Dave Rauschkolb
Beach Fanatic
Coastal Erosion solutions: Seawalls, Geo-tubes, Beach Scraping and Beach Nourishment. What is the answer?
Basically, when the ocean rises due to a hurricane there are three powerful forces at work: wind, rising tide and ocean swells from a storm. The water that is moved by those forces moves in three directions. The tide brings the water up, the storm moves the wave action in and the wind pushes the water/waves in the direction of the wind.
Most of us who have experienced a hurricane know that when a storm approaches and we are on the east side of that storm we get winds from the northeast, then east, then southeast, then south and on around to the west and so on. The inverse would be true if we were on the west side of the storm. The key point is that for a large portion of the time the tide is abnormally high, the swells are abnormally big and the east or west current is scouring the beaches parallel to the beach.
The beach sand is a porous movable material that is completely vulnerable to these forces. Solid structures are also vulnerable to these forces but, more importantly the sand next to any solid structure will be scoured away much more rapidly than if there was no solid structure near it.
Let's dispense with scraping first. It makes the beach nicer to look at but that's it. It is newly pushed sand that has no level of impaction so it washes away in minutes. Placing sand back on the cliff/dunes and planting sea oats provides a favorable cosmetic solution.
Seawalls and geo-tubes are solid, heavy structures. Any porous sand next to these structures gets scoured away very rapidly making the situation worse near them. If you have a house next to a seawall, your backyard will go faster as the east riptide and oncoming waves collide with the seawall. The same is true with the beach in front of the seawall. The impact of the water hitting it and pushing sideways with the tide completely eliminates the beach in front of it. All you need to do is look at the wall in Galveston Texas; there used to be a beach there, now you just jump off the wall into the water; no beach. A geo tube is heavy and more solid than the sand. Any thing near these things will have sand scouring next to them too. Also when the water gets behind a seawall it washes away the sand behind it with the same impunity. Some of you might have seen the photo of the breached seawall on Dog Island I posted after Hurricane Dennis.
The largest seawall in the county is being installed just east of Seaside and it runs from the Wheel House/Seagrove villas and ends at the 30-A/395 intersection and could go further as adjacent homeowners buy on. It is roughly 20 feet high and runs 4 blocks long. Adjacent homeowners will be affected and the beach behind that wall will disappear if we get a few more storms to start the scouring activity. The prevailing winds here are from the east and the river of sand that runs along our beach could soon be interrupted and affected by this seawall.
The only solution to our erosion problem is to focus on getting our beaches nourished by pumping sand back on to the beaches. All of Walton County is being surveyed and the wheels are in motion. All these seawalls will do is destroy adjacent property and eliminate the beaches behind them. Geo-tubes will have a similar effect as the water washes over and around them.
Rosemary Beach has investigated thoroughly all options including geotubes and has decided to push for the sand dredging/beach nourishment option. There will be no geotubes or seawalls in Rosemary Beach. They did decide to do some cosmetic work (scraping) on the dunes/cliffs and finish with sea oat plantings. The town manager, James Bagby gave a very informed talk at the Rosemary Beach Homeowners meeting on where the county and federal agency's are in the beach nourishment process and it looks like it could happen countywide if approved. Jim said the pumping would take 3 days to do Rosemary Beach and would raise the beach 6 to 8 feet and go out 100 to 150 feet out.
The nourishment effort/process has taken its course in the west end of the county and they will soon begin pumping sand there. They are beginning the process for our part of the county from Inlet beach down and there will soon be a stage for public input. The whole beachfront of the county is being surveyed for this purpose and sand core samples are being taken in the gulf for sources of white sand. Funding will be an issue but if approved the beaches will be automatically nourished by the federal government after major storms. Panama City beach has been doing this for years already.
In Okaloosa County 5 beachfront homeowners disputed the nourishment project delaying it in lawsuits for 2 years. They were concerned that the thin strip of public access from the high tide waterline to the water would be enlarged if the beach was widened and people would set up beach chairs behind their property. I believe they are now being sued by adjacent owners who lost their homes in recent storms. When the time comes for public input our county voices must be united behind the nourishment answer. That?s the answer.
Basically, when the ocean rises due to a hurricane there are three powerful forces at work: wind, rising tide and ocean swells from a storm. The water that is moved by those forces moves in three directions. The tide brings the water up, the storm moves the wave action in and the wind pushes the water/waves in the direction of the wind.
Most of us who have experienced a hurricane know that when a storm approaches and we are on the east side of that storm we get winds from the northeast, then east, then southeast, then south and on around to the west and so on. The inverse would be true if we were on the west side of the storm. The key point is that for a large portion of the time the tide is abnormally high, the swells are abnormally big and the east or west current is scouring the beaches parallel to the beach.
The beach sand is a porous movable material that is completely vulnerable to these forces. Solid structures are also vulnerable to these forces but, more importantly the sand next to any solid structure will be scoured away much more rapidly than if there was no solid structure near it.
Let's dispense with scraping first. It makes the beach nicer to look at but that's it. It is newly pushed sand that has no level of impaction so it washes away in minutes. Placing sand back on the cliff/dunes and planting sea oats provides a favorable cosmetic solution.
Seawalls and geo-tubes are solid, heavy structures. Any porous sand next to these structures gets scoured away very rapidly making the situation worse near them. If you have a house next to a seawall, your backyard will go faster as the east riptide and oncoming waves collide with the seawall. The same is true with the beach in front of the seawall. The impact of the water hitting it and pushing sideways with the tide completely eliminates the beach in front of it. All you need to do is look at the wall in Galveston Texas; there used to be a beach there, now you just jump off the wall into the water; no beach. A geo tube is heavy and more solid than the sand. Any thing near these things will have sand scouring next to them too. Also when the water gets behind a seawall it washes away the sand behind it with the same impunity. Some of you might have seen the photo of the breached seawall on Dog Island I posted after Hurricane Dennis.
The largest seawall in the county is being installed just east of Seaside and it runs from the Wheel House/Seagrove villas and ends at the 30-A/395 intersection and could go further as adjacent homeowners buy on. It is roughly 20 feet high and runs 4 blocks long. Adjacent homeowners will be affected and the beach behind that wall will disappear if we get a few more storms to start the scouring activity. The prevailing winds here are from the east and the river of sand that runs along our beach could soon be interrupted and affected by this seawall.
The only solution to our erosion problem is to focus on getting our beaches nourished by pumping sand back on to the beaches. All of Walton County is being surveyed and the wheels are in motion. All these seawalls will do is destroy adjacent property and eliminate the beaches behind them. Geo-tubes will have a similar effect as the water washes over and around them.
Rosemary Beach has investigated thoroughly all options including geotubes and has decided to push for the sand dredging/beach nourishment option. There will be no geotubes or seawalls in Rosemary Beach. They did decide to do some cosmetic work (scraping) on the dunes/cliffs and finish with sea oat plantings. The town manager, James Bagby gave a very informed talk at the Rosemary Beach Homeowners meeting on where the county and federal agency's are in the beach nourishment process and it looks like it could happen countywide if approved. Jim said the pumping would take 3 days to do Rosemary Beach and would raise the beach 6 to 8 feet and go out 100 to 150 feet out.
The nourishment effort/process has taken its course in the west end of the county and they will soon begin pumping sand there. They are beginning the process for our part of the county from Inlet beach down and there will soon be a stage for public input. The whole beachfront of the county is being surveyed for this purpose and sand core samples are being taken in the gulf for sources of white sand. Funding will be an issue but if approved the beaches will be automatically nourished by the federal government after major storms. Panama City beach has been doing this for years already.
In Okaloosa County 5 beachfront homeowners disputed the nourishment project delaying it in lawsuits for 2 years. They were concerned that the thin strip of public access from the high tide waterline to the water would be enlarged if the beach was widened and people would set up beach chairs behind their property. I believe they are now being sued by adjacent owners who lost their homes in recent storms. When the time comes for public input our county voices must be united behind the nourishment answer. That?s the answer.
