cochi
1939
2004
66
0.45
0.11
MSL trend
0.18
+/-95% confidence
0.17
INTRODUCTION
Salinity intrusion modifications can significantly impact
established water uses like- Agricultural,
Domestic &
Industrial water supply.
INTRODUCTION
The extent of salinity intrusion depends on:
The balance between Fresh water discharges & Saltwater flow
from the sea.
METHODOLOGY
To develop a methodology to
assist the operators of the reservoir
Planning the release of water
down the river
To control the salinity in the
estuary
GAUTHAMI-GODAVARI RIVER ESTUARY
1-4 Observation stations
Gauthami-Godavari River Estuary is located in central East Coast of
India, which discharge to the Bay of Bengal
River discharges
The Godavari reservoir at Dhawaleswaram
is designed to control flooding and provide
irrigation water.
The Godavari River has fresh water flows
ranging from 50 to 3800 m3/s
The dam is being built only 60 km
upstream of the river mouth and near the
tidal reach
The Godavari River has fresh water flows
of <100 m3/s during Dec. to April.
Max. freshwater flow of 3800 m3/s in Aug.
during flood season
Variation of average monthly
discharge (m3 s-1)
at Dawaleswaram in the Godavari
river
Sea level changes
Dec. 1989 and April 1990
Tidal currents
Dec. 1989 and April 1990
Different River discharges
Temperature (oC) & Salinity (PSU)
 Sea level rise could increase the salinity of an
estuary by altering
the balance between fresh water and
salt water.
 Million people are served by coastal surface water
systems that are unprotected (by a dam or other
structure) from sea-level rise.
 People are ranked highly vulnerable to salt water
intrusion, meaning they are unprotected&
 Within a tidal fresh-water reach with estuarine
wetlands nearby (indicating slightly saline water a
short distance downstream).
Observations indicate that sea levels have risen
from four to eight inches in the 20th century
Temperature (oC) and Salinity (PSU) at Stas 1-3 during
(A) Winter (Dec. 1989)
(B) Dry (April 1990) &
(C) Flood (July 1990) season
Temperature (oC) &
Salinity (PSU)
Dry season
Vertical profiles of Temperature (oC) &
Salinity (PSU) at Stas 1-4 in Dry season,
April, 1990
Temperature-Salinity
(T-S) relationships
Salinity intrusion
Surface & Bottom
along main channel
 Models indicate the possibility of an additional
rise of eight to 15 inches over the 21st century.
 Changes will vary locally, and impacts will vary
as well.
Assessments of the possible consequences of
climate change and climate variability on water
quality.
Our focus in these assessments has been on the
ability of drinking water systems to continue to
provide clean, safe water as climate changes
especially on surface water systems.
Our concern is the possible impact of sea level
rise and salt-water intrusion on community water
systems.
(A) Temperature (oC) at (a) Surface and (b) near Bottom
(B) Salinity (PSU) at (a) Surface and (b) near Bottom
along the main channel of the Gauthami-Godavari Estuary
Temperature-Salinity (T-S) plots
Temperature-Salinity (T-S) plots
from Dec. 1989 to Oct. 1990 at Stas 1-3
for (a) Surface and (b) near Bottom.
Temperature-Salinity (T-S) plots
Temperature-Salinity (T-S) plots at Stas 1-3.
The month is indicated by the first three letters
Salinity intrusion
 In an effort to assess the potential magnitude of the
problem, we developed a screening methodology to
identify systems that are potentially vulnerable.
 Factors other than sea level rise will impact the
vulnerability of freshwater intake points to salt
intrusion.
For surface water systems:
River flow,
The distance of the intake point from the salt front &
Withdrawal rates are among the factors
that can influence vulnerability &
Complicate the evaluation of that vulnerability.
Multiple factors affect the vulnerability of freshwater
intake points at any one location &
local changes in sea level deviate from the global
average.
Salinity (PSU) in (a) Winter (Dec. 1989), (b) Dry (April
1990) and (c) Flood (July 1990) seasons
Salinity Vs. Scaled axial distance x/L
Mean salinity (PSU) at Stas 1-4
for Winter & Dry season
• This straight line fits the mean value
distribution surprisingly well (R2=0.99)
and is given by
S = 29.25 - 45 (x/L)
• Mean axial salinity gradient is dS/d(x/L) =
-45 x 10-3 or
• dS/dx = -1.5 x 10-3 km-1.
• This simple fit predicts the landward end of
salt intrusion (S = 0 at x/L = 0.65).
• The upstream limit of the mean position of
the salinity intrusion is located about 40 km
from the mouth.
Salinity Vs. Scaled axial distance x/L. The numbers 1-4 show
mean salinity (PSU) at four observation stations for winter and
dry season
Estuarine classification
Station Nos. 1-3
For ground water system:
Withdrawal rates,
The depth and gradient of the aquifer &
Recharge rates affect vulnerability.
 Even within a small geographic area:
these factors vary, making it difficult to
provide reliable estimates of impacts for
the large population of coastal drinking
water systems.
A diagram of estuarine classification.
1-3 are station numbers
APPROACH

Screening analysis to identify systems withdrawing water
 from tidal & freshwater reaches of rivers.
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Systems vulnerable to sea level rise
(as well as more frequent droughts, another possible effect of climate change)
due to the potential for the intake water to become brackish.
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Determine the locations and characteristics of water supplies
BASINS (Better Assessment Science Integrating Nonpoint and Point Sources).
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Latitude and longitude coordinates for Public Water System (PWS) intake
points.
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Sort-out the sites by elevation class
using 90 meter-square area Digital Elevation
APPROACH

Each intake point was labeled according to the following code: 0 = below
0.5 meters; 1= 0.5-1.5 meters; 2 = 1.5 to 2.5 meters; 3 = 2.5 to 3.5 meters; 4
= above 3.5 meters.

Although the elevation data apply to the average elevation of the land in a 90
meter-square area around the intake and not to the intake itself (which is
below the level of the land),

For screening purposes we considered intakes below 3.5 meters elevation to
be in low-lying areas and therefore vulnerable to sea level rise.
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This screening step yielded 156 low-lying, coastal surface water intakes.

Working with these surface water intakes in low-lying areas, we then
screened for intakes protected by a dam.
APPROACH
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The next challenge is to find an indicator of vulnerability to sea level rise.
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Sites closest to brackish water would be the first to be affected by a
migrating salt front, and needs an indicator of the proximity of brackish
water to the remaining intakes.
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Wetland plants are often grouped by biologists into freshwater, brackish, and
saltwater species.
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The boundary between estuarine and freshwater wetlands is defined by
salinity, during average annual flow, of 0.5 ppt (PSU, Practical Salinity
Units).
APPROACH

A PWS drawing water at 0.5 parts per thousand or higher
Would have difficulty meeting the EPA’s secondary Maximum Contaminant
Level (MCL) for chloride and
• Total dissolved solids (2.5 parts per million (ppm) or
• 0.0025 ppt and 5 ppm or 0.005ppt, respectively
(http://www.epa.gov/safewater/mcl.html)
•
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Unless it used desalination techniques.

Therefore,
 An intake in an estuarine area might face salinity problems now, and
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One in close proximity to an estuary might be vulnerable to sea level rise.
APPROACH

Proximity of an estuarine wetland is an indicator of vulnerability
for a public water system intake.
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Intake coordinates from locations and characteristics of water
supplies
generate maps of the area around the intake.
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These maps were overlaid on the wetland maps
to measure the distance from the intake to the nearest estuarine
area.

Intake distance from 0 km (i.e., the intake is in an estuary) to the
nearest estuary
APPROACH

Intake which is within an estuary
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Intake seems to be within one km of an estuary
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Fresh water creeks separated from the estuary by land &
are designated as being at medium vulnerability.
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Low-lying ponds, having low vulnerability to contamination
from sea level rise
APPROACH

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An area that is home to estuarine plants
might be only slightly brackish &
Suitable for a drinking water supply.
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Water systems may use
De-salinization processes,
Enabling them to meet the EPA’s secondary standards for salt.
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Public Water System (PWS) intake point of Yanam Administration:
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Relocated its intake 20 km upstream in 1985
APPROACH
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The original intake continued to be used
To provide a backup source, though it was useable only at low
tide.
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In 1995 it was taken out of use after a cyclone destroyed it.
It would be good to model the migration of the salt front up each
coastal river basin
in order to get a more specific understanding of PWS
vulnerability.
CONCLUSIONS
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All the plants reported that they have had salinity problems
Following storms or during droughts
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The vulnerability of the system depends on the occurrence of
•
drought
•
as well as sea level rise,
•
yet a coping strategy should still be developed.
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Better screening tools
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Capture vulnerabilities such as this
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Should be developed.
CONCLUSIONS
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Given that some systems are vulnerable &
Others may be vulnerable,
It is important to consider adaptation strategies.
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Examples include those already employed by the system operators:
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Operate the plant at low tide;
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Prepare for storm surges by storing fresh water or
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Construct barriers to block the storm surge &
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Move to higher ground when it is no longer practical to rely on the
existing intake.
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CONCLUSIONS
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Each of these options comes with costs
•
That will have to be borne by the communities being served.
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Other adaptation options exist,
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Some of which are foresighted
in their consideration of future sea level rise.

It would be a shame for a permit to be issued
•
for a new system and
•
a community to invest in a capital project
•
whose useable life will be cut short by salt water intrusion.
CONCLUSIONS

Salinity intrusion reaches a river section located about 40 km
upstream the river mouth.

For more frequent river flows, the salinity gradients occur mainly
downstream of the Sta. 2 (10 km from river mouth).

Achieved results will be used as an important auxiliary source of
information in order to select gauge stations for measurements of
tidal water elevations, current velocity, and salinity concentrations.

The developed model can be used to establish discharge operational
schemes of the upstream hydropower plants safeguarding
downstream water intakes.
RESULTS AND DISCUSSION
Salinity intrusion
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Sea level rise will cause an intensification of saltwater penetration into rivers and
freshwater canals,
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Which could be further increased in summer by reduced river flows.

The larger extension of the salt wedge would prevent the use of freshwater for
agricultural purposes &

could lead to salt accumulation in soil.

Saltwater penetration would influence the distribution &

Consistence of the typical estuarine communities

Storm surge is one of the major natural calamities along the coast of the Godavari
River Delta region.
Acknowledgement
The author would like to thank to the Administration of
Superintendent Engineer, Irrigation Department, Dhawaleswaram, A.P.
& Naval Hydrographic Office (NHO) for the authorization to use River
Discharge and Tidal data in this work.
Background and Justification
The studies on storm surges along the East Coast of India is
multifaceted due to the cyclones that develop over the Bay of
Bengal flooding the low-lying coastal regions.
 Synoptic disturbances (cyclones) originate during premonsoon (Apr-May) and post-monsoon (Oct-Nov).
Tropical depressions: max. winds of 60 km/hr,
 Tropical storms: max. wind speeds between 60 and 120
km/hr
Hurricanes/Typhoons: max. wind speeds of 120 km/hr
influence the upper ocean dynamics.
 The effect of tropical cyclones cause immense damage by
wind, pressure, rain and indirectly through storm surges on
the East Coast of India.
Contd….
The initial field needed for the model run in the Bay of
Bengal requires to be prepared including the effect of
cyclones in generating storm surges and waves.
Surge computations by using a model.
Significant input in the surge prediction is the predicted
track of the cyclone.
 The system significantly affects the East Indian Coastal
region during pre and post monsoon seasons by causing
flooding across the shelf along the coast.
Narasimha Rao (1998) Proc. Vol. of the Int. Conf. on “Natural and
Technological Hazards”, Int. work shop on “Storm surges”,
S.V.University,Tirupati, Sponsored by UNESCO (IOC).
Fig. 5 Location of all earthquakes from 26th December 2004 to now
Fig. 6 Tsunami 26 December 2004 prepared by INGV Istituto
Nazionale Geofisica e Vulcanologia, Indonesia
Fig. 6 In deep water the Tsunami cannot be noticed, but in shallow
water it rapidly increases in height as it slows.
Fig. 7 Equipment for fixed stations:
(1) Acoustic Doppler Current Profiler (ADCP): for measuring water column velocity and
pressure,
(2) Acoustic Doppler Velocimeter (ADV): for measuring water velocity, temperature,
pressure and bed elevation and
(3) Optical Backscatter Sensor (OBS): for measuring near-bottom and mid column
suspended sediment concentration,
Frame for bottom mooring
Rationale

Natural phenomenon like storm surges and tsunamis cause
abnormal fluctuations in sea level along the coasts.

The tide gauges installed to measure the rhythmic raise and
fall of sea levels due to astronomical tides are also capable of
recording such abnormal fluctuations in sea levels.

The analysis of tide gauge records along the Indian coast and
elsewhere showed that the recent event of tsunami, that
occurred on 26 December 2004, was well recorded by the
tide gauges in the Indian Ocean.
 It is possible that such events occurred in the past escaped our
attention because of their low impacts on human life and property.
 The recent observations at a tide gauge located at Manzanillo,
Mexico, a location very far from the epicentre of 26 December
tsunami, showed the signature of Indian Ocean tsunami as much as
2.6 m (crest-to-trough). ).
 At present, it is not known how many such events occurred in
the past in Pacific or Atlantic have left their trace in the tide gauges
along Indian coast.
 Identifying such events in instrumental data records and
developing the ability to simulate them will allow us to generate
reliable statistics.
 In the case of tsunamis, confidence in a model is critical
because it will then allow us to prepare a scenario database that
can be used when a tsunami is triggered.
 Similarly, in the case of storm surges, identifying past surges
and simulating them accurately (with validation based on tidegauge data rather than eyewitness accounts) will lead to better,
more reliable models and statistics.
 Investigations summarised in this group envisage the
identification of past storm surges or tsunamis in historical sealevel records and their simulation to understand the pattern of
tsunamis and storm surges along the Indian coast and its
impact on energy, water & air borne diseases.
Objectives

Identify the extreme sea level events along the Indian coast in
the historical tide gauge data.

Simulation of storm surges and tsunamis along the Indian coast
for historical events.

Assessment of the impact of climate change on storm surges
along the Indian coast.

Generation of wave statistics along the coast of India during past
cyclones.
Improvements in the storm track prediction in the Bay of
Bengal.

Diseases


Screening component:
Screening of the population by History, clinical examination and
simple laboratory testing for chronic kidney disease, diabetes
mellitus and hypertension in rural adult population.
Prevention component:
Prevention of life-style diseases in general by health education and
imparting knowledge on healthy diets, exercise and anti-smoking
measures etc.

To retard the progression by diet, exercise and appropriate
medication where applicable.

A sort of integrated control of non-communicable diseases will be
attempted at Mahatma Sri Ram Chandra Centemary Hospital
personnel which is located in Hyderabad with a satellite center in
Kanukunta Village
Research component:
 To assess the GFR Profile in the rural community
by measuring the creatinine clearance( 10% of the
randomly selected rural population GFR will be
determined by DTPA also).

To compare the performance of various available
formulae to estimate GFR(eGFR)

To assess the decline in GFR level among persons
with a GFR level < 60ml/min,during the study
period in the rural population.

To improve performance of soldiers stationed at
higher altitudes

At high altitudes due to hyponia, soldiers face
pulmonary edena, cerebral edena

Other problem is frostbile due to cold at high altitude.

Hyponia bags to reduce hyponia related problems
Approach
This study aims at understanding of the storm surges
and prediction of surge profiles along the East Coast of
India in response to varying forces due to cyclones
generated in the Bay of Bengal.
 Compilation of storms data from the Bay of Bengal
and storm surge data along the East Coast of India.
 Impact of storm surges on the coast by different
cyclones with variations of wind and pressure in the Bay
will be investigated.
This helps in formulating the timely precautionary
measures in mitigating coastal hazards and so reducing
its impact on power disruption, causing water & air borne
diseases
Action plan

Digitise the tide gauge charts available with survey of India
(for the past 120 years or so) at a finer interval (say 5 min.)
so that the signals of extreme sea level due to tsunamis will
not be lost.

Collect the information on past events of weather
disturbances (cyclones, storm surges etc.) and earthquakes
from all available sources and corroborate them with the
extreme sea level signals identified in the tide gauge
records.

Statistical analysis of the extreme sea level events
identified in the tide gauge records.
 Simulation of tsunamis for the past events in the
Indian Ocean.
 Simulation of storm surges for the past events using
MIKE21 and Jelesnianski's model.
 Storm surge simulations using HadRM3 winds for
future climate scenarios.
 Development of a tsunami simulation model for the
Indian Ocean.
 Modelling the wave climate along the coast of India for
different cyclones and identifying high wave
concentration zones.
Data Requirement
Weather Map products of storm: Position of the storm centre or
eye, Minimum sea level pressure at landfall, Speed of storm
movement, Crossing angle of storm track with respect to the coast
at landfall, Radius of maximum winds, Mean sea level pressure
drop and Time of the eye crossing the coast.
Upper air data: Wind, Pressure and Temperature
Surface meteorological parameters derived from buoys, ships:
Air temperature, Wet bulb temperature, Wind speed, Wind
direction, Pressure and Sea Surface Temperature (SST)
Vertical profiles: Temperature and Salinity
Cyclone weather information: Satellites and radars will be
envisaged.
Data on power plants & their emergency action plans
Data on water & air borne diseases
 Rescue operation by Soldiers & their problems in high altitudes
Milestones
Period
Milestones
Phase1 - May 2011 – Mar 2012 Collection of data on storm
surges and the observed met.
and ocean parameters from
past records and data related to
power plants, water & air borne
diseases, and rescue operation
of soldiers.
Phase 2 - Apr 2012 – Mar 2013 Modeling storm surges with
appropriate inputs.
Phase 3 - Apr 2013 – Mar 2014 Model verification
MANPOWER
Investigators
T. V. Narasimha Rao
Dr. K. V. Dakshinamurty
Sandeep Rairikar
R. K. Kamble
Dr. Deepika Bhaskar
Ruma Dutta
Uday Puntambekar
Budget (Manpower / Equipment / Travel & Contingencies etc.)
TOTAL COST OF THE PROJECT (IN RUPEES): Rupees 30.0 Lakhs.
BUDGET ESTIMATES (SUMMARY)
: (Rupees in lakhs)
S. No.
Item Name
1St Year
2nd Year
3rd Year
Subtotal
Remarks
1.
Manpower
4.56
4.56
4.45
13.68
For RA @
11000/- month
+ 15% HRA
2.
Consumables
0.5
0.4
04
1.3
3.
Contingencies (including
external service and software)
0.5
0.5
0.5
1.5
4.
Travel TA/DA
0.9
0.9
0.8
2.6
5.
Equipment
7.0
--
--
7.0
6.
15% of total cost institutional
overhead charges
2.02
0.97
0.95
3.91
Subtotal
15.48
7.21
7.2
29.99
Total Cost (Rs. In Words): Rupees thirty lakhs only
PROPOSED EQUIPMENT:
(Rupees in lakhs)
S. No.
Description and
technical
specifications
Approx. cost
Remarks
1.
Workstation
6.0
--
2.
1 PC + 1 Scanner +
1 CD writer + 1
Laser printer
1.00
--
Total (Rupees in
lakhs)
7.0
--
JUSTIFICATION FOR EACH COMPONENT:
The following equipment is essential for the smooth running of the
proposed project:
1. Work Station is required for running the model.
2. PC with scanner, CD writer, laser printer are essential for
computational facilities.
PERSONAL INFORMATION
1. NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR ALONG WITH FAX, TELEX, TELEPHONE NUMBERS, e-mail etc.
Thota V. Narasimha Rao,
Fax: 0891-543595
Scientist F
Tel: 0891-539180 (o), 0891-532423 ®.
Regional Centre,
E-mail: [email protected] / [email protected]
National Institute of Oceanography,
176, Lawson's Bay Colony,
Visakhapatnam - 530 017.
2. PLACE OF WORK FOR THE PROPOSED PROJECT: NIO, RC, Visakhapatnam.
3. BRIEF VITA OF PRINCIPAL INVESTIGATOR
i) Name: Thota V. Narasimha Rao
ii) Date of Birth: 28-11-1954
iii) Institution: National Institute of Oceanography, Regional Centre,
Address:
Street:176, Lawson's Bay Colony,
City: Visakhapatnam
State: Andhra Pradesh
Pin: 530 017
Telephone No. :0891-539180 (o), 0891-532423 ®
Fax No. : 0891-543595
E-Mail: [email protected] / [email protected]
iv) Educational Qualifications : M. Sc. (Tech) Meteorology & Oceanography, Andhra University, Visakhapatnam.
v) Research Work (areas) : Physical Oceanography, Coastal & estuarine dynamics.
vii)
Publications (details) :
Published 20 papers (Total)
Papers relevant to this proposal: 6 (Given below)
S. No.
Title of paper
Co-authors
Name & No. of journal
Flow field in the inner shelf
along the central East Coast of
India during the southwest
monsoon season
---
Journal of Coastal
Research, Vol.20, No.3
Year
Page No.
From - To
1.
July, 2004
814 - 827
2.
Spatial distribution of upwelling
off the East central East Coast
of India
---
Estuarine, Coastal and
Shelf Science Vol. 54,
No. 2
February, 2002
Estuaries,
Vol. 24, No.1
February, 2001
141 - 156
3.
Time-dependent stratification in
the Gauthami Godavari Estuary
---
18 - 29
4.
Variability of the flow field in the
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---
Proceeding Volume of
the International
Conference on “Natural
and Technological
Coastal hazards”;
international workshop
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S.V.University, Tirupathi,
Sponsored by UNESCO
(IOC), 1998
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1998
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