JOUR.GEOL.SOC.INDIA, VOL.83, JAN. 2014

114 NEWS AND NOTES

Unravelling the Enigma called Coast – John Jacob Puttur, Indian Navy (Retired)

Unfortunately, even these are generallystudied using models or some or other age-old myths. For example, everyone generallybelieves that waves are generated by winds,but ‘how’ has so far not been establishedempirically. Tidal processes are normallystudied on models, yet no model cansimulate the actual tidal process driven bysun and moon gravity phenomena, thereforeeven that goes haywire. The net result is toomany incorrect inferences about coastalprocesses, which in turn are wrecking thecoast world over. Nearly 75% of the world’sbeaches are eroding, and not one is due toany natural causes. Besides, ports andharbour designed after extensive ‘modelstudies’ are silting profusely. The ignoranceabout the coast and its processes is rampant,not only in India, but world over. However,the enigma can be unravelled by an open-minded study of the coastal problems likeerosion, accretion and siltation, rather thanblame all that as natural acts of nature.Everyone seems to believe that the rough

waves during the monsoon cause erosion.That is actually a myth borne out of a verypopular theory that waves transportsediments, by themselves or through thelittoral currents the waves seem to generate.This theory is blatantly wrong, becausewaves, a surface phenomenon, cannot eventransport a floating body, let alone the densesediments that must remain on the seabeddue to gravity. But the experts staunchlybelieve in this myth. Another element thatis known to affect the coast is wind. Eventhough it is such a common phenomenon,the experts do not seem to know how itblows. Wind blowing from high pressureto low pressure is yet another myth.Therefore, before we can get to unravel theenigma called coast, we must firstunderstand the winds, waves and tides.Once that part is clear, we can get on to thereal coastal processes. That is the maindiscussion in my book—The Untold Storyof a Coast.

We are all quite familiar with coast, yetit remains an enigma, particularly when itcomes inferring the coastal processes.Unlike land and sea, the coast is difficultplace to survey or study. There is no suitableplatform to survey the coast as yet. Thehydrographer, whose primary job is tosurvey the sea and its adjoining coast, onlymanages to map the low and high waterlines, and the coast that lies in betweenremains practically unsurveyed. Coastalscientists and engineers however study thecoast on models, hydraulic or mathematical.The models are invariably based on thehydrographic or nautical chart, the primaryinstrument for marine navigation. The chartis not necessarily a tool for coastal studies.As a result, the model, hydraulic ormathematical, ends up giving a wrongpicture of the ‘real’ coast. The problem isfurther compounded by an abject lack ofunderstanding of the elements of nature thatis purported to influence or drive coastalprocesses, namely, winds, waves and tides.