The June 2012 High Park Fire burned over 87,000 acres of forest and 259 homes to the west of Fort Collins, CO. The fire has had dramatic impacts on forest ecosystems. Of particular concern are its effects on the Cache la Poudre watershed, as the Poudre River is one of the most important headwaters of the Colorado Front Range, providing important ecosystem and economic services before flowing into the South Platte, which in turn flows into the Missouri River. Within a week of the fire, the area received several days of torrential rains. This precipitation—in conjunction with steep riverbanks and the loss of vegetation by fire—caused soil and ash runoff to be deposited into the Poudre’s channel, resulting in a river of choking mud and black sludge. Monitoring the effects of this disaster is critical and requires establishing immediate baseline data to assess impacts over time. Utilizing LANDSAT imagery, GIS layers, and boosted regression trees modeling, the NASA DEVELOP team based at the North Central Climate Science Center at Colorado State University conducted an investigation into riparian, wetland and headwaters modeling within the Cache la Poudre watershed. These efforts produced a preliminary model of predicted wetlands across the watershed, which is currently being refined by field data collection and modeling within three elevation-based “life zones.” The ultimate goal of this ongoing project is to provide important spatial data for land managers and create a riparian and wetlands modeling methodology that can be reproduced throughout the intermountain west region.

1. Wildfire &
Wetlands
Mapping with Landsat,
GIS and Statistical
Models
Stephen Chignell
Sky Skach
Colorado State University
A NASA DEVELOP Project

2. High Park Fire
• On June 9th, 2012,
lightning ignited Roosevelt
National Forest west of
Fort Collins, Colorado.
• At the time of
containment the fire had
impacted over 87,000
acres and burned 259
homes.

3. • Days later, torrential
downpours caused
major flooding and
erosion in the Poudre
Canyon.
• Large amounts of soil
and ash run-off were
deposited into the
Cache la Poudre River.

4. Monitoring effects of fires such as these on sensitive
habitats like wetlands and riparian areas is critical, and there
is urgent need for baseline data to assess change over time.

5. Cache la Poudre
Watershed
• The Poudre River runs
140 miles from its
headwaters in the
Rockies
• Drops 7,000 feet to
its confluence with
the South Platte
River, ultimately
flowing into the
Missouri River
• Annual flow of
280,000 acre feet

6. Community Concerns
• One of the most
important river systems
on the Colorado Front
Range:
– Drinking Water
– Agricultural Water
• Vulnerable to a range of
environmental and
anthropogenic stressors

7. Importance of Wetlands
• Biogeochemical processes:
• water cycling
• carbon storage
• Ecosystem services:
• water purification
• flood protection
• shoreline stabilization
• groundwater recharge
• stream-flow
maintenance
• Biodiversity:
• home to a diverse array
of flora and fauna

8. Wetland Mapping Status
Percentage of basin mapped:
• Digital NWI Mapping: 61%
• CPW Riparian Mapping: 70%
• Potential Fen Mapping: 0%
Total area of NWI
mapped wetlands: 30,145 acres
Percent of total area: 4%
Colorado Natural Heritage Program, 2013: http://www.cnhp.colostate.edu/wetlandinventory/

9. Project Objectives
• Provide a current map of wetlands in the Cache la Poudre
watershed for use by local land managers.
• Create a reproducible methodology for mapping wetlands
in other headwaters regions of the Intermountain West.

10. Project Partners
Colorado Natural Heritage Program
Colorado State University
Geospatial Centroid at CSU
Natural Resource Ecology Laboratory at CSU
North Central Climate Science Center
USDA Forest Service Rocky Mount. Research Station
USGS Fort Collins Science Center

11. Methodology
Landsat 5 TM
Ancillary GIS Data
Statistical Regression
Model
Map of Predicted Wetlands
Existing Wetland
Data

12. Landsat 5 Data
Image Acquisition
• Landsat 5 Thematic Mapper
• Path/Row: 34, 32
• Cloudless
• Multiple years and months
Available Cloudless LANDSAT Data for Path 34, Row 32
June 2011
March 2010
March 2009
November 2010
January 2010
February 2007
September 2010
August 2009
December 2006
April 2010
May 2009
July 2003

13. Landsat Data Processing
• Atmospheric Correction
Derived Environmental
Variables
• Tasseled Cap: Brightness,
Greenness, Wetness
• NDVI, NDMI, NDWI, SAVI,
Edge Filter
Ancillary Data
• NED Digital Elevation
Model (30 m)
• Slope, Aspect, CTI,
Curvature
Normalized Difference Moisture Index (NDMI)

14. Landsat 5 TM
Ancillary GIS Data
Statistical Regression
Model
Map of Predicted Wetlands
Existing Wetland
Data

15. Existing Wetlands Data

16. Presence Data Preparation
1. Exclude water bodies
2. Select only palustrine
– Includes all inland, non-tidal,
wetlands which lack flowing
water.
3. Exclude all polygons less
than one hectare
4. Inverse -30 m buffer
5. Generate 150 random
presence points within
polygons
– 30m distance between points

17. Background Data Preparation
1. Buffer 60 m away
from wetland
polygons
2. Exclude buffered
areas from all
analysis.
3. Generate 150 random
absence points from
background

18. Landsat 5 TM
Ancillary GIS Data
Statistical Regression
Model
Map of Predicted Wetlands
Existing Wetland
Data

19. USGS Software for Assisted
Habitat Modeling (SAHM)
1. Project, Aggregate,
Resample, and Clip (PARC)
2. Merged Dataset Builder
 i.e. “Extract Multi Values
to Points” in ArcMap

20. 3. Covariate
Correlation
Matrix
Removal of
highly
correlated
predictor
variables

21. Boosted Regression Trees Modeling
Split Wetland Presence Points
BRT Code
within SAHM
20 %
Test
80 % Train
(Figure: Elith et al, 2008)
Binary Map

22. Landsat 5 TM
Ancillary GIS Data
Statistical Regression
Model
Map of Predicted Wetlands
Existing Wetland
Data

23. Initial Results

24. Refinement: Elevation Zones
Three models for three zones:
• Foothills and Plains (< 1800 m)
• Montane (1800 m – 3500 m)
• Alpine (> 3500 m)

25. Results
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

26. Plains and Foothills
PCC: 72.5%
AUC: 0.82
Kappa: 0.46
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

27. Montane
PCC: 91.3%
AUC: 0.99
Kappa: 0.99
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

28. Alpine
PCC: 86.7%
AUC: 0.97
Kappa: 0.73
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

29. Validation Statistics
Elev. Zone
Lower
Middle
Upper
Correctly Classified
72.5 %
91.3 %
86.7 %
AUC
0.82
0.99
0.97
Kappa
0.46
0.99
0.73
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

30. Results and the High Park Fire
Visual assessment of model against current Landsat 8 imagery (June 29, 2013)

32. Conclusions
• Numerous unmapped wetlands in the CLP watershed,
including the High Park Fire burn area.
• Modeling within distinct elevation zones is a valuable
strategy for refining wetland models.
• Modeling wetlands in developed areas continues to be a
challenge for methodologies relying on moderateresolution remotely sensed data but may be less important
than less urbanized areas.
• Potential methodology to aid monitoring effects of wildfire
and land use change in wetlands.

33. Future Work
• Field validation through wetland plant identification
• Refinement of model in developed regions
• Inclusion of forthcoming cloudless Landsat 8 imagery in model
• Application to other watersheds in the Intermountain West

34. Project Partners
David Merritt, U.S. Forest Service
Jeremy Sueltenfuss, Colorado Natural Heritage Program
The City of Fort Collins
Science Advisors
Paul Evangelista, Natural Resource Ecology Lab, CSU
Jeff Morisette, USGS, North Central Climate Science Center
Melinda Laituri, Ecosystem Science and Sustainability, Geospatial Centroid, CSU
Nicholas Young, Natural Resource Ecology Lab, CSU
NASA DEVELOP Past Contributors
Amy Birtwistle, CSU
Brenda Kessenich, CU Boulder
Matthew Luizza, CSU
Amber Weimer, CSU