Posted by Doreen Higgins on Aug 26, 2019
Dr. Clark Alexander, Director of the University of Georgia Skidaway Institute of Oceanography, talked to us this week about our ever changing coastline, its history, forces that shape it, its present formation, and actions we might consider as we live in its immediate vicinity.
Dr. Alexander is a coastal and marine geologist and a professor at the Institute with masters and doctoral degrees in marine geology from North Carolina State University. He has published many papers, participated in many field programs, spent more than two years at sea as the chief scientist on marine research, and works closely with the Georgia Department of Natural Resources on coastal management needs.
Georgia has multiple barrier islands for the entire length of its coastline, many uninhabited and many of those uninhabitable. They are beautiful, home to vast varieties of wildlife, and subject to constant change. These changes are due to natural causes, principally tidal activity, storms, river deposits, and other weather related events. We have high tides of 10 feet, swift tidal currents, low wave energy (there aren’t any waves crashing on our beaches) and large ebb tide deltas. Sea levels have risen about one inch in the past 100 years. All this natural activity has created and continues to affect these islands, and maps show changes over time.
Dr. Alexander showed us the different types of island; most of the differences are caused by the particular combination of forces affecting each island. Of the principal rivers of Georgia, the Savannah, the Ogeechee, the Altamaha, the Satilla and St Mary, the Savannah and the Altamaha bring down the most sediment for deposit at or near the islands closest to them. Storms affecting the islands include hurricanes and tropical storms as well as Nor’easters, in addition to the normal oceanic and tidal activity. Dr. Alexander spoke briefly about global sea level rise. Measurements from 200 years ago show constant steady rise around the world. Measurements up to about 80 years ago were taken from records deemed reliable; then from installed tidal gauges, and now from satellites.

If we wish to consider making changes, constructing defenses, or otherwise mitigating the dangers of storms on our islands, we have some options but usually nature will have the last word. We can erect what Dr. Alexander called “hard stabilizations” – seawalls, breakwaters, etc. We can make “soft stabilizations” such as beach replenishment. Alternatively, we can acknowledge the long term inevitability of nature, and relocate ourselves instead. Dr. Alexander concluded his talk by showing us the shorelines of Jekyll, Tybee, and Wassaw Islands over the past 200 years. The changes are substantial and it seems unlikely that humans could have altered the outcomes.

Below is a photo of Dr. Alexander.