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• Stream Channel Parameters <br />Exhibit 558 and Changes Due to Mining - Induced Subsidence Page 7 <br />STREAM CHANNEL HYDRAULIC CHARACTERISTICS <br />The stream channel regime and characteristics were defined using still photographs, videotapes, <br />USGS topographic maps, detailed topographic maps prepared for the mine area, soil surveys, <br />geological evaluations prepared by John Rold (consultant to WWE), aerial photographs, and <br />related evaluations. Channel profiles portraying the pre - mining slope and the range of slopes for <br />each stream segment are presented in Figures 3 through 14. <br />A summary of the stream channel hydraulic characteristics for each of the 12 drainage basins is <br />provided in Table 3. The slope in the lower reach of the channels is shown in addition to the <br />average channel slope since only the lower reach will receive the full basin runoff. <br />The dominant discharge is the flow for the stream that tends to shape the stream channel and help <br />establish the width and depth of the defined channel. The dominant discharge flow in cubic feet <br />per second for each basin is the peak flow expected to occur there once every 2 years. <br />Erosion and sediment yield of a stream basin is normally related to multiple factors, including <br />rainfall, ground cover, land use, topography, upland erosion, runoff, soil types, geology, sediment, <br />and channel hydraulic characteristics. All of these factors were considered. <br />The channel characteristics shown in Table 3 for the dominant discharge are for the stream near <br />the mouth or at a point just downstream of each segment of stream channel. The width and depth <br />values at the dominant discharge in Table 3 are approximate values based upon computed physical <br />basin regime characteristics and identification of characteristics from photographs taken on <br />selected stream channels in the area. <br />The adopted mean annual runoff for the subject basins is used for sediment and channel stability <br />purposes only. It is not proposed for use in water rights studies or for site - specific water budgets. <br />.J <br />831 - 032.810 Wright Water Engineers, Inc. <br />