Coastal erosion due to rising sea levels has been dramatically underestimated
9th September 2012
A new model is allowing researchers to predict future coastline erosion due to rising sea levels far more accurately. It would appear that the effects of coastline erosion due to sea-level rise in the vicinity of inlets, such as river estuaries, have until now been dramatically underestimated.
The anticipated rise in sea levels due to climate change will result in coastlines receding worldwide through erosion. This is a known phenomenon that can in principle be calculated and predicted based on a given sea-level rise, by means of the so-called "Bruun effect". However, things are a little more complicated when it comes to coastlines in the vicinity of inlets, such as river mouths, lagoons and estuaries. These places are affected by other factors – such as changes in rainfall due to climate change, and certain compensating effects (basin infilling).
Until now, science has lacked a model that takes all these effects into account in the calculations of a coastline's future development, even though a demand for this existed among engineers, coastal managers and planners. The majority of coastline prognoses only took the Bruun effect into consideration.
Scientist Rosh Ranasinghe, an associate professor at TU Delft and UNESCO-IHE, has now succeeded in developing a new model able to produce much more accurate prognoses. He did so together with researchers at the faculty of Civil Engineering and Geosciences in TU Delft, UNESCO-IHE and knowledge institution Deltares. With the model, it is possible to make accurate predictions quickly – within just a few minutes – of how the coastline will develop in the vicinity of inlets as a result of rising sea-levels.
The new model was applied to coastal regions in Australia and Vietnam. The research found that only 25 to 50 per cent of anticipated coastline change in these areas can be predicted using the Bruun effect. The other processes that occur in the vicinity of inlets are of at least equal importance, and coastline erosion in these areas as a result of rising sea levels has, until now, been strongly underestimated.
This new model substantially improves forecasts of coastline erosion, and will make a valuable contribution to coastal management projects in the future.
Video showing measures taken against coastal erosion at Phan Thiet in Vietnam.