Geomorphic Responses of Burned Outline Watersheds in...
Transcript of Geomorphic Responses of Burned Outline Watersheds in...
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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
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250
1990
1991
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2003
2004
2005
2006
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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)
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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
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
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RAIN
RUNOFFINFILTRATION
STORAGESTORAGE
INFILTRATION
RUNOFF
HYDROLOGIC CYCLE:Runoff = Rainfall – Infiltration – Storage
Unburned watershed Burned watershed
RAIN
Slide: Deb Martin, USGS
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!
Slide: Deb Martin, USGS
3-8 mm
2-11 mm
Unburned --STORAGE--Burned
CanopyInterception
Litter & Duff
Mineral Soil
Ash ?
Skeletons ?
1-2 mm
Slide: Deb Martin, USGS
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
Slide: Deb Martin, USGS
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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
Slide: Deb Martin, USGS
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)
S. Thomas W. Willow N. Thomas
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)
S. Thomas W. Willow N. Thomas
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)
Slide: Deb Martin, USGS
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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
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 (
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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.
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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
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
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
Slide: Deb Martin, USGS
HILLSLOPE EROSION
(Rainsplash Impact)
RR: Arizona, medium
VOLCANICCerro Grande Fire
New MexicoB
Slide: Deb Martin, USGS
HILLSLOPE EROSION
CHANNEL EROSION
RR: Arizona, medium
VOLCANICCerro Grande Fire
New MexicoB
Slide: Deb Martin, USGS
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Photos: Sue Cannon and Deb Martin
CHANNEL EROSION and DEPOSITION (Debris Flow)
RR: Arizona, medium
SEDIMENTARYMissionary Ridge Fire
ColoradoC
Slide: Deb Martin, USGS
HILLSLOPE EROSIONHILLSLOPE DEPOSITION
RR: Plains, medium
GRANITICBuffalo Creek Fire
ColoradoD
Slide: Deb Martin, USGS
Photos:USFS
CHANNEL EROSIONCHANNEL DEPOSITION
RR: Plains, medium
GRANITICBuffalo Creek Fire
ColoradoD
Slide: Deb Martin, USGS
CHANNEL DEPOSITION: (Alluvial Fan Formation)
RR: Plains, medium
GRANITICBuffalo Creek Fire
ColoradoD
Slide: Deb Martin, USGS
HILLSLOPE EROSIONCHANNEL EROSIONRR: Sub-Pacific, low
GRANITICIdaho Batholith“Rain-on-snow”
E
Slide: Deb Martin, USGS
CHANNEL EROSIONCHANNEL DEPOSITION (Debris Flow)
RR: Sub-Pacific, low
GRANITICIdaho Batholith
D
Slide: Deb Martin, USGS
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CHANNEL DEPOSITION(Alluvial Fan Formation)
RR: Sub-Pacific, low
GRANITICIdaho Batholith
D
Slide: Deb Martin, USGS
Photos thanks to Joshua RoeringUniv. of Oregon
SURFACE EROSIONRR: Pacific, medium
(Dry Ravel)50% of sediment released
within 24 hours
SEDIMENTARYOregon Coast Range
F
Slide: Deb Martin, USGS
HILLSLOPE EROSIONCHANNEL DEPOSITION
RR: Sub-Pacific, low
GRANITICMojave National Monument
CaliforniaG
Slide: Deb Martin, USGS
SEDIMENTARYVaseax Lake Fire
Canada
CHANNEL EROSIONCHANNEL DEPOSITION
Slide: Deb Martin, USGS
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
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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
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
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
Slide: Deb Martin, USGS
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
Slide: Deb Martin, USGS
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Sediment Is Major Water-quality Issue
Photo: John Moody, USGSSlide: Deb Martin, USGS
Buffalo Creek Fire: Coarse organic debris etc.
Slide: Deb Martin, USGS
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
Slide: Deb Martin, USGS
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
Slide: S. E. Desilets
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Cs = a Qb
Monsoon 2003
Monsoon 2004
Winter 03-04
Winter 04-05
Slide: S. E. Desilets
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
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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
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
Wildfires
(and other disturbances)
Leave
a
Geomorphic
Legacy
Slide: Deb Martin, USGS
Disturbance and Temporal Scales• Monthy (immediately following the fire)• Decadal• Centennial• Millennial• Millions of years
Slide: Deb Martin, USGS
“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
Slide: Deb Martin, USGS
“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
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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
Slide: Deb Martin, USGS
Spring Creek Channel RecoveryMouth at confluence with the
South Platte River
1997
2001
2003
Slide: Deb Martin, USGS
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
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SEDIMENT:
1/3 in reservoir
2/3 still in watershed
RESIDENCE TIME300 YEARS
Decadal → Centennial Time Scale
Slide: Deb Martin, USGS
Centennial Time Scale: 1800’s – 1900’sSpring Creek Watershed
Slide: Deb Martin, USGS
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
Slide: Deb Martin, USGS
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
Slide: Deb Martin, USGS
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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
• 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
• 2-5 yrs - hillslope runoff rates ~background levels
• Qp also declines decreasing entrainment and transport capacity
• How long before aggraded channels recover?
• 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
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
Slide: Deb Martin, USGS
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
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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]