Debris Flow Model

Debris Flow Model

Description

The Debris Flow Models are used to estimate 1) the probability, 2) the volume of debris flow for drainage basins within the burn area, (Staley et al., 2016 and Gartner et al., 2014) and 3) the combined hazard in a drainage basin based on both the probability and volume of debris flow.?The Debris Flow Model can also be used to assess the increased hazard of debris flow that can occur during or following an intense rainstorm.?To produce an official Debris Flow Model, the BAER team in the field will validate the BARC Map, which produces the Soil Burn Severity (SBS) map.?This map will be passed on to the Landslide Hazard Program.?The Landslide Hazard Program runs the Debris Flow Models, sediment delivery and probability maps are created, results are given to BAER team, and the information is posted to a publicly accessible site.?However, it is not always possible for the Landslide Hazard Program to receive validated data.?In this situation the BARC map will be sent to the Landslide Hazard Program, and they can produce a Debris Flow Model.

Duration: 3 hours-3 days

Upon receiving the SBS map, it typically takes between three hours to three days to produce a Debris Flow Model.?This variability is primarily due to the amount of data received and driven by the physical size of the fire.

Responsible Resources

The Debris Flow Model is produced by the Landslide Hazards Program at USGS, located in Golden, Colorado.

Triggers

Requests are made by parties interested in the model output (debris flow maps).

Predecessor

Requires either 1) validated SBS map [data] or 2) BARC map [data] to run this model.

Input Requirements

Debris Flow modeling requires:

1)?????Information on slope derived from digital elevation data.

2)?????Satellite data (differenced Normalized Burn Ratio derived from Landsat images)

3)?????Soil properties within the burned area (STATSGO soils database, Schwartz, and Alexander, 1995)

4)?????The Soil Burn Severity map

5)?????Design storm (rainfall accumulation in 15 minutes)

Products

·????????Expected probability for design storms*

·????????Expected volume of debris flow for design storms*

·????????Combined hazard (probability and volume of debris flow)*

o??Shows relative hazards ranking of the basins (on a low to high scale) which enables a localized analysis of stream channels within and downstream of the burn area.?This includes combined effects of debris flow and floods from tributaries

·????????Associated data for debris flow.

·????????*Maps can be viewed https://landslides.usgs.gov/hazards/postfire_debrisflow/

Issues/Other Considerations

1)?????Format the hazard maps, so they can be used more readily by local communities and their emergency management programs.?The products should include both stream watch areas and consequence models.

2)?????Data partners are reliant on the BAER teams releasing SBS data.

3)?????Landslide Hazard Program can experience a shortfall of modelers during the wildfire season.?

Debris Flow Modeling Spatial Mapping Products

These maps show the probability of debris flow, volume of debris flow, and combined risk posed by probability and volume of debris flow (in low, moderate, and high hazard categories) which can help FEMA make better decisions in the future. Decisions about reasonable setbacks for buildings and infrastructure depend on many factors including the shape and steepness of the channel, how the structure or infrastructure will be used, and what level of risk is acceptable. This can help FEMA in the future with both Individual Assistance and Public Assistance missions.

The following is an example of a GIS text box required for Debris Flow Modeling Spatial Mapping Products:

Potentially Impacted Culverts: Culverts intersecting polygons from the USGS debris flow model. Research Scientists at USGS’ Landslide Hazards Program used empirical models to estimate the probability and volume of debris flows for selected basins in the Valley and Butte Fire.?Their models utilize data regarding topography (using 10m DEMs), field-verified burn severity, soil properties (STATSGO), and rainfall (NOAA Atlas 14). The data is symbolized using the Probability Percent Rating assigned to each basin.

Table 2 represents the products produced by the Debris Flow Spatial Mapping activities including name of the map, descriptions, naming conventions, and inputs.

Table 2: Debris Flow Modeling Spatial Mapping Products (Watershed Clearinghouse FEMA-4240-DR-CA)

Debris Flow Vulnerability: USGS Model Combined Hazard 2-yr Event - PFWERT Sites

Description

This map depicts assessment sites from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The map also includes the Combined Hazard Rating for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_CF_Assessment_LifeHazard_DebFlo_CombHaz2yr_date

Input (Key Data Layers)

PFWERT Sites, USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Combined Hazard 100-yr Event - PFWERT Sites

Description

This map depicts assessment sites from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The map also includes the Combined Hazard Rating for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_CF_Assessment_LifeHazard_DebFlo_CombHaz100yr_date

Input Layers (Key Data) PFWERT Sites, USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Probability 2-yr Event - Phase 1 Assessment

Description

This map depicts assessment sites from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The map also includes the Debris Flow Probability Percentage for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_CF_Assessment_LifeHazard_DebFlo_ProbPerc2yr_date

Input Layers (Key Data) PFWERT Sites, USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Probability 2-yr Event - PFWERT Sites

Description

This map depicts assessment sites from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The map also includes the Debris Flow Probability Percentage for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_CF_Assessment_LifeHazard_DebFlo_ProbPerc2yr_date

Input Layers (Key Data) PFWERT Sites, USGS Debris Flow Model, PFWERT

Debris Flow Vulnerability: USGS Model Probability 100-yr Event - PFWERT Sites

Description

This map depicts assessment sites from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The map also includes the Debris Flow Probability Percentage for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_CF_Assessment_LifeHazard_DebFlo_ProbPerc100yr_date

Input Layers (Key Data) PFWERT Sites. USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Combined Hazard 2-yr Event - NGA Building Damage Assessment

Description

This map depicts the damage assessment buildings layer created by the National Geospatial-Intelligence Agency (NGA) for the Valley/Butte Fire. The map also includes the Combined Hazard Rating for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_NGA_Assessment_DebrisFlow_CombHaz2yr_date

Input Layers (Key Data) NGA Preliminary Damage Analysis, USGS Debris Flow

Debris Flow Vulnerability: USGS Model Combined Hazard 100-yr Event - NGA Building Damage Assessment

Description

This map depicts the damage assessment buildings layer created by the National Geospatial-Intelligence Agency (NGA) for the Valley/Butte Fire. The map also includes the Combined Hazard Rating for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_NGA_Assessment_DebrisFlow_CombHaz100yr_date

Input Layers (Key Data) NGA Preliminary Damage Analysis, USGS Debris Flow

Debris Flow Vulnerability: USGS Model Probability 2-yr Event - NGA Building Damage Assessment

Description

This map depicts the damage assessment buildings layer created by the National Geospatial-Intelligence Agency (NGA) for the Valley/Butte Fire. The map also includes the Debris Flow Probability Percentage for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention FireName_NGA_Assessment_DebrisFlow_ProbPerc2yr_date

Input Layers (Key Data) NGA Preliminary Damage Analysis, USGS Debris Flow

Debris Flow Vulnerability: USGS Model Probability 100-yr Event - NGA Building Damage Assessment

Description

This map depicts the damage assessment buildings layer created by the National Geospatial-Intelligence Agency (NGA) for the Valley/Butte Fire. The map also includes the Debris Flow Probability Percentage for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_NGA_Assessment_DebrisFlow_ProbPerc100yr_date

Input Layers (Key Data) NGA Preliminary Damage Analysis, USGS Debris Flow

Debris Flow Vulnerability: USGS Model Combined Hazard 2-yr Event - Bridges/Culverts/Dams

Description

This map depicts locations of bridges, culverts, and dams that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The sites are made of field assessed locations from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report, the National Bridge Inventory (NBI), and the National Inventory of Dams (NID). The map also includes the Combined Hazard Rating for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_Bridge_Fextent_DebrisFlow_CombHaz2yr_date

Input Layers (Key Data) Bridges, Culverts, Dams, Gages; USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Combined Hazard 100-yr Event - Bridges/Culverts/Dams

Description

This map depicts locations of bridges, culverts, and dams that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The sites are made of field assessed locations from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report, the National Bridge Inventory (NBI), and the National Inventory of Dams (NID). The map also includes the Combined Hazard Rating for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_Bridge_Fextent_DebrisFlow_CombHaz100yr_date

Input Layers (Key Data) Bridges, Culverts, Dams, Gages, USGS Debris Flow Model

Debris Flow Vulnerability: USGS Model Probability 2-yr Event - Bridges/Culverts/Dams

Description

This map depicts locations of bridges, culverts, and dams that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The sites are made of field assessed locations from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report, the National Bridge Inventory (NBI), and the National Inventory of Dams (NID). The map also includes the Debris Flow Probability Percentage for a 2-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_Bridge_Fextent_DebrisFlow_ProbPerc2yr_date

Input Layers (Key Data) Bridges, Culverts, Dams, Gages, USGS Debris Flow Model 2-yr

Debris Flow Vulnerability: USGS Model Probability 100-yr Event - Bridges/Culverts/Dams

Description

This map depicts locations of bridges, culverts, and dams that may potentially be impacted by debris flow from the burned areas of the Valley/Butte Fire. The sites are made of field assessed locations from the State Post Fire Watershed Emergency Response Team (SPFWERT) Phase 1 report, the National Bridge Inventory (NBI), and the National Inventory of Dams (NID). The map also includes the Debris Flow Probability Percentage for a 100-year event rainfall as developed by the USGS Debris Flow Model for the Valley/Butte Fire.

Naming Convention

FireName_Bridge_Fextent_DebrisFlow_ProbPerc100yr_date

Input Layers (Key Data) Bridges, Culverts, Dams, Gages, USGS Debris Flow Model 100-yr

Debris Flow Vulnerability: USGS Model Probability 100-yr Event 100 feet near Roadways

Description

USGS Debris Flow Model:100 feet from Roadways. Research Scientists at USGS’ Landslide Hazards Program used empirical models to estimate the probability and volume of debris flows for selected basins in the Valley and Butte Fire.?Their models utilize data regarding topography (using 10m DEMs), field-verified burn severity, soil properties (STATSGO), and rainfall (NOAA Atlas 14). The data is symbolized using Debris Flow Probability percentages assigned to each basin.

Naming Convention

FireName_Bridge_Roadway_DebrisFlow_ProbPerc100yr_date

Input Layers (Key Data) Bridges, Culverts, Dams, USGS Debris Flow Model

(Watershed Clearinghouse Data and Products_20151120.xlsx, Eskridge)

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