Riparian vegetation monitoring w

remote sensing 

Annual Reporting Meeting, January 26, 2015

Joel Sankey (USGS) jsankey@usgs.gov,

Laura Cagney (USGS), Temuulen Sankey (NAU), Ashton Bedford (NPS), Rene Horn

Phil Davis (USGS), Joshua Caster (USGS), Paul Grams (USGS), Barbara Ralston 
Talk Outline 

• 2013 Overflight image mosaic • Long-term riparian vegetation changes 

1964 to 2013

• Remote sensing of tamarisk changes and 

tamarisk beetle impacts 2009 to 2013
2013 Overflight Image Mosaic

Timeline:• Acquisition

– Memorial Day weekend 2013

• Image mosaic complete

– December 2015

• Image mosaic dataset publication

– 2016

• Riparian vegetation mapping and other analyses of data

mosaic for Triennial Workplan studies – Fiscal years 2015,

2016,

& 2017
2013 Overflight Image Mosaic 

Details:•

4 Image Bands – Blue, Green, Red, Near Infrared

• Pixel Resolution – 0.20 meters

• 215 GB un

‐compressed storage size

• 144 Image Scenes cover the Colorado River from Lake Powell

(15.8 miles upstream of Lees Ferry) to Lake Mead (281.1 miles

downstream of Lees Ferry)

– 270 river miles and 285.7 km

2 of river/riparian/upland are

• Registered to 2009 overflight image mosaic for change detectio

– Error (horizontal positional accuracy) is

< 30 cm
2013 Image Mosaic Examples

Slough in Glen Canyon ‐ River Mile
2013 Image Mosaic Examples

Little Colorado River Confluence‐River Mile 61.8
2013 Image Mosaic Examples

2013 National Canyon –River Mile 167
2009

2009 National Canyon –River Mile 167
2013 Image Mosaic Examples

Paria Beach 2013 – River Mile 1.2
2009

Paria Beach 2009 – River Mile 1.2
2013 Image Mosaic Examples

Kanab Creek 2013 –

River Mile 144.0
2009

Kanab Creek 2009 –

River Mile 144.0
Talk Outline 

• 2013 Overflight Image Mosaic • Long-term riparian vegetation changes 

1964 to 2013

• Remote sensing of tamarisk changes and 

tamarisk beetle impacts 2009 to 2013
Monitoring long-term riparian 

vegetation changes

• In FY2015 published long

‐term riparian vegetation changes

from analysis of imagery from 1964 to 2009

– Sankey, J. B., B. E. Ralston, P. E. Grams, J. C. Schmidt, and L.

E. Cagney (2015), Riparian vegetation, Colorado River, and

climate: Five decades of spatiotemporal dynamics in theGrand Canyon with river regulation, Journal of Geophysical

Reseach Biogeosciences, 120, 1532–1547,

doi:10.1002/2015JG002991.

• In this presentation, I’ll extend the analysis of changes from

1964 to 2013
Long-term riparian vegetation cha

- methods
Long-term riparian 

vegetation changes 

- methods

• Analyze by

5 “zones” of the

historical riparian areainundated by discharges:

• 8,000 to 25,000 ft

3/s

• 25,000 to 31,000 ft

3/s

• 31,000 to 45,000 ft

3/s

• 45,000 to 97,000 ft

3/s

• 97,000 to 210,000 ft

3/s

R. Hereford 
Long-term riparian 

vegetation changes 

1964 to 2009

Sankey et al., 2015 

2009 
Long-term riparian 

vegetation changes 

1964 to 2013

- results

2009 2013 
Monitoring long-term riparian 

vegetation changes - summary

• No change or small decrease in vegetated area in all zones from 2009

to 2013

• However, long‐term trend is vegetation increase in zones inundated

by discharges less than 45,000 ft

3/s

• 2013 data doesn’t alter statistical importance of predictors (Sankey et

al., 2015)

– Vegetation decoupled from river hydrology in zones inundated

by discharges

> 97,000 and possibly

> 45,000 ft

3/s; vegetated

area decreases due to rainfall drought

– Vegetated area increases in zones below 45,000 ft

3/s with (i)

elevated baseflows that make more water available to plantroots, and (ii) lower frequency and magnitude of peak

flows/floods

• How do we explain the 2009 to 2013 changes in zones below 45,000

CFS? HFE deposition and shoreline changes? Rainfall drought?

   

Brown and

defoliated

Tamarisk in

2013 due to

Tamarisk Beetle

impacts

Vegetated Area (%)

2009

2013
Talk Outline 

• 2013 Overflight Image Mosaic • Long-term riparian vegetation changes 

1964 to 2013

• Remote sensing of tamarisk changes and 

tamarisk beetle impacts 2009 to 2013
Tamarisk

(Tamarix spp.)

 History 

 In the US since 1800s  Decorative species  Invasive species 

 Biology 

 Salt cedar  Tap-root 

 Management 

 Dominant in the Southwest  Spread rate: 20 km/year  Expensive mechanical control 
Tamarisk Beetle

(Diorhabda carinulata) 

 Biology 

 Natural predator of the shrub  Eats the leaves  Tamarisk defoliation 

 History of Introduction 

 Asia  Texas- early 2000s  Utah- 2005 

 Found in Grand Canyon NP and 

Glen Canyon NRA in 2009 
Objectives and Methods

 Map area and biomass of green and defoliated tamarisk – new 

remote sensing for monitoring tamarisk and beetle impacts 

 Change detection of multispectral imagery 

 What percent of green tamarisk in 2009 was defoliat

2013? 

 Glen Canyon, Kanab Creek, National Canyon (3 reach Ashton Bedford, M.S. Thesis NAU, Defending Spring 2

 Fusion of multispectral imagery with lidar data 

 Quantify and map spatial distribution of biomass of t

green-leaf, and defoliated leaf (litter) tamarisk in 2013 

 Glen Canyon (one reach)  Sankey, TT, Sankey, JB, Bedford, A, Horne, R, in review, Remote sof tamarisk biomass, insect herbivory, and defoliation: novel methodapplications in the Grand Canyon region, Arizona, USA. PhotogrammEngineering and Remote Sensing 
What percent of green tamarisk in 2009 was 

defoliated in 2013?

(Bedford, M.S. Thesis) 

Reach Percent of Tamarisk

Vegetation

Total Area(m

2)

Glen Canyon(Glen Canyon Dam to

Lees Ferry)Green 76

% 20,005

Defoliated 24

% 9,053

Kanab(RM 134.6 to 155.7 )Green 77

% 4,047

Defoliated 23

% 1,095

National(RM 158.6 to 180.5)Green 88

% 21,727

Defoliated 12

% 2,893
Spatial 

distribution of 

tamarisk biomass 

(Sankey et al., 

manuscript in review) 
Remote sensing of tamarisk and 

defoliation - summary

• Biomass maps in Glen Canyon

• 8.68 kg/m

2 mean total above ground tamarisk biomass

• 0.52 kg/m

2 mean total above ground tamarisk “green leaf

absent” (i.e., litter) biomass

• 4,300 kg of tamarisk leaf biomass potentially shed

within the riparian area of Glen Canyon

• Practical utility of the maps and data:

• Future monitoring of defoliation and beetle impacts

• Planning for vegetation management

• Identify locations of widespread defoliation for

vegetation removal

• Estimate biomass that would need to be removed

mechanically, or consumed (fuel) by prescribed fire

• Tamarisk and defoliation relative to inundating flows
Thanks for listening!
Acknowledgements
Summary

• 8.68 kg/m2 : mean total above ground tamarisk biomass

• 0.52 kg/m2 : mean total above ground tamarisk “green leaf abs

litter) biomass

• 4,300 kg : potential tamarisk leaf biomass potentially shed 

riparian zone within Glen Canyon

• Practical utility of the maps and data:

• Planning for vegetation management

• Identify locations of high degree of defoliation for vege

removal treatments

• Estimate amount of biomass that would need to be re

either mechanically, consumed as fuel in a prescribed 

• Identify areas of high degree of defoliation that are wit

flood stage
PERS paper intro with methods

• Research Objectives

• Develop a remote sensing method to estimate total aboveground 

biomass as well as leaf‐only tamarisk biomass using lidar and exis

allometric relationships,

• Demonstrate how the fusion of lidar and multitemporal, mulstisp

imagery can be used to monitor the effects of green leaf biomass 

• Quantify the uncertainties associated with the above estimates in 

manner that accounts for each of the key sources of uncertainty i

biomass estimates.

• Paper in review

• Sankey, TT, Sankey, JB, Bedford, A, Horne, R, in review, Remote se

tamarisk biomass, insect herbivory, and defoliation: novel method

applications in the Grand Canyon region, Arizona, USA. Photogram

Engineering and Remote Sensing

• Methods

• Fusion of lidar (2013) and multispectral imagery (2009 and 2013) 

overflights: Glen Canyon Dam to ~6 miles upstream of Lees Ferry

• Use multispectral imagery to map tamarisk

• Use lidar allometry to estimate tamarisk biomass

• Use change detection of multispectral imagery with lidar‐derived 

estimate biomass of total, green‐leaf, and defoliated leaf (litter) ta

2013



Summary


2013 Overflight Image Mosaic

Details:• During mosaic preparation remove “smear”

(mechanical error) from the data.

– Smear could not be removed in less than

0.24 km2 or 0.09% of the total image area
2013 Image Mosaic Examples

Inner Gorge ‐ River Mile 81.2
2013 Image Mosaic Examples

Submerged Sand at 182mile Camp –

River Mile 182.8
Methods

 Overflight Multispectral Image Mosaics 

 2009: Pre-beetle image  2013: Post-beetle image  2009:2013 (Pre/Post Comparison) 

 NDVI (Normalized Difference 

Vegetation Index) 

 2009  2013  2009:2013 

 3D Lidar images 

 2013  Vegetation height  Canopy volume and biomass density 
Methods 

 Overflight Multispectral Image Mosaics 

 2009: Pre-beetle image  2013: Post-beetle image  2009:2013 (Pre/Post Comparison) 

 NDVI (Normalized Difference 

Vegetation Index) 

 2009  2013  2009:2013 

 3D Lidar images 

 2013  Vegetation height  Canopy volume and biomass density 
Change detection vegetation greenness indices from 2009 to 

Remote sensing of tamarisk defoliation

• Research Question 

• What percent of green tamarisk in 2009 was defoliated in 2

• M.S. Thesis (Ashton Bedford), Northern Arizona University, defen

2015 

• Three reaches 

• Glen Canyon (19.6 miles from Glen Canyon Dam to 3.6 mile

of Lees Ferry) 

• Kanab (From 134.6 to 155.7 miles downstream of Lees Ferry• National (From 158.6 to 180.5 miles downstream of Lees Fe

• Methods 

• Image classification of tamarisk in 2009 

• Glen Canyon Tamarisk Classification accuracy = 87 % • Kanab Tamarisk Classification accuracy = 83 % • National Tamarisk Classification accuracy = 72 %

•
Remote sensing of tamarisk defoliati

Reach Percent of Tamarisk

Vegetation

Total Area(m2)

Glen Canyon(Glen Canyon Dam to

Lees Ferry)Green 76 % 20,005

Defoliated 24 % 9,053

Kanab(RM 134.6 to 155.7 )Green 77 % 4,047Defoliated 23 % 1,095National(RM 158.6 to 180.5)Green 88 % 21,727

Defoliated 12 % 2,893
Remote sensing of tamaris

- Lidar Fusion – Tamaris