A beached casino is probably a world record. The United Nations estimates that there are more than three million shipwrecks around the world, both sunken and beached. Ships that once ruled the seas, now serve as a windows into the past. Whereas the study of shipwrecks forms a passion for some, abandoned vessels are designated as sites of archaeological importance, and even included in tourist circuits. From an ecological perspective however, scientific literature is replete with data that shipwrecks can eventually inflict dramatic modifications in the geomorphology of beaches, alter coastal landforms and create hazards to seaside infrastructure and beach users.
The grounding of River Princess off Candolim in June 2000 has taught us grave lessons. But public memory is short, the issue is forgotten. Our research on the influence of shipwrecks on coasts worldwide revealed that marooned vessels have the potential of altering local sediment transport in general and the sandy shorelines in particular. The initial shoreline changes occur at a rapid rate, often within days. Frontal sand dunes at Candolim and Sinquerim were demolished and vegetation was uprooted leaving 4 to 6 metres high gaping vertical scarps in the dunes along 1.5 km of coast; these features are still visible at present.
By 2006, erosion attained alarming proportion; shoreline topography of the beach had altered. The maximum shoreline shift over a stretch of 1.5 km of coast attained about 85 metres in 2011. By analyzing wrecks globally, we concluded that the major factors that determine the fate of the coast subsequent to a shipwreck are: distance of the wreck from the shore, the depth of water, the span of time when the wreck remains aground, the orientation of the vessel with respect to the shore, the direction and intensity of prevailing winds, the consequent wave regime, the resultant littoral currents and the disruption of sediment transfer along the shore.
The kind of short-term coastal erosion witnessed in Goa, as a consequence of a marooned vessel, appears unprecedented in India. This study confirms that shipwrecks in shallow seas drastically alter the face of the coast. Such situations create grave hazards to the seaside tourism related activities and regular beach users in general and beach – dune ecosystems in particular. There was virtually no beach left even at low tide. Such drastic geological changes may pose significant risks to seaside infrastructure, fishing activities, tourism or leisure.
Eventually, the removal of shipwrecks turns difficult, as was the case with River Princess which was removed in 2012 with great difficulty and a huge loss to the exchequer. We concluded that if damage to the beach dune system in the form of rapid shoreline erosion is to be prevented, any grounded vessel needs to be removed as quickly as possible.
We have insisted relentlessly that coastal processes cannot and should not be hindered. Any obstruction in the littoral sand movement can induce unforeseen irreversible modifications the beach systems. Shipwrecks across the world have proved this hypothesis. Research conducted during the 1970’s by NIO scientists CS Murty and BU Nayak is valid even today. Littoral currents flow from south (Caranzalem) to north (Miramar); a coastal process that is in operation for decades and explains sediment transport with the consequent formation of the sand hump off the traffic circle. This site is highly dynamic with a fluctuating shoreline; the vessel is stranded precisely where it should never have come.
This author visited the site several times since the casino ran aground. Initially, the vessel was located about 100 metres parallel to the coast; within days, it was dragged, and positioned itself perpendicular to the shoreline. By August 15, 2017, the vessel veered a semicircle, and positioned itself at the present location. On August 17, 2017, at 6 pm, the tide was at its maximum having risen to 1.79 metres, the wind direction was 270 (from west), and the wind speed was of the order of 16-20 kmph (see https://www.tide-forecast.com/).Three distinct morphological changes could be identified: (1) An indentation in the shoreline was clearly visible. Although satellite images show that this feature was present prior to grounding, the presence of the vessel definitely accentuated an embayment leading to erosion of the frontal dune by a minimum of two metres. The eroded strip is about 70 metres long. The battered dune scarp with overhanging ‘ipomoea’ creepers is still visible; at high tide, sea water reached just two metres from the dune base. (2) A large sand flat on the (northern) Miramar side has formed rapidly since the arrival of the boat. Accretion of sand on the lee side of the shipwrecks is a characteristic feature in such cases. This large body of sand is prominently seen at low tides. (3) Unrelated to grounding, human impact on the existing low dune due to the machinery and ancillary activities was evident. Even a dredger was parked on the dune. Impacts noted are in addition to ones by the tourism watch tower located inappropriately. The frontal pioneer sand dune is severely damaged.
Miramar constitutes the most dynamic sandy coast compared to any other beach of Goa. At present (August 25, 2017), the boat is leaning dangerously on port side, and is embedded at least 1.5 metres into the sand. It is highly doubtful whether the vessel can be declared seaworthy; the stranded vessel has already become a liability. Importantly, this is a high value coast in terms of tourist footfalls; the sandy strip is under intense anthropogenic pressure. Nevertheless, the beach shows unique geo-morphological patterns as the prominent sand bar accretes and erodes seasonally.
The navigation channel closes and opens all by itself, a coastal process that is in operation since historical times. Ancient records mention the annual natural opening of the sand bar and scientific documents have proved this observation. Miramar beach thus offers a perfect coastal equilibrium. Therefore, human folly cannot be allowed to interfere with such a natural marine coastal setting.
Our research has proved that shipwrecks along coasts world-wide have created hazardous impacts within a short time. The casino is now entrenched in sand, and has obviously started disintegrating. The consequences of a marooned vessel at Miramar can be insurmountable in terms of ecology, environment, economy and leisure.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
