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Stream Channel Parameters <br />Exhibit SSA and Changes Due to Mining-Induced Subsidence Page 6 <br />each stream segment ate presented in Figures 3 through 13. <br />A summary of the stream channel hydraulic characteristics for each of the 11 drainage basins is <br />provided in Table 3. The slope in [he 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 dischazge 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 dischazge flow in cubic feet <br />per second far 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, <br />sediment, 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 neaz <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 <br />physical basin regime characteristics and identification of characteristics from photographs taken <br />on selected stream channels in the area. <br />The adopted mean annual runoff far 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 />IMPACTS OF SUBSIDENCE ON STREAM CHANNELS <br />The projected subsidence under each of the 11 stream channels has been determined using the <br />output from the Comprehensive and Integrated Subsidence Prediction Model (CISPM), Version <br />2.0 (Department of Mining Engineering, College of Mineral & Energy Resources, West Virginia <br />University), as calibrated using site-specific subsidence data and as reviewed by Mr. Richazd <br />Dunrud, recognized subsidence expert. Exhibit 60B presents a detailed discussion of the <br />subsidence evaluation performed by WWE and Mr. Dunrud. <br />I- <br />L_ <br />DRAFT <br />