HomeMy WebLinkAboutSouthKona_PublicMeeting April 29, 2009
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Hydrology
• Data Collection and Review
• LiDAR Mapping for Flood Studies
• Project Stakeholders
· FEMA
· County of Hawaii
· NRCS
· USACE
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Meeting Agenda – South Kona
Introductions
Background
Data Collection & Review
Technical Discussion
Study Results
FEMA Map Revision Processing
Wrap-up
Background
Purpose of this Flood Study to update the 1976 NRCS Flood Study
South Kona Flood Hazard Study area divided into 2 phases
This project is one of the current County’s flood related projects
Project Team:
County of Hawaii
USACE-Honolulu
Group 70 International
MRC LLC
Meeting Format
Team Presentation
Meeting will end promptly at top-of-the-hour
Please reserve questions until the end of the presentation
Additional questions requiring further discussion will be addressed after the meeting
Questions may also be submitted to the County in writing
Study Areas 1 and 2
New Terrain Data Collected for Area 2
Area 1: Flood Hazard Study
Area 2: New Topographic Map
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Hydrology
• Flood Hazard Hydrologic Analysis
• Field Investigation
• Geology/Infiltration
• Comparative Hydrologic Analysis
· HEC-HMS Model Analysis
· Regional Equations
· County of Hawaii Method
· Log Pearson III
Captain Cook
Kiilae
Honokua
Kealakekua Bay
Honaunau
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Hydrology – HEC-HMS Analysis
• GIS and Hydrologic Analysis Integration
• HEC-HMS Model Calibration
• Storm Frequencies – 10, 25, 50, 100, 500
• TR-55 – CN & TC Methodology
• TP-43 – Precipitation
• Site Geology
• Soil Infiltration
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Watercourses Studied with New Detailed Analysis
• Watercourse 13
• Watercourse 15
• Watercourse 16
• Watercourse 17
• Watercourse 18
• Watercourse 19
• Watercourse 20
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Hydraulics – HEC-RAS Modeling
• Development of Floodplain and Floodway Boundaries
• Development of Base Flood Elevations
• DEM/TIN Development
· HEC-RAS Cross-sections
· GIS Flood Hazard Development
• Analysis Criteria:
· 10%, 4%, 2%, 1%, 0.2% Annual Chance Flood Events (10, 25, 50, 100, 500 -year)
• No Approximate Zones
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Detailed Flood Study Benefits
• Updated Topographic Maps
• Updated Hydrologic Methodology
• Updated Hydraulic Modeling
• Establish Base(100-year) Flood Elevations
• Future Land Use and Development
• Proper Flood Insurance Premium Rates
• Elevation Certificates
FEMA Review Process
• Area 1 – Completion of Hydrology and Watercourses Hydraulic Work
• USACE and County Review and Approval of Final H&H Flood Hazard Analysis Deliverables
• Submittal of TSDN to FEMA for QC and Approval
• FEMA Review
· Issuance of Letter of Map Revision
· Revise DFRIM Panels in a Future Physical Map Revision
LOMR and Map Revision for These Panels
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Wrap-up
Please be sure to pick-up flood related materials
Mahalo for attending today’s public meeting for the South Kona Flood Hazard Study
Questions