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<br />Oil.....c('\ <br />U '-- uU._ <br /> <br />30.5--1 <br /> <br />'" <br /> <br />WATER INFORMATION MANAGEMENT SYSTEM HANDBOOK <br /> <br />CHAPTER 30 - PROCEDURE FOR QUANTIFYING CHANNEL <br />MAINTENANCE FLOWS <br /> <br />This chapter describes the methods for determining which <br />streamflows are necessary for the self-maintenance of river, <br />stream, or creek channels to retain their capability for passing <br />flood-flow discharges. The retention of channel capacity is <br />accomplished through, among other things, maintaining the <br />stream's transport of sediment and minimizing the growth of <br />vegetation within the channel. The procedure described in this <br />chapter focuses on determining which streamflows are required to <br />maintain stability of stream channel systems. <br /> <br />~ _ Obiect~~. Determine the amount of streamflow necessary <br />to maintain the hydrologic functioning of stream channels and <br />stream systems where water diversion or storage projects are <br />proposed, or as required for preparation of water right claims. <br /> <br />~ _ Policv. Use the procedures described in this handbook to <br />determine streamflows in circumstances where the applications, <br />limitations, and assumptions apply as stated in Section 31 - <br />1l~1ni. When the procedures in this handbook do not apply, <br />use alternate methods only after review to ensure technical <br />adequacy (FSM 2541.12). <br /> <br />~ - Definitions <br /> <br />Active Channel. The channel cros~ section at the stage <br />corresponding to bankfull discharge. <br /> <br />A~~radation. The geologic process by which stream beds, <br />floodplains, and the bottoms of other water bodies are raised in <br />elevation by the deposition of material eroded and transported <br />by water from other areas. It .is the opposite of degradation. <br /> <br />~full Dischar~e. The flow which just fills the channel to <br />the top of the banks. <br /> <br />aaD~full Sta~e. The level of the active flood plain; therefore, <br />it is the stage at which overbank flooding occurs. <br /> <br />ll.M.ef.l..QH. The sustained or fair-weather runoff, composed of <br />groundwater runoff and delayed subsurface runoff. In this <br />Chapter baseflow is the discharge that just fills the thalweg <br />channel. <br /> <br />Channel Maintenance Flows. A range and duration of in-channel <br />flows necessary to maintain the stability and effective function <br />of the stream channel. This include. those flows which are <br />necessary to provide for the self-maintenance of the stream <br /> <br />*-FSH 4/89 AMEND 3-* <br />