Laserfiche WebLink
Stream Channel Parameten: <br />Exhibit SSA and Changes Due to Mining-Induced Subsidence Page 8 <br />due to mining subsidence will range from a minimum of -1.5 percent to a maximum of 2.0 <br />percent. Figure 17 depicts the pre-and post-mining stream profiles and demonstrates the overall <br />channel slope is not significantly impacted by subsidence. <br />CHANGES IN STREAM CHANNEL HYDRAULIC CHARACTERISTICS <br />The channel characteristics for each of the basins (as shown in Table 3) were then analyzed using <br />geomorphological and sedimentation engineering relationships and fonnulas to determine the <br />extent and type of change to each channel segment and then to estimate the amount of sediment <br />yield change. <br />Hydrologic review has determined that the following basin characteristics will not change <br />significantly as a result of subsidence: <br />1. Mean annual runoff <br />2. Peak discharge <br />3. Dominant discharge <br />4. Forest cover <br />Due to the fact that the mean annual runoff, peak discharges, and the dominant discharge are <br />greatest for the lower end of each stream segment studied, which is where the channel changes <br />would be maximized, this analysis has concentrated primarily on the lower portion of each <br />stream segment. The computations were performed for the lowest channel reach within the <br />influence of the mining. <br />A principle of fluvial morphology, as confirmed by Manning's equation, is that the stream <br />channel characteristics described in Table 3 for channel width and depth will change as shown <br />below. <br /> <br />DRAFT <br />