$\"Long$ <\/a>
Fig. 1 A storm in Long Island 2004 has taken the beach and more<\/p><\/div>\n
Storm. When a storm hits a beach it is almost impossible to avoid erosion. The beach may be\u00a0lost completely and damages made to the hinterland as was the case at Long Island, NY\u00a0in October of 2004. Luckily, these events happen very seldom for a given beach as there is very little to do to prevent damage.<\/p>\n
A strong stable foreshore and dune with plants will provide some protection.<\/p>\n
<\/p>\n
Day-to-day erosion<\/strong><\/p>\n
Ongoing erosion is a common problem. Of Florida’s 825 miles of beaches, 410 miles are considered critically eroding by Florida DEP. The reasons for the erosion vary but often include:<\/p>\n
\n
Up-stream groins<\/li>\n
Inlets<\/li>\n
Poor beach drainage<\/li>\n
Sea level rise<\/li>\n<\/ul>\n
Groins<\/strong> are known to cause down-drift erosion as the sand in littoral drift is forced away from the coast. This reduces the amount of sand available to the beaches further down.<\/p>\n
Inlets<\/strong> may trap the sand in littoral drift. A sand bypassing system can mitigate the loss, or frequent dredging of the inlet\u00a0where the sand is placed on a down-drift beach. However, dredged sand from the inlet may not\u00a0have optimal beach quality.<\/p>\n
$\"Poor$ <\/a>
Fig. 2 Poor Beach Drainage<\/p><\/div>\n
Poor Beach Drainage<\/strong> can be a major cause of erosion. If the beach does not drain as fast as the sea sinks during falling tide the beach will be full of water and the waves can’t sink in, and the sand they contain is washed back to sea instead of being deposited on the beach.<\/p>\n
If the beach is well-drained it can accommodate more water, and\u00a0the swash sinks in easily,\u00a0leaving sand on the beach during each swash cycle. The sand dries out and is blown to the dunes.<\/p>\n
The constant movement of sediment during the tide cycle form layers (strata) in the beach. Some layers limit drainage and others promote drainage. Fine particles such as clay, has the shape of\u00a0pancakes, and it\u00a0only takes a tiny layer of clay to\u00a0limit the drainage.\u00a0\u00a0This is why clay is used underneath waste dumps, to ensure that contaminated rainwater does not seep further down and into the groundwater.<\/p>\n
$\"Beach$ <\/a>
Fig. 3 Layers in a beach<\/p><\/div>\n
A beach\u00a0may have 10 or more layers per vertical foot.\u00a0The cross-section photo Fig. 3 shows several fine and coarser layers.\u00a0Typically some of these layers include clay which limits the water’s ability to connect in the beach. It also limits air access to the lower layers of the beach.<\/p>\n
The result is that during falling tide the groundwater drains at a slower pace than the sea, leaving a part of the beach wet and prone to erosion.<\/p>\n
A high water input to the hinterland combined with poor beach drainage\u00a0is a\u00a0dangerous\u00a0cocktail that leads to chronic beach erosion.\u00a0The water may come from heavy rain but could also origin\u00a0from excessive irrigation.<\/span>\u00a0This is often found on highly populated barrier islands, where automated irrigation systems keep the grass green at all times and tarmac covered surfaces allow little water evaporation.<\/p>\n
A groundwater study performed in February 2008 at Hillsboro Beach, FL showed a very high groundwater level, that could be attributed to irrigation and covered surfaces, combined with poor beach drainage.\u00a0Another sign of extreme groundwater level is the formation of small\u00a0drainage channels on top of the sand from the back beach to the sea. This too has been documented at Hillsboro Beach (2014) during a period without heavy rain, ruling out natural causes.\u00a0As a result, Hillsboro Beach <\/a>has been critically eroding for decades, except from 2008 to 2011 when\u00a0a passive dewatering system (PEM) was installed.<\/p>\n
Sea level rise<\/strong>\u00a0is for real and has at least two negative effects on beaches.<\/p>\n
\n
For every inch the sea rises the beach loses a foot or more in width depending on the slope of the beach.<\/li>\n
Saltwater is heavier than freshwater and is wedged under the land with the freshwater reservoir (groundwater) sitting on top. As the sea rises saltwater moves further inland and pushes groundwater higher. Eventually, this will result in a saturated and unstable ground.\u00a0The phenomenon is well illustrated in a TED talk<\/a> by FAU.<\/li>\n<\/ul>\n
The elevated groundwater requires the beach to be even better at draining, in order to avoid a wet beach and erosion. That is where PEM comes in.<\/p>\n","protected":false},"excerpt":{"rendered":"
What is Beach Erosion? Beach erosion is the removal of sediment from the beach. The layer of sand becomes thinner and narrower and\u00a0the hinterland becomes exposed. A narrow beach has less recreational and commercial value. The sand may be lost permanently or have moved offshore, from where it will return during a calmer period. A […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"templates\/template-full.php","meta":[],"_links":{"self":[{"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/pages\/91"}],"collection":[{"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/comments?post=91"}],"version-history":[{"count":53,"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/pages\/91\/revisions"}],"predecessor-version":[{"id":758,"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/pages\/91\/revisions\/758"}],"wp:attachment":[{"href":"http:\/\/ecoshore.com\/wp-json\/wp\/v2\/media?parent=91"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}