An Inter-agency collaboration for An Inter-agency collaboration for developing decision tools: developing decision tools: How the U.S. Geological Survey How the U.S. Geological Survey works with the National Weather works with the National Weather Service to issue warnings for post-Service to issue warnings for post-fire flash floods and debris flowsfire flash floods and debris flows

Sue Cannon, USGS

Wildfire:Wildfire:

Wildfire: potentially disastrous consequencesWildfire: potentially disastrous consequences

It’s not over once the smoke It’s not over once the smoke clears………..clears………..

Missionary Ridge Fire,Durango CO

Cedar Fire,San Diego, CA

Wildfire effects on watershedsWildfire effects on watersheds::

•Consumption of rainfall-intercepting canopy and Consumption of rainfall-intercepting canopy and of soil-mantling litter and duffof soil-mantling litter and duff•Intensive drying of the soilIntensive drying of the soil•Generation of wood ash and water-repellent Generation of wood ash and water-repellent soilssoils•Removal of obstructions to flowRemoval of obstructions to flow

Results in dramatic changes Results in dramatic changes in erodibility, infiltration, and in erodibility, infiltration, and

runoffrunoff

Debris flows!!Debris flows!!

Southern California Wildfires: Oct 21, 2003Southern California Wildfires: Oct 21, 2003

NASA ImageNASA Image

>700,000 acres>700,000 acresGrand Prix, Grand Prix, Old Old

Simi, Simi, Piru, Piru, VerdaleVerdale

ParadiseParadise, Cedar, Cedar

Debris flows:Debris flows:

Old FireGreenwood Cyn, Southern CA12/25/03

Debris Flow:Debris Flow:Hazards to Life Hazards to Life and Propertyand Property

Old FireWaterman CynSouthern CA 12/25/03

Cable Canyon, Dec 25, 2003

Camp St Sophia, Dec 25, 2003

Report of the Report of the Joint NOAA-USGS Joint NOAA-USGS

Debris Flow Debris Flow Warning System Warning System

Task ForceTask Force

Task Force Assignment:Task Force Assignment:

Establish a prototype flash flood and debris flow warning system for burned areas in Southern California

San Bernardino Mountains, Dec. 2003

Identify scientific opportunities, necessary advancements, and costs

Landslide overview map, conterminous U.S.

Expand system to other burned areas, unburned areas, and to a national scope

• Save lives and protect propertySave lives and protect property• Provide timely information to emergency Provide timely information to emergency

response personnel and the publicresponse personnel and the public• Demonstrate merging of NOAA and USGS Demonstrate merging of NOAA and USGS

state-of-the-art forecast and prediction toolsstate-of-the-art forecast and prediction tools

Wind profiling radar

Prototype Warning System:Prototype Warning System:

Missionary Ridge Fire, Durango CO

Prototype Warning System:Prototype Warning System:Links NWS and USGS expertise and NWS 24x7 operational capabilities

Southern California radar coverage (blue regions), and real-time rain gage locations (red dots).

Threshold rainfall conditions for flash flood and debris flow from recently burned basinsin the San Bernardino Mountains

Threshold for Conditions Unique to December 25, 2003 Storm

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Duration (hours)

Peak

Rai

nfal

l (in

ches

)

Dec25, 2003 DF and Flood

Dec 25, 2003 No response

Jan 2, 2004 No response

Feb 2, 2004 No response

Threshold

safety

danger

Peninsular Ranges

Peninsular Ranges

San Gabriel, San Bernardino San Gabriel, San Bernardino and San Jacinto Mtnsand San Jacinto Mtns

Santa Lucia Range, Sierra Madre, Santa Lucia Range, Sierra Madre, and Santa Ynez, Topatopa, and Santa Ynez, Topatopa, Santa Susana and Santa Monica MtnsSanta Susana and Santa Monica Mtns

RainfallRainfall thresholdsthresholds

0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 1 2 3 4 5 6 7 8 9 10 11 12

Hours of Rainfall

Peak S

torm

Rain

fall

(in

ch

es)

San Gabriel, San Bernardino and SanJacinto Mtns

Penninsular Ranges

Santa Lucia Range, Sierra Madre, andSanta Ynez, Topotopa, Santa Susana,and Santa Monica Mountains

San Gabriels, San Bernardinos, andSan Jacintos - 1 year of recovery

Ventura - 1 year of recovery

Penninsular Ranges - 1 year ofrecovery

Fresh Fires

1-2 years of recovery

RainfallRainfall thresholdsthresholds

• Continuous monitoring of rainfall rates and accumulations in comparison to Continuous monitoring of rainfall rates and accumulations in comparison to threshold conditions for individual stream basinsthreshold conditions for individual stream basins

• Automatically alerts forecasters when a dangerous flash flood or debris flow Automatically alerts forecasters when a dangerous flash flood or debris flow situation may be developingsituation may be developing

Flash Flood Monitoring and Prediction (FFMP)Flash Flood Monitoring and Prediction (FFMP)

Map of Storm Precipitation

Basin conditions relative to rainfall thresholds

Wildfire in southern CA

steeplands

Prototype System Operation:Prototype System Operation:

NWS compares forecasts and precip measurements

with rainfall thresholds, and makes decision for

Watch or Warning

NWS precipitation observations and forecasts

USGS rainfall thresholds for burned areas in So Cal

Here comes a storm

USGS develops Outlook that specifies areas

that could be impacted

Immediately post-fire

Outlooks, Watches and Warnings issued through NWS channels to County OES, Public Works Depts and Flood Control Districts,

and to the Public, and posted on the USGS NHSS web site

Outlooks:Outlooks: NNatural atural HHazards azards SSupport upport SSystem web site:ystem web site:

Tovey

Yorba Linda Soboba

Pioneer

Paradise

Southern CA Fire Perimeters: August 25, 2005Southern CA Fire Perimeters: August 25, 2005

The watersheds burned this summer by the Tovey Fire in Los Angeles County near the town of Palmdale are particularly susceptible to flash floods and debris flows during rainstorms…..

The watersheds burned this summer by the Tovey Fire in Los Angeles County near the town of Palmdale are particularly susceptible to flash floods and debris flows during rainstorms…..

http://nhss.cr.usgs.gov/

Tovey FirePalmdale

Watches:Watches:– Risk of hazardous weather or

hydrologic event has increased significantly, but its occurrence, location, and/or timing are still uncertain

– 3 days to a few hours lead time

Warnings:Warnings:

– Issued when hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring

- 1 day to 30 minute lead times

A test of the System: October 19, A test of the System: October 19, 20052005

Floods and debris flows down County Club Drive and in Wildwood Canyon at 2:00 and 3:00 pm

Burbank

Harvard Fire:

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7

Duration (hours)

Pe

ak

Ra

infa

ll (

inc

he

s)

`

2:00 pm event: 0.28 inches of rain in 29 minutes 3:00 pm event: 0.19 inches of rain in 7 minutes

Immediate System ExpansionImmediate System Expansion

Peninsular Ranges

Peninsular Ranges

San Gabriel, San Bernardino San Gabriel, San Bernardino and San Jacinto Mtnsand San Jacinto Mtns

Santa Lucia Range, Sierra Madre, Santa Lucia Range, Sierra Madre, and Santa Ynez, Topatopa, and Santa Ynez, Topatopa, Santa Susana and Santa Monica MtnsSanta Susana and Santa Monica Mtns

Refine existing rainfall thresholds and develop new ones

Potential System ExpansionPotential System Expansion Provide spatially specific information as storms develop

Probability of debris flow from drainages burned by the Missionary Ridge Fire near Durango, Colorado

Burned areaBurned area

0.6 inches of rainfall in 30 minutes

Burned areaBurned area

1.2 inches of rainfall in 60 minutes

Burned areaBurned area

1.5 inches of rainfall in 1.5 hour

0-25%26-50%51-75%76-100%

Model A: Probability ofdebris flowoccurrence

=ex

1 + ex

Ab = % of basin burned at high and moderate severitiesR = Basin ruggedness (Melton’s number = ΔH/A-0.5) C = % clay in soilO = % organic matter (by wt) in soil I = Average storm rainfall intensity

x = -7.6 + 0.6 (Ab) - 1.1(R) + 0.1(C) – 1.4(O) + 1.1(I)

Example:Example:

1. Delineate basins of interest1. Delineate basins of interest

Model ImplementationModel Implementation

Burn Severity-Burn Severity-High and moderateHigh and moderate

2. Extract data necessary for model input for each basin2. Extract data necessary for model input for each basinModel ImplementationModel Implementation

Burn Severity

Ruggedness

Model ImplementationModel Implementation2. Extract data necessary for model input for each basin2. Extract data necessary for model input for each basin

%Organics and Clay

Burn Severity

Ruggedness

2. Extract data necessary for model input for each basin2. Extract data necessary for model input for each basinModel ImplementationModel Implementation

Burn Severity

Ruggedness

Soil O and C

Storm Rainfall

Model ImplementationModel Implementation2. Extract data necessary for model input for each basin2. Extract data necessary for model input for each basin

3. Calculate Probability for each basin, and parse into classes3. Calculate Probability for each basin, and parse into classes

Probability of debris-flow occurrence – Probability of debris-flow occurrence – Missionary Ridge Fire, ColoradoMissionary Ridge Fire, Colorado

Probability of Debris- Flow Occurrence 1-25% 25-50% 50-75% 75-100%

In response In response to 0.5 inches to 0.5 inches of rainfall 30 of rainfall 30 minutesminutes

Burn Perimeter

Potential System ExpansionPotential System Expansion

SMART-R radar

Real-time stream gage network

with video cameras

Intensive Research Area: Harvard FireIntensive Research Area: Harvard Fire

Repeat Ground-Based LiDAR surveys

Potential Future DevelopmentPotential Future Development Expansion to unburned areas throughout the US

Seattle, WA

Questions???