INTEGRATED FLOOD MANAGEMENT PLANNING APRIL 2013 Integrated Flood Management Planning April 2013 1 INTRODUCTION .................................................................................................. 1-1 1.1 Background ..................................................................................................................... 1-1 1.2 Integrated Flood Management Approach ....................................................................... 1-3 1.3 General Regional Flood Management Issues ................................................................... 1-3 1.4 California Statewide Flood Management Program Study ................................................ 1-5 1.5 Work Program and Objectives ........................................................................................ 1-6 1.6 Watershed Stakeholder Involvement ............................................................................. 1-8 2 FLOOD MANAGEMENT DATABASE ............................................................... 2-1 2.1 Data Needs ..................................................................................................................... 2-1 2.2 Data Sources .................................................................................................................. 2-3 2.3 Data Gaps ...................................................................................................................... 2-4 3 EXISTING FLOOD HAZARDS AND MANAGEMENT PROGRAMS ............ 3-1 3.1 Definition of Flood and Nature of Hazard ....................................................................... 3-1 3.1.1 Critical Flood Prone Facilities/Assets ...................................................................... 3-2 3.2 Existing Floodplain Management Programs and Agencies .............................................. 3-3 3.3 History of Flooding ......................................................................................................... 3-4 3.4 Flood Hazard Identification ............................................................................................ 3-5 3.5 Defining Flood Risk ........................................................................................................ 3-7 3.5.1 Flood Event-Specific Factors Influencing Flood Damage ......................................... 3-8 3.5.2 Repetitive Flood Damage Losses ............................................................................. 3-9 3.6 Assessment of Flood Risks ............................................................................................ 3-10 3.6.1.1 Landuse Located within Flood Hazards – City Boundaries ............................. 3-11 3.6.2 Planning Estimates of Flood Damage Loss Areas ................................................... 3-15 3.7 Existing Community Watershed Programs ................................................................... 3-18 4 REGIONAL WATERSHEDS DESCRIPTION ................................................... 4-1 4.1 Regional Watersheds Hydrologic Characteristics ........................................................... 4-1 4.1.1 Tijuana River .......................................................................................................... 4-2 4.1.1.1 Water Quality ...................................................................................................... 4-4 4.1.1.2 Biological / Habitat Natural Resources ............................................................. 4-4 4.1.1.3 Watershed Floodplain Hydrology – Major Drainages ....................................... 4-4 4.1.1.4 Flood Rist and Exposure Mapping ....................................................................... 4-5 i San Diego Integrated Regional Water Management Plan DRAFT Integrated Flood Management Planning April 2013 4.1.2 Otay River ............................................................................................................... 4-6 4.1.2.1 Water Quality ...................................................................................................... 4-7 4.1.2.2 Biological / Habitat Natural Resources ................................................................ 4-7 4.1.2.3 Watershed Floodplain Hydrology – Major Drainages ....................................... 4-7 4.1.2.4 Flood Risk and Exposure Mapping .................................................................... 4-8 4.1.3 Sweetwater River .................................................................................................... 4-9 4.1.3.1 Biological / Habitat Natural Resources ............................................................... 4-11 4.1.3.2 Watershed Floodplain Hydrology – Major Drainages ...................................... 4-11 4.1.3.3 Flood Risk and Exposure Mapping .................................................................. 4-12 4.1.4 Pueblo San Diego .................................................................................................. 4-13 4.1.4.1 Water Quality .................................................................................................... 4-14 4.1.4.2 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-14 4.1.4.3 Flood Risk and Exposure Mapping .................................................................. 4-15 4.1.5 San Diego River ..................................................................................................... 4-16 4.1.5.1 Water Quality .................................................................................................... 4-18 4.1.5.2 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-19 4.1.5.3 Flood Risk and Exposure Mapping .................................................................. 4-19 4.1.6 Los Peñasquitos Creek .......................................................................................... 4-20 4.1.6.1 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-21 4.1.6.2 Flood Risk and Exposure Mapping .................................................................. 4-22 4.1.7 San Dieguito River................................................................................................. 4-23 4.1.7.1 Water Quality ................................................................................................... 4-25 4.1.7.2 Biological / Habitat Natural Resources .............................................................. 4-25 4.1.7.3 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-25 4.1.7.4 Flood Risk and Exposure Mapping .................................................................. 4-26 4.1.8 Carlsbad ................................................................................................................ 4-27 4.1.8.1 Water Quality .................................................................................................... 4-28 4.1.8.2 Biological / Habitat Natural Resources .............................................................. 4-29 4.1.8.3 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-29 4.1.8.4 Flood Risk and Exposure Mapping .................................................................. 4-30 4.1.9 San Luis Rey River ................................................................................................ 4-31 4.1.9.1 Watershed Floodplain Hydrology – Major Drainages ..................................... 4-34 ii San Diego Integrated Regional Water Management Plan DRAFT Integrated Flood Management Planning April 2013 4.1.9.2 Flood Risk and Exposure Mapping .................................................................. 4-35 4.1.10 Santa Margarita River ........................................................................................... 4-36 4.1.10.1 Water Quality ................................................................................................ 4-38 4.1.10.2 Biological / Habitat Natural Resources .......................................................... 4-38 4.1.10.3 Flood Risk and Exposure Mapping .............................................................. 4-39 4.1.11 San Mateo / San Juan ............................................................................................ 4-40 4.1.11.1 Biological / Habitat Natural Resources .......................................................... 4-41 4.2 Metrologic Conditions / Historic Precipitation ............................................................. 4-42 4.3 Floodplain Hydrology – Major Regional Flood Sources ................................................. 4-45 5 INTEGRATED FLOOD MANAGEMENT (IFM) PLANNING GUIDING PRINCIPLES ................................................................................................................. 5-1 5.1 Overview of IFM and Basic Planning Principles .............................................................. 5-1 5.1.1 Basic Planning Principles of IFM ............................................................................. 5-1 5.1.2 General Elements of IFM ......................................................................................... 5-3 5.2 Risk Assessment and Management ................................................................................. 5-4 5.3 Resource Management Using an Ecosystem Approach ................................................... 5-4 5.4 General Flood Management Opportunities / Constraints ................................................ 5-5 6 FORMULATION