Laserfiche WebLink
Hydrology Calculations <br />All subwatershed peak flow data was calculated assuming the condition of the watershed area is <br />topsoiled and seeded and using a fast hydrograph response in the SEDCAD software program, <br />both of which are conservative assumptions. The NHN-001 East and NHN-001 West ditches <br />were each modeled in SEDCAD independently, with all segments and culverts linked together in <br />each model. The SEDCAD output reports are found on the following pages. <br />Ditch Cross Section Methodolo�v <br />Cross sections were generated at a five foot interval along each ditch to determine the section of <br />each segment with the smallest available flow cross sectional area. This smallest segment was <br />then evaluated in the SEDCAD to ensure proper cross-sectional area was available for the <br />smallest cross sectional area present in each ditch segment. This flow cross sectional area also <br />took into account the required 0.3 feet of freeboard. Each ditch segment is installed at a single <br />grade and with a single channel lining, meaning that the only variable along the segment that <br />could affect ditch capacity is the flow cross section. Table 2.05.3(4)-7-1 shows a comparison of <br />the ditch segments' worst case flow cross sections from Map 2.05.3(4)-7 to the SEDCAD <br />determined ditch segment flow cross sectional requirements. <br />Appendix 2.05.3(4)-7 Page 2 April 2016 (PR -01) <br />