Protecting coastlines

Every year, around 24 percent of the world’s sandy shoreline erodes away, causing significant financial loss from damage to property and infrastructure. With around 40 percent of the global population living within 100 km of the coast, erosion presents a real and immediate challenge. Coastal erosion is a costly affair. In the USA, for example, coastal erosion causes an estimated US$500 million in property loss and damage every year.

Cutting-edge environmental research in Israel is taking advantage of new technologies and the unique environment of the Dead Sea to better understand the processes behind coastal erosion and sediment transport. “Understanding coastal erosion and the transport and sorting of coarse sediments along shores is highly important for assessing coastal stability,” says Haggai Eyal, a PhD candidate at the Hebrew University of Jerusalem.

He is supervised by Professor Nadav Lensky from the Geological Survey of Israel and Professor Yehouda Enzel from the Hebrew University of Jerusalem. Eyal’s PhD focuses on the fluvial (relating to rivers) and coastal movements of sediments in the Dead Sea, a hypersaline lake located between Israel, Jordan and the West Bank.

The Dead Sea is primarily fed by the Jordan River and does not drain or discharge to the ocean, making it a terminal lake. Sediments from the Jordan River and other channels make their way to the Dead Sea through a variety of sediment transport processes.

“Fluvial channels supply unsorted sediment to the lake during winter storms,” says Eyal. During these storms, waves transport sediments from the channel mouth along the shore, creating berms – beach ridges that extend along the shore. During the drier and hotter summer months, the lake level drops about 1 m.

According to Eyal, because of the dramatic seasonal drop in water level, these berms are unique to each winter season, creating an environment where sediments from each storm are preserved separately. This is unlike other areas where the water level is relatively stable from one season to the next.

To understand the role different atmospheric and oceanographic processes play in coastal erosion and apply that knowledge to other parts of the world, real-world oceanographic measurements are necessary.

“This is where the science of coastal erosion is challenging, specifically where waves break,” says Lensky. “You need the wind measured properly, which is easy enough, but then you need to measure currents and waves, which is very hard to achieve.”

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Protecting Coastlines was written for (and can be read in full at) Oceanographic Magazine