HYDROLOGIC AND HYDRAULIC ANALYSES FOR FEMA LEVEE CERTIFICATION IN SAN BERNARDINO COUNTY, CALIFORNIA

摘要

This paper summarizes hydrologic and hydraulic analyses performed for the SanBernardino County Levee Certification Project (Project) and the challenges encounteredduring the course of the study. The Project included forty-three non-Federal levees onthe national levee inventory list, currently mapped by FEMA as Provisionally AccreditedLevees (PALs). WEST Consultants performed detailed hydrologic/hydraulic analyses forthirty-five Category 2 levees in order to determine whether they are in compliance withFEMA’s regulatory requirements for certification as identified in Title 44 of the Code ofFederal Regulations, Section 65.10 (44 CFR 65.10). In most cases, a completehydrologic model (HEC-HMS) was built for the contributing watershed todetermine/verify the 100-year base flood. Detailed hydraulic models (HEC-RAS) werebuilt for the majority of the levees, some of them with split flow components, lateral spillstructures, and unsteady routing. Each levee presented its own challenge in terms of dataavailability and modeling approach. The results of the hydrologic and hydraulic analyseswere eventually used to verify levee freeboard, evaluate sedimentation and potentialscour problems at the levee toes, and address any interior flooding issues.