Contents -- Foreword -- 1. Introduction -- 1.1 Introduction -- 1.2 Alluvial Fan Hazards -- 1.3 Playa Lakes -- 1.4 Conclusion -- References -- 2. Geologic and Hydraulic Concepts of Arid Environments -- 2.1 Introduction -- 2.1.1 Desert landscape formation -- 2.2 Geologic Theories of Formative Processes -- 2.2.1 Catastrophism -- 2.2.2 Gradualism (Uniformitarianism) -- 2.2.3 Integration -- 2.3 Flow Processes -- 2.3.1 Fluvial -- 2.3.2 Hyperconcentrated flows -- 2.4 Soils -- 2.4.1 Soil formation in arid environments -- 2.4.2 Desert pavement -- 2.4.3 Indurated soil layers -- 2.4.4 Vegetation and biologic role in soil development -- 2.5 Runoff, Infiltration Potential, and Transmission Losses -- 2.5.1 Runoff and infiltration potential -- 2.5.2 Channel transmission losses -- References -- 3. Traditional Approaches to Flood Hazard Identification and Mitigation on Alluvial Fans -- 3.1 Introduction -- 3.2 Background -- 3.3 Technical Issues Regarding the Assumptions -- 3.4 Implementation of the Assumptions -- 3.4.1 Understanding the traditional approach -- 3.4.2 Implementation for hazard identification -- 3.5 An Approach to Hazard Mitigation -- 3.6 Conclusion -- References -- 4. New Approaches for Alluvial Fan Flood Hazard -- 4.1 Predicting Alluvial Fan Flooding - Background -- 4.2 FEMA's Three Phase Approach to Alluvial Fan Flood Mapping -- 4.2.1 Identification of fan geomorphology -- 4.2.2 Active versus inactive fan areas -- 4.2.3 100-year flood hazard modeling and mapping -- 4.3 Alluvial Fan Flood Modeling -- 4.3.1 Developing an alluvial fan flood model -- 4.3.2 2-D unsteady alluvial fan model limitations -- 4.3.3 Alluvial fan sediment issues -- 4.4 Important Criteria for Flood Hazard Delineation -- 4.5 Hazard Mapping as a Planning Tool -- 4.6 Flood Damage Mapping -- 4.7 Alluvial Fan Mitigation Measures -- References.

5. Flood Hazard Mapping Versus Flood Risk Analysis -- 5.1 Risk and Uncertainty of Alluvial Fan Flooding -- 5.1.1 Concepts of flood hazard and flood risk: Hazard = risk -- 5.2 Stochastic versus Deterministic Flood Hazard Assessment -- 5.3 Stochastic Methods for Fan Flood Hazards -- 5.3.1 Monte Carlo simulations -- 5.3.2 Probability distributions representing physical fan parameters -- 5.3.3 Random walk algorithm to determine flow paths -- 5.3.4 Alluvial fan flood probability - creating the linkage between the stochastic model and the deterministic model -- 5.3.5 Evolution of the alluvial fan - modeling future conditions -- 5.4 Integrating Alluvial Fan Flood Hazard Mapping and Damage Assessment -- References -- 6. Playa Lake Hazards and Resources -- 6.1 Introduction -- 6.1.1 Historic role of playas in military and civilian use -- 6.2 Inundation of Playas -- 6.2.1 Predicting the depth of inundation on playa lakes -- 6.2.2 Predicting the duration of inundation on playa lakes -- 6.3 Geologic Hazards on Playa Lakebeds -- 6.3.1 Evolution of desiccation cracks on playas -- 6.4 Playas as a Water Resource: Studies in Jordan -- 6.4.1 Azraq basin -- 6.4.2 Playas in the Northeastern Badia -- 6.4.2.1 Determining water volume on playas within the Azraq basin of Jordan -- 6.5 Conclusions -- References -- 7. Needs and Benefits of Co-Operation -- 7.1 Introduction -- 7.2 Identifying the Alluvial Fan Hydrologic Apex -- 7.3 Watershed Delineation -- 7.4 History -- 7.5 Surficial Geology -- 7.6 Paleohydrology -- 7.7 Aggradation and Scour -- 7.8 Climate Change -- 7.9 Planning -- 7.10 Summary -- References -- 8. Meeting the Challenge -- Case Study #1: Two-Dimensional Hydraulic Modeling for Alluvial Fan Floodplain Hazard Identification -- 8.1 Introduction -- 8.1.1 Local regulatory framework -- 8.1.2 Project setting -- 8.1.3 Hydraulic model development.

8.2 Hydraulic Model Data and Assumptions -- 8.2.1 Topography and grid development -- 8.2.2 Discharge -- 8.2.3 Precipitation -- 8.2.4 Infiltration -- 8.2.5 Manning's n-values -- 8.2.6 Boundary conditions -- 8.2.7 Flow obstruction -- 8.2.8 Froude number -- 8.2.9 Computational time step and grid element size -- 8.3 Hydraulic Model Results -- 8.4 Summary and Conclusions -- References -- Case Study #2: Numerical Modeling of the 2005 La Conchita Landslide, Ventura County, California -- 8.5 Introduction -- 8.6 Background, Geology, and Kinematics -- 8.6.1 Introduction -- 8.6.2 Historical setting -- 8.6.3 Geologic conditions -- 8.6.4 Vegetation and soils -- 8.6.5 Sedimentology -- 8.6.6 Physical dimensions -- 8.6.7 Velocity -- 8.7 Previous Studies of Debris Flow Behavior -- 8.8 FLO-2D Numerical Modeling -- 8.8.1 Introduction -- 8.8.2 FLO-2D modeling of debris flows -- 8.8.3 Input parameters -- 8.8.3.1 FLO-2D grid -- 8.8.3.2 Inflow hydrograph -- 8.8.3.3 Unit weight -- 8.8.3.4 Yield strength -- 8.8.3.5 Dynamic viscosity -- 8.8.3.6 Surface roughness -- 8.8.3.7 Modeling of temporary wall -- 8.8.4 Model results -- 8.8.4.1 General observations -- 8.8.4.2 Main (Eastern) lobe -- 8.8.4.3 Minor (Western) lobe -- 8.8.4.4 Channel fill -- 8.8.4.5 Sensitivity analyses -- 8.9 Summary -- References -- Case Study #3: Tiger Wash, Western Maricopa County, Arizona, USA -- 8.10 Site Description -- 8.10.1 Watershed -- 8.10.2 Geologic setting -- 8.10.3 Surficial geology -- 8.10.4 Channel morphology -- 8.10.5 Outfall -- 8.11 Flood History -- 8.11.1 Gauge record -- 8.11.2 Peak discharge estimates -- 8.11.3 September 26, 1997 flood -- 8.12 Previous Studies -- 8.13 Discussion -- 8.13.1 What is an alluvial fan? -- 8.13.2 What are the key elements of alluvial fan flooding? -- 8.13.3 Alluvial fan boundary delineation -- 8.13.4 Predicting avulsions.

8.13.5 Importance of infiltration and attenuation -- 8.13.6 Flood hazard delineation -- 8.14 Summary -- References -- 9. Future Directions -- 9.1 Introduction -- 9.2 What We Know - What We Don't Know -- 9.2.1 Education -- 9.2.2 Precipitation and flow data issues -- 9.2.3 Geology and geomorphology -- 9.2.4 Monitoring and modeling -- 9.3 Conclusion -- References.