Water Canyon/Canyon de Valle investigation was conducted by Glorieta Geoscience, Inc., in collaboration with Los Alamos National Laboratory during 2010-2011 to assess contaminant inventory in post-1942 sediments. Characterization of post-1942 sediments using hand-dug pot holes, dendrochronology and measurement of cross sections following post-fire floods.

1. Post-Fire Sediment Transport and Erosion
in the Water Canyon and Cañon de Valle
Watershed, Jemez Mountains, NM
DRAKOS, Paul, RENEAU, Steven, SCHULTZ-FELLENZ, Emily, RIESTERER,
Jim, KELLEY, Rick, MILLER, Elizabeth, GOETZE, Phillip, and
CHAMBERLAIN, Paul
GLORIETA GEOSCIENCE INC

2. Pajarito Plateau watersheds

3. Water Canyon/Cañon de Valle investigation
conducted 2010-2011 to assess contaminant
inventory in post-1942 sediments
• 1:200 scale mapping in 25+ reaches
• Characterization of post-1942 sediments using hand-dug pot
holes (identified based on presence of exotic clasts, buried
soils, bedrock, etc.)
• Dendrochronology utilized to provided supplemental
information to constrain the age of flood deposits
• Reworked ash from 1977 La Mesa fire and 2000 Cerro
Grande fire preserved in situ within sediment deposits
provides additional age control
• Measurement of cross sections following post-fire floods on
8/3/11 and 8/21/11
• 8/21/11 flood est. ~3000 cfs in CDV, larger than 8/3/11 flood
GLORIETA GEOSCIENCE INC

4. Extent of 1977 La Mesa fire within Water Canyon/
Cañon de Valle Watershed

5. Extent of 2000 Cerro Grande fire within Water Canyon/Cañon de
Valle Watershed and maximum post-fire discharge (6/2000)
740 cfs
840 cfs
274 cfs

6. Extent of 2011 Las Conchas fire within Water Canyon/Cañon de
Valle Watershed, and estimated discharge from 8/21/2011 flood
~3000 cfs (estimated)
1600+ cfs (estimated)
3500 cfs (est.)

7. Sediment delivery after Cerro Grande wildfire
(Reneau et al., 2007)
• Over 90% of ash delivered to LA Canyon reservoir in
the first year after the fire
• Slurries dominated by ash flow (suspended sediment)
follow first convective storm after the wildfire
• Sediment transport rates declined after first year, but
remained above pre-fire levels five years after the fire
• Significant increase in erosion rates in the first year
following the fire
• Rapid decline in fine-grained sediment transport,
whereas coarse-grained sediment transport is
prolonged (bedload transport during snowmelt runoff)
• Post-fire sediment is primarily deposited within first
two years after the fire

8. Preservation of in situ ash in post-1942 sediment deposits
Cerro Grande muck deposit
(June 2000)

9. Methods – 1:200 Scale Mapping

10. Methods – Characterization of post-1942 sediment deposits

11. Methods – Characterization of post-1942 sediment deposits
GLORIETA GEOSCIENCE INC

12. Methods – Measure geomorphic cross sections
Location selection based on contaminant concentrations and
dendrochronology, prior to Las Conchas fire

13. Water Canyon/Cañon de Valle watershed showing reaches

14. Reach WA-2 Geomorphology, cross section location
c3
Qbt
f1
c1
c2

15. Reach WA-3 Geomorphology, cross section location
f1
f2
c3
c2 Qt
Qc
c1
c1

16. Cross sections in Reaches WA-2 and WA-3 showing post-1942
sediment deposition and post-Las Conchas fire muck deposits
23 of 58 cm post-fire sed (f1s)
CG ashy si-fs
10 of 10 cm
post-fire sed (f2)
~58 of 123 cm
~58 of 123 cm post-fire sed (f1)
post-fire sed (c2)
CG ashy si
CG ashy si LM(?) ashy vfs
CG ashy si at base
LM deposit at base
17 of 127 cm post-fire sed (c3)

17. Water Canyon/Cañon de Valle watershed showing reaches

18. Cross sections in Reach CDV-1E showing post-1942 sediment
deposition and post-Las Conchas fire muck deposits and erosion
measured after floods on 8/3/11 (left) and 8/21/11 (right)
> 50% (+/-75%) of post 1942 sediment deposits are post-fire seds
CG muck
at base
CG ashy si

19. Cross sections in Reach
CDV-2W showing post-
1942 sediment
deposition and post-Las
Conchas fire muck
deposits and erosion
measured after flood
on 8/21/11
Note in lower cross section
Some channel incision but
most post-1942 sediments
remain in place.
CG muck
CG ashy si+vfs
GLORIETA GEOSCIENCE INC

20. Cross sections in Reach CDV-2W showing post-1942
sediment deposition and post-Las Conchas fire muck
deposits and erosion measured after flood on 8/21/11
Note erosion of
c2 sediments
next to channel,
preservation of
c3/f1 deposits on
higher surface,
deposition of
muck from
8/3/11 and
coarse sediment
from 8/21/11
flood.

21. Sampling location CV-613603 in reach CDV-2W where c2 unit
was completely eroded during 8/21/2011, flood.

22. c3
c1 Reach CDV-3
Qc
Geomorphology, cross
Qbt section locations
c2
f1

23. Cross sections in Reach CDV-3 showing post-1942 sediment deposition
and post-Las Conchas fire muck deposits measured after flood on
8/3/11; upstream (left) and downstream (right); post-fire sediment
<20% of total post-1942 deposition

24. Water Canyon/Cañon de Valle watershed showing reaches

25. Cross sections in Reach WA-4 showing post-1942 sediment deposition
and post-Las Conchas fire muck deposits; < 20% are post-fire deposits
CG dk vfs+si

26. Reach WA-5 Geomorphology, cross section location
GLORIETA GEOSCIENCE INC
c2
f1
c1
Qc
Tb
c1

27. Cross sections in Reach WA-5 showing post-1942 sediment
deposition and post-Las Conchas fire muck deposits and erosion
measured after floods on 8/3/11 (left) and 8/21/11 (right)
GLORIETA GEOSCIENCE INC

28. 8/23/11 Flood coarse sediment
deposits and scouring

29. Coarse sediment deposits in Cañon de Valle from August 21,
2011, flood. Gravel bar adjacent to channel in reach CDV-1E.

30. Coarse sediment deposits in Cañon de Valle from 8/21/2011
flood. ~2 to 4 m wide gravel deposit buries 0.5m wide
channel in Reach CDV-2W

31. Scour hole in reach CDV-1E demonstrating channel erosion
in Cañon de Valle from August 21, 2011, flood.

32. Water Canyon fan deposit at Rio Grande (left) and
detail showing ~10 cm thick L.C. muck deposit (right)
Water Canyon Fan
Coarse (ms-cs) sediment
from 8/21/11 flood?
Muck from
8/3/11 flood?
Photos taken 11/30/11
Post-Las Conchas sediment deposits along Rio Grande

33. Conclusions
• First post-Las Conchas fire flood on 8/3/11 deposited muck layer
(ashy silt) with a maximum thickness of 22 cm at cross section
locations
• Some erosion also occurred
• Second post-Las Conchas fire flood on 8/21/11 was larger
discharge event. Coarser-grained sediment deposits up to 50 cm
thick at cross section locations were observed in both overbank
and channel settings.
• Considerable scour and bank widening also observed during
second flood event.
• Total post-fire related sediment deposits from LM, CG, and LC
fires at randomly selected cross sections ranges from up < 20% to
75%, shows a general down-stream attenuation trend
• Post-LC muck and coarser-grained sediment deposits observed at
mouth of Water Canyon at Rio Grande.
GLORIETA GEOSCIENCE INC

34. Pending Investigation (2012)
• Systematic assessment of post-Las Conchas erosion and
deposition in reaches investigated in 2010/2011
• Reoccupy and resurvey cross sections to quantify post-Las
Conchas fire erosion and deposition at specific locations
GLORIETA GEOSCIENCE INC

35. Acknowledgements
Steve Veenis
LANL Environmental Programs
TerranearPMC.com
GLORIETA GEOSCIENCE INC