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INTRODUCTION <br />Soil erosion is the wearing away of the land surface by moving water, <br />wind, ice, and gravity. It is a natural process and probably one of <br />the most important geologic processes to exist. All the sedimentary <br />rocks result from the erosion process. The Grand Canyon was created <br />by erosion. Most of the croplands in [he valleys of the Western <br />States are on alluvial deposits resulting from the erosion process. <br />u <br />J <br />When man uses the land, he commonly reduces the amount of vegetative <br />cover that existed under natural conditions. Vegetation tends to slow <br />down the rate of erosion because it protects the soil from the attacks <br />of €alling raindrops, flowing water, and wind. Reducing the amount of <br />natural vegetation by grazing, tillage practices, logging, or any <br />other method, commonly increases the rate of erosion above that under <br />natural conditions. The increased rate of erosion caused by the <br />influence of man is called "accelerated erosion". Accelerated erosion <br />generally is detrimental. It often reduces [he productivity of the <br />land and also increases the sediments in the water courses and the <br />flood plains. <br />Man cannot completely stop erosion, but his goal should be to keep <br />accelerated erosion to a minimum. The rate of erosion should not be <br />greater than the rate of soil formation. Otherwise, the productivity <br />of the land will diminish and managing the soil on the basis of <br />sustained yields will not be possible. Where accelerated erosion has <br />been excessive, remedial action must be taken to slow down the rate to <br />a safe minimal or tolerance level as shown in Figure I. Land use and <br />management practices, which keep erosion losses at a safe level, will <br />not only keep the soils permanently productive, but they will also <br />maintain the natural quality of the water resources. This will <br />benefit the aquatic and riparian wildlife as well as [he terrestrial <br />wildlife and domestic livestock. Use of the land for grazing, wood <br />fiber production, wildlife habitat, recreation, and water supply will <br />all be enhanced simultaneously under a system which keeps accelerated <br />erosion to a minimal level. <br />In order for the BLM to determine whether extent of accelerated <br />erosion on the public lands under its jurisdiction is excessive or <br />within tolerated levels, i[ is necessary to make an inventory of the <br />degree of erosion that has taken place. A prerequisite of the <br />inventory system is a system for defining and classifying different <br />degrees of accelerated erosion. The purposes of this technical note <br />are to: (i) present the erosion condition classification system and <br />(2) to give guidance for the inventory procedure. <br />1 <br />