Table : Summary of Hydrologic and Hydraulic Analyses Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations 2.3 miles 1994 State Confluence with Ice jam analysis evaluated by Modified upstream of Regression Culvert Creek South Fork HEC-2 4.6 03/22/1997 AE Indirect Method (CRREL 2004). Flood confluence of Equations – Inundation River Profile reflects results of ice jam analysis. Ripple Creek Region 3 Approximately 2004 State With and without levee analyses were Inundation Confluence with 500 feet upstream Regression AE w/ HEC-RAS 3.1 06/30/2007 performed for the reach affected by Levee River Big Ocean of State Highway Equations Floodway – IDs 1354212346 and 1234545362. 999 Region 3 Approximately Confluence of N. 2004 State Inundation 500 feet upstream Fork Inundation Regression Effects of hydraulic structures were not HEC-RAS 3.1 06/30/2007 A River of State Highway River and S. Fork Equations considered in the model. – 999 Inundation River Region 3 Elevations determined using ICPR. Survey Lily Pond Pear Tree Circle Westwood Lane ICPR 2.20 ICPR 2.20 05/28/2002 AE data utilized in model was based on county information collected in 2008. 0.7 miles Log Pearson North Fork Gage No. 19999998 was used in hydrologic Confluence with upstream of Type III Inundation HEC-RAS 4.0 12/12/2010 AE analysis. Hydraulic models incorporated Inundation River confluence of Frequency River field measured bridge and culvert data. Lilac Stream Analysis 3.2 miles Hydraulic model was calibrated to high South Fork Confluence with upstream of Unsteady AE w/ water marks collected for flood of 2007, Inundation HEC-HMS 3.4 12/12/2010 Inundation River confluence of HEC-RAS 4.0 Floodway which was estimated to be the 2% annual River Culvert Creek chance flood.
Table : Summary of Hydrologic and Hydraulic Analyses Flooding Source Study Limits Downstream Limit Study Limits Upstream Limit Hydrologic Model or Method Used Hydraulic Model or Method Used Date Analyses Completed Flood Zone on FIRM Special Considerations Culvert Creek Confluence with South Fork Inundation River 2.3 miles upstream of confluence of Ripple Creek 1994 State Regression Equations – Region 3 HEC-2 4.6 03/22/1997 AE Ice jam analysis evaluated by Modified Indirect Method (CRREL 2004). Flood Profile reflects results of ice jam analysis. Inundation River Confluence with Big Ocean Approximately 500 feet upstream of State Highway 999 2004 State Regression Equations – Region 3 HEC-RAS 3.1 06/30/2007 AE w/ Floodway With and without levee analyses were performed for the reach affected by Levee IDs 1354212346 and 1234545362. Inundation River Approximately 500 feet upstream of State Highway 999 Confluence of N. Fork Inundation River and S. Fork Inundation River 2004 State Regression Equations – Region 3 HEC-RAS 3.1 06/30/2007 A Effects of hydraulic structures were not considered in the model. Lily Pond Pear Tree Circle Westwood Lane ICPR 2.20 ICPR 2.20 05/28/2002 AE Elevations determined using ICPR. Survey data utilized in model was based on county information collected in 2008. North Fork Inundation River Confluence with Inundation River 0.7 miles upstream of confluence of Lilac Stream Log Pearson Type III Frequency Analysis HEC-RAS 4.0 12/12/2010 AE Gage No. 19999998 was used in hydrologic analysis. Hydraulic models incorporated field measured bridge and culvert data. South Fork Inundation River Confluence with Inundation River 3.2 miles upstream of confluence of Culvert Creek HEC-HMS 3.4 Unsteady HEC-RAS 4.0 12/12/2010 AE w/ Floodway Hydraulic model was calibrated to high water marks collected for flood of 2007, which was estimated to be the 2% annual chance flood.
FIS_Report_Template_May2014.docx