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CHAPTER

FOUR SITE SELECTION FOR

MODEL VALIDATION

4.0 INTRODUCTION

God commanded: “Let the water below the sky come together in one place, so that the

land will appear” and it was done. He named the land “Earth”, and the water, which

comes together, He named “Sea”. And God was pleased with what He saw….. (Genesis

1:9,10).[61]

Unfortunately, God probably would not be pleased if He looks at the current status of

the seas. Rivers have become universal sewers that carry away the waste of people and

the seas have become ultimate sink for these wastes. For many years, it was believed

that the oceans are immense and theoretically capable of diluting all waste inputs into

undetectable levels. But in reality, it is not so because these waste loads are not

uniformly spread over the oceans. Rather, they are almost invariable concentrated in

the coastal waters.

The coastal waters, estuaries, backwaters, lagoons and mangroves serve as breeding

ground for many special and have rich in species diversity representing 32 animal phyla.

Of these, 15 have no representative in land. The coastal problems due to destructive

oil spills, marine organisms contaminated by heavy metals, pesticides, pathogenic

organisms, massive algal blooms caused by nutrients present sewage discharged into

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marine waters, unsightly beaches caused by solid waste and petroleum materials

washed up on the shore, are wide spread in many countries. Even the high seas face

the threat of pollution through crude oil and hazardous chemicals. Fortunately, many

of the incidents are short duration and have localized effect. Unfortunately, we are

not aware that what the long-term efforts of them may be. We may be permanently

despoiling our most essential natural asset.[61]

Oil pollution of the Sea attracts great public attention because it is visible and most

people encounter it. Most of the oil spills occurred is mainly due to negligent attitude

of shipping lines and the accidents may become very spectacular. About 5 million

tonnes of petroleum hydrocarbons reach the world seas every year. About 40% of

Crude oil[61] from the major production areas is transported in the routes of Indian

Ocean, Arabian Sea and Bay of Bengal. Petroleum hydrocarbons are introduced in the

marine environment by the variety of pathways including natural seepage from the sea

bed, tanker accidents, tanker ballast discharges, oil-well blowout and leaks, land run-

off, refineries, sewage effluents, disposal of spent lubricants, motor boat activity and

fall out of air born hydrocarbons.

India has an EEZ (Exclusive Economic Zone) of 2.04 million sq km out of its coastline

of 7516 km and out of its one billion[13] population, nearly 25% live in the coastal areas.

[13, 14] Many highly populated & industrialized cities, like Mumbai, Chennai, Kolkata,

Cochin, Visakhapattnam, are located along/ near the coastal areas. There are 11 major

ports & a number of minor ports handling shipping to various degrees of intensity. The

coastline of the main land falls under the divisions of 9 States & 2 Union Territories.

The coastline of islands belongs to Andaman, Nicobar & Lakshadweep (Luccadive) group

of islands. The details of its population, area, etc. are given in table-4.1. Along the

Indian coastline, the brackish water areas including marshes, backwaters, mangroves,

inter- & sub-tidal, measures about 1 416 300 hectares. These areas act as feeding &

nursery grounds for a variety of commercially important fishes, prawns & crabs, and

media for inland transportation, fishing, etc.[14]

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Table-4.1: Population & related data and some estimates of Pollutants

entering the sea around India (as of 1991)

Sl. No. Parameter Figure

1. Population 840 million

2. Coastal population (19% of total) 159.6 million

3. Area of the country 3.287 x 106 km2

4. Agricultural area 1.65 x 106 km2

5. Exclusive Economic Zone 2.015 x 106 km2

6. River runoff (annual mean) 1645 km3

7. Rainfall per year (on land) 3.5 x 1012 km3

8. Rainfall per year (on Bay of Bengal) 6.5 x 1012 km3

9. Rainfall per year (on Arabian Sea) 6.1 x 1012 km3

10.

Domestic sewage added to the sea by coastal

population per year (@ 60 l/head/day) 4.6 x 109 m3

11.

Industrial effluents added to the sea by

coastal industries per year 0.4 x 109 m3

12.

Sewage & effluents added by the rivers to

the sea per year 55 x 106 m3

13.

Solid waste & garbage generated by coastal

population per year (@ 0.8 kg/head/day) 53 x 106 tons

14. Fertilizer used per year (@ 30.5 kg/ha/year) 13 x 106 tons

15. Pesticides used per year (@ 336 kg/ha/year) 80 000 tons

16. Synthetic detergents used per year 125 000 tons

17.

Oil transported across the Arabian Sea

per year 550 metric tone

The West coast of the country handles nearly 70% of India’s crude import, half of it

in single-hull vessels over 25 years old. Plagued by poor maintenance & ill-equipped

crews, these vessels often beach on the heavily crowded West Coast. On average

there are 5 to 6 tanker accidents every year, compounding what is already a serious

environmental crisis. Global ship owners rarely follow the regulations framed by the

International Maritime Organization (IMO). The seas off major Goan beaches are

unfit for bathing. The Maharashtra coast faces the similar crisis. How did the problem

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get aggravated? “The region’s proximity to West Asia and large movement of oil

tankers on the route have aggravated the crisis”, remarks Sudhir Mulji, Director of

the Great Eastern Shipping.[15]

Indian Maritime Institute president, K. Chidambaram, feels governments of coastal

states should take a lesson from the recent incident of the fully laden 31 068 DWT

tanker Castor, which suffered damages in the Mediterranean Sea en route Lagos,

Nigeria. “Immediately after the accident, the American certifying agency withdrew all

certificates from the company so as to prevent a recurrence. Indian states must also

enforce international laws with an iron hand”, says Chidambaram. Till that happens,

environmental tensions on the western coast are set to escalate.[15]

The Indian Ocean, north of the Equator, comprising of the Arabian Sea, the Bay of

Bengal, the Andaman & Luccadive Seas, in addition to the equatorial region, comes

under the monsoon gyre. However, the hydrographical & hydrochemical characteristics

are widely different in different parts of this gyre itself owing to the diverse

meteorological & geographical factors characteristic of each area.

The Arabian Sea is bordered on the northern, eastern & western sides by the

landmasses of Asia & Africa. A 50m deep sill at the Hormuz Strait connects it to the

Gulf through the Gulf of Oman. Similarly, a 125 m deep sill at the Strait of Bab-el-

Mandab separates the Red Sea from the Arabian Sea through the Gulf of Aden. The

Arabian Sea is an area of negative water balance where evaporation exceeds

precipitation and runoff. The excess of evaporation over precipitation is maximum (100

– 150 cm) off the Arabian coast and decreases steadily towards the southeast. A

slight excess of precipitation over evaporation (<20 cm) occurs annually off the

southwest coast of India. The high rate of evaporation results in the formation of

several high-salinity water masses. The Arabian Sea high-salinity water, formed in the

northwestern Arabian Sea, flows southward and can be traced as a tongue of high-

salinity within the surface layer. The high-salinity water in the Gulf, characterized by

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a sigma value of 26.6, flows through the Hormuz Strait & the Gulf of Oman into the

Arabian Sea and maintains the density level at about 300 m depth. This water-mass

flows south, mostly east of 63˚E longitude, and loses its characteristics in the

southern Arabian Sea. The Red Sea water enters the Arabian Sea through the Strait

of Bab-el-Mandab & the Gulf of Aden along sigma 27.2 at the surface. This water-mass

is generally confined to south of about 17˚N latitude.[14]

Occasionally, the sub-surface high-salinity water-masses originating in the Gulf & the

Red Sea form a thick layer, which is vertically of almost uniform salinity, although the

individual layers can still be recognized as weak salinity maxims. The whole-layer is

called the North Indian high-salinity intermediate water. The deep & bottom waters

are of circumpolar origin, probably transported by a deep western boundary current

through a chain of basins. They are called the North Indian Deep Water & North

Indian Bottom Water.

Surface circulation in the Arabian Sea undergoes biannual reversal associated with the

southwest (SW) & northeast (NE) monsoons. The NE monsoon is weak in this region,

but the SW monsoon is very intense. Strong winds blowing with the Somali and the

Arabian coasts to the left cause intense upwelling off these coasts during the SW

monsoon period. Moderate upwelling also occurs off the southwest coast of India,

partly due to the cyclonic motion in the neighborhood of the Maldives & the

Luccadive.[14]

In contrast to the Arabian Sea, the Bay of Bengal is a region of positive water balance.

The average annual excess of precipitation is of the order of 70cm. The total annual

river runoff in the Bay of Bengal has been estimated to be about 2000 km3. The high

excess of precipitation over evaporation and the massive river runoff result in low

surface salinities, especially in the northern Bay of Bengal. The salinity, lower at any

level in the Bay of Bengal as compared to the Arabian Sea, increase steeply within the

thermocline / pycnocline and a weak salinity maximum may be observed at a depth of

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about 500 m. The salinity thereafter decreases monotonously with depth. The SW

monsoon current probably carries the North Indian high salinity intermediate water

from the Arabian Sea and fills the Bay of Bengal at intermediate depths, resulting in

the salinity maximum. The deep water is of circumpolar origin probably derived from

the Central Indian basin.[14]

As in the Arabian Sea, the surface circulation in the Bay of Bengal changes its the

monsoon cycle. The NE monsoon is much more intense here as compared to the Arabian

Sea. Induced by favorable currents & winds, moderate upwelling occurs along the coast

of India during SW monsoon, even though the runoff from the rivers may partially

compensate for the offshore movement of surface waters.

4.1 SITE SELECTION

The coastal waters from Kanyakumari to Bangladesh border unto a distance of about

25km from the shoreline along the pre-determined transects was monitored. These

transects were selected on the basis of (a) location of industries, (b) Ecologically

Sensitive areas, and (c) location of urban establishments, and (d) based on earlier

baseline survey. Accordingly, 78 locations have been selected and the details of these

locations are given below:[14]

Gujarat: Kandla, Poshitra, Vadinar, Okha*, Dwarks, Porbandar*, Verabal*,

Hazira.

Diu, Daman,

Maharashtra: Trombay*, Bassein*, Mahim*, Thane*, Bombay Harbour*,

Verrova*, Ulhas creek*, Murud, Thai, Ratnagiri, Reddy.

Goa: Mandovi, Zuari, Marmagao*.

Karnataka: Karwar, Honawar, Calicut, Ponnani, Kochi*, Alleppey, Kayamkulam,

Paravur, Quilon*, Veli*.

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Tamil Nadu: Kanyakumari, Koodankulam, Arumuganeri*, Tuticorin*, Vaiparu

estuary, Gundaru estuary, Mandapam (Palk Strait), Mandapam

(Gulf of Mannar), Uchipulli, Thondi, Nagapattinam, Cuddalore*,

Cooum*, Madras Harbour*, Ennore*.

Pondicherry: Pondicherry*, Karaikal, Yanam (Gautam-Godavari).

Andhra Pradesh: Krishnapatnam, Nizampatnam, Machilipatnam, Kakinada Bay*,

Visakhapattnam Harbour, Visakhapattnam Steel Plant,

Kalingapatnam.

Orissa: Dhamra, Gopalpur*, Paradip*, Puri*, Konark, Chandipur.

West Bengal: Saptamukhi, Digha, Sandheads*, Diamond Harbour, Holiday

Island, Dalhousie Point, Sunderbans, Indo-Bangladesh Border*.

Andaman &

Nicobar Islands: Port Blair

Lakshadweep: Kavaratti.*

It has been estimated that the annual transport of Oil through marine routes is about

1.3 billion tons of which nearly 579 million tons of oil is shipped from the Gulf

countries alone. The main routes are across the Arabian Sea. Studies on the floating

petroleum residues along the tanker routes in the Indian Ocean has revealed that

fairly high concentration of residues could be seen at times. In the Arabian Sea it was

1.52 mg/m2. The oil tanker route in the Arabian Sea during 1981 showed 12.7 mg/m2.

Similarly, in the North Atlantic Ocean it ranged from 0.02 to 0.64 mg/m2. In the

northwestern Pacific it ranged from 0.12 to 13.0 mg/m2. This clearly indicates that the

tanker routes in the northern Indian Ocean region are as polluted as other routes

(Qasim, 1991). It has also been estimated that about 35% of total oil transported

across the Arabian Sea goes through the Bay of Bengal route and 1.0% of the total

input ends up as floating tar. The amount of oil on the seas around India is estimated

to be about 0.36% of the flow and the residence time of tar in the northern Indian

Ocean ranges from 33 to 38 days (Qasim, 1991). The concentrations of petroleum

* Intensively monitored as an area of concern/ definite source of pollution

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hydrocarbons observed in the coastal waters of India during 1996 to 2000 varied

between not detectable to 116.20μg/l, which are well within the prescribed limits for

coastal water quality.[2, 49]

The World’s proved reserve of oil at the end of 1999 was 140400 million tonnes, out of

which 65.4% come from Middle East countries, while India’s contribution is only 0.5%.

This indicates the strong hold of Middle East countries in the World of oil sector. Now

on examination of the decadal trend of global oil production (table-4.2), i.e., from 1989

to 1999 it is seen that there is a gradual increase in production. The world oil

production in 1989 was 3096.30 million tones, which has increased to 3533.10 million

tones in 1998, while the production has declined by 2.3%, i.e. the production has

touched 3452.20 million tones in 1999. Further it was seen that the major contributor

to the world oil production is the Middle East countries, accounting 25.6% in 1989 to

31.0% in 1998. In 1991 it has reduced to 30.5%. On the other hand, India’s

contribution is around 1.0% throughout the decade, ranging between 29 & 37 million

tones.[49]

Table-4.2: Trend of world Oil production, shares of Middle East & India

during 1989 – 99 (million tones/ Year)

Year 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Total World

production 3096.3 3164.1 3151.9 3184.1 3184.2 3225.2 3272.0 3370.9 3468.5 3533.1 3452.2

Middle East

countries 792.2 846.8 835.9 909.6 46.8 960.8 970.8 994.8 1037.1 1096.2 1052.0

India’s

contribution 35.0 34.8 33.1 30.2 29.0 33.2 37.1 36.2 37.1 36.4 36.2

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0

200

400

600

800

1000

1200

1400

1600

1800

2000

197

0

197

2

197

4

197

6

197

8

198

0

198

2

198

4

198

6

198

8

Worldwide trade movement Share of Middle East countries

0

500

1000

1500

2000

2500

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

Year

Qua

ntity in

million

ton

nes

Worldwide trade movement Share of Middle East countries

A.

Year

Qua

ntity in

million

ton

nes

Figure-4.1: Decadal trend of worldwide trade movement of oil and the

share of Middle East countries (Million tonnes) – A. from

1970 to 1989 & B. from 1989 to 1999

B.

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The worldwide trade movement of Oil & the share of Middle East countries from 1970

to 1999 are depicted in figure-4.1. The trade movement of oil from Middle East

constitute about 45% of the total movement out of which almost 95% is transported

through marine environment via two main oil tanker routes leading to various

destinations throughout the World as shown in figures-2.2 & 2.3. The decadal global

growth of oil trade movement is 30.5% while from Middle East countries it is 29%. As

mentioned earlier, the major oil tanker routes originating from Gulf countries and

passes through Arabian Sea. One of the main international tanker routes passes

through India’s Exclusive Economic Zone that is close to Luccadive Islands in the

Arabian Sea, adjoining peninsular India, round Sri Lanka across the Bay of Bengal close

proximity to Andaman & Nicobar Islands. While the other route is through the

Mozambique Channel round South Africa to Europe & America. From the figure-4.1 it is

clear that, the Global transport reached a peak in 1979 (1572 metric ton) after which

it was on the decline till 1983 (1100 metric ton), a reduction of one-third. Middle East

transport also showed a similar trend. However, the global as well as Middle East

transport increased considerably from 1985 onwards. On average 40 super tankers

pass through Indian waters daily. This is followed by increasing oil exploration and

development of oil transfer facilities in this region makes the Indian Ocean more

vulnerable to oil pollution. Besides, Indian ports & harbors both on the west & east

coasts handle about 3810 tankers carrying about 84 million tonnes of petroleum/ oil/

lubricant (POL) every year. Followings are the major oil fields/ Ports from where

Crude is imported in India:[49, 62, 63]

1. Knarg Island Terminal, Iran.

2. Adnoc Terminal, Abu Dhabi

3. Basra Terminal, Iraq

4. Al-Fateh/ Yan Bu Terminal, Saudi Arabia

5. SNP Singapore Port

6. Rotterdam, Netherlands

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7. Shetland Oil Field, UK

8. Black Sea Port, Russia

9. National Oil Terminal, Mexico

10. Qua-Iboe Port Terminal, Nigeria

11. Libyan Oil Terminal, Alexandria

In view of the growing oil demand of Indian economy and considering other geo-

political factors, tankage cover of the Indian Oil security is required to be

significantly enlarged. Presently, demand cover of only 40 days is available. A total of

nearly 25-30 million K1 additional tankage cover has been planned to be built-up during

the coming 10 years. It will create a demand cover of additional 45 days over the

present facilities, especially for the states of Himachal Pradesh, Punjab, Jammu &

Kashmir and the North-Eastern States. At the same time, the infrastructure facilities

for handling import/ export of oil & gas product at the Indian sea ports need to be

reinforced and expanded. At present, the port facilities for handling crude oil &

petroleum products are available in the ports at Kandla, Vadinar, Mumbai, Cochin,

Tuticorin, Chennai, Vizag, and Paradip & Haldia. The facilities at the new ports are in

the process development. These ports are at Hazira, Nhava Sheva, Ennore, Kakinada

and a few other minor ports, like Cambay (for Reliance Industries Ltd.). The fig-4.1

depicts all the oil handling ports in India. IOCL utilizes various port locations in the

country for handling POL. The locations are as follows:

Southern Region: Mangalore, Cochin, Tuticorin, Chennai & Vishakhapatnam.

Western Region: Vasco, Mumbai, Kandla, Okha & Vadinar.

Eastern Region: Haldia, Paradip, Port Blair & Calcutta.

Certain port locations, like Kakinada & Pondicherry, are under development. IOC –

Marketing has more than one location at certain ports, such as Mumbai, Chennai &

Calcutta.[64, 65]

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Oil Industry in India is poised for rapid growth to meet the ever-growing demand for

petroleum products. As per the estimated projection, the demand will be well above

100 MMTPA by the end of Ninth Five Year Plan. With limited indigenous crude

production, dependence on imported crudes & to some extent on products will be on

the increase. The total quantum of oil produced from the offshore Wells of Oil &

Natural Gas Corporation (ONGC), India along the western coast of India is

approximately 30 million tones per year. This oil is transported mainly through the

pipelines & the oil tankers. Besides approximately 30 million tones of crude oil

imported to India from foreign countries as mentioned above, is being handled at

major ports is about 50 million tonnes per year at present and is likely to increase in

near future. Tankers & Ships carry this crude oil with a total number exceeding 1600

per year. In addition, offshore oil exploration & production activities, transfer

operations of oil at SBM stations, as well as in lightering operation & during bunkering

operations in the major ports, also cause spillage of oil, particularly during accidents.

Therefore, oil enters into the Indian Ocean predominantly through operational/

intentional discharges, oil well blowouts, and accidental spillages from offshore

activities and natural seepage from the seabed. Also, the character of a coastal area is

the function of the existing coastal materials and the dynamic processes acting upon

those materials, which in turn influence the oil spilled in the coastal areas as well as

the oil reaching the coastal areas from offshore spills.

Now, oil traffic at different ports will increase substantially. Total traffic of crude &

POL, including for power production, is anticipated to reach a level of around 190

mmtpa during 2001-02 at Kandla, Vadinar, Mumbai, JNPT, Goa, Mangalore, Cochin,

Tuticorin, Chennai, Vizag, Paradip, Haldia & Calcutta ports. Maximum traffic is

envisaged at Kandla & Vadinar at the Gulf of Kutch (around 82 mmtpa together),

followed by Mumbai with a load of around 25 mmtpa. Mangalore, Cochin, Chennai, Vizag,

Paradip & Haldia are expected to handle individually traffic in the range of 10-16

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mmtpa by 2001-02. Goa & Calcutta each will be handling around 2 mmtpa and at

Tuticorin, it will be 0.5 mmtpa.[49, 62, 65]

Therefore, in view of the above facts & figures and with the objective as stated in

section-3.2 in consideration, the present research work has been undertaken to

validate the result obtained from the developed numerical model with the available oil

spill data used in Environment Impact Analysis (EIA) study for Vadinar Port (figure-

4.2) in the Gulf of Kutch in the Western Coast of the country. This site has been

chosen for the study as because:[15, 22]

[Source: Sengupta & Deshmukh, “Coastal &

: VADINAR Marine Environment of Gujarat”]

Figure-4.2: Location Map of Vadinar

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(a) The west coast handles nearly 70% of India’s crude import, half of it in single-

hull vessels. There are 5 to 6 accidents every year. Global ship owners rarely

follow regulations framed by the International Maritime Organization (IMO).

The seas off major Goa beaches are unfit for bathing. The Maharashtra coast

also faces a similar crisis.

(b) Indian Maritime Institute President, K. Chidambaram feels that, governments

of coastal states should take a lesson from the recent incident of the fully

laden 31068 DWT tanker Castor, which suffered damages in the Mediterranean

Sea en route Lagos, Nigeria. “Immediately after the accident, the American

certifying Agency withdrew all certificates from the company so as to prevent

a recurrence. Indian states must also enforce international laws with an iron

hand”, says Chidambaram. Until that happens, environmental tensions on the

western coast are set to escalate.

(c) Out of the various sites in India, Gulf of Kutch has the maximum tidal ranges

of around 11 meters and annual average of around 6 meters, wherein, Vadinar is

one of the largest oil handling port having two Single Point Mooring (SPM)

Platforms popularly called Single Buoy Mooring (SBM) as shown in figure-4.3.

Vadinar port is handling more than 25 mmtpa crude oil cargo in large VLCC

tankers (imported as well as indigenous) for meeting the highest crude

processing capacity of the three Refineries in the country.

4.2 AN OVERVIEW OF THE SITE SELECTED

4.2.1 BRIEF REPORT ON GULF OF KUTCH

4.2.1.0 DESCRIPTION OF AREA

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The Gulf of Kutch in the state of Gujarat of the Country, which occupies an area of

7300 sq km, abounds in marine wealth and with its diversified flora & fauna of coral as

well as mangrove ecosystems is considered one of the richest biotic habitats along the

west coast of India. This high density and diversity of life demands special attention &

measures for preventing degradation of the Gulf several areas of which are protected

under the Marine National Park & the Marine Sanctuary (MNP&MS).[66]

Figure-4.3: A typical SBM with connected submarine Pipelines

The actual fairway in the outer Gulf is obstructed by the presence of several shoals.

The high tidal influx covers the lying areas of about 1500 sq. km. comprising a network

of creeks and alluvial marshy tidal flats in the interior regions. The creek system

consists of 3 main creeks: Nakti, Kandla, & Hansthal and the Little Gulf of Kutch

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interconnecting through several major & minor creeks. All along the coast a few rivers

drain into the Gulf and they carry only a small quantity of fresh-water except during

monsoon. They are broad valleys and the riverbeds are mostly composed of coarse sand

& gravel.

The topography of the outer Gulf is more ragged as compared to the inner Gulf. The

southern shore has numerous islands & inlets covered with mangroves & surrounded by

coastal reefs. The northern shore is predominantly sandy or muddy confronted by

numerous shoals.[21]

The availability of relatively deeper waters near the southern shore and protection

from the monsoon waves, have made the Gulf attractive for the import of crude oil

through VLCCs (Very Large Crude Carriers) and unloading the Cargo via SPM (Single

Point Mooring) systems to the shore-based tank-farms. One SPM is operational in the

Gulf of Vadinar since late seventies & another one is operational since late nineties and

a few more are under installation. When the SPMs are fully commissioned, the traffic

of crude oil is projected to increase from the present more than 25.0 MMTPA to

cover 70.0 MMTPA. With this the traffic of VLCCs is expected to increase from 80

at present to over 480 by 2005. The additional traffic of tankers carrying Petroleum

Products and Other Liquid chemicals (POL) which is 900 ships today, is expected to

increase to 1500 when the Refineries at Vadinar & Sikka go into operation and increase

in petroleum traffic at Kandla & Mundra Ports is taken into account.

This multifold increase in traffic of Crude Oil & Petroleum products enhances the risk

of oil spills due to tanker accidents, hose ruptures, sub-sea pipeline leakages,

operational discharges, etc. If a large spill occurs, the Gulf ecology, particularly of the

intertidal & subtidal nearshore habitats will be severely damaged or even destroyed

irreversibly. Hence, proper strategies for: (a) minimizing the risks of petroleum spills,

(b) preparedness to combat a spill if it occurs, and (c) periodic monitoring of ecology

of the Gulf designed to identify changes in the marine environmental components, are

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necessary for efficient management of the Gulf environment. A comprehensive study

for predicting the oil slick spreading and behavior of a probable spill based on reliable

long-term field data is necessary for effective combating and to identify areas to be

selectively protected in the event of an oil spill.[10, 66]

4.2.1.1 GEOMORPHOLOGY

The ecology of offshore Kutch basin is an extension of inland Kutch basin, which forms

a part of the foreland shelf of Indus-Baluchistan geosynclines. A thick sequence of

Jurassic-cretaceous (about 2400 m) and a complete tertiary sequence (about 700 m)

separated by about 600 m Decan trap. Volcanoes are exposed in the Southwestern

part of Kutch, peninsula adjoining offshore basin. This basin is separated from the

Bombay offshore basin by a prominent arch of the level of Eocene & Miocene

sediments. The difference between the Bombay offshore basin and the Kutch basin

lies in the absence of Mesozoic rocks in the former. While the presence in the latter

which are not only present, but also quite wide & thick.

A number of prominent shoals (Ranwara, Lushington, Gunur, Samiyan), which are

present in the Gulf, could have resulted from the resistant rock capping on

topographic high-remnants from an earlier phase of terrestrial erosion or the

structural highs in the bedrock or combination of both.

Several major geomorphic features are identified in the Gulf. The prominent among

these is an elongated ENE-ESW depression with very steep slopes and very rough to

rugged surface extending from the entrance to the Ranwara shoal. West of the Kutch

peninsula, the depth gradually increases to 40 m at the Kori Great Bank in Arabian Sea,

130 km away from the coast. The seabed is mostly sandy & muddy. Depth ranges from

20 m at the head to 60 m at the mouth of the Gulf of Kutch. The topography is very

irregular at the mouth and central part of the Gulf with pinnacles and scraps ranging in

height from 6m to 32m. These scraps are considered to have formed due to tectonic

instability during quaternary sea-level fluctuations, later accentuated by tidal scour.

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In addition to these, other prominent geomorphic features observed are extensive

eroded terraces with relatively flat floor, dormal smooth surfaces and sharp pinnacles

of 10 m to 25 m height.

Decan Traps and older Jurassic formations are exposed in the interior Saurashtra and

Kutch areas. Tertiary rocks are exposed between the older interior formations and

Pliocene formations, namely Dwarka beds, which are exposed in certain portions along

the western & northern Saurashtra coasts. On the low energy southern side of the

Gulf wide tidal flats with patches of corals occurring 2-7m above in the inter-tidal &

sub-tidal zones are present. The origin is considered to be due to the coastal uplift.

Incidentally, the Gulf & the surrounding region are highly active seismically with a

number of recorded earthquakes. Due to great earthquakes of 1789, the Indus River

then traversing the delta, changed its course and found its way to the sea at the

western extremity of Kutch and brought sudden depression of a large portion of the

Rann north of Lakhpat and caused elevation of Allah Bund.[21, 37, 67]

4.2.1.2 HYDRODYNAMICS

Tides in the Gulf are of mixed, semi-diurnal with large diurnal inequality and varying

amplitude, dominating all along the Gujarat coast. The tidal front enters the Gulf from

westerly direction and due to the shallow inner regions & narrowing cross-section, the

tidal amplitude increases as the front approaches the inner Gulf. The mean-high water

spring increases from 3.04 m at Kori Creek to 5.64 m at Mundra and to the maximum

of 7.31 m at Navalkhi – gradually decreasing to 3.47 m at Okha (Table-4.3). As the

tidal front advances through the Gulf, the high tide is first felt at Okha, then at

Vadinar, Sikka, Kandla & Navalkhi in that order. The phase-lag between Okha & Kandla

is 2 hrs to 3 hrs 45 minute while between Okha & Navalkhi it is 3 hrs to 3 hrs 20

minute. Due to high tidal ranges, vast stretches of mud flats and coastal low lands,

which get submerged during high tide, are fully exposed during low tide.[21, 67]

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The currents that are strong in all seasons, are largely tide induced, influenced by

wind & thermal gradients. The currents are bimodal with two prominent directions –

one during flood tide and the other during ebb tide. These directions depend on the

local bathometry & general topography of the area. Around the mouth region the

currents are moderate with speeds of 75 cm/s to 125 cm/s. The speed increases

considerably in the mid-Gulf to 200 cm/s to 250 cm/s. The speeds of around 100 cm/s

occur off Vadinar with northeasterly flood direction and southwesterly direction

during ebb. Strong currents normally occur during mid tide, i.e. 2 hrs. to 3 hrs before

& after low tide & high tide. The speeds however, decrease considerably near-shore &

in creeks and tidal inlets. Out of the various sites in India, Gulf of Kutch has the

maximum tidal ranges of 11 m & annual average of around 6 m.[21, 22]

Table-4.3: Tidal Elevation (m) in the Gulf

Station MLWS MLWN MSL MHWN MHWS

Okha +0.41 +1.20 +2.04 2.96 +3.47

Sikka +0.71 +0.71 +3.04 +4.35 +5.38

Kandla +0.78 +1.81 +3.88 +5.71 +6.66

Navalkhi +0.78 +2.14 +4.15 +6.16 +7.31

MLWS = Mean Low-Water Spring

MSL = Mean Sea Level

MHWS = Mean High-Water Spring

MLWN = Mean Low-Water Neap

MHWN = Mean High-Water Neap

4.2.1.3 WATER QUALITY

Water balance in the Gulf of Kutch is negative with evaporation being the dominant

control over the sum of rainfall & river runoff. Residence/ turnover time varies from 8

to 51 days decreasing upstream. The prevalent tidal oscillations cannot flush out the

gulfs completely leaving behind parcels of perennially undulating water, whose

residence time will continuously increase with increasing number of oscillations. Such

residual tidal effects will control the environmental impact of all the pollutants. The

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prograding sediments of river Indus regulate sediment movement in the Gulf of Kutch.

These accumulate only on the northern shores. Movement of the southern shores is

hindered by the dynamic tidal barrier existing in between.[21]

The quality of water of the Gulf in general is assessed on the basis of investigations

undertaken between 1985 & 1994 by NIO (National Institute of Oceanography), Goa.

Temperature in the Gulf varies in accordance with the air temperature are

considerably smoothened, as expected. The inner Gulf in general, has marginally lower

temperature (20.2 – 27.8C)[21] under the influence of local air temperature as

compared with the outer Gulf. The water temperature in the outer Gulf generally

varies between 23C & 29C with occasional maxima of around 30C at inshore areas.

Shallow depths, medium to high tidal amplitudes, moderately strong tidal currents with

associated turbulence create a perennially homogenous one-layer water mass all along

the Gujarat coast. The Gulf receives negligible freshwater inflow during dry season.

Thus, the evaporation exceeds precipitation leading to salinities higher than the

typical seawater salinity especially, during the pre-monsoon & post-monsoon periods.

The inner Gulf in particular, sustains high salinities & values exceeding 39 ppt are quite

common off Kandla & Navalkhi. Salinities as high as 50 ppt have been recorded in some

creeks of the Little Gulf of Kutch under the influence of monsoon runoff; the impact

of this decrease in the Gulf proper is small. In general, high salinity (35 – 40 ppt), high

dissolved oxygen (5 – 8 mg/l), fairly low nutrient concentrations (PO4-P: 0.7 – 1.5

µmol/l; NO3-N: 0.8 – 7.0 µmol/l); low BOD5 values (<3 mg/l) lend a near-pristine water

quality to the Gulf of Kutch. On the west Saurashtra coast water quality is good,

except near discharge points of wastewater. The swift tidal movements keep the

water well mixed vertically & there is no stratification. The pH of seawater

throughout the Gulf is fairly constant & seldom deviates from the typical range (7.9 –

8.3) for seawater. Toxic trace metals concentrations are high at or in the vicinity of

such discharge points. Sabarmati is the worst polluted of all the Indian rivers where

industrial effluents comprises of 4.6% of its annual runoff. Because of the cumulative

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effect of all these dissolved oxygen in this Gulf often decreases to 0.4 – 0.5 mg/l at

bottom associated with high nutrients concentration near the head region, in spite of

strong tidal flashings twice every day. Under such conditions, the residual tidal effect

should play a significant role in the Environmental Impact Assessment (EIA) of any or

all pollutants.[21, 67]

4.2.1.4 MARINE ECOLOGY

Primary production in the Gulf of Kutch is moderate with 31 genera and 41 species of

phytoplankton. Off the west coast of Saurashtra 28 genera and 71 species were

recorded. In all the three areas of Gulf, as usual, the primary production exhibited

temporal & spatial variability with seasons and tidal phases. Diatoms constituted the

major bulk of phytoplankton everywhere.[67]

In all the three areas, zooplankton-standing stocks are moderate to fairly high.

Species diversity is quite good everywhere. The compositions of zooplankton are

diverse. Dominant groups are copepods & decapods. Fish-eggs & larvae are rich &

abundant everywhere. Crustacean fauna are rich at places providing good feeding

grounds for prawns & fish. In short, all the 3 areas appeared to have good fishery

resources and recruiting grounds for fisheries. Temporal & spatial variations also

exist.

Gujarat tops the list of the 10 littoral states of India in marine fish production

accounting for 23.1% of the National total. In 1997-98 the State exported 17.9% of

its marine catch, which was 32.5% of National export. But, due to over-fishing, the

quantity & size of catches in several prized varieties, like Jumbo prawns, Lobsters,

Dara, Karkara, Koth, Ghol & Wam off the Gujarat-Maharashtra coast, are decreasing.

So, these can be classified as endangered to critically endangered species.

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Benthic fauna are moderate to good in the Gulf of Kutch with good biomass and

population density of both micro & meiobenthos. Foraminifera, polychaetes, gastropods

& crustaceans dominate population of both. The sub-tidal macro-faunal population

density off west Saurashtra indicates high fertility of the region.

Vast inter-tidal expanse, gentle slope & mostly coralline sub-stratum make the coast

of the Gulf of Kutch very conducive for algal growth with number of species varying

from 40-89 at various locations. Dominating species are the green algae: Ulva,

Ernodesemis, Struvea & Microdictyon; brown algae: Padina, Dictyota, Colpomenia,

Iyengaria; red algae: Kjellimania, Halimenia, Griffithsia in the various inter-tidal zones.

Sub-tidal regions are dominated by Sargassum, Turbinaria & Kjellimania. Several

seaweed species are being harvested for production as Agarophytes, Alginophytes &

Carragenophytes. Several marine algae can be exploited for their pharmacological

properties. A few seagrass species are observed to grow in sub-tidal regions of some

islands in the Gulf of Kutch.

The Gulf of Kutch region alone has mangrove vegetation covering 954 km2 out of the

state Gujarat’s total covering of 991 km2. Maximum part of this cover, 836 km2 is in

the Kutch district of which over 800 km2 borders the Kori Creek with a dense patch of

about 640 km2. The coast of Jamnagar district covers 118 km2. Species diversity is

dominated by Avicennia marina, through small stray patches of other species do exist.

Due to high salinity, grazing & cutting pressure their growth is stunted (1-2 m). In

areas free from human interference, e.g. Kori Creek, Pirotan Island, they grow fairly

tall (~10 m) with good girth of their trunks. State Forest Department of Gujarat has

undertaken monospecies (A. Marina) afforestation around the Gulf of Kutch. Mangrove

vegetation is sparse in the semi-arid Junagadh coast. Mangrove trees are very

important to maintain shore stability and protection of the coast from natural

disasters, like cyclones, etc. Several commercially important marine fish breed & spend

a part of their life cycles in this environment.[67]

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The Gulf of Kutch is the only area in Gujarat where corals exist. This Gulf has 42

islands, 34 of which have coral reefs on one side or more. Satellite imageries indicated

that the total reef area of the Gulf was 217 km2 in 1975, in the inter-tidal zone, which

reduced to 118 km2 in 1985 & 123 km2 in 1986. The core area of the Marine National

Park was 116 km2 in 1975, which was reduced to 83 km2 in 1982, & 53 km2 in 1985.

Between 1985 & 1991 a net improvement from 53 to 85 km2 was noted. Siltation was

concluded to be the main cause for the coral decay from the imageries. A total of 44

species of Scleractinian corals (stony corals) & 12 species of soft corals were reported

from inter-tidal observations. Most of these corals are hermatypes (reef forming)

[figure-4.4] while a few are ahermatypes. Subsequently, in 1999, a video graphic

survey of sub-tidal reefs of 4 islands revealed fantastic mosaics of stony corals, 7

species of soft corals, 28 species of benthic marine algae & 23 species of benthic

fauna have been videographed from these underwater gardens teeming with life. Sub-

tidal zones of all these coral reefs can be expected to reveal similar pictures, revising

upwards the existing concept of 20-30% live corals in these reefs. Coral reefs protect

the coast, increase its stability & help to create sheltered harbors. Because of the

existence of these coral reefs, the northern coast of Saurashtra is protected from

erosion & storm surges. This surely has been helping the ongoing industrial

developments along the Gulf coast of the Jamnagar district. Existence of live coral

patches off Mungra reef on the east & off Mundra (Adani Port) and off Mandovi on

the north in the Gulf of Kutch (figure-4.5)[67] have been confirmed for the first time

in February 2000. The southern shores of the Gulf of Kutch in Jamnagar district have

been demarcated as Marine National Park & Sanctuary (MNP&S) between 1980 & 1982.

4.2.1.5 POLLUTION THREAT

Threats to marine ecology of the state of Gujarat are from the fast growing

industrialization and its associated urbanization. The Gulf of Kutch region (figure-4.5)

is being aggressively developed for economical import of crude oil & its products from

the Middle East countries, transporting a part of these overland to Refineries inland

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and establishing huge grass-root Refineries for petroleum & petrochemicals. Cement,

Soda-Ash & Salt industries also contribute to these threats together with growing

urbanization. Accidental &/ or operational oil spills and release of industrial & urban

wastewater are potential threats to the fragile & unique ecology of the MNP&S. The

threat may be aggravated by allowing industries to discharge wastewater to the Gulf

while Refineries are, rightfully, forbidden to do so. Indiscriminate collections of

marine flora & fauna for scientific research and commercial purposes may endanger

them leading to their ultimate extinction. The only saving grace in the coastal waters

of Gulf (i.e. in Gujarat) is the semi-diurnal tide with large amplitude, which flush the

sea twice everyday. But the residual tidal effect will have its impact on the

environment. The country needs industrial development for its growth. But also Plans

for conservation and management of the environment aiming at Sustainable

Development with Symbiotic Coexistence need to be worked out.[67]

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Figur

e-4.4

: Cor

al Reefs

along

the G

ulf

of K

utch

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Figur

e-4.5

: Cor

al pa

tches

on t

he n

orth

ern

& e

ast

ern

shor

e s

of

the G

ulf

of K

utch

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Figure-4.6: Coastal talukas of Kutch

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4.2.2 A BRIEF REPORT ON VADINAR OIL PORT

4.2.2.1 DESCRIPTION OF AREA

Vadinar oil Port is located in the outer Gulf of Kutch in the western coast of the state

of Gujarat in India and the Gujarat is the western boundary of the country. The

approach from the Arabian Sea to the terminal (at SBM) is through a 125 km long

navigation channel maintained by Kandla Port Trust (KPT) & Gujarat Maritime Board

(GMB). The water depths of 30-40 m[21] are available for about 60% of the length. Two

Mooring platforms, known as SBM are there at Salya (i.e. Vadinar) for receiving

Imported & Bombay High crude oils required to meet the highest crude processing

capacity of the 3 biggest Refineries of Indian Oil Corporation Limited (IOCL). Vadinar

is the 2nd largest oil handling port after Kandla and is one & only one to have two SBMs.

Presently, it is handling more than 25 mmtpa oil-cargo.

The Single Point Mooring (SPM) System or SBM, which is considered as point of oil

discharge/ spill, is located on the offshore at the latitude 22˚30'14. 36" North & the

longitude 69˚43'27. 33" East of the Gulf of Kutch. The crude received, is transported

to IOCL’s terminal station at Vadinar through 6.4 km which is taken as 6.5 km for

simplicity of calculation in the subject study (figure-4.7), submarine pipeline and

thereafter 5.7 km long twin onshore pipelines for further transportation to its 3

Refineries.

An water depth of around 32 m is available at the SBM (Bathometry contour from the

SBM up to the shore is shown in figure-4.8. The datum of the surroundings as

recorded by the Naval Hydrographic Office, Dehradun (India), is the chart datum,

which is 3.04 m below Indian Mean Sea Level. Two types of Crude oil are handled at

the SBMs at Vadinar: (i) Imported Crude oils of which Arabian Light (AL) & Arabian

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Heavy (AH) form the bulk and (ii) significant quantities of the indigenous Bombay High

(BH) crude. The physical characteristics of the AL, AH & BH are shown in table-4.4.[21]

Table-4.4: Characteristics of Crudes handled at SBM

Parameter AL AH BH

Specific Gravity 0.86 0.89 0.83

API Gravity 37.7 27.5 39.35

Pour Point (°C) Low Low + 30

Viscosity (cst) at 15°C 14 55 186

% Boiling below 200°C 30 25 30

% Boiling above 370°C 40 49 55

Goos Reef

13.0 km (approx.)

13

.0 k

m (

ap

pro

x.)

SBM or the Point of Oil Discharge

Kalubhar Reef

Figure-4.7: Key Map of the Site at Vadinar Oil Port

Area of concerned

[6.5 x 6.5 km]

COASTLINE

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0.00 10.00 20.00 30.00 40.00 50.00 60.000.00

10.00

20.00

30.00

40.00

50.00

60.00

COAST LINE

4.2.2.2 HYDRODYNAMICS

Tide at Vadinar, which leads by 10-15 minutes over that at Sikka, is semi-diurnal with a

considerable diurnal inequality. The characteristics of Vadinar are expected to be

similar to that of Sikka as shown in table-2.5. However, according to the Admiralty

DIS

TA

NC

E [

IN ’

20

0M

]

DISTANCE [IN ’200M]

Goose Reef Kalubhar Reef

Area

13.0 x 13.0 km

Figure-4.8: Bathometry contour of the Site

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Tide Tables, UK the normal tidal range in the area under the study ranges from 1.8 m

(neap) to 6.0 m (spring) within the following mean tidal variations:[21]

Mean High Water Springs (MHWS) : + 6.2 m

Mean High Water Neaps (MHWN) : + 4.1 m

Mean Low Water Neaps (MLWN) : + 0.3 m

Mean Low Water Springs (MHWS) : + 0.2 m

Based on the IMODCO International Inc., USA Study report regarding wave & current

measurement at the Site under study, the normal wind peak is in the Southwest

Monsoon. The normal wind speed frequency based on ships reported wind data by

Indian Meteorological department for the period 1961-69 is as shown in the Table

given below. The yearly peak wind is estimated to be about 75 kmph. During cyclonic

period sustained hourly winds are as high as 111 kmph have been experienced.[21]

Table-4.5: Normal wind speed at Vadinar

Wind Conditions Normal wind speed (Km/hr)

39 50 62

North East Monsoon

(Nov.-Feb.) 0.4% - -

Spring Transition

(March-April) 1.0% - -

South West Monsoon

(May-Aug.) 8.9% 1.7% 0.5%

Autumn Transition

(Sep.-Oct.) 1.4% 0.7% -

Annual Summary 3.5% 0.7% 0.2%

According to Indian Meteorological Deptt, a cyclone occurred in the vicinity of the

site between 21st & 23rd October 1975. An observatory at Jamnagar has reported

hourly-sustained winds of 170 kmph during the cyclone. The same observatory

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recorded instantaneous wind speeds of up to 200 kmph during the cyclone on

instruments with capability of recording a maximum wind speed of 200 kmph.[21]

Wave generation in the area is predominantly local and is influenced by wind conditions.

The normal significant wave height frequency is as mentioned in the table-4.6.

Table-4.6: Normal significant Wave heights at Vadinar

Wind Conditions Normal Significant Wave Height (m)

1.0 1.5 2.0

North East Monsoon 3.5% - -

Spring Transition 7.4% 1.4% -

South West Monsoon 24.6% 8.2% 1.4%

Autumn Transition 5.5% 0.8% 0.2%

Annual Summary 11.5% 3.1% 0.5%

The current in the region of the site is predominantly tidal. The maximum surface

current during normal conditions can be about 1.1 m/s excluding wave-induced currents.

Bottom currents at 2.0 m above seabed at the location of the terminal (point of oil

discharge) can attain a maximum of 0.6 m/s, & at mid-pipeline location can attain a

maximum of 0.7 m/s. As per EIA study carried out by Engineers India Limited (EIL) in

1996, currents at site are bimodal with E-NE direction during flood & S-SW direction

during ebb. The maximum near surface current is about 80 cm/s with an average of 40

cm/s over a tidal cycle during spring & 25 cm/s during neap. N-S components are

generally weak, though in the vicinity of creek mouths they may dominate over the E-

W components due to the change in channel geometry. Dominant E-W components can

be expected at SBM location during tidal change for a short period though they are

relatively weak. The near bottom current velocities are also weak (maximum 40 cm/s).

However, the following data are used for the model solution:

i) Wave height = 3 m with a period of 7.0 sec.

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ii) Induced wave angle = 30° with the shore

iii) Tidal current = 1.1 m/s with an angle of 10° to the shore

iv) Wind speed = 14.0 m/s with an angle of 10° to the shore for 72 hours after oil

spill occurs

v) Volume of spill = 100 m3 of Arabian Heavy crude having specific gravity of 0.890

vi) Duration of discharge = 100 minutes.

4.2.2.3 WATER QUALITY

The water quality off Vadinar-Sikka was investigated during 1993-94. The water

temperature varies from 24.0°C to 29.5°C in the coastal waters of Vadinar-Sikka with

a mean of below 29°C. The values are comparable to those observed for the outer Gulf.

The coastal waters are well mixed with absence of any thermal stratification. The

mean pH of water varies from 7.8 to 8.5, which is within the range expected for

coastal tropical seas.

The salinities of the region (semi-arid) often exceed 38 ppt during premonsoon and

during post monsoon these are considerably low (33-35 ppt). The nearshore

premonsoon high salinities (39.2-40.5 ppt) are mainly due to the drainage of high saline

waters from tide pools, intertidal regions & saltpans, into the coastal system.

The suspended particulate matter (9-74 mg/l) is uniformly distributed throughout the

area within the natural availability inherent to a dynamic coastal environment.

Relatively high-suspended load is associated with the bottom waters, which is largely

inorganic in nature. The mean DO value (7.7-8.7 mg/l) observed in the water indicates

good oxidizing conditions. The BOD varies in a narrow range of negligible to 4.5 mg/l &

the average values are below 2.5 mg/l. The overall low BOD indicates that the dead

organic matter is effectively consumed and that there is no gross influence of existing

anthropogenic oxidisable matter inputs to the Gulf.

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The average concentrations of nutrients off Vadinar-Sikka vary in the following

ranges:[21]

Nutrients Range (g/l) Mean (g/l)

NO3-N ND-57 55

NO2-N ND-44 20

NH4-N ND-109 34

PO4-P ND-337 54

In general, the nutrients are uniformly distributed in the waters. The concentration of

total nitrogen & total phosphorous in water are also low.

The concentrations of Petroleum Hydrocarbons (PHC) & Phenols (1 m below the sea

surface) vary in a narrow range of 5 µg/l to 68 µg/l and there is no significant seasonal

variability noticed in the values. The concentrations of phenols are also low (3-58 µg/l)

and appear to represent a national background. The concentrations of trace metals in

water vary as follows:[21]

Metal* Vadinar Sikka

Manganese 7 5

Iron 17 7

Cobalt ND ND

Nickel ND ND

Copper 5 10

Zinc 15 12

Lead ND 5

Cadmium ND ND

* Concentrations are expressed as µg/l

The concentrations of trace metals are low & can be taken as baseline concentrations.

The central portion of the Gulf extending from the mouth to upstream of Sikka is

rocky with sediment confined only to margins. The texture of surfacial sediment can

however, vary considerably over short distances.

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4.2.2.4 MARINE ECOLOGY

Prevailing biological potential is evaluated largely based on the investigations during

1993-94[21] pertaining to phytoplankton, zooplankton, benthos, intertidal fauna, fishes,

seaweeds, corals, mangroves, reptiles & mammals. The concentration of chlorophyll a.

varies widely from 0.5 mg/m3 to 6.4 mg/m3 (average: 1.6 mg/m3) indicating moderate to

high primary productivity, which is comparable with available data for the Gulf. The

concentration of phaeophytin: 0.1-3.1 mg/m3 (average: 1.0 mg/m3) is lower than that of

chlorophyll as expected, revealing a healthy balance between the growth & mortality of

algae. The phytoplankton cell counts vary from 4 x 103/l to 1702 x 103/l (average: 118 x

103/l) with maximum during post-monsoon period. More than 60 species of

phytoplankton are identified in the coastal water. Among them Chaetocerose socialis &

Chaetocerose sp. are the most dominant. Other major species are: Nitzschia sp.,

Thalassiosira sp., Navicula sp., Coscinodiscus sp., Nitzschia clostarium, N. seriata and

Biddulphia sinnensis.

The zooplankton standing stock in terms of biomass (0.5-93.1 ml/100 m3) & population

(0.7 x 103 - 109 x 103/100 m3) vary widely. Overall the region is moderately rich in

zooplankton with frequent occurrence of high standing stock of organisms. The

varieties of zooplankton are mainly of: decapods, copepods, gastropods, mysids, Lucifer

sp., chaetognaths and Fish eggs & larvae. The average intertidal macro faunal standing

stock in terns of population (325-62400 per m2) and biomass (0.1-126.7 g/m2) vary

widely in the regions. The total number of faunal groups in the intertidal area varies

from 9 to 12 (average; 6). Polychaetes, copepods, amphipods, isopods, ostracods,

caprila, tanaidaceans, cumacenas, decapods, brachyurang, mollusks, echinoderms,

pycnogonids, foraminifera, numertines, Crustacean larvae, Insects & Fish eggs, mainly

constitute the fauna. Polychaetes, foraminifera, crustaceans & mollusks in the area

dominate the fauna.

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The subtidal macrofaunal stock in terms of population & biomass vary from 25/m2 to

246000/m2 & 0.1 g/m2 to 66.7 g/m2 respectively. The faunal diversity is comparable.

However, a significant difference in the numerical abundance of individual faunal

groups between pre- & post-monsoon is evident. About 98% of the subtidal macrofauna

is contributed by polychaetes (57%), foraminifera (19%), crustaceans (14%) & mollusks

(7%).

Landings at Vadinar-Sikka reveal a fluctuating trend, which contribute meager 1% to

the total landings of Jamnagar district. The composition of fish catch indicates

incidence of 27 different groups. The common groups are: small Scianeids, Perches,

Mullets, Catfishes, Prawns, Pomfrets, Jew fishes & Shrimps. Overall, 47 species of

fishes, 5 species of prawns, 3 species of crabs, one species of squilla, loligo & sepia

each have been encountered in the catch. Secutor insidiator, Pelates quadrillineatus,

Pristipoma maculatum & Ilish megalopetra dominate the region. The other common

species are Paramonocanthus sp., Johnius glaucus, Pseudotricanthus strigilifer,

Anodontoshtoma chacunda, Cynoglossus arel, & Trichiurus haumela. Out of 47 species

of fishes, 31 species are recorded during post-monsoon and 27 species during pre-

monsoon with 8 species common during both the seasons. Percentage contribution of

prawns is fairly high during the post-monsoon with Metapanaeopsis stridulens &

Penaeus indicus dominating the catch.

All along the creeks & reef environments around Vadinar, the mangroves are seen

crowded with Grey Herons, Pond Herons, Painted Storks, large & small Egrets,

Darters, Cormorant, etc. Along with receding a hectic activity of various Gulls,

Avocets, Whimbrel, Curlew, term & elegant Crabs, Plovers, etc. is a common sight. The

marine mammals, like Dolphin (Dolphinus delphis), Whale (Balanoptera spp.) & Dugong

(Dugong dugon) and the marine reptiles, like Leatherback turtle (Dermochelys

coriacea), Green turtle (Chelonia mydas) and Olive Redley (Lepidochelys olivacea) are

common in the region.

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Vast stretches of intertidal areas around Vadinar such as Narara reef, Kalubhar

(Karumber) reef & Dhani reef are protected under MNP&MS because of their rich bio-

diversity. The southwest region of Kalubhar reef is heavily silted & sustains extensive

mudflats dominated by mangroves. Heavy siltation is also observed in southeast region

of this island causing the coral death except for a few sturdy coral colonies. However,

northeast region of the island is very rich in marine biota, particularly corals &

seaweeds. The density of corals is in reducing trend from the reef slope & the reef

flat towards further upstream. Toward the high-tide area, the reef is totally dead.

Entire Kalubhar reef is reach in marine algae dominated by Digenea simplex, Graciloria

corticata, G. crassa, Padina gymnospora, Hydroclathrus spp., Ulva lactuca, U. reticulata

& Hypnea species. The corals are represented by 35 species and dominated by genera,

like Goniastrea, Gonipora, Porites, Turbinaria, Favia & Favites – commonly occurring

elsewhere also in the Gulf. The dominating species in mangrove zone of the island are:

Avicennia marina, Ceripos tagal, Salvadora persica, Salicornia brachiata & Sueda

fruiticosa. Large number of birds & jackals are observed in the mangrove regions.

Major species of seagrasses, like Halophila ovata, Halodula univervis & Halophila

beccarii are also observed.

Overall assessment indicates that the entire Narara reef is relatively rich in coral

populations compared to the nearby reefs & island. The dominant forms of coral are:

Goniastrea aspera, Porites lutea, Montipora striata, Gonipora stokisi & Favites species.

The seaweed flora though well represented qualitatively, abundance is poor, which

could be due to their seasonal occurrence. The algal zone of the reef is of great

potential for economically important seaweeds such as, Graciloria & Sargassum species.

The common species of seagrasses recorded are: Halophila beccarii, Halophila ovata,

Sargassum, Cystoseira, Hydroclathrus. Other major varieties of algae are of Padina

tetrastromatica, Enteromorpha, Dictyota, & Cladophora species. Monospecific stands

of mangrove, particularly Avicennia marina, are quite common. The open mud flats

devoid of mangroves are potential sites for mangroves nurseries & afforestation. The

dominating coral species in the island are: 15 species of Scleractinian. However, the

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dominant forms are: Goniastrea aspera, Porites lutea, Montipora striata, Gonipora

stokisi & Favites species. The destruction of corals is evident all over the reef. Live

corals, particularly in the algal zones are under severe stress from heavy

sedimentation.

4.2.2.5 POLLUTION THREAT

Populations and community structure of the marine biota are subject to considerable

natural fluctuations due to changes in climatic & hydrographic conditions and the

availability of food. Hence, it is difficult to assess the effect of an oil spill and to

distinguish changes caused by the oil from those due to natural variability. Moreover,

different life-stages of species may show widely different tolerances to oil pollution

depending on their physiogeneric, ecophysiological & biochemical adaptations to varying

environmental conditions. Usually the eggs, larval & juvenile stages are more

susceptible than the adults. Even moderate spills up to 100 m3 may cause large-scale

mortality of plankton & eggs, larvae & juveniles due to a multifold increase in

concentrations of PHC in water soon after the spill. However, under the dynamic Gulf

environment rapid dilution of naturally dispersed oil and soluble components is

expected, soon restoring pre-spill conditions & continuity structure are expected to be

restored fairly soon. Many tropical marine species have very high fecundity that

provides a reservoir to compensate for any extreme losses due to adverse local

conditions. These facts make it unlikely that any localized losses of eggs or larvae

caused by a moderate oil spill will have discernible effect on the size or health of

future adult populations. However, populations of long life, and slowly maturing species

with low fecundity rates may take many years to recover their populations and age

structures, particularly if large areas are affected by oil for a prolonged period. The

major dangers of an oil-spill in the marine environment are:[2, 10, 21, 67]

When oil is spilled on a calm water-surface, only soluble components in the oil

affect organisms in the underlying water. Most waters however, are not calm

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and waves & currents mix oil into the underlying water due to which the water

is unable to absorb oxygen necessary for the living organisms under the surface

of water. Besides this, the growth of marine organisms depends on the quantity

& quality of the primary production of phytoplankton (algae). Apart from the

toxic effects of oil, marine micro-fauna can experience indirect food effects

since algae production can be changed after an oil-spill.

As the oil enters shallow waters during its shoreward transport, oil in water

may reach the bottom particularly during periods of rough weather. This may

cause local damage to benthic organisms. However, it is unlikely that lethal

concentrations will be reached to cause widespread damage except in nearshore

subtidal regions. The impact however, may be particularly severe when large

areas of mudflats, coral reefs, mangrove swamps, saltpans; rocky & sandy

shores are exposed to oil. Depending on the tidal range & topography, the

floating oil may be transported to the shallow interior regions and with the fall

in water level during low tide the oil will form a layer on the exposed inter-tidal

regions destroying the rich inter-tidal fauna of the affected areas. The animals

may be killed by toxic oil components or physically smothered by viscous and

weathered oils & emulsions. The stranded oil may remain for long periods and

recolonization & establishment of normal community structure may take years.

More widespread damage can occur from repeated contamination or if the oil

penetrates into the sediment where it may persist for several years. Due to

weathering & tidal action the part of the oil may get mixed with sediment,

eventually forming tar balls which may subsequently be transported to far away

places and deposited on clean areas. Such tar balls however, do not cause

significant damage to biota.

Salt marshes are extremely valuable components of many estuaries &

coastlines. Salt/ marsh environments are extremely productive & provide

nursery grounds for fisheries and are major energy sources in many coastal

estuaries. Marshes control tidal erosion, buffer the impact of the coastal

storms and act as an interface between the land & sea. This last role prompts

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concern for the vulnerability of marshes when inundated with crude oil or

refined petroleum products.

Large swimming animals, such as squids, fishes, turtles & dolphins are highly

mobile and rarely affected in offshore waters even in major oil-spills. In coastal

areas, some marine mammals, such as seals and reptiles, such as turtles, may

particularly vulnerable to adverse effects from oil contamination because of

their need to surface to breathe & to have the water to breed. Adult fish living

in nearshore waters and juveniles in shallow water nursery grounds may also be

at risk from exposure to dispersed or dissolved oil. It has been observed that,

fish crustaceans & mollusks under prolonged exposure to concentrations of oil

may acquire an objectionable oily odour or tainting. Consumption of such oil

affected fishes may cause vomiting, nausea, etc.

Animals depending on fur or hair for thermal insulation (sea otters, fur seals,

polar bears) suffer loss of body temperature when their hair is fouled with oil.

Moreover, loss of waterproofing reduces the insulation and can result in chilling,

hypothermia & death.

The effects of oiling on sea-birds may be twofold:

External effects associated with oiling of plumage.

Internal effects associated with the pathological effects of ingested

oil.

Oil destroys the waterproofing and insulating properties of the plumage. The

birds will suffer from chilling and it is often unable to fly or remain afloat in

the water. The bird has difficulty in obtaining food or escaping predators. On

internal effects, oil aspiration pneumonia is common in oiled birds. Visceral gout

due to kidney damage as a direct toxic effect of oil or due to dehydration has

been documented. Oil from the feathers of an incubating bird may pass through

the pores in eggshells & either kill the embryos or induce abnormalities.

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Mangroves show greater sensitivity to fresh light crude or light refined

products than weathered oils. Of the four mangrove species, the red mangrove

is the most seaward in occurrence and makes up nearly all of the fringing

forest. The labyrinthine prop roots of red mangroves serve as a firm substrate

that supports a number of plants & animals. After the spill, the mangrove trees

in oiled areas become defoliated & the leaves yellow. Moreover, if the roots

decompose then there is a potential threat to nearby corals & other organisms

that are intolerant to Siltation.

The proportion of toxic components in oil, the duration of exposure as well as

the degree of other stresses largely determine the effects of oil on corals &

their associated biota. Coral reefs are important in supporting coastal fisheries,

protecting tropical coastlines from wave action & erosion and providing a basis

for tourism & recreation. Coral reefs along the Gulf are usually submerged but

get exposed briefly to air at low tide. The oil floating above corals may not

cause severe damage but if it settles on them during low tide may be severely

affected. Oil spills cause substantial mortality among fish and invertebrates

(including lobsters, crabs, gastropods, bivalves, octopus, sea urchins, sea stars

& sea cucumbers) in inter-tidal areas, on the surfaces and margins of coastal

fringing reef platforms, and in adjacent shallow sub-tidal areas. Numerous

colonies of shallow water corals were dead or dying at a depth of 1 - 2 m in

heavily oiled areas. The proportion of dead or dying colonies averaged between

17% & 30% on oiled reefs.

Other problems include accidental poisoning by ingesting oil, blindness from oil

exposure, liver damage and other disabilities. Any animals that come into

contact with this oil will likely be poisoned.

Contamination of coastal amenity areas is a common feature of many oil spills

leading to public disquiet and interference with recreational activities such as

bathing, boating, angling and diving. Hotel & restaurant owners and others who

gain their livelihood from the tourist trade can also be affected. However, the

disturbance to coastal areas and to recreational pursuits from a single oil spill is

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comparatively short-lived and any effect on tourism is largely a question of

restoring public confidence once cleanup is completed.

Industries that rely on a continuous supply of clean seawater for their normal

operations can be adversely affected by oil spills. Power stations, in particular,

are often located close to the coast in order to have access to the very large

quantities of water required for cooling purposes. If substantial quantities of

oil are drawn through intakes, contamination of condenser tubes may result,

requiring a reduction in output or total shutdown whilst cleaning is carried out.

Similarly, the normal operation of desalination plants may be disrupted by oil,

causing water supply problems for consumers.

The following data will show the effect of oil spills on the lives of the sea birds:[2, 68]

Sl. Spill No. of sea birds died

1. Cap Tourmente, Fall 1963 Contaminated the habitat of snow geese. 2. Arrow, February 1970 More than 4800 - mostly Murres & Dovekie;

Inshore: more than 2400 including diving Ducks,

Grebes & Murres.

3. Irving Whale, March 1970 Around 5000 - mostly Eiders. 4. Eastern Lake Erie, Dec. 1975 2800 - mostly diving Ducks. 5. Kurdistan, March 1979 4000 - mostly Murres & Dovekie. 6. Nestucca, Dec. 1988 Around 40 000 - mostly Murres & Auklets. 7. Exxon Valdez, March 1989 More than 30 000 - mostly diving Ducks, Auks &

Pelicans.

The above data shows its devastating effect on the lives of the sea birds in the area

where the oil spill happens, but in the ecosystem there are not only birds but a large

number of other living organisms like fishes, turtles, otters, whales, etc., as the oil

spill during the 1991 Gulf War killed 400 to 500 tons of fish.

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As per EIA study, the spill movements’ predictions indicate, the spill reaching the

Kalubhar & Goos reefs. Hence, even a moderate spill of 100 - 200 m3 may cause a

considerable damage to the reef-ecology of these islands. A large spill of 3000 m3 will

produce a devastating effect on nearshore subtidal & intertidal ecosystems at a

considerable stretch of the coastline. As a result, the intertidal mudflats, sandy

beaches, mangrove areas & saltpans will suffer severe damage and recovery will be a

slow process.