Los Alamitos Creek Flood StudyFMA Conference Presentation

September 09, 2015

Gabriel Vallin

Presentation

• Study Description

• Study Limits

• Approach

• Current Work Status

• Next Steps

• Levee Analysis – Structural and Hydraulic

• Floodplain Evaluation

• Mapping

Study Description

• 1980 Levees – Outdated Hydrology/Hydraulics

• FEMA Standards updated – more Freeboard

• Levees no longer provide 100 year protection with updated FEMA guidelines

• Current Flooding - Zone AE

• Updating – Hydrology, Hydraulics, Geotech, Remapping

• Possible Benefits – Remove parcels from Floodplain, accurate mapping of flood risk, real time flood warning system, technical basis for future flood protection

Study Limits

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Mapping Approach

Field Survey Channel Geometry

Overflows

Channel Capacity

HEC-RAS(S&US)

HEC-RAS 2D(Floodplain)

2006 LiDAR(LAS to adf)

Floodplain Mapping

Hydrographs (100yr)Hydrologic Study

Current Work Completed and In Progress

• Updated Hydrology

• Steady and Unsteady HEC-RAS Models

• Freeboard Analysis – Deficient in most areas

• Levee’s Non-accredited

• Channel Capacity Evaluation

• Geotechnical Analysis

Next Steps

• Levee Analysis– Structural– Hydraulic

• Floodplain Evaluation

• Remapping

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LAMP – Levee Analysis and Mapping Procedures

• Non-Accredited Levees

• Previous – Without Levee Approach

• Multiple Reaches

• Sound Reach

• Freeboard Deficient

• Overtopping

• Structural Inundation

• Natural Valley

Levee – Freeboard Deficient

Levee – Structural

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FloodplainEvaluation

This is the End…any questions?

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