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<br />DIIlB Collection & AnBlyala . <br /> <br />e <br /> <br />presents a system based upon a checklist whereby an evaluation of sedimentation <br />concerns may be addressed. (Peterson, 1986) <br /> <br />The checklist, developed by Colin Thome, is set out in three major sections, each on a <br />separate page. Section 1 - Valley and Channel Survey deals with the broadest scale. The <br />aims are: first to define the geologic, geomorpbic and human environment around the <br />channel, particularly by establishing the relationship between the river channel and its <br />valley; second to estaI)lish a clear picture of the channel in terms of its characteristic <br />dimensions, plan geometry, flow type, and bed and bar sediments; and third to <br />determine the nature of the instability problem both in terms of severity and spatial <br />extenl. Reference is made here to vertical and lateral channel instability rather than just <br />instability, because it is vital at this early stage to identify whether the direction of <br />channel instability is in the vertical plane, horizontal plane, or both. <br /> <br />Section 2 - Left Bank Survey deals in greater detail with all aspects of bank assessment <br />for the left bank. The aim is to establish a clear picture of the bank in terms of its <br />characteristic geometry and materials, vegetation, erosion processes, failure <br />mechanisms, and state of toe sediment balance. It is divided into 5 parts dealing with <br />each of these topics. Section 3 - Right Bank Survey repeats the survey for the other <br />channel bank and completes the assessmenl. <br /> <br />The data collected in the sedimentation checklist may be used in two ways. First, it may <br />be addressed qualitatively by engineers and geomOlphologists interested in establishing <br />the channel characteristics and sediment impacts before making recommendations <br />regarding the best approach to mitigating or preventing continued problems of channel <br />sedimentation or instability. Second, the assessment sheets could be used to supply most <br />of the input data reqttired for stable channel design. <br /> <br />In this respect, the framework established here for characterizing the channel, its <br />morphology and its sediments should be very useful in determining the applicability of <br />the different equations for flow resistance, sediment transport and one- dimensional <br />modeling. On this basis, the most appropriate quantitative approach can be selected. <br /> <br />5.3.6 Velocity & Streamflow Measurement . <br /> <br />Direct measurement of streamflow and velocity in the project area is the best way to <br />establish these important parameters. It is not feasible to gage every location where flow <br />data is desired along a river networlc. Three alternatives are available when the project <br />must proceed without delay. They are, in order of preference: extend information from <br />nearby gaging sites, estimate streamflows from precipitation data, and make general <br />estimates using an empirical approach. <br /> <br />. <br /> <br />Colorado Erosion Control Manual <br /> <br />59 <br />