Any attempt to deepen the channel to 12 m depth will seriously reduce the stability of the Pamban Channel. Hence, further detailed studies are warranted before offering this as an alternative Sethusamudram Channel. The best option is to keep the Pamban Channel intact only for movement of fishing vessels and tugs including catamarans and small ships considering the curved nature of the channel, the shallow waters and the serious dangers of any vessel hitting a sandbank which will require special salvage facilities as provided for in the Suez Canal with bollards on both banks and steel chain tugs to rescue and salvage vessels hitting sandbanks. The approaches to the channel are full of conchshell colonies and algae apart from being Green turtle habitats rendering this a very environmentally fragile marine bio-reserve. No environmental damages should occur by deepening the navigational pathways in the Gulf of Mannar approaching the Palk Straits and Pamban Channel.
In summary, GOI should:
Note in particular the concluding warning of the following technical note: "The likely reactivation of faults due to tsunami causing future mega-earthquakes may direct the waves to move with added force along fault movements to hit the coast, as probably happened in the case of heavy damages caused to Phuket in Thailand and to the Cuddalore- Nagapattinam coast in Tamil Nadu during 2004 tsunami." The types of protective measures against future tsunamis can be learnt from the high walls build along the coastline in Japan to protect against high tidal waves and recurrent tsunamis in Japan coastline.
In conclusion, GOI should declare the Sethusamudram channel projects as a closed chapter in the saga of alternative navigation routes and look for alternative transportation arrangements to move into Trans-Asian Railroad and Trans-Asian Railway Networks on the anvil together with improved container port facilities and high-speed freight corridors.
To avoid future tensions, Ramasetu should be declared a National Monument together with Gulf of Mannar already declared as Marine Bio-Reserve to protect the environment along the long coastline of Bharatam.
No high-risk navigational arrangements should be contemplated on Pamban Channel which does NOT make any nautical sense given the shallow waters and curved nature of the Pamban pass. It is good to recall the warning recorded by every committee which considered the very first Townshend Committee which considered Pamban Channel in 1861. " Mr. Townshend’s Proposal - 1861The next proposal was by Mr. Townshend. He proposed siting the canal through the Pamban Pass. His proposal was to deepen the existing tortuous Pamban Channel to enable the passage of large vessels. However, the objections to its adoption, with a curved channel, and subject to the strong currents through the Pamban Pass were so obvious that it put the Scheme outside the pale of practical consideration."
S. Kalyanaraman
President, Rameshwaram Ramasetu Protection Movement
Herewith a detailed technical note to facilitate further studies.
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A close-up view of the above image.
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In summary, GOI should:
- Declare Ramasetu as National Monument
- Explore alternative transport arrangements to move freight from east coast to west coast from container ports through freight corridors from Collachel to Kolkata to serve Tuticorin, Vizhinjam and Cochin container ports and oil/gas pipelines and opening up a Colombo-Madurai highspeed rail-cum-road for freight and passenger traffic
- Create Special Marine Economc Zones along the coastline for Marine cooperatives with improved fishery port facilities and air-conditioned storage facilities for the cooperatives
- Allow only fishing vessels and small ships to traverse the Pamban Channel without causing any irreparable damage to the adjacent lands and fragile ecosphere
- Provide for protection measures against future tsunamis and to safeguard the placer deposits (monazite, rare earth atomic mineral) along the coastline of the country: Manavalakurichi, Aluva, Chavara, Bhimunipatnam, Puri, Konkan coastal deposits.
Note in particular the concluding warning of the following technical note: "The likely reactivation of faults due to tsunami causing future mega-earthquakes may direct the waves to move with added force along fault movements to hit the coast, as probably happened in the case of heavy damages caused to Phuket in Thailand and to the Cuddalore- Nagapattinam coast in Tamil Nadu during 2004 tsunami." The types of protective measures against future tsunamis can be learnt from the high walls build along the coastline in Japan to protect against high tidal waves and recurrent tsunamis in Japan coastline.
In conclusion, GOI should declare the Sethusamudram channel projects as a closed chapter in the saga of alternative navigation routes and look for alternative transportation arrangements to move into Trans-Asian Railroad and Trans-Asian Railway Networks on the anvil together with improved container port facilities and high-speed freight corridors.
To avoid future tensions, Ramasetu should be declared a National Monument together with Gulf of Mannar already declared as Marine Bio-Reserve to protect the environment along the long coastline of Bharatam.
No high-risk navigational arrangements should be contemplated on Pamban Channel which does NOT make any nautical sense given the shallow waters and curved nature of the Pamban pass. It is good to recall the warning recorded by every committee which considered the very first Townshend Committee which considered Pamban Channel in 1861. " Mr. Townshend’s Proposal - 1861The next proposal was by Mr. Townshend. He proposed siting the canal through the Pamban Pass. His proposal was to deepen the existing tortuous Pamban Channel to enable the passage of large vessels. However, the objections to its adoption, with a curved channel, and subject to the strong currents through the Pamban Pass were so obvious that it put the Scheme outside the pale of practical consideration."
http://sethusamudram.gov.in/History/History.htm (Sethusamudram Official website)
The strong currents continue to exist requiring Tamilnadu Maritime Board to issue daily weather reports for the fisherfolk. The weather situation and the hotspot around Ramasetu and fault-lines and closeness to tsunami generating tectonics make this Sethusamudram a kaarasthan (Marathi: conspiratorial place). GOI should move with abundant care and concern for the coastal people before venturing into project channel alternatives. The submission is that the issue should be considered a transport problem and alternative freight movement and pipeline alternatives should be explored in the context of the development of the long coastline of Bharatam and its destined role of leadership in the Indian Ocean Community with due consideration to answer the concerns of neighbouring country, Sri Lanka which shares the historical waters of Sethusamudram. No decisions should be made without consulting Sri Lanka with due regard to the amended Law of the Sea.
S. Kalyanaraman
President, Rameshwaram Ramasetu Protection Movement
Herewith a detailed technical note to facilitate further studies.
A NOTE ON THE GEOLOGICAL, GEO-TECHNICAL AND GEO-ENVIRONMENTAL CONDITIONS IN THE PAMBAN CHANNEL, TAMIL NADU
BY K.GOPALAKRISHNAN, DIRECTOR (RETIRED), GEOLOGICAL SURVEY OF INDIA
(This note is for submission to Sri. Nitin Gadkari, Honble. Minister for Shipping & Transport, Govt. of India on 03 November, 2014 at Chennai.)
Introduction
It is reported that the Govt. of India is considering a proposal for deepening the existing Pamban Channel in Tamil Nadu as an alternate alignment for the Sethu Samudram Shipping Canal Project (SSCP) based on the recent studies conducted by RITES. As a geo-scientist of this nation who has a fair knowledge about the geological setting of Tamil Nadu, I wish to bring before the Govt. of India some specific geo-scientific data for due consideration. It is hoped that RITES might have taken into account many of the points being raised in this note and already examined them in detail during their studies. But I would like to stress some salient points for further consideration.
Geological setting of Pamban Channel Area.
Various sedimentary rocks of Sub-recent to Recent age are exposed on the land in the Mandapam side (west) and on the Rameswaram side (east). These rocks are also exposed during low tides in the Pamban sea channel in between along a rocky ledge.
Previous studies
Geological Survey of India had carried out the geological and geo-technical studies of the Pamban channel environs for the construction of the Road Bridge across the channel. Two reports pertaining to Pre-project (Road bridge) studies are relevant for the proposed project of deepening of the channel for SSCP. They are –
1. A Geo-technical report on the Investigation of the Foundations of the Pamban Road Bridge, National Highway-49, Tamil Nadu by V.S.Krisnaswamy, Director, Geological Survey of India, 1972. (Sri. V.S.Krishnaswamy is one of the great experts in the field of Engineering Geology (Geo-technical Studies) of India, and had carried out and guided almost all the major Engineering Projects of India. He is well recognized and respected world over in this field. He retired as the Director General of GSI. At present he is over 90 years of age and living in New York city, USA).
2. A Short Note on the Sub-surface Explorations carried out at certain pier locations of Pamban Road Bridge by D.N.Seshagiri, Senior Geologist, GSI, 1977. (Sri.D.N.Seshagi is also a specialist in Engineering Geology. He was associated with and guided many projects giving geo-technical advices).
The salient points brought out by them are –
Surface and drill-hole data suggest the following sequence of formations at the Pamban channel site.
Calcareous Sandstone Around 5m thick Loose Sand 8 – 10m thick Clay 3 – 5m thick Soft Calcareous Sandstone & Shelly Limestones Around 18m (upto 30m depth)
Out of the total thickness of 5m of the Top, Krishnaswamy states “at least 1/3 of the total thickness of the Top Sandstone from the base is believed to be SOFT to VERY SOFT in nature; the middle 1/3 being Soft to Moderately Soft and the top 1/3 being Fairly Hard.”That means about 1/3 of total 5m thickness, only about 1.5m of this Calcareous Sandstone is HARD. Krishnaswamy also states “this top layer is characterized by formation of “Large rectangular blocks, caused by widely spaced Gaping Joints. The depth of penetration of such gaping joints seems to be around 0.91 to 1.52m”. This shows that even this hard top layer is unstable.
On Geotechnical Considerations, Krishnaswamy further states “In view of the fact that the Top Sandstone member is largely Non-existent in the Deep Channel Section and vicinity, and as there is the suspicion of sand-back-fill here, I would suggest recourse to Pile Foundations and consideration of at least 1.5m of embedment of pile into the bottom mostargillaceous / Calcareous sandstone (and Shelly Limestone) member, under the navigational and anchorage spans. Krishnaswamy also suggests for provision of deep pile foundations also for the two piers adjacent to the anchorage span on either side, as for providing against any disturbances of the SAND Layer due to increased erosion of the Deep Channel Floor and Sides,should this happen at the time of any future Strong Gales with tides, which are not uncommon in this area.”. This advice is for the pile foundations of the road bridge.
The new proposal by RITES will be along this Deep Channel Section. The present channel depth is reported to be about 2.5 to 3m. As per the original SSCP proposals, the Shipping Channel for at least 30,000 tonne ships should be 300m wide and 12m deep. So, in the new proposal of RITES, the channel has to be deepened to a depth of at least 12m below MSL. It will certainly go upto the SAND LAYER. The above observations of Krishnaswamy for the road project are very valid for the geo-technical considerations of RITES’ proposal of Deepening Pamban channel. The likely hood of erosion of the undercutting of the Sand Layer below the top sandstone is applicable in this case too. Besides the Sand Layer, the lower 1/3 thickness of the Soft and Very Soft top Sandstonealso will be easily eroded. This will lead to submarine sand slides. It will further induce the overhanging 1.5m thick hard sandstone, which is already affected by gaping joints upto that depth will easily give way for rock slides of large sized rectangular blocks into the shipping channel. This point has to be taken care of to strengthen the sides (walls) of the deepened shipping channel.
Geotectonic (Neotectonic) considerations and Uplifts/ Subsidences (submergences) due to Faulting
The Vaigai Fault is extending from the land on Tamil Nadu to the Mandapam-Rameswaram-Dhanushkodi. Very recent Neo-tectonic activity in the form of faulting had been reported during 1948-49, where the southern part of parts of Dhanukodi went down by 5m into the sea. This had been studied and proved beyond doubt by the Marines studies by GSI, as shown by the figures given below.
TThis faulting establishes the uplift of Rameswaram-Dhanushkodi island with respect to Gulf of Mannar. Krishnaswamy and Seshagiri had also inferred an uplift of the land with respect to the sea by the presence of recent shells in the top Sandstoneformations, as well as from the occurrence of most recent Coralline Limestones on top of this top Sandstone much above present day sea level and above the level required for the growth of coralline colonies, on the northern side of Rameswaram island and its absence on the southern side, indicating an uplift of the northern side. Recurrence of such faulting in future may lead the rocky ledge extending from Mandapam to Pamban along the channel, to be uplifted and thus reduce the depth of the channel hindering the passage of ships. Also this faulting will destabilize all the rocks in the vertical section, bringing further Sandand rock (Sandstone) slides into the channel obstructing the passage.
Another aspect which may affect the stability and depth of the channel is the nature of the current movements and the likely quantum of sediment transport along and deposition in the channel.It is hoped that RITES would have studied this aspect during the different seasons along the Pamban channel.One Google Earth image of the area taken in 2008 during a particular season, and given below shows the forceful nature of the sediment laden currents from Palk Bay to Gulf of Mannar along the Pamban channel.
It is to be remembered that at present, the force of the currents and the sediment load are distributed over the entire length of the hard rocky ledgein the Pamban channel for about 3km extending from Pamban to Mandapam , which (the rocky ledge) is reported to have a width of about 120m. Further scale modeling and mathematical modeling studies are needed to know the possible nature (manifold increased force) of the currents and sediments when a much narrower shipping channel of 300m width and higher depth of 12m is cut and available for currents across the Pamban channel. As the deep shipping channel will be cutting through the underlying SAND layer, the rate of erosion of this layer due to increased force of the currents may also have to be studied for taking necessary steps for protecting the sides (wallls) of the shipping channel.
RITES would have also made similar studies on the nature and sediment transport from Gulf of Mannar northwards, which may have an impact on the stability of the rocky reef / ledge across the Pamban channel. Actually, Krishnaswamy makes a point that the coral islands on the southern side of the Pamban channel forming a barrier to these northerly speeding and large currentsand acts as insurance to the stability of the channel rocks. The actual plan of the proposed channel with orientations and depth of digging to be done in the different sectors, particularly for the entrance from the south, is not available at present to this writer. It is not known whether any islands and or coral reefs will be cut through, and even if passage through the gap between the existing coral reefs etc. A general caution is given that these points are to be studied very carefully, keeping in mind these geomorphic features together form a natural geological barrier protecting the Pamban channel from the various adverse oceanic activities and are not to be destabilized in any manner as well as to be protected in suitable manner.
In the absence of the terms of reference and the non-availability of the report of RITES at present, it is not clear whether the studies by RITES restricted to only the deepening of channel for SSCP or for the entire Project. In the later case, the following additional points on various other geo-scientific aspects related to entire SSCP, are submitted for consideration.
Geo-scientific findings and recommendations from the above report are summarized below.
A. There are 4 sets of ‘deep crustal faults’ occur in the project area, oriented in 4 different directions, viz., NNE-SSW to NE-SW, NW-SE, N-S and E-W .
Faults are deep crustal fractures and fissures or weak zones which extend over hundreds of kilometers in length and to depths of over tens of kilometers. The disturbances deep within the earth known as ‘tectonism’, cause the release of pressure built-up there along the faults, which in turn brings about both vertical and lateral movements of blocks of earth’s crust.
• All the four fault systems in SSCP area are neo-tectonically active even today bringing out both vertical and strike-slip movements. Recent studies by GSI have indicated such activities along the southern parts of Rameswaram – Dhanushkodi area extending along Rama Sethu as well as in the off-shore areas of Vellar river in Palk Bay
B. Occurrence of a number of thermal springs on land around the entire Palk-Bay region as well as the indications of a very high heal-flow zone in this area are documented by the maps given below. It is inferred from the ‘High Heat Flow Zone II and IIIthat is similar to such high heat zones along the Himalayan front and along Andaman – Niccobar Islands where active volcanoes are present. Occurrences of buried volcanic vents are known from Gulf of Mannar (GM) area. During the middle of 18thcentury, volcanic eruptions off the coast of Pondicherry are reported. A press report in June, 2013 indicated that Smithsonian Institute, USA had identified buried volcanoes in the Bay of Bengal region, corroborating the earlier findings. The fault zone connecting all these reported buried submarine volcanoes passes through Palk-Bay – Gulf of Mannar region.
C. The high heat flow transmitted along the deep crustal faults, are also manifested on the surface all along the coast surrounding Palk Bay in the form of flowing bore-wells with hot water.
The faults on land extend into Palk Bay and activities along them may induce thermal activities in the off-shore regions, thus destabilising the channel.
D. Occurrences of earthquakes all along the Tamil Nadu coast are known during the last two centuries and the epicenter of one earthquake with 3-4 Magnitude is located within PB area. Three earthquakes of 5 to 7 M are reported in GM during recent times (in 1938 and 1993). One earth tremor of ~5 M is recorded in 2001 off the Pondicherry coast. Geophysical signatures in the project area such as highgravity and high heat flow also point to the high vulnerability to future earth tremors.
Thus it can be seen that the PB-GM area is not only fragile with respect to tectonic movements, but also highly sensitive for higher heat flow manifestations coupled with seismically vulnerable nature for future earthquakes.
The Mandapam-Rameswram-Dhanuskodi –Rama Sethu-Talai Mannar feature is not merely a group of simple sandy shoal or sandy bars of migratory nature. Evidences are available to prove below such sandy bars, this physical feature forms a distinct geological, geotectonic, oceanographic and oceanic divide that has got a specific and very important role to play as a barrier in controlling the different geological and oceanographic activities in this highly fragile and sensitive area.
Geo-environmental Considerations
Environmental Assessment Report from competent agency clearance from the Ministry of Forests and environment are mandatory for according sanction to any major project. Geo-environmentral assessment is a very important and integral part of this Environmental Assessment.
- The geo-environmental assessment report should normally cover the following :
Ø Assessing the “Geo-environmental Resource Potential”such as minerals, ground water, natural geological and geo-morphological features etc.
Ø “Geo-environmental Impact Assessment” indicating impacts likely to be caused to the above resources as well as to the environment as a whole
Ø “Geo-environmental Management Planning” defining the methodology and remedial measures for reducing the impacts for a sustainable developmental activity.
Ø The task of preparation of Environmental Impact Assessment (EIA) was entrusted to National Environmental Engineering Research Institute (NEERI). The EIA report of NEERI was submitted in August, 2004. This report does not cover all the requisite aspects of Geo-environmental Assessment as stipulated in the beginning of this note. The only geological aspect of importance dealt with in NEERI’s report concerns about sedimentation rates in the Palk Bay. The various geological activities in the project area such as neo-tectonic activity with faulting, earthquakes related seismic activity, geothermal manifestations with higher heat flow, all of which accompanied by submergence, slumping, submarine landslides, blocking of passages etc .as well as the changes in the ocean current movements are probably not addressed properly.
Ø It is to be stressed here that once the geo-morphological features are destroyed, natural geological processes are hampered and geo-environmental degradation is permitted, and has taken place, the original geo-environmental system is irrecoverable, irretraceable and lostfor ever, leading to calamities and destructions beyond repair.
De-stabilisation of the multifarious barrier zone of this entire feature will bring in the following Geo-Environmental Impacts:-.
· Tectonic movements along the active fault zones bringing about subsidence and submergence of areas with inundations and flooding as well as collapse of structures
· Causing submarine landslides which in turn will lead to changes in ocean currents and mini-tsunamis besides blocking ocean passages.
· Inducing earthquakes and earth tremors, which in turn may cause damages to structures, causing submarine land-slides and other concomitant disruptions.
· Inducing movements along this fragile zone of high heat flow will bring in excessive heat to the surface, thus changing current movements, affecting the lives of biota as well as higher corrosive and erosive effects of the hot waters causing instability to the canal and bringing about land-slides and blocking the passage of sea, etc.
Effect on the Placer mineral Deposits
Monazite, ilmenite garnet etc. are heavy minerals with higher specific gravity. Therefore for separation by jigging, concentration and transport, ocean currents should possess enough strength and high velocity, and they should move in a specific orientation / direction for the concentrated minerals to be deposited along our coasts. It can be seen from the Geological and Mineral Map of Tamil Nadu and Pondicherry (GSI, 1995) that these heavy mineral placer deposits occur only to the south of Adam’s Bridge , all along the southern Tamil Nadu and Southern Kerala coasts. This is mainly due the specific nature of current conditions and their directions in the Gulf of Mannar region, which is a deep water ocean with clear water. It is significant that the absence of any such placer deposit of importance around the shallow Palk Bay Palk Bay Gulf of Mannar that will disturb and agitate the tranquility if the Mannar waters as well as the existing current directions. This may be further aided by other tectonic events like sudden rise in temperature due higher geothermal manifestations, faulting, subsidence, collapse of materials, and formation of submarine landslides leading to local tsunamis. As a consequence, the current directions will automatically change. Under these conditions, the heavy minerals will neither get concentrated nor deposited in the future on our shores.
It was witnessed very clearly during the December, 2004 tsunami, large tsunami waves made in-roads to considerable distances on the coast and withdrawing immediately dragging a lot of materials from land into the ocean depths. Recurrence of such oceanic incursions and withdrawals has become very common during the past 5 years all along the Tamil Nadu coast from Kanyakumari upto Chennai. These instances are probably caused by fault movements along the coast. Thus, the removal of already existing deposits of placer minerals from the coast to deep-ocean by future tsunami waves is a clear probability.
Effects of Tsunamis on the PB – GM area
a) The view of Government and SSCP authorities that the SSCP canal will reduce the impact of future tsunami waves is erroneous. Running water will always flow with high velocity and energy along any new narrow linear channel.
b) Evidences are available from the Tamil Nadu coast, where in spite of reduced energy on hitting the coast, the 2004 tsunami waves moved ferociously inland upto 3 km along the existing river channels and caused heavy devastations.
c) Tad S. Murthy , the renowned tsunami expert objected to SSCP project and suggested re-alignment the canal.
d) The Palk Strait and the Mandapam-Rameswaram-Dhanushkodi-Rama Sethu feature have acted as barrier zonesand protected the Palk-Bay – Gulf of Mannar (PB – GM) area as a tsunami shadow zone during 2004 tsunami.
e) In addition, the likely reactivation of faults due to tsunami causing future mega-earthquakes may direct the waves to move with added force along fault movements to hit the coast, as probably happened in the case of heavy damages caused to Phuket in Thailand and to the Cuddalore- Nagapattinam coast in Tamil Nadu during 2004 tsunami.