INTRODUCTION

Erosion is the detachment and transport of organic and mineral particles caused by the forces of water, wind, and gravity Sediment, the by-product of the erosion process, is the solid material that is in suspension or transport or has been relocated from its origin. Deposition of these particles is sedimentation.

Natural soil erosion and sedimentation are important processes responsible for the creation and evolution of natural landforms and essential for maintaining a balance between plant and animal life. Features such as the Grand Canyon, the badlands of the Dakotas, escarpments on mountains, fertile soils, and delta areas along rivers are the result of a slow, uniform process of erosion and sedimentation occurring over time. Deposition of nutrient-rich sediment contributes to the creation of topsoil and spurs vegetation growth, which, in turn, supports various animal species. Because of the long length of time required for this change to occur, ecosystems are able to gradually adapt to the changes.

Human-induced activities, such as logging, farming, and construction, cause erosion at greatly accelerated rates. Such activities alter the natural surface runoff patterns by denuding large areas of vegetation, loosening the soil, changing land slopes, and accelerating the time of concentration of site runoff, often through structural conveyance systems such as storm drains, open channels, and curb and gutter. Such extreme and rapid changes to the natural landform can increase the erosion rate from two to several tens of thousands of times...