The National Green Tribunal (NGT) had organised a national conference on environment on December 3-4, 2017 in which there was a session on coastal zone concerns. In the afternoon, the auditorium was agog with the announcement that the beaches in Goa were flooded by sea water due to the rise in sea level coupled with the high tide that occurred in the morning of December 3, 2017. This was precisely a part of the topic that this author had presented. Due to sudden invasion of sea water, the shacks on the beach were affected, loss of belongings were reported, as usual nature’s “fury” was blamed, and compensation was sought, as if these operators and stakeholders can do anything and everything on a public beach. Note that marine incursions occurred during fair weather.
The concerned authorities had in fact warned about the impending rise in the sea level on December 2-4, 2017. No one bothered. Flooding on several beaches lasted for a day. Again, on January 3, 2018, the next spring tide raised the sea level to 2.37 metres, wind speed of 10-20 km/h was observed, with wave heights of 0.4-0.6 metres. This time hardly any impact was noted simply because the winds were mild and waves were weak. Another advisory followed prior to May 2, 2018. High tide was of the order of 2.10 metres at 1237 hours; the impact on sandy beaches was minimal. Observations in the evening at some beach points by this author showed that water reached the base of dunes; erosive activity was nil. Recently, the INCOIS from Hyderabad issued a full moon spring tide alert for the coastal low-lying areas of the country. According to the alert, the spring tide would induce flooding of the coastal areas during August 13-16, 2018. INCOIS has said that high tides in the range of 3.0-3.6 metres are forecast along the coast of Goa.
A modest study by this author revealed that during the week August 12 to 18, 2018, high tides were expected between 1.73 to 2.36 m with predicted wind speeds of around 25 to 35 km/h that could even reach 55 km/h. The wave heights would range between 2.4 to 4.0 metres (see: https://www.tide-forecast.com/ locations/ Panaji/ forecasts). So as to check the morphological changes along the beach, this author carried out field observation at Miramar beach during high tide on August 13, 2018 at 12.30 hours. Strong winds forced the ensuing high waves to overshoot the beach and break at the base of dunes; erosion of dune base was evident at several places; thick carpet of ipomoea creepers was effective against wave attack and arrested sand loss, a large breach (gap) created on the frontal dune due to excessive footfalls facilitated marine water to advance some 50 metres onto the beach; influx of marine water lasted for an hour. Therefore, the major reasons/parameters that govern marine transgression on the beach are attributed to: wind speed and direction, tidal height, wave height, beach width, beach level, dune elevation and morphology, and the state of dune vegetation. Thus, the fact that the sea transgressed the beach (even during fair weather in January) implies that the level of the beach is/was lower than the level of the sea. By analogy, if the level of the beach was higher, if the volume of sand was larger, and if the dune was tall, well preserved, with dense vegetation, the geological stability of the pioneer dune is ensured. Thus, if the inherent buffer capacity of the beach-dune system is functional, the likelihood of marine incursions into the hinterland is negligible.
Unfortunately, the CRZ amendment of March 2017 has complicated matters further. Temporary beach shacks need not be dismantled, but can remain in place, provided they are in-operational. This decision is absurd, as beach configuration alters every day, at every tide, and thus undergoes monthly, seasonal and annual morphological changes. As such, irrespective of which part of a beach a structure is located, it will be stranded on an open sea front, devoid of natural protection, and hence vulnerable to heavy winds with a merciless invasion by powerful ocean waves. That is what happened during the high spring tide on December 3-4, 2017.
Can the sandy coasts of Goa be spared from sudden marine invasion? Yes, to a large extent. This author insists that the sandy beaches of the world constitute a property of the ocean. Goa is no exception. Open beaches face the expansive ocean. That is where the ocean comes to rest by dissipating energy. Note that there was a similar distressed situation in Morjim in December 2013. The effect of the highest high tide lasted for a few hours only. That happened because Morjim beach was under the grip of erosion earlier in July that year. Despite scientific research that calls for allowing the beach to recover from loss of sand, 15 shacks were erected on a wounded beach, precisely where human interference should have been banned. Eroded dunes were damaged further; vegetation was uprooted. The sea level rose very high, bypassed the beach and invaded the shacks. Not surprisingly, flooding was aggravated in fair weather only because the beach had lost sand, the dune had retreated and its morphological contour was low.That is why beaches are termed as inter-tidal zones, and often called as oceans’ playing fields. Wider and higher sandy beaches are thus imperative to take care of unsuspecting marine transgressions.
If the laid down principles of coastal management are not followed, such episodes (losses) will recur. The coast is the site of an extraordinary release of ocean energy. There is no way to defend a structure from a powerful incoming wave. Stronger the defence, more drastic will the consequences be.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
