Geomorphic Responses of Burned Watersheds in the Modern Fire Regime: Floods, Debris Flows and Long-Term Recovery. Fire Regimes: Tree Ring Data

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Erica Moody
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Trends Post-fire Hydrologic Changes Post-fire Geomorphic Responses

Water Quality Post-fire Disturbance Regimes and implications for

Ribbing Horseshoe 2 Fire June 8 th, 2011 2010 Schultz Fire Fire

Spruce-fir Patch mosaic w/stands of varying ages High-severity,

conifer-aspen Complex variations in species composition and stand ages

Swetnam, Bandelier NM Ponderosa Pine Open, park-like setting w/abundant

Zac Polly Chris Ribbing, Haessig O Conner, Historic Pinaleno CimaMtns

Swetnam Fire scar on Ponderosa pine snag Swetnam, Thomas W.

rings, PAGES News, 10(1), 6-9. Slide adapted from S.

huge canopy holes Unprecedented fuel loadings Increased stand densities

Cannon Horseshoe 2 Fire, 18 July 2011 Area Burned (1000s ac) Largest

150 100 50 0 Piety Dude Rattlesnake Lone Bridger Perkins Redington

1 Geomorphic Responses of Burned Watersheds in the Modern Fire Regime: Floods, Debris Flows and Long-Term Recovery 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 Ann Youberg Arizona Geological Survey Photo: Zac Ribbing Horseshoe 2 Fire June 8 th, Schultz Fire Fire Regimes: Tree Ring Data Fire Regimes: Pre-settlement Fire Regime: Spruce-fir Patch mosaic w/stands of varying ages High-severity, stand-replacing fires Recurrence: yrs Elevation Mixed conifer-aspen Complex variations in species composition and stand ages Mixed fire severity, Surface and crown fires, Recurrence yrs T. Swetnam, Bandelier NM Ponderosa Pine Open, park-like setting w/abundant herbaceous understory Low-severity fires Recurrence: 5-25 yrs Photo: Zac Polly Chris Ribbing, Haessig O Conner, Historic Pinaleno CimaMtns Cabins Canopy cartoons: T. Swetnam 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. Slide adapted from S. Cannon Removal of natural disturbance: leaving forests devastated With huge canopy holes Unprecedented fuel loadings Increased stand densities Extensive, high-severity fires Slide from S. Cannon Horseshoe 2 Fire, 18 July 2011 Area Burned (1000s ac) Largest Arizona Wildfires, (SWCC Historic Data) Piety Dude Rattlesnake Lone Bridger Perkins Redington Aspen Ryan Bullock 469K Rodeo/Chediski Wallow Cave Creek 250K Horseshoe 2 222K 119K Willow Edge Warm Nuttall Kinishba K

SEVERITY VS. INTENSITY Soil Burn Severity Keeley, Jon E., 2009.

usage. International Journal of Wildland Fire, 18 116-126.

Organic Matter Loss Erosion Vegetation Recovery Societal Impacts Loss of life or

Changes Post-fire Geomorphic Responses Post-Fire Erosion and Rainfall Regimes

2 SEVERITY VS. INTENSITY Soil Burn Severity Keeley, Jon E., Fire intensity, fire severity, and burn severity a brief review and suggested usage. International Journal of Wildland Fire, Ecosystem Response Fire Intensity Energy released Fire Severity or Burn Severity Organic Matter Loss Erosion Vegetation Recovery Societal Impacts Loss of life or property Suppression costs 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

RAIN SPLASH IMPACT & SURFACE SEALING WATER

3 HYDROLOGIC CYCLE: Runoff = Rainfall Infiltration Storage Post-fire Hydrologic Changes RAIN RAIN STORAGE INFILTRATION RUNOFF RUNOFF STORAGE Unburned watershed INFILTRATION Burned watershed 61% 20% Interception Slide from D. Martin, USGS LOSS OF COVER Post-fire Runoff Garden variety storms can produce postfire debris flows. Water repellency is ubiquitous in the western United States, especially when conditions are dry! RAIN SPLASH IMPACT & SURFACE SEALING WATER REPELLENCY & INCREASED CONNECTIVITY Modified from S. Cannon & D. Martin Unburned --STORAGE--Burned Quick review: Fire Effects on Landscape Susceptibility (particularly water routing) Canopy Interception 3-8 mm Skeletons? Loss of storage Surface Sealing 1-2 mm Fire-induced water repellency 2-11 mm Litter & Duff Ash? Change in surface roughness Mineral Soil Change in connectivity

Slope Effects Runoff Generation Photo: Grant Loomis 2004 Willow Fire, Arizona Schultz Fire Channel Scour Increased

Subsequent storms will have flashier hydrographs Rate of Runoff or Rainfall Runoff Magnitude and Timing Hyetograph

watershed Time Hydrograph from unburned watershed Wallow Fire, 10 Aug 2011 11.

-1 km -2 = 1 ft 3 s -1 mi -2 ) S. Thomas W. Willow N. Thomas 1-yr I 30 Pre-fire maxima y y = 103x 83x 287 459 R² = 0.

Wagenbrenner Slide: J. Wagenbrenner POST-FIRE PEAKFLOWS 0-900 TIMES > THAN UNBURNED (Neary et al.

found a 5 18X increase in runoff after <1 yr storms How do you visualize that?

4 Slope Effects Runoff Generation Photo: Grant Loomis 2004 Willow Fire, Arizona Schultz Fire Channel Scour Increased Runoff on steep slopes = increased erosion Channels often scour to bedrock => decreased bank or channel storage Subsequent storms will have flashier hydrographs Rate of Runoff or Rainfall Runoff Magnitude and Timing Hyetograph Stalagtite--Stalagmite slide Rainfall peak Time lag Runoff Peaks for Unburned Hydrograph and from Burned burned watershed Time Hydrograph from unburned watershed Wallow Fire, 10 Aug mm rainfall, I 30 = 11 mm hr -1 Peak flow rate (L s 1 km 2 ) Wallow Fire Peak flows (11 L s -1 km -2 = 1 ft 3 s -1 mi -2 ) S. Thomas W. Willow N. Thomas 1-yr I 30 Pre-fire maxima y y = 103x 83x R² = y = 93x 308 R² = 0.63 y = 37x 51x R² = I 30 (mm hr 1 ) Video: J. Wagenbrenner Slide: J. Wagenbrenner POST-FIRE PEAKFLOWS TIMES > THAN UNBURNED (Neary et al. 2005) After the 2011 Wallow Fire Wagenbrenner et al. found a 5 18X increase in runoff after <1 yr storms How do you visualize that? Runoff from Burned Watersheds A function of: HEAT (effects quantified as BURN SEVERITY) Loss of soil cover (storage + protection) Changes to soil (fire-induced water repellency) SLOPE, GEOLOGY UnBurned Burned WHAT HAPPENS AFTER THE FIRE (sequence, magnitude, and location of rain events)

Outline Fire Regimes and Trends Post-fire Hydrologic Changes Post-fire

US Post-fire Water Quality Post-fire Disturbance Regimes and implications for

Loss of soil resources Effects on humans and infrastructure Effects on water

Geomorphic Responses High frequency (<1-5 RI), low magnitude storms can result

64 in an hour (2-yr, 60 minute storm) Peak 15-minute intensity = 0.

36 (2-yr RI) Miller Canyon, 10 July 2011 Photo: Chris Stewart, USFS, 10 July

debris flows (this same canyon had debris flows after the 1977 Carr Fire)

6 rainfall in ~1 hr (2 yr storm) First significant monsoon rain debris flows

July 2011 scour to bedrock in larger channels Post-fire debris flows: intense

5 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 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 2010 Schultz Fire Left Photos: USFS Post-fire Geomorphic Responses High frequency (<1-5 RI), low magnitude storms can result in tremendous post-fire responses. On this day Miller Canyon received 1.64 in an hour (2-yr, 60 minute storm) Peak 15-minute intensity = 0.92 Peak 30-minute intensity = 1.36 (2-yr RI) Miller Canyon, 10 July 2011 Photo: Chris Stewart, USFS, 10 July 2011, Miller Canyon Miller Canyon, 10 July 2011 July 10, 2011 Marshal Canyon debris flows (this same canyon had debris flows after the 1977 Carr Fire) Other Miller Canyon debris flows 1.6 rainfall in ~1 hr (2 yr storm) First significant monsoon rain debris flows initiate in channels on steep, severely burned hillslopes Miller Canyon, 10 July 2011 scour to bedrock in larger channels Post-fire debris flows: intense runoff channel bank failure channel scour deposit coarse boulder fans Damage to Beatty s and Tombstone water pipe (again) Marshall Canyon channel reloaded since 1977 and had enough sediment for debris flows in 2011.

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

storm Post-Aspen Fire Flood in Romero Canyon Aspen Fire June 17

flood event on July 24, 2003 August 21, 2004 Compared NWS-Mt Ord

over SR-87 basins = ~2-2.5 Reduces to ~1.4-1.

Data NWS Radar Data Start End T total P (in) I 30 Est I 60 Est

25 1.5 2 White Tail 6:21 PM 7:17 PM 0:56:07 2.17 1.81 0.5 0.75 1.

5 2 Cargodera Canyon 6:42 PM 7:31 PM 0:49:09 1.42 1.14 2 2.

35 basin average 1-hour rainfall 63% radar-indicated precip

00 adj basin ave 1-hour rainfall ~80% fell within 30 min = 1.

basin ave pptn freq Post-Aspen Fire Flood in Romero Canyon

Aerially reduced 100-yr, 1-hr rainfall depth = 2.53 /hr (M.

cross-sections Q p 8,000-10,000 cfs Modified from House, P.K.

6 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 Post-Aspen Fire Flood in Romero Canyon Aspen Fire June 17 to July 14, 2003 Photo: Dave & Sally Clement, Dec 2002 Post-fire flood event on July 24, 2003 August 21, 2004 Compared NWS-Mt Ord ALERT gage; Radar over estimated ~30% Radar rainfall estimates over SR-87 basins = ~2-2.5 Reduces to ~ /hr NOAA Atlas 14 = 2- to 5-yrs Rain Gauge ALERT Rain Gauge Data NWS Radar Data Start End T total P (in) I 30 Est I 60 Est Storm Total Green Mountain 6:15 PM 6:55 PM 0:40: White Tail 6:21 PM 7:17 PM 0:56: Mt. Lemmon 6:35 PM 7:37 PM 1:02: Cargodera Canyon 6:42 PM 7:31 PM 0:49: Post-Aspen Fire Flood in Romero Canyon Radar 2.35 basin average 1-hour rainfall 63% radar-indicated precip reached ALERT gages 0.85 correction factor = 2.00 adj basin ave 1-hour rainfall ~80% fell within 30 min = 1.60 adj basin ave 30-min rainfall NOAA Atlas 14 = 10 yr 30-min basin ave pptn freq Post-Aspen Fire Flood in Romero Canyon Hydrologic Modelling Largest Predicted Q p100 (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 Q p 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 Photo: Dave and Sally Clement

Quick review: Post-fire floods and debris flows: Can be generated from

can be many magnitudes greater than pre-fire flows (documented up to

quickly after a storm starts Antecedent soil moisture is typically not

Post-fire Hydrologic Changes Post-fire Geomorphic Responses Post-Fire

Quality Post-fire Disturbance Regimes and implications for Watershed

D C B VOLCANIC Rattlesnake Fire Chiricahua Mountains Arizona A Rainfall

and rainfall intensities based on a 2-yr 30-min storm.

wildland fire in different rainfall regimes in the western United

A Photo: UofA Tree Ring Lab CHANNEL EROSION RR: Arizona, high VOLCANIC

7 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 of Post-Fire Response F G E D C B VOLCANIC Rattlesnake Fire Chiricahua Mountains Arizona A Rainfall regimes based on rainfall types associated with different air masses and rainfall intensities based on a 2-yr 30-min storm. Source: Moody and Martin, 2009, Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States, IJWF. A Photo: UofA Tree Ring Lab CHANNEL EROSION RR: Arizona, high VOLCANIC Cerro Grande Fire New Mexico B VOLCANIC Cerro Grande Fire New Mexico B HILLSLOPE EROSION (Rainsplash Impact) RR: Arizona, medium HILLSLOPE EROSION CHANNEL EROSION RR: Arizona, medium

8 SEDIMENTARY Missionary Ridge Fire Colorado C CHANNEL EROSION and DEPOSITION (Debris Flow) RR: Arizona, medium GRANITIC Buffalo Creek Fire Colorado D HILLSLOPE EROSION HILLSLOPE DEPOSITION Photos: Sue Cannon and Deb Martin RR: Plains, medium GRANITIC Buffalo Creek Fire Colorado D GRANITIC Buffalo Creek Fire Colorado D CHANNEL EROSION CHANNEL DEPOSITION RR: Plains, medium CHANNEL DEPOSITION: (Alluvial Fan Formation) RR: Plains, medium Photos: USFS GRANITIC Idaho Batholith Rain-on-snow GRANITIC Idaho Batholith D E HILLSLOPE EROSION CHANNEL EROSION RR: Sub-Pacific, low CHANNEL EROSION CHANNEL DEPOSITION (Debris Flow) RR: Sub-Pacific, low

9 GRANITIC Idaho Batholith D SEDIMENTARY Oregon Coast Range F CHANNEL DEPOSITION (Alluvial Fan Formation) RR: Sub-Pacific, low SURFACE EROSION RR: Pacific, medium (Dry Ravel) 50% of sediment released within 24 hours Photos thanks to Joshua Roering Univ. of Oregon GRANITIC Mojave National Monument California G SEDIMENTARY Vaseax Lake Fire Canada CHANNEL EROSION CHANNEL DEPOSITION HILLSLOPE EROSION CHANNEL DEPOSITION RR: Sub-Pacific, low Volcanic 1977 Carr Fire and 2011 Monument Fire Arizona Volcanic 2011 Schultz Fire Arizona CHANNEL EROSION and DEPOSITION (Debris Flow) RR: Arizona, extreme Photo: USFS, 1977 CHANNEL EROSION and DEPOSITION (Debris Flow) RR: Arizona, medium 1 2 3

Volcanic 2011 Schultz Fire Arizona HILLSLOPE EROSION RR:

geology on Landscape Susceptibility Rain is not the same

influence erosion Geology plays a key role in post-fire

hillslopes, the rest from channels Outline Fire Regimes

Geomorphic Responses Post-Fire Erosion and Rainfall

Post-fire Disturbance Regimes and implications for

EFFECTS OF FIRE Gasses Sediment Fire retardants/fire

matter Aspen Fire Arizona Photo: Randall A.

particulates and gasses while fire is burning Use of

10 Volcanic 2011 Schultz Fire Arizona HILLSLOPE EROSION RR: Arizona, medium 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 Aspen Fire Arizona Photo: Randall A. Smith, USFS Coronado National Forest Input of particulates and gasses while fire is burning Use of fire retardants Photo: Clear Creek Fire 2000, Salmon-Challis NF Many thanks to Jason Dunham, USFS Slide from Bob Gresswell, USGS

vegetation Underlying geology Temperature

CWSC http://sabinocanyon.org/aspenimages.

Suspended sediment rating curves Monsoon

11 Sediment Is Major Water-quality Issue Buffalo Creek Fire: Coarse organic debris etc. Photo: John Moody, USGS ASH is another major water quality issue Pikes Peak YMCA Camp, Four Mile Creek 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 Photo by Greg Smith, USGS, CWSC Post-Aspen Fire Flooding 2003 Suspended sediment rating curves Monsoon Ash Removal Intercept Slope C s = a Q b Slide: S. E. Desilets Slide: S. E. Desilets

Suspended sediment rating curves Movement of elements during fire: Monsoon 2003

mechanisms C s = a Q b SMOKE P K, Ca, Mg, C ASH REDEPOSITION ASH CONVECTION P K, Ca,

1990; Caldwell and others, 2002 After fire: Slide by Sheila Murphy, USGS WIND EROSION

Mg, C, S, Mn RUNOFF Delmas, 1982; Raison and others, 1985a, 1985b, 1990; Caldwell and

Temperature Dissolved oxygen Turbidity and TSS Nitrate Phosphorus Total organic carbon

carbon Mercury See presentation by Steve Lohman, Denver Water Department Fire Effects

radiation -increased water temperatures -change in water chemistry including ASH

12 Suspended sediment rating curves Movement of elements during fire: Monsoon 2003 Monsoon 2004 Winter Winter Seasonally different runoff- Generating mechanisms C s = a Q b SMOKE P K, Ca, Mg, C ASH REDEPOSITION ASH CONVECTION P K, Ca, Mg, C K ASH LEFT IN-SITU VOLATILIZATION Ca, Mg K, Na, Mn, P, N, C, S C, N K, P, S Slide: S. E. Desilets Slide by Sheila Murphy, USGS Delmas, 1982; Raison and others, 1985a, 1985b, 1990; Caldwell and others, 2002 After fire: Slide by Sheila Murphy, USGS WIND EROSION UPTAKE BY NEW PLANTS N C, K, Na, Mg, S, Mn Ca K, Na, Mg, P, N, C, S LEACHING N K, Na, Mg, C, S, Mn RUNOFF Delmas, 1982; Raison and others, 1985a, 1985b, 1990; Caldwell and others, 2002 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 Wildfire Effects on Aquatic Environments -increased solar radiation -increased water temperatures -change in water chemistry including ASH -increased erosion and sedimentation Fourth order Effects on stream shading depends on stream order - increased water yields Example from the 1996 Buffalo Creek Fire Second order Slide from Bob Gresswell, USGS

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

13 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 Disturbance and Temporal Scales Monthy (immediately following the fire) Decadal Centennial Millennial Millions of years Post-fire Effects: Time Sediment Response to Fire Punctuated Sediment Supply (Benda and Dunne, 1997 a,b) Also called pulsed disturbance Fire-Induced Accelerated Sediment Yield Sediment Yield FIRE Baseflow Sediment Yield Sediment Yield FIRE FIRE FIRE TIME After Swanson, 1981 TIME After Swanson, 1981

14 Aspen Fire, Lower Romero Canyon Monthly: 10/03 3/04 Immediately after fires trampoline channels Monument Fire Marshall Canyon Debris Fan, July September, 2011 View up-fan to the apex and channel. July 11, 2011 August 3, 2011 September 1, 2011 Decadal Time Scale: Spring Creek Watershed Spring Creek Channel Recovery Mouth at confluence with the South Platte River Spring Creek Channel Recovery Cross Section Chiricahua 1994 Rattlesnake Fire ~2 m ? 8-10 m 3-4 m Decadal: ? Photo: Phil Pearthree 2003 Photo UofA Tree Ring Lab (photo from 1996 but erosion occurred during the monsoon after the fire in 1994) June 2011

Decadal Centennial Time Scale Centennial Time Scale: 1800

reservoir 2/3 still in watershed RESIDENCE TIME 300 YEARS

! Millennial Time Scale Buffalo Creek Watershed ~100

~1,970 years BP ~2,900 years BP Elliott and Parker, 2001

15 Decadal Centennial Time Scale Centennial Time Scale: 1800 s 1900 s Spring Creek Watershed SEDIMENT: 1/3 in reservoir 2/3 still in watershed RESIDENCE TIME 300 YEARS Modern view: More (burned) trees!! Millennial Time Scale Buffalo Creek Watershed ~100 years BP ~950 years BP ~1,020 years BP ~1,030 years BP ~1,970 years BP ~2,900 years BP Elliott and Parker, 2001 Photo by Bob Meade So what does this mean for Watershed Recovery? Post-fire recovery in ~3-5 years What Does Recovery Mean? Vegetation + ~pre-fire Q p 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. Hydrological response of burned watersheds: Cerro Grande Fire YEAR 1 Photo: Thomas Trujillo YEAR 3 Photo: John Hogan

Post-fire Recovery Declines in post-fire sedimentation if a function of: Soil Texture %bare soil Rainfall Intensity 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 Post-fire Recovery McDonald, L.

~background levels Q p also declines decreasing entrainment and transport capacity How long before aggraded channels recover? McDonald, L.H. Ro

2008, Post-fire erosion and the effectiveness of emergency rehabilitation treatments over time, Stream Notes, Rocky Mountain Research Station, 1-6 Sept 1, 2005 Longer duration storm Similar 30-minute

16 Post-fire Recovery Declines in post-fire sedimentation if a function of: Soil Texture %bare soil Rainfall Intensity 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 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, yrs - hillslope runoff rates ~background levels Q p 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 Sept 1, 2005 Longer duration storm Similar 30-minute intensity Q p = 680 cfs Campo Bonito August 14, 2003, 1 mo after containment of Aspen Fire 1.51 in 30 min, RI = 10 yr, 30 min One death Q p = 1,900 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 intensities 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

17 Deb Martin, USGS Karletta Chief, UofA Sue Cannon, USGS John Moody, USGS Sharon Desilets Karen Koestner, RMRS Dan Neary, RMRS Acknowledgements Jim Washburn, UofA Joe Wagenbrenner, RMRS Phil Pearthree, AZGS Jess Clark, RSAC Online resources Inciweb.org GeoMac Google Earth GeoSetter ( USGS Watersheds ( NOAA Atlas 14 GeoSetter Photo: Zac Ribbing, Cima Historical Cabins My Contact Info Ann Youberg Research Geologist Arizona Geological Survey 416 W Congress, Suite 100 Tucson, Arizona ann.youberg@azgs.az.gov

Geomorphic Responses of Burned Watersheds in the Modern Fire Regime: Floods, Debris Flows and Long-Term Recovery. Fire Regimes: Tree Ring Data

Geomorphic Responses of Burned Watersheds in the Modern Fire Regime: Floods, Debris Flows and Long-Term Recovery Outline Fire Regimes and Trends Post-fire Hydrologic Changes Post-fire Geomorphic Responses