1	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis EXISTING CONDITIONS * June 1972 inundation * 100-year inundation
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4	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis Flow Frequency Analysis * Peak Flow Frequency on the Susquehanna River - 100-year discharge = 260,000 cfs * Peak Flow Frequency on Fishing Creek - 100-year discharge = 47,400 cfs * Results Compare with 1979 FEMA FIS - COE 100-year discharge on Susquehanna River is 5% lower than FEMA FIS - COE 100-year discharge on Fishing Creek is 19% lower than FEMA FIS
5	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis HEC-RAS Model * Used surveyed stream cross sections
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10	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis HEC-RAS Model (cont.) * Assumed railroad mitigation bridge and Rt. 44 (Double Track) bridges remain * Modeled 2, 5, 10, 25, 50, 100,200, 500- year and June 1972 * Modeled 4 project alternatives and existing conditions
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12	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis HEC-RAS Model (cont.) * Without project * Interior alignment * Fringe without Fernville alignment * Fringe with Fernville alignment * 5 and 10 foot depth dredging
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15	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis Top of Protection * Used results of HEC-RAS model to set top of protection profile * Performed a risk and uncertainty analysis to take into account: - uncertainty in flow frequency - contraction and expansion coefficients - debris at bridges - roughness of channel and floodplain
16	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis Top of Protection (cont.) * 100-year with-project water surface elevations vs. June 1972 with-project water surface elevations along Fishing Creek - 100-year higher than June 1972 upstream of Reading Railroad Bridge - June 1972 is a 440-year event on Susquehanna River - June 1972 is a 53-year event on Fishing Creek - Top of protection set to highest event to provide at least 100-year protection throughout community
17	Bloomsburg, PA Local Flood Protection Project Hydraulics and Hydrology Analysis Interior Flooding * Area behind Bloomsburg alignment - Preliminary analysis using computer model HEC-IFH - Divided into 4 subbasins - Two conditions: blocked or unblocked drainage structures - 10, 25, 50, and 100- year storm events analyzed - Some interior flooding still remains with project * Area behind Fernville alignment - Preliminary analysis using existing mapping - provided 5-24” drainage structures thru levee
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