Waves, tides and sediment movement

Systematic and long-term scientific monitoring is crucial

Sir, – It is true that “Bull Island came from the sea and may return there” and emerged as a “byproduct” of the South and North Bull Wall construction (Opinion & Analysis, July 28th), but this truth applies to so-called “soft” (sedimentary) coasts in general. Readers who have been walking along the beach near Booterstown Dart station in south Dublin, for example, may have noticed the emergence, over the past 15 years or so, of an expanse of dunes and salt marsh seaward of the railway tracks. Several tens of thousands of cubic meters of sand have been deposited here by the tides and waves since 2008 and have become colonised by coastal plants. As the opinion piece states, Bull Island formed shortly after the construction of the South and North Bull Walls – but the large-scale shifting of sand and mud within Dublin Bay, as in many of our planet’s estuaries, is an entirely natural and dynamic process. It is when we interfere with these dynamic processes, encroach upon their territory, and importantly, when we underinvest in the monitoring and observation of our naturally dynamic environment, that the loss (erosion) or gain (deposition) of land becomes unexpected or a “byproduct”. At a time when sea levels are rising faster than ever before in human history and coastal populations at risk from flooding are rising at three times the global average, we must recognise that it is not enough to accept that places that “grew from the sea in the wake of human intervention may soon revert to from whence [they] came”.

Instead, it is high time we invested more nationally in the systematic and long-term scientific monitoring and modelling of waves, tides, and sediment movement in nearshore waters in a way that produces openly and centrally accessible data and furthers our capacity to prepare our coastal communities (including those in and around Bull Island) for future change that could, with sound science, in fact, be anticipated. – Yours, etc,

IRIS MÖLLER,

ABBIE NUGENT,

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Coastal Research Group,

Department of Geography,

Trinity College Dublin,

Dublin 2.