ºÝºÝߣ

ºÝºÝߣShare a Scribd company logo

12 Fragility Curves.ppt

?Download as PPT, PDF?
?
Jorge Atau
Jorge Atau

This document discusses using levee fragility curves and safe storage concepts in flood modeling. It explains that fragility curves represent the link between geotechnical risk and predicted flood levels, implicitly defining levee failure risk. Safe storage refers to the volume of water levees can hold before failure initiates, even in poor condition. The document provides background on developing fragility curves based on levee material properties and construction. It notes benefits of using FLO-2D software's fragility curves are combining geotechnical and hydraulic analyses to spatially assess levee failure and flood risk.

1 of 14
Safe Storage and Levee Fragility Curves
FLO-2D Software, Inc. Safe Storage Concept ? Relates to levee removal for FIS mapping. ? Safe storage has been considered on several projects including a recent FLO-2D model FIS Study approved by FEMA. ? Safe storage can be linked to fragility curves.
FLO-2D Software, Inc. Safe Storage Concept Even levees in the poorest condition will store some water before failure initiates. Safe storage may only extend 1 or 2 ft above the toe of the levee but constitutes a large volume of water.
Levee Safe Storage Safe Storage = ?
FLO-2D Software, Inc. Safe Storage Issues ? For the Sacramento River Basin, this volume of storage may reduce downstream flood volumes and peak discharges. ? If safe storage elevation is exceeded¡­ Levee removal vs. leave breach? For what reach length? ? Negotiate with FEMA and DWR.
FLO-2D Software, Inc. Levee Fragility Curves Fragility represents a link between a geotechnical risk model and predicted water surface elevations with a flood model. Implicitly defines levee failure risk for hazard mapping.
FLO-2D Software, Inc. Background ?Levee core and shell materials vary significantly especially in older levees ?Levees often failure before overtopping due to piping
FLO-2D Software, Inc. Corps Developed Fragility Curves on the Sacramento River Method: 1. Select curve 2. Select likely failure point 3. Determine distance below crest
FLO-2D Software, Inc. Fragility Curve Based on Levee Geotechnical Investigation ? Core and shell material Percent fines vs. local spoil material ? Construction methods Compaction vs. spoils ? Foundation condition Sand boils Field inspection, in-situ borings, lab testing
FLO-2D Software, Inc. FS1 0.03 6.0 FS1 0.15 3.5 FS1 0.50 2.5 FS1 0.85 1.0 FS1 0.95 0.0 FS2 0.03 9.0 FS2 0.15 5.5 FS2 0.50 4.0 FS2 0.85 2.0 FS2 0.98 0.0 Curve ID LFP Dist. Below Crest Create Fragility Curves Data in BREACH.DAT
C FS3 0.5 P 3450 FS1 0.5 P 3558 FS1 0.9 P 3559 FS2 0.7 P 3669 FS3 0.5 P 3670 FS4 0.5 P 3782 FC1 0.3 P 3783 FS1 0.5 GLOBAL DATA INDIVIDUAL LEVEE ELEMENT DATA Assign Levee Element, Select Curve ID, and LFP in LEVEE.DAT
FLO-2D Software, Inc. Results ?FLO-2D finds the breach based on flood hydraulics and the weak levee locations ?Breach can occur anywhere at any time ?FLO-2D initiates piping based on water surface and prescribed duration ?Pipe expands to channel breach to collapse to complete failure
FLO-2D Software, Inc. Benefits of FLO-2D Fragility Curves ? Combines geotechnical characteristics with flood routing hydraulics for a spatial assessment of levee failure and floodwave attenuation ? Identifies flood risk ~ levee failure
NEXT UP: Flood Hazard Mapping

More Related Content

12 Fragility Curves.ppt

  • 1. Safe Storage and Levee Fragility Curves
  • 2. FLO-2D Software, Inc. Safe Storage Concept ? Relates to levee removal for FIS mapping. ? Safe storage has been considered on several projects including a recent FLO-2D model FIS Study approved by FEMA. ? Safe storage can be linked to fragility curves.
  • 3. FLO-2D Software, Inc. Safe Storage Concept Even levees in the poorest condition will store some water before failure initiates. Safe storage may only extend 1 or 2 ft above the toe of the levee but constitutes a large volume of water.
  • 5. FLO-2D Software, Inc. Safe Storage Issues ? For the Sacramento River Basin, this volume of storage may reduce downstream flood volumes and peak discharges. ? If safe storage elevation is exceeded¡­ Levee removal vs. leave breach? For what reach length? ? Negotiate with FEMA and DWR.
  • 6. FLO-2D Software, Inc. Levee Fragility Curves Fragility represents a link between a geotechnical risk model and predicted water surface elevations with a flood model. Implicitly defines levee failure risk for hazard mapping.
  • 7. FLO-2D Software, Inc. Background ?Levee core and shell materials vary significantly especially in older levees ?Levees often failure before overtopping due to piping
  • 8. FLO-2D Software, Inc. Corps Developed Fragility Curves on the Sacramento River Method: 1. Select curve 2. Select likely failure point 3. Determine distance below crest
  • 9. FLO-2D Software, Inc. Fragility Curve Based on Levee Geotechnical Investigation ? Core and shell material Percent fines vs. local spoil material ? Construction methods Compaction vs. spoils ? Foundation condition Sand boils Field inspection, in-situ borings, lab testing
  • 10. FLO-2D Software, Inc. FS1 0.03 6.0 FS1 0.15 3.5 FS1 0.50 2.5 FS1 0.85 1.0 FS1 0.95 0.0 FS2 0.03 9.0 FS2 0.15 5.5 FS2 0.50 4.0 FS2 0.85 2.0 FS2 0.98 0.0 Curve ID LFP Dist. Below Crest Create Fragility Curves Data in BREACH.DAT
  • 11. C FS3 0.5 P 3450 FS1 0.5 P 3558 FS1 0.9 P 3559 FS2 0.7 P 3669 FS3 0.5 P 3670 FS4 0.5 P 3782 FC1 0.3 P 3783 FS1 0.5 GLOBAL DATA INDIVIDUAL LEVEE ELEMENT DATA Assign Levee Element, Select Curve ID, and LFP in LEVEE.DAT
  • 12. FLO-2D Software, Inc. Results ?FLO-2D finds the breach based on flood hydraulics and the weak levee locations ?Breach can occur anywhere at any time ?FLO-2D initiates piping based on water surface and prescribed duration ?Pipe expands to channel breach to collapse to complete failure
  • 13. FLO-2D Software, Inc. Benefits of FLO-2D Fragility Curves ? Combines geotechnical characteristics with flood routing hydraulics for a spatial assessment of levee failure and floodwave attenuation ? Identifies flood risk ~ levee failure
  • 14. NEXT UP: Flood Hazard Mapping