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Stream Channel Parameters and Changes <br />Exhibit 55B Due to Longwall Mining-Induced Subsidence Page 17 <br /> <br /> <br /> <br />831-032.923 Wright Water Engineers, Inc. <br />December 2021 <br />then the changes were applied to the existing channel slope to determine the resultant post-mining <br />channel slope. For purposes of determining changes in channel hydraulic characteristics, the <br />channel slope near the lowest reach with predicted subsidence was used for calculations. <br />Utilizing geomorphic channel regime relationships, it was determined that the changes to channel <br />geometry shown in Table 5 would typically occur over a period of approximately three to five <br />years. There is potential for more rapid channel change in localized areas depending on factors <br />such as forest cover, soil saturation, and channel composition. The changes in depth and width <br />are the maximum computed values considering both a slope increase and slope decrease. <br />However, it should be recognized that the maximum changes in channel width and depth would <br />not occur over the same channel reach.