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experienced in the past. <br />h. Erosion (Soil) — Hazard Identification. Soil erosion is the <br />deterioration of soil by the physical movement of soil particles <br />from a given site. Wind, water, animals, and the use of tools <br />by man may all be reasons for erosion. The two most powerful <br />erosion agents are wind and water, but in most cases, these <br />are damaging only after man, animals, insects, diseases, or <br />fire have removed or depleted natural vegetation. Accelerated <br />erosion caused by human activity is the most serious form of <br />soil erosion, and can occur so rapidly that surface soil may <br />sometimes be blown or washed away down to the bedrock. <br />Undisturbed by man, soil is usually covered by shrubs and <br />trees, dead and decaying leaves, or a thick mat of grass. <br />Whatever the vegetation, it protects the soil when rain falls or <br />wind blows. Root systems of plants hold soil together. Even in <br />drought, the roots of native grasses, which extend several feet <br />into the ground, help tie down the soil and keep it from blowing <br />away. With the vegetation cover stripped away, soil is <br />vulnerable to damage. Whether through cultivation, grazing, <br />deforestation, burning, or bulldozing, once the soil is bare to <br />the erosive action of wind and water, the slow rate of natural <br />erosion is greatly increased. Losses of soil take place much <br />faster than new soil can be created. With the destruction of <br />soil structure, eroded land is even more susceptible to erosion. <br />The occurrence of erosion has greatly increased. This is <br />because of the activities of modern development and <br />population growth, particularly agricultural intensification. It <br />also is in the field of agriculture that most efforts have been <br />made to conserve soils, with mixed success (Union of <br />International Associations, 1999). <br />Particles scattered by erosion can also cause problems <br />elsewhere. Stormwater drainage systems, both natural and <br />mechanical, are frequently clogged by loose sediment. If <br />drainage systems are not cleared of uncontrolled sediment on <br />a regular basis, they lose function. <br />Extent. Due to the low probability of occurrence, this hazard <br />will not be fully profiled. <br />Indian River County Comprehensive Emergency Management Plan Basic Page 42 <br />