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Question: Why aren't we considering taking the same kind of action against the Sebastian Inlet Taxing District and the state of Florida? I have additional questions I would like to ask but in the interest of time I will wait until we get some written response back to my questions. -- How Seawalls; Revetments; Jetties; Et. Al. RECEIVED Accelerate the Loss of Beach Sand on Indian River County Beaches. JAN 19 1999 An essay by Glenn Legwen, Landscape Architect, CLERK Tp on how the construction of seawalls and other sand retaining methods used by THE BOARD developers/homeowners in Indian River County will cause accelerated loss of beach sand. We begin by accepting the fact that a beach is similar to a living entity. Beaches typically grow larger during the summer and smaller during the winter. The primary dune expands and contracts in accordance with the seasons (See enclosed sketches). Nature maintains the dynamic equilibrium of the beaches through unceasing trade-offs of four factors: material, energy, shape of the beach, and sea level. The size and effectiveness of this primary dune is controlled by these four factors. Whenever man interferes with any of them it alters the natural equilibrium. The Littoral Drift helps provides a constant supply of new sand to continuously build the dune lines. The Littoral Drift is defined by Dr. Ian Mc. Harg in his book Design With Nature as: "Waves usually approach the beach from an angle, the water tuns over the sand and recedes at right angles to the shore. As a result the sand carried by the receding wave is transported downdrift of it origin'. There are the five stages that Dr. Ian McHarg uses to define the rise of a barrier island. Under normal conditions, a sandbar is created by large waves breaking offshore (Stage 1). Dune formation begins at the thicket line with deposition of windblown sand (Stage 2). Secondary dune formation begins as the dune -grass community is established (Stage 3). The dune -grass community advances seaward to the high - tide line. Primary dune formation begins (Stage 4). The primary dune is established and the secondary dune is stabilized (Stage 5).' It is in this manner that barrier islands are formed. Barrier islands provides protection to the inland community and it is the first barrier of defense against violent storms. North Hutchinson Island is a barrier island. During the summer months off shore breezes pick up sand and carry it inland over the primary dune line where Uniola paniculata (Sea Oats) filter out the sand like humpback whale's baleen extracts krill from sea water. The primary dune line on undisturbed east coast beach areas have been known to rise as much as seventeen feet in one summer! During the winter months the winds shifts blowing off the land instead of the sea. The process of dune building slows considerably and in some cases reverses itself. Giving up as much sand to one storm, as it has taken the summer months to accumulate. Without this reserve supply of sand from the Littoral Drift and the primary dune Vero's beaches will continue to erode. Man in his haste to be close to the oceans, has built his structures on top of the stabilized secondary dune and in some cases on top of the primary dune itself. The primary dune is by no means a stable platform on which to build and he becomes concerned when a severe nor'easter (storm) remove five, ten, fifteen feet of his existing beach. Exposing the footings of his structure's foundation to the raging ocean waves. A knee jerk reaction typically follows this untimely incident. And the unhappy homeowner is begging the municipal authorities to grant him/her an emergency injunction to prevent any further sand from being washed away. This emergency injunction usually takes the form of a protective barrier. A concrete sea wall, a rock jetty, a parapet or some other man made structure. This is only a temporary solution and the walls longevity is based on the degree of severity of the following years storm. Without the ability to rise and fall with the changing seasons, the primary dune's function to mute or suppress the wave action from violent storms, ceases to exist. In its conspicuous absence, ie. when sea walls or other structures are installed, the reserve sand of the primary dune is unavailable to slow the brutal, eroding force of water. The most breathtaking force I have observed in nature is the continuous and adamant force a wall of water has when it strikes an object. One of the numerous hurricanes that moved into the Gulf of Mexico struck the Eastern Shore of Alabama during the eighties. A fifteen foot wall of ' Design With Nature, Ian L McHarg Natural History Press/ Library of Congress Card # 76-77344; Copyright 1969 7 pg. Design With Nature, Ibid water, a storm surge, bowled ashore destroying everything in its path. It struck a five story building breaking it off its foundation as though it were a match stick (killing thirty five individuals in the process) and proceeded inland another two miles before its incredible power subsided. A seawall (also known as a retaining wall) by its very nature is a static object. It depends on sand to remain in front of it as well as in back of it. The loss of sand in front of the wall will cause it to overturn. Whenever a property owner is permitted to build a seawall, either by emergency means or otherwise, the downdrift property owners must do likewise to preserve their property. Without a continuous sea wall the. downdrift beach properties will begins to erode (ecrete) more rapidly (see illustration on Groin). A seawall stops the normal flow of sand that is held in abeyance by the primary dune. As the waves strike the seawall and return to the sea, they carry with it the vital sand that helps hold the seawall perpendicular to the shore line. Without a resupply of sand in front of the seawall the pressure from the sand behind the seawall becomes such that the wall topples over into the ocean. Broken areas in the seawall will accelerate erosion as sand escapes through the openings in the wall. Additional sand escapes around the unprotected ends of the seawall. JANUARY 19, 1999