Geomorphic Responses of Burned Outline Watersheds in ...web.sahra.arizona.edu/education2/wrtt/lecs/Youberg_Intro...reloaded since 1977 and had enough sediment for debris flows in 2011

Geomorphic Responses of Burned Watersheds in the Modern Fire Regime: Floods, Debris Flows

and Long-Term Recovery

Ann YoubergArizona Geological Survey

Photo: Zac Ribbing Horseshoe 2 Fire

June 8th, 2011

Outline• Fire Regimes and Trends• Post-fire Hydrologic Changes• Post-fire Geomorphic Responses• Post-Fire Erosion and Rainfall Regimes

across the Western US• Post-fire Water Quality• Post-fire Disturbance Regimes and

implications for Watershed Recovery

2010 Schultz Fire

Fire scar on Ponderosa pine snag Swetnam, Thomas W., 2002, Fire and climate history in the Western Americas from tree rings, PAGES News, 10(1), 6-9.

T. Swetnam, Bandelier NM

Fire Regimes: Tree Ring DataEl

evat

ion

Fire Regimes: Pre-settlement

Spruce-firPatch mosaic w/stands of varying agesHigh-severity, stand-replacing firesRecurrence: 100-300+ yrs

Mixed conifer-AspenComplex variations in species composition and stand agesMixed fire severity, Surface and crown fires, Recurrence 25-100 yrs

Ponderosa PineOpen, park-like setting w/abundant herbaceous understoryLow-severity firesRecurrence: 5-25 yrs

Fire Regime:

Slide adapted from S. Cannon

Canopy cartoons: T. Swetnam

Photo: Chris O’Conner, Pinaleno MtnsPhoto: Polly HaessigPhoto: Zac Ribbing, Historic Cima Cabins

Removal of natural disturbance:

Unprecedented fuel loadings

Increased stand densities

Extensive, high-severity firesSlide from S. Cannon

… leaving forests devastated With huge canopy holes

Horseshoe 2 Fire, 18 July 2011

WarmEdge

Cave Creek

Nuttall

Willow

Kinishba

Aspen

Bullock

RyanBridgerLone

PerkinsRedington

RattlesnakePiety

Dude

Horseshoe 2

0

50

100

150

200

250

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

Rodeo/Chediski

Wallow

450

500

550

Largest Arizona Wildfires, 1990-2011 (SWCC Historic Data)

222K250K

469K

538K

119K

Area

Bur

ned

(100

0s a

c)

Keeley, Jon E., 2009. Fire intensity, fire severity, and burn severity a brief review and suggested usage. International Journal of Wildland Fire, 18 116-126.

SEVERITY VS. INTENSITY

FireIntensity

Energy released

Fire Severityor

Burn Severity

Organic Matter Loss

EcosystemResponse

ErosionVegetation Recovery

SocietalImpacts

Loss of life or propertySuppression costs

Slide: Deb Martin, USGS Slide: Deb Martin, USGS

Soil Burn Severity

Slide: Deb Martin, USGS Slide: Deb Martin, USGS

Slide: Deb Martin, USGS




2010 Schultz Fire

RAIN

RUNOFFINFILTRATION

STORAGESTORAGE

INFILTRATION

RUNOFF

HYDROLOGIC CYCLE:Runoff = Rainfall – Infiltration – Storage

Unburned watershed Burned watershed

RAIN


61% Interception

Post-fire Hydrologic Changes

20% InterceptionSlide from D. Martin, USGS

Post-fire Runoff

LOSS OFCOVER

RAIN SPLASHIMPACT &

SURFACE SEALING

WATER REPELLENCY& INCREASEDCONNECTIVITY

Garden variety storms can

produce post-fire debris

flows.

Modified from S. Cannon & D. Martin

Water repellency is ubiquitous in the western United States, especially when conditions are dry!


3-8 mm

2-11 mm

Unburned --STORAGE--Burned

CanopyInterception

Litter & Duff

Mineral Soil

Ash ?

Skeletons ?

1-2 mm


Quick review:

Fire Effects on Landscape Susceptibility(particularly water routing)

• Loss of storage

• Surface Sealing

• Fire-induced water repellency

• Change in surface roughness

• Change in connectivity


Photo: Grant Loomis

Slope Effects Runoff Generation

2004 Willow Fire, Arizona

• Increased Runoff on steep slopes = increased erosion• Channels often scour to bedrock => decreased bank or

channel storage• Subsequent storms will have flashier hydrographs

Schultz Fire Channel Scour

Stalagtite--Stalagmite slide

Rainfall peak

Runoff Peaks for Unburned and Burned

Runoff Magnitude and Timing

Time lag

Hyetograph

Hydrograph fromburned watershed

Hydrograph fromunburned watershed

TimeRat

e of

Run

off o

r R

ainf

all


Wallow Fire, 10 Aug 201111.6 mm rainfall, I30= 11 mm hr-1

Video: J. Wagenbrenner

Wallow Fire Peak flows(11 L s-1 km-2 = 1 ft3 s-1 mi-2)

0

1

10

100

1000

10000

0 10 20 30 40 50 60

Peak flow

rate (L s‐

1km

‐2)

I30 (mm hr‐1)

S. Thomas W. Willow N. Thomas

y = 83x ‐ 287R² = 0.80

y = 93x ‐ 308R² = 0.63

y = 51x ‐ 331R² = 0.90

0

1

10

100

1000

10000

0 10 20 30 40 50 60

Peak flow

rate (L s‐

1km

‐2)

I30 (mm hr‐1)


y = 103x ‐ 459R² = 0.69

y = 93x ‐ 308R² = 0.63

y = 37x ‐ 167R² = 0.760

1

10

100

1000

10000

0 10 20 30 40 50 60

Peak flow

rate (L s‐

1km

‐2)

I30 (mm hr‐1)


Pre-fire maxima

1-yr I30

Slide: J. Wagenbrenner

POST-FIRE PEAKFLOWS

How do you visualize that?

After the 2011 Wallow Fire Wagenbrenner et al. found a 5 – 18X increase in runoff after THAN UNBURNED (Neary et al. 2005)

Runoff from Burned WatershedsA function of:

• HEAT (effects quantified as BURN SEVERITY)– Loss of soil cover (storage + protection)– Changes to soil (fire-induced water repellency)

• SLOPE, GEOLOGY

• WHAT HAPPENS AFTER THE FIRE(sequence, magnitude, and location

of rain events)





2010 Schultz Fire

Why do we care about post-fire flooding and

erosion?• Loss of soil resources• Effects on humans and

infrastructure• Effects on water quality and

aquatic ecosystems

Left Photos: USFS

Photo: Chris Stewart, USFS, 10 July 2011, Miller Canyon

High frequency (

Post-fire flow in CA Non post-fire debris flow but important to see

Burned Willow Fire watersheds along SR87 after July 23, 2004, storm

Compared NWS-Mt Ord ALERT gage; Radar over estimated ~30% Radar rainfall estimates over SR-87 basins = ~2-2.5”

Reduces to ~1.4-1.75”/hr NOAA Atlas 14 = 2- to 5-yrs

Post-Aspen Fire Flood in Romero Canyon

Photo: Dave & Sally Clement, Dec 2002 August

21, 2004

Post-fire flood event on July 24, 2003

Aspen FireJune 17 to

July 14, 2003

Start End Ttotal P (in) I30 Est I60 Est Storm TotalGreen Mountain 6:15 PM 6:55 PM 0:40:05 2.24 2.17 1‐1.25 1.5‐2White Tail 6:21 PM 7:17 PM 0:56:07 2.17 1.81 0.5‐0.75 1.5‐2Mt. Lemmon 6:35 PM 7:37 PM 1:02:24 0.91 0.74 0.75‐1.25 1.5‐2Cargodera Canyon 6:42 PM 7:31 PM 0:49:09 1.42 1.14 2‐2.5 2‐3

NWS Radar DataALERT Rain Gauge DataRain Gauge

Photo: Dave and Sally Clement

Post-Aspen Fire Flood in Romero CanyonRadar 2.35” basin average 1-hour rainfall 63% radar-indicated precip reached ALERT gages0.85 correction factor = 2.00” adj basin ave 1-hour rainfall~80% fell within 30 min = 1.60” adj basin ave 30-min rainfallNOAA Atlas 14 = 10 yr 30-min basin ave pptn freq

Post-Aspen Fire Flood in Romero Canyon

• Hydrologic Modelling

– Largest Predicted Qp100 (COT) 6,500 cfs• Aerially reduced 100-yr, 1-hr rainfall depth

= 2.53 “/hr (M. Zeller)

– Indirect Discharge Estimates• HEC-RAS from 5 surveyed cross-sections• Qp 8,000-10,000 cfs

Modified from House, P.K., and Baker, V.R., 2001, Paleohydrology of flash floods in small desert watersheds in western Arizona: Water Resources Research, v. 37, p. 1825-1839.

Quick review:Post-fire floods and debris flows:

• Can be generated from high frequency, low magnitude (garden variety) storms

• Flood magnitudes can be many magnitudes greater than pre-fire flows (documented up to 900x greater)

• Debris flows are very destructive and tend to occur quickly after a storm starts

• Antecedent soil moisture is typically not a factor in generating these flows




2010 Schultz Fire

A Rogues’ Gallery ofPost-Fire

Response

A

DC

B

FE

G

Source: Moody and Martin, 2009, Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States, IJWF. Slide: Deb Martin, USGS

Rainfall regimes based on rainfall types associated with different air masses and rainfall intensities based on a 2-yr 30-min storm. Photo:

UofA Tree Ring Lab

CHANNEL EROSION

RR: Arizona, high

VOLCANICRattlesnake Fire

Chiricahua MountainsArizona

A


HILLSLOPE EROSION

(Rainsplash Impact)

RR: Arizona, medium

VOLCANICCerro Grande Fire

New MexicoB


HILLSLOPE EROSION

CHANNEL EROSION

RR: Arizona, medium

VOLCANICCerro Grande Fire

New MexicoB


Photos: Sue Cannon and Deb Martin

CHANNEL EROSION and DEPOSITION (Debris Flow)

RR: Arizona, medium

SEDIMENTARYMissionary Ridge Fire

ColoradoC


HILLSLOPE EROSIONHILLSLOPE DEPOSITION

RR: Plains, medium

GRANITICBuffalo Creek Fire

ColoradoD


Photos:USFS

CHANNEL EROSIONCHANNEL DEPOSITION

RR: Plains, medium


ColoradoD


CHANNEL DEPOSITION: (Alluvial Fan Formation)

RR: Plains, medium


ColoradoD


HILLSLOPE EROSIONCHANNEL EROSIONRR: Sub-Pacific, low

GRANITICIdaho Batholith“Rain-on-snow”

E


CHANNEL EROSIONCHANNEL DEPOSITION (Debris Flow)

RR: Sub-Pacific, low

GRANITICIdaho Batholith

D


CHANNEL DEPOSITION(Alluvial Fan Formation)


GRANITICIdaho Batholith

D


Photos thanks to Joshua RoeringUniv. of Oregon

SURFACE EROSIONRR: Pacific, medium

(Dry Ravel)50% of sediment released

within 24 hours

SEDIMENTARYOregon Coast Range

F


HILLSLOPE EROSIONCHANNEL DEPOSITION


GRANITICMojave National Monument

CaliforniaG


SEDIMENTARYVaseax Lake Fire

Canada

CHANNEL EROSIONCHANNEL DEPOSITION


CHANNEL EROSION and DEPOSITION (Debris Flow)

RR: Arizona, extreme

Volcanic1977 Carr Fire and 2011 Monument Fire

Arizona

Photo: USFS, 1977 CHANNEL EROSION and DEPOSITION (Debris Flow)

RR: Arizona, medium

Volcanic2011 Schultz Fire

Arizona1

2

3

12

3

HILLSLOPE EROSION RR: Arizona, medium

Volcanic2011 Schultz Fire

Arizona

Quick review:Effects of rainfall and geology on

Landscape Susceptibility

• Rain is not the same everywhere

• Rainfall intensity, timing and storm type influence erosion

• Geology plays a key role in post-fire erosion

• ~20% of post-fire eroded sediment comes from hillslopes, the rest from channels




2010 Schultz Fire

WATER QUALITY EFFECTS OF FIRE

• Gasses

• Sediment

• Fire retardants/fire suppression chemicals

• ASH and partially burned organic matter

Photo: Randall A. Smith, USFSCoronado National Forest

Aspen FireArizona


Photo: Clear Creek Fire 2000, Salmon-Challis NFMany thanks to Jason Dunham, USFS

Input of particulates and gasseswhile fire is burning

Slide: Deb Martin, USGSSlide from Bob Gresswell, USGS

Use of fire retardants


Sediment Is Major Water-quality Issue

Photo: John Moody, USGSSlide: Deb Martin, USGS

Buffalo Creek Fire: Coarse organic debris etc.


ASH is another major water quality issuePikes Peak YMCA Camp, Four Mile Creek

Photo by Greg Smith, USGS, CWSCSlide: Deb Martin, USGS

ASH chemistry is a function of:

• Type of vegetation• Underlying geology

• Temperature and duration of heat pulse

• Atmospheric deposition– Short term– Long-term– Long-range


Post-Aspen Fire Floodinghttp://sabinocanyon.org/aspenimages.htl

http://www.azstarnet.com/wildfire/30724FIRE2fBELOW2fSABINO2fpmb.html

2003

2004

Slide: S. E. Desilets

Cs = a Qb

Monsoon 2003

Suspended sediment rating curves

AshRemoval

Intercept

Slope


Cs = a Qb

Monsoon 2003

Monsoon 2004

Winter 03-04

Winter 04-05


Suspended sediment rating curves

Seasonally different runoff-Generating mechanisms

Movement of elements during fire:

KSMOKEVOLATILIZATION

ASH CONVECTION

ASH REDEPOSITION

C, N

P

K, P, SP

ASH LEFT IN-SITU

K, Na, Mn,P, N, C, S

Delmas, 1982; Raison and others, 1985a, 1985b, 1990; Caldwell and others, 2002

Ca, Mg

K, Ca, Mg, C

K, Ca, Mg, C

Slide by Sheila Murphy, USGS

After fire:

WIND EROSION

LEACHING

Delmas, 1982; Raison and others, 1985a, 1985b, 1990; Caldwell and others, 2002

K, Na, Mg,P, N, C, S

CaUPTAKE BYNEW PLANTS

C, K, Na, Mg, S, Mn

N

RUNOFF

K, Na, Mg,C, S, Mn

N

Slide by Sheila Murphy, USGS

Water quality variables most affected by fire:

Short term:• Discharge• Temperature• Dissolved oxygen• Turbidity and TSS• Nitrate• Phosphorus• Total organic carbon• Manganese• Mercury

Longer term:• Discharge• Turbidity and TSS• Nitrate• Total organic carbon• Mercury

See presentation by Steve Lohman, Denver Water Department“Fire Effects at Treatment Plants”Slide: Deb Martin, USGS

-increased solar radiation

-increased water temperatures

-change in water chemistry including ASH

-increased erosion and sedimentation

- increased water yields

Wildfire Effects on Aquatic Environments

Example from the 1996 Buffalo Creek Fire

Slide from Bob Gresswell, USGS

Effects on stream shading depends on stream order

Second order

Fourth order

Quick review:Fire effects on water quality

• Magnitude and timing of peak flows changes with fire

• Surface sealing is major factor determining runoff in granitic environments [and elsewhere]

• Sediment is main water quality effect

• Chemistry of ash is function of type of vegetation, heat, underlying geology, legacy of atmospheric deposition

• Watershed size and %burned matters




2010 Schultz Fire

Wildfires

(and other disturbances)

Leave

a

Geomorphic

Legacy


Disturbance and Temporal Scales• Monthy (immediately following the fire)• Decadal• Centennial• Millennial• Millions of years


“Baseflow “ Sediment Yield

Fire-Induced “Accelerated” Sediment Yield

Sedi

men

t Yie

ld

TIME After Swanson, 1981FIRE

Sediment Response to Fire

Post-fire Effects: Time


“Punctuated Sediment Supply”(Benda and Dunne, 1997 a,b)

Also called “pulsed disturbance”

FIRE FIRE FIRE

Sedi

men

t Yie

ld

TIME After Swanson, 1981Slide: Deb Martin, USGS

Immediately after fires –trampoline channels

Aspen Fire, Lower Romero CanyonMonthly: 10/03 – 3/04 Marshall Canyon Debris Fan, July – September, 2011

View up-fan to the apex and channel. July 11, 2011

August 3, 2011

September 1, 2011

Monument Fire

Decadal Time Scale: 1996-2005Spring Creek Watershed


Spring Creek Channel RecoveryMouth at confluence with the

South Platte River

1997

2001

2003


Spring Creek Channel RecoveryCross Section 550

1998

2000

2003Slide: Deb Martin, USGS

Chiricahua – 1994 Rattlesnake Fire

7?

123 45

6

7?

123

4

5

6

8-10 m 3-4 m

~2 m

1996

2004

Photo UofA Tree Ring Lab (photo from 1996 but erosion occurred during the monsoon after the fire in 1994)

Photo: Phil Pearthree

Decadal: 1996-2011

June 2011

SEDIMENT:

1/3 in reservoir

2/3 still in watershed

RESIDENCE TIME300 YEARS

Decadal → Centennial Time Scale


Centennial Time Scale: 1800’s – 1900’sSpring Creek Watershed


Modern view: More (burned) trees!!

Slide: Deb Martin, USGSPhoto by Bob Meade

~100 years BP

~1,030 years BP

~2,900 years BP

~1,970 years BP

~950 years BP

~1,020 years BP

Elliott and Parker, 2001

Millennial Time ScaleBuffalo Creek Watershed


So what does this mean for “Watershed Recovery”?

“Post-fire recovery in ~3-5 years”What Does Recovery Mean?

Vegetation + ~pre-fire Qp levels = Recovery??What about riparian zones?Sediment pulses and channel conditions?

Cerro Grande Watershed…major flooding 3 yrs later.Hayman Fire…major flooding 8 yrs later.

YEAR 1

YEAR 3

Photo:John Hogan

Photo:Thomas Trujillo

Hydrological response of burned watersheds:Cerro Grande Fire


Post-fire RecoveryDeclines in post-fire sedimentation if a function of:

• McDonald, L.H. Robichaud, P.R. 2008, Post-fire erosion and the effectiveness of emergency rehabilitation treatments over time, Stream Notes, Rocky Mountain Research Station, 1-6

• Soil Texture• %bare soil• Rainfall

Intensity

Post-fire Recovery


• 2-5 yrs - hillslope runoff rates ~background levels

• Qp also declines decreasing entrainment and transport capacity

• How long before aggraded channels recover?


Campo BonitoAugust 14, 2003, 1 mo after containment of Aspen Fire 1.51” in 30 min, RI = 10 yr, 30 minOne deathQp = 1,900 cfs

Sept 1, 2005 Longer duration stormSimilar 30-minute intensityQp = 680 cfs

Possible Effects of Climate Change on Post-fire Erosion

• “Bigger, hotter fires”, i.e. greater extent of high severity areas

• Extensive areas of tree mortality from insects and drought -> stand-replacing fires

• As more precipitation falls as rain instead of snow, larger window for erosion

• Higher rainfall intensitiesSlide: Deb Martin, USGS

How can information about potential for post-fire erosion inform pre-fire management

• Pre-fire fuel reduction• Pre-fire planning

– Permits for debris/sediment basins– Strategies for closing intakes and diverting

fire-affected water– Pre-disaster mitigation; floodplain planning,

building code and ordinance updating– Land-use decisions


Conclusions• Fires trends increasing in size and severity• Fires significantly change basin hydrology• Rainfall regimes and geology influence

post-fire erosion• Different components of the watershed

recover at different rates– Veg Recovery ≠ Hydrologic Recovery– Veg + Hydro Recovery ≠ Ecosystem or Riparian

Recovery– Sediment pulses

Photo: D. Greenspan, Schultz Fire from Humphrey's Peak

Acknowledgements

Photo: Zac Ribbing, Cima Historical Cabins

Deb Martin, USGS Jim Washburn, UofAKarletta Chief, UofA Joe Wagenbrenner, RMRSSue Cannon, USGS Phil Pearthree, AZGSJohn Moody, USGS Jess Clark, RSACSharon DesiletsKaren Koestner, RMRSDan Neary, RMRS

Online resources• Inciweb.org• GeoMac• Google Earth• GeoSetter (http://www.geosetter.de/en/)• USGS Watersheds

(http://water.usgs.gov/GIS/huc.html)• NOAA Atlas 14

http://dipper.nws.noaa.gov/hdsc/pfds/• GeoSetter http://www.geosetter.de/en/

My Contact Info

Ann YoubergResearch GeologistArizona Geological Survey416 W Congress, Suite 100Tucson, Arizona [email protected]

Documents

Geomorphic Responses of Burned Outline Watersheds in ...web.sahra.arizona.edu/education2/wrtt/lecs/Youberg_Intro...reloaded since 1977 and had enough sediment for debris flows in 2011