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<br />e <br /> <br />. <br /> <br />CHAPTER 4 <br /> <br />Methods For Controlling <br />Erosion <br /> <br />4.1 General- <br /> <br />Stream bank erosion may be easy to identify. but the causes of erosion diagnosed <br />incorrectly may adversely effect the selection of remedial measures. Not only are there a <br />variety of causes of stream bank deterioration. but also an array of potential solutions. <br />Since different causes may have similar effects. selecting a method that treats the <br />symptom rather than the source could amplify the erosion problem. Erosion protection <br />structures unquestionably affect the hydmuIics. sediment transport. and geometty of the <br />adjacent channel. The degree to which these parameters are impacled varies with <br />structure type. design. location. materials. and construction practices. Changes may be <br />so slight as to hardly be noticed. or they may be substantial. Impacts to the environment <br />can be positive. negative. or both. Sound management practices dictate that impacts be <br />minimized by proper selection and design of erosion control structures. <br /> <br />4.2 Stream Response to Change - <br /> <br />The major physical processes in an alluvial channel are those relaled to water discharge. <br />channel slope and shape. geology and soils. sediment trnnsport. vegetative effects. and <br />man's intluence. Each of these is intertwined in a set of complex relationships. <br />Alterations in any of the above parameters can initiate changes in other parameters and <br />in channel characteristics. <br /> <br />Water discharge is a key process. resulting from other processes. that affects channel <br />shape and sediment transport. Hydraulic variables such as velocity. depth. and t10w area <br />are important in analysis of channel response. Coinciding with these are channel shape. <br />channel slope. and /low resistance from gmins and bed forms. Geology and soils of the <br />channel bottom and banks belp determine the relative erodibility of the system. <br /> <br />Colorado Erosion Control Manual <br /> <br />25 <br />