Laserfiche WebLink
Gabion Lined Downslope Structures <br />Runoff from each subwatershed is routed by drainage terraces to gabion lined downslope <br />structures. All downslope structures have been designed to handle the peak flow generated by <br />the corresponding watershed. Figure 2 shows the location of each downslope structure. <br />Calculations provided below and in the model output show the range of velocity and computed <br />water depth for flows during the 25 year, 24 hour event for the following input parameters: <br />Bed Slo e: 33% Bottom Width: 8 feet <br />Left & Ri ht Sideslo e: 3H:1V Mannin s n: 0.035 <br />STRUCTURE SEGMENT PEAK Q <br />CFS FLOW DEPTH <br />FT FLOW VELOCITY <br />FT/SEC <br />1 U er 33.2 0.36 10.2 <br />1 Lower 46.2 0.48 10.2 <br />2 U er 21.4 0.27 9.0 <br />2 Lower 26.4 0.35 8.4 <br />3 U er 21.7 0.27 9.0 <br />3 Lower 25.9 0.33 8.8 <br />4 U er 19.6 0.30 7.4 <br />4 Lower 22.7 0.31 8.3 <br />5 U er 36.3 0.38 10.6 <br />5 Lower 51.6 0.45 12.3 <br />6 U er 25.9 0.31 9.5 <br />6 Lower 36.1 0.37 10.6 <br />7 U er 24.0 0.29 9.4 <br />7 Lower 31.8 0.3 8 9.1 <br />8 U er 26.8 0.33 9.0 <br />8 Lower 74.5 0.61 12.3 <br />Based on the expected velocities, each downslope structure will be lined with rock gabions <br />mats. Energy will be dissipated upstream of access path crossings with a line of gabions <br />perpendicular to flow and at the toe of the slope. Flow will be forced to flow over the gabions <br />and dissipate on gabion splash pads. <br />• <br />• <br />• <br />I:~3230~323008001~Reports~.Application~Drainage Calculations -Surface Water Management.doc <br />