Deltares: Research on Eroding Sand Beaches

Researchers from Deltares, Delft University of Technology and IHE, have found that the eroding of sand beaches is less dramatic than is generally assumed.

There are more sandy beaches that grow worldwide, than ones that shrink. This is the outcome of the study by the researchers who analysed changes in 50,000 beaches over a 35-year period.

They present their findings last week in the Nature Scientific Reports.

For the first time, coasts and their long-term behavior have been analysed on a global scale. The researchers were able to calculate that exactly 31% of the total coastline consists of sandy beaches. Beaches are monitored because they are vulnerable to changes in tide, wind direction and sea level rise.

Arjen Luijendijk, researcher at Deltares/Delft University of Technology: “Indeed: there are more beaches that grow than beaches that shrink. The main reason is that we are able to maintain our coasts well (as in the Netherlands) or even to expand them (as in Dubai and Singapore). A sometimes forgotten source of sand is the discharges from the mining industry.”

The fastest rate of beach growth, eight meters a year no less, was seen in Namibia. It is caused by a mining company that has built sand hills in the sea for diamond mining.

The Netherlands is also in the top ten of beach growth due to the country’s beach nourishment policy and the construction of the Sand Motor.

Four of the seven largest eroding beaches are in the United States. Beaches in Louisiana and Texas are being hit particularly hard, sometimes receding by 15 meters a year.

The Mississippi is the culprit in Louisiana where the sand supply has fallen sharply due to the damming of the river. One of the causes in Texas is groundwater extraction in response to the rapid growth of Houston.

The researchers processed all the data and made it available on a public map.