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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 />