The Use of Aerial Photography

to Manage Riparian-Wetland Areas

U.S. Department of the Interior

Bureau of Land Management

RIPARIAN AREA MANAGEMENT

TR 1737-10 1994, Revised 2001

NT ME T RAPE D . S. U

OF THE I NTER I OR

3 1 8 4 9

c h r a M

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U.S. DEPARTMENT OF THE INTERIOR

BUREAU OF LAND MANAGEMENT
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i

 RIPARIAN AREA MANAGEMENT

The Use of Aerial Photography

to Manage Riparian-Wetland Areas

by

Pam Clemmer

Cartographer/Remote Sensing

Bureau of Land Management

National Science and Technology Center

Denver, Colorado

Technical Reference 1737-10

1994, Revised 2001

U.S. Department of the Interior

Bureau of Land Management

National Science and Technology Center

P.O. Box 25047

Denver, CO 80225-0047
ii

Suggested citations:

Clemmer, Pam. 1994, Revised 2001. Riparian area management: The use of aerial

photography to manage riparian-wetland areas. Technical Reference 1737-10.

Bureau of Land Management, Denver, CO. BLM/ST/ST-01/002+1737. 54 pp.

U.S. Department of the Interior. 1994, Revised 2001. Riparian area management: The

use of aerial photography to manage riparian-wetland areas. Technical Reference

1737-10. Bureau of Land Management, Denver, CO. BLM/ST/ST-01/002+1737. 54 pp.
iii

Acknowledgments

This is an enhanced version of Technical Reference 1737-2, The Use of Aerial

Photography to Inventory and Monitor Riparian Areas (Batson et al. 1987). Although

much of the original content remains, this revised reference approaches the topic from

a broader perspective.

The author wishes to thank the following individuals from the BLM Service Center

(now the National Science and Technology Center) for the time they offered in review,

comment, and development of this document: Don Prichard, Alan Amen, Larry

Cunningham, and especially Ed Work.

A special thanks to Jason Swegle of the Remote Sensing Staff and to Linda Hill and

Janine Koselak of the Technology Transfer Staff at the BLM Service Center (now the

National Science and Technology Center) for making this a quality document.
iv
v

Table of Contents

Page

I. Introduction ........................................................................................................ 1

II. Purpose ............................................................................................................... 3

III. Acquiring Aerial Photography ........................................................................... 5

A. Planning the Project .................................................................................... 5

1. Choosing Photo Parameters ................................................................ 5

2. Researching Existing Photos ............................................................... 7

B. Contracting for Aerial Photography ......................................................... 10

1. Planning for an Aerial Contract......................................................... 11

2. Initiating an Aerial Contract .............................................................. 13

3. Placing Ground Targets ..................................................................... 14

4. Collecting Data On-Site .................................................................... 15

IV. Interpreting and Analyzing Aerial Photos ........................................................ 17

A. Involving Others in Analysis .................................................................... 17

1. Using Local BLM Staff ..................................................................... 17

2. Requesting Service Center Assistance .............................................. 17

3. Contracting for Analysis ................................................................... 17

B. Initiating Interpretation ............................................................................. 17

1. Preparing the Photos ......................................................................... 18

2. Selecting the Minimum Mapping Unit (MMU) ................................ 19

3. Developing the Vegetation Analysis Framework .............................. 20

4. Analyzing the Photos ........................................................................ 20

5. Using Photo Mensuration .................................................................. 21

C. Capturing Data for GIS Input ................................................................... 22

1. Determining the Map Base................................................................ 22

2. Transferring Data to the Map Base ................................................... 22

3. Capturing Data in a GIS .................................................................... 23
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V. Using Remote Sensing for Field Applications ............................................... 25

A. Inventorying and Monitoring Riparian-Wetland Areas........................... 25

1. Acquiring Photos for Monitoring .................................................... 26

2. Analyzing Photos for Monitoring .................................................... 26

B. Determining Classification ..................................................................... 26

C. Assessing Functionality .......................................................................... 27

D. Supporting Other Management Techniques ............................................ 28

VI. Summary......................................................................................................... 31

Literature Cited ........................................................................................................ 33

Appendix A: Minimum Mapping Unit Templates ................................................ 35

Appendix B: Sample Vegetation Analysis Framework ......................................... 39

Appendix C: Remote Sensing Application Guide for Riparian-Wetland

Area Management............................................................................ 41

Appendix D: Aerial Photo Samples ...................................................................... 47
1

The Use of Aerial Photography

 to Manage Riparian-Wetland Areas

I. Introduction

Under the Federal Land Policy and Management Act (FLPMA) of 1976, the Bureau

of Land Management (BLM) is required to inventory lands and resources on a continuing basis. Aerial photography and other remote sensing techniques can be used to

obtain inventory data and can be valuable tools for making management decisions.

Aerial photos have proven especially useful in the management of riparian-wetland

areas.

There are many benefits to using aerial photography for managing riparian-wetland

areas. For example, using large-scale color infrared or natural color aerial photography can accelerate and enhance collection of ground data. Percent of canopy and

ground cover, bare soil, and acreage can also be calculated from aerial photos. Riparianwetland plant communities can be delineated for mapping purposes, and generalized

vegetation/soil correlations can also be made. Aerial photos furnish a historical

record of the condition of an area at a given point in time; therefore, changes in

riparian-wetland areas can be visually assessed by comparing aerial photos taken at a

later date. Aerial photos also link data geographically, allowing detailed vegetation

maps to be transferred to a Geographic Information System (GIS) for spatial modeling

purposes.

Remote sensing techniques provide valuable information for both ecosystem-based

and site-specific riparian-wetland management decisions. As BLM moves toward

ecosystem-based management, resources will be managed across jurisdictional

boundaries on a global, regional, or watershed basis. Small-scale aerial photos (e.g.,

1:40,000) and satellite imagery can provide a broad ecosystem perspective of a

watershed. Specific problem areas or limiting factors in the management of a riparianwetland area can be identified through preliminary analysis. Once problem areas are

identified, larger scale imagery (e.g., 1:12,000, 1:6,000, or 1:4,800), acquired using an

aerial camera on board a low-flying aircraft, can be used to focus on site-specific

areas of interest.

Baseline data is required to effectively manage riparian-wetland areas. Aerial photo

baseline data, when carefully selected prior to a project, allows analysis of a large

area of interest, at a minimum cost, in less time per hectare than conventional on-theground methods (Keating 1993). Properly documented baseline data can support or

disprove management decisions.
2
3

II. Purpose

The purpose of this technical reference is to provide resource specialists with the

basic information, concepts, and procedures associated with using aerial photography

to establish baseline data for effective management of riparian-wetland areas. This

technical reference provides suggestions for the use of various scales of photography,

guidance for acquiring aerial photography, and general procedures for conducting a

vegetation inventory.
4
5

III. Acquiring Aerial Photography

Successful projects using aerial photography are carefully planned prior to initiation.

The ultimate objective of a project must be defined before aerial photos are acquired.

Once the objective is defined, the project can proceed to the next phases, which

include: choosing the correct photo parameters (i.e., scale, type of film), acquiring

the data, preparing the data, interpreting the data, analyzing the data, transferring the

data to an appropriate map base, and capturing the data in a GIS. Although the initial

effort is time-consuming, once the data is entered into a GIS, the resource specialist

has developed a baseline that can be used for modeling analysis with other data sets.

State Office or National Science and Technology Center personnel are available to

lend technical assistance as needed.

A. Planning the Project

Planning for photo acquisition and analysis is a critical phase of the interpretive

effort that is often overlooked or ignored. First, and most importantly, the intended use of the resulting photography must be clearly defined prior to selection

and acquisition of the photography. Careful planning ensures that the correct

photo parameters (i.e., scale of photos, film type) are selected to accomplish the

task.

1. Choosing Photo Parameters

Remotely sensed data is most effective when used from a multistage perspective, which involves studying the overall area or ecosystem with satellite

imagery, or small-scale aerial photography, gradually focusing in on the sitespecific areas of interest with larger scale photography. Standard 7 1/2-

minute-scale topographic maps should be used in conjunction with satellite

imagery or small-scale (1:40,000 to 1:80,000) photos to delineate and determine overall condition of the watershed or limiting factors that help define

capability and potential. Once a broad overall perspective is acquired, riparianwetland areas in need of further study can be identified. Scale and film type

are selected based on the desired result. For example, after studying the

watershed using 1:40,000-scale photos, the resource specialist might want a

more intensive inventory over the project area at scales of 1:12,000, 1:6,000,

or larger.

a. Selecting Film

Resource specialists should determine the ultimate objective of their study

and select the scale and film type accordingly. If vegetation composition

is needed, color infrared photography should be chosen. Infrared film

allows the interpreter to detect subtle differences in vegetation due to

high sensitivity of the film in the infrared portion of the electromagnetic

spectrum. The human eye is not capable of discerning the infrared portion
6

of the electromagnetic spectrum. Advances in film technology allow us to

“see” a part of the spectrum that we do not see with our naked eye. Natural color film is adequate if more general information is desired, such as

acreage, percent of canopy cover, channel widths, stream lengths, general

improvement, or increase of riparian-wetland vegetation. Photos 1a and

2a in Appendix D provide a comparison of natural color and color infrared, respectively.

b. Selecting Scale

Resource specialists should determine the smallest scale possible to

accomplish the task. The concept of large scale versus small scale is often

confusing. When comparing a large- and small-scale photo over the same

site, features on the small-scale photo appear smaller. The representative

fraction (RF) scale is a small fractional number. For example, 1/24,000 is

a smaller scale than 1/12,000. These fractional scales are commonly

expressed as ratio scales of 1:24,000 and 1:12,000. If the film format is

the same for both photos (e.g., 9- x 9-inch), the small-scale photo (1:24,000)

covers a greater ground area than the large-scale photo (1:12,000).

Relatively speaking, a smaller scale requires fewer photos and covers a

larger area (Table 1). The interpretive process is accelerated because there

are fewer photos to interpret and transfer to a map base. With the proper

optical equipment, interpretation can be accomplished at a much smaller

scale (Aldrich 1979).

Care should be taken to select a scale that is small enough to make the job

easier, but large enough to interpret the detail needed. (Photos 2a and 3a

in Appendix D provide a comparison of different scales of the same area.)

As a test, several different scales of film transparencies or prints can be

ordered for the area of interest, such as stereo pairs at scales of 1:40,000

and 1:24,000, and larger scales of 1:12,000, 1:6,000, or 1:4,800. (Photos

5, 6a, and 7 in Appendix D are examples of larger scales.) The photos can

then be carefully studied and compared to determine the level of detail

derived from each. A smaller scale should be selected for synoptic coverage

and a larger scale for site-specific analysis.
7

Table 1. Estimating Photo Coverage per 100,000 Acres Based on Scale 1

Number acres Number acres Number photos

Photo per square per photo 2 per

scale inch (3.6 by 6.3 inches) 100,000 acres

1:2,400 1 23 4,348

1:4,800 4 91 1,099

1:6,000 6 136 735

1:12,000 23 522 192

1:15,840 40 907 110

1:20,000 64 1,452 69

1:24,000 92 2,087 48

1:40,000 255 5,783 17

1 Aldrich, Robert C., 1979. Remote Sensing of Wildland Resources: A State-of-the-Art Review,

General Technical Report RM-71; Table 4, p. 33.

2 60% overlap; 30% sidelap.

2. Researching Existing Photos

Before a new aerial contract is initiated, research should be done to determine whether

photos for the area of interest already exist. Photos are accessible from several sources.

a. National High Altitude Photography (NHAP)

The NHAP program acquired photos from 1979 to 1987. This photography

was funded by several Federal agencies and includes coverage of the lower

48 States in color infrared at 1:58,000 scale and in black and white at

1:80,000 scale. Although older, these photos provide excellent resolution

and historical perspective. The scale of the photos is appropriate for synoptic

viewing of an area, watershed delineation, general riparian-wetland analysis,

and change detection applications. The U.S. Forest Service produced

several case studies that use NHAP for riparian-wetland inventory applications (Mereszczak et al. 1990). U.S. Fish and Wildlife Service has used

1:58,000 color infrared NHAP for wetlands delineation.

b. National Aerial Photography Program (NAPP)

NAPP replaced the NHAP program in 1987. Funded by the same agencies,

NAPP provides complete cyclic coverage of the lower 48 States beginning

in 1987. NAPP photos were originally obtained using color infrared film

at a scale of 1:40,000 (Photo 3a, Appendix D). Coverage is available for

nearly all the Western States. Due to national mapping requirements for

the Digital Orthophotography Quadrangle (DOQ) program, NAPP now uses

black-and-white film almost exclusively. Black-and-white film provides
8

higher resolution needed for orthophoto production at lower cost than

color infrared film. The scale of the NAPP photos (1:40,000) is appropriate

for the same applications as those listed for NHAP. Both NHAP and

NAPP provide high-quality photographic products that can be satisfactorily

enlarged to 1:24,000 scale. Photos 3a and 4 in Appendix D provide a

comparison of these scales. Anderson and Hardin (1992) have demonstrated

the use of NAPP color infrared photos for delineating wetlands in Utah.

NHAP and NAPP photography can be aquired from EROS Data Center (EDC)

in Sioux Falls, South Dakota, or the U.S. Department of Agriculture's Aerial

Photographic Field Office (APFO) in Salt Lake City, Utah. Online searches

and ordering can be conducted at http://edcsns17.cr.usgs.gov/EarthExplorer/.

c. BLM Photography

BLM has acquired a considerable amount of aerial photography over the

years. Most of this photography is archived at BLM's Aerial Photography

Archive and Processing Lab, Denver Federal Center, CO 80225, with the

remainder stored at EDC. BLM photos consist of resource block photography

at scales from 1:12,000 to 1:24,000. Block photography implies photography

acquired as adjacent photo flight lines. Block photography usually has 60

percent endlap between successive photos with a sidelap between adjacent

flight lines of 30 percent. Smaller scales (e.g., 1:24,000) are appropriate for a

broad perspective of a stream reach and generalized riparian-wetland analysis.

Smaller areas of strip photography (riparian-wetland and special projects)

are acquired in select areas at larger scales of 1:6,000, 1:4,800, or 1:3,000

(Photo 5, Appendix D). Strip photography consists of a single flight line

of photos (e.g., stream reaches) where an endlap between successive

photos of 60 percent is commonly maintained for purposes of stereoscopic

viewing. Site-specific riparian-wetland inventory is easily accomplished

at scales of 1:12,000, 1:6,000, or greater. If vegetation differentiation is a

requirement, color infrared film is preferred over natural color.

d. Aerial Photography Summary Record System (APSRS)

The APSRS is a photography database maintained by the Earth Science

Information Center (ESIC) of the United States Geological Survey (USGS).

This record system lists photos available from various Federal, State, and

local governments, and from private companies that maintain aerial

photography film archives. NHAP, NAPP, and BLM photos are found in

this listing, in addition to photos from many other sources. The listing is

referenced by the geographic coordinate (latitude/longitude) of the southeast

corner of any 7 1/2-minute topographic map. BLM's National Science and

Technology Center (NSTC) staff can supply a microfiche listing from the

database for any specified topographic map upon request. The APSRS

database is also available on CD-ROM from the USGS for a nominal

cost. Figure 1 shows a sample of the APSRS listing for the Palmer Lake

7 1/2-minute quadrangle.
9

Figure 1. Palmer Lake, Colorado (39° 00' N, 104° 52' W), APSRS listing.
10

If aerial photos for the area of interest already exist, adequate time should be

allowed to order and receive the prints or film. In many instances, it can take

up to 8 weeks to receive photos. State Office remote sensing coordinators or

BLM's Aerial Photography Archive and Processing Lab can provide assistance

in obtaining photos from any of these sources.

Once the photos are received, resource specialists are ready for interpretation

and analysis. It is highly recommended that film transparencies be used

instead of prints. When viewed with adequate back-lighting, transparencies

provide sharper images, making interpretation easier. Of course, the stereoscopic equipment available to the interpreter determines whether film or prints

are ordered.

B. Contracting for Aerial Photography

If larger scale, more current aerial photos are desired, or if no photos exist for the

area of interest, an aerial photo contract should be considered. The following

contract guidelines are aimed primarily toward large-scale strip photography

contracts. Generally the same procedures apply for block photography acquisition. Tables 2 and 3 show approximate costs for both strip and block projects.

Table 2. Scale, Coverage, and Costs for Resource Block Aerial Photography Contracts

Approximate Cost

Per Square Mile ($)1

Descriptive

Scale Scale Color Infrared

1:12,000 1" = 1,000' 36.00 42.00

1:15,840 = 1,320' 29.00 32.00

1:24,000 = 2,000' 12.00 14.00

Table 3. Scale, Coverage, and Costs for Strip (i.e., riparian) Aerial Photography Contracts

Approximate Cost

Per Linear Mile ($)1

Descriptive

Scale Scale Color Infrared

1:2,400 1" = 200' 200.00 225.00

1:4,800 = 400' 175.00 200.00

1:6,000 = 500' 150.00 175.00

1:12,000 = 1,000' 100.00 125.00

1 Approximate costs are based on 1994 average contract costs. Actual cost may vary significantly

depending upon the region and size of the job.

1 Approximate costs are based on 1994 average contract costs. Actual cost may vary significantly

depending upon the region and size of the job.
11

1. Planning for an Aerial Contract

It is strongly recommended that resource specialists consult the State Office remote

sensing coordinators or NSTC remote sensing staff before initiating an aerial contract.

a. Selecting the Riparian-Wetland Area

Areas that are of primary concern should be selected carefully. The

beginning and end points of stream reaches requiring coverage should be

identified on a 1:24,000-scale USGS 7 1/2-minute topographic map

(Figure 2). It is best not to skimp on photo coverage. Once the aircraft is

over the area, an additional two or three exposures do not add significantly

to the overall cost of the project.

b. Determining Season and Time of Day

Ideally, the photos should be obtained as near to “peak of green” as possible.

This is generally near the point where vegetation is growing vigorously

and is at a full leaf stage. Local resource specialists usually know when

peak of green occurs. In addition, if deep canyons are in the area, field

specialists should specify a higher sun angle than normal (i.e., time of day)

for the flight in order to minimize shadows within the canyon depression.

The objective of the project should be considered when selecting the date

of photography. Generally, riparian vegetation is more easily distinguished

from upland vegetation in photos taken later in the growing season.

c. Selecting Film

The intended use of the imagery directly relates to the type of film required.

For example, if the extent of a riparian-wetland area is to be outlined and

quantified (in acres), natural color film is adequate. If vegetation composition (i.e., trees, shrubs, grasses) is to be analyzed, color infrared film is

preferred. Color infrared film captures a greater range of spectral reflectance

variation between vegetation types than does natural color film.

d. Selecting Scale

Intended use also has a direct bearing on scale requirements. For example,

a scale of 1:24,000 or smaller is sufficient to locate most riparian-wetland

areas, make linear (mileage) measurements, and determine watersheds.

However, to visually analyze, delineate, and measure areas to the community level for later comparison (monitoring), a scale of 1:2,400 to 1:6,000

is recommended for narrow strips of riparian-wetland vegetation. Wider

meandering riparian-wetland zones may require photo scales from 1:4,800

to 1:12,000 in order to photographically cover the area with a single flight

line. If the adjacent uplands are of interest, a smaller scale should be

considered. Again, the larger the scale, the more costly the project, so the

smallest possible scale for accomplishing the task should be selected.
12

Figure 2. Coverage required for Muddy Creek is identified on a USGS 7 1/2-minute topographic map.
13

2. Initiating an Aerial Contract

The necessary paperwork for an aerial contract should be initiated at least 6

months prior to the expected flight date to allow time for preparing specifications, requesting photo lab work, securing bids, awarding the contract, and

holding a prework conference. Contracts under $100,000 can be handled by

the State or Field Offices. Contracts of $100,000 or greater are handled by the

procurement staff at BLM's National Business Center.

a. Preparing Specifications for Aerial Photography

Technical aerial photography specification packets are available from

NSTC's aerial photo coordinator. These specifications incorporate the

preplanning considerations mentioned, in addition to other requirements

for obtaining quality imagery. Form 9672-3, Specification Detail Sheet

(July 1984), is an attachment to the specifications. The form provides

space for specific information relative to the acquisition of the photography and any additional requirements not covered in the specifications.

NSTC can provide these packets or assist in completing this form.

b. Preparing the Flight Map

Flight maps should be prepared from USGS topographic maps. The

1:24,000-scale, 7 1/2-minute topographic map is used for large-scale strip

projects (i.e., riparian) and the 1:100,000-scale map is used for smaller

scale block projects (e.g., 1:12,000, 1:24,000). Generally these maps are

prepared by the State Office remote sensing coordinators or the NSTC

aerial photo coordinator in consultation with the State or Field Office.

c. Procuring the Photography

The procurement process is usually handled by State Offices or NSTC.

Technical assistance on photo procurement procedures is available from the

NSTC aerial photo coordinator. The method of contracting for photography

is usually determined by the estimated size and cost of a project.

Cooperative planning between BLM offices and other Federal, State, and

local agencies can significantly reduce project costs. A major cost item is

ferry time for the flight crew from the contractor’s home base to the

project site. If the project is combined with another project in a nearby

area, the ferry charge is minimized.

Assuming the project cost is within the authority of the local contracting

officer, the following options for contracting the job are available:

1) A formal Invitation for Bid can be issued. This is done through the

National Business Center when large contracts are involved.
14

2) Standard Form 18 can be used to obtain written quotations. Under this

procedure, specifications, maps, and other items that clarify the request

for price quotations can be sent. At least 3 weeks should be allowed to

receive bids.

3) The Oral Quotations Form 1510-42 for supplies and services can be

used. This form is generally used for small aerial photo contracts with

requirements that can be described sufficiently over the phone to

obtain price quotes.

Any questions regarding the procurement process should be directed to

NSTC's aerial photo coordinator.

3. Placing Ground Targets

Ground targeting, also called paneling, is essential for larger scale photo contracts (i.e., 1:2,400 to 1:12,000). With larger scale photos, it is often difficult to

determine the photo scale using map identifiable features. Acquiring the known

ground distance between two targets allows the interpreter to calculate the

actual photo scale (Photo 6a, Appendix D). Once the photo scale is determined,

photo mensuration (linear measurements and acreage determination) can be

accomplished directly on the photo using a simple formula (see section IV.B.5).

Targeting should be completed not more than 1 week prior to flying to avoid

target loss from wind, animal disturbance, or vandalism. Target panels can be

constructed from butcher paper, which is readily available from butcher shops

and grocery stores, or from plastic material. Butcher paper is biodegradable,

but the plastic material is not. Targets should be anchored with twine, rocks,

or nails and large washers. The target material should be removed once the

aerial photography has been accepted. Sometimes photos from portions of

contracted flights are rejected due to clouds or excessive tip, tilt, or crab of the

aircraft, and those areas are required to be reflown.

For riparian areas along stream corridors, two targets should be placed at each

end of a stream reach. For longer stream segments, another set (two targets)

should be placed at approximately 2-mile intervals along the stream or at the

midpoint of the segment. The following guidelines are acceptable for photo

scales of 1:2,400 to 1:6,000:

• Targets should be placed 200 to 500 feet apart within the photo coverage

area, with one of the targets near the stream where ground data and photos

will be taken. An accurate ground distance between the targets should be

measured and recorded for later use in determining photo scale. Targets

should be placed in relatively flat terrain within clear view of the aircraft.

• Target panels should be in the form of crosses (+). Each target panel

should be 10 feet long and at least 18 inches wide for large-scale projects.
15

If photogrammetric work is anticipated, the requirements for target placement

are more strict. Horizontal and vertical control points need to be collected

using survey quality Global Positioning System (GPS) units. Photogrammetry

techniques are used to obtain extremely accurate measurements. NSTC's

photogrammetry staff should be consulted on target placement and is available

to assist in mission planning upon request.

4. Collecting Data On-Site

On-site data collection efforts should be accomplished at the time of target

placement. Data collected on-site provides the interpreter with valuable

information about on-ground conditions at the time the photos are acquired.

Photos 1b, 2b, and 3b of Appendix D show on-ground conditions for the areas

in Photos 1a, 2a, and 3a, respectively. Although field verification is valuable

anytime during the project, it is important for the interpreter to know the site

conditions at the time of photo acquisition.

Slides (35-mm) of the riparian-wetland area should be taken at the site where

the targets are placed, and inventory data should be collected for the reach.

The dominant and subdominant herbaceous vegetation, shrubs, and trees, and

the percent bare soil should be determined. Data acquired in the field can be

used to develop interpretive guidance once the photos have been acquired.

This data should include any additional field notes that may assist in photo

interpretation. Sketched maps annotated to indicate the presence and type of

land cover (e.g., plant species, soil type) are useful for developing photo

interpretation keys.

The approximate coordinate locations of the targets should be determined

from a topographic map (Photo 6a and 6b, Appendix D). Coordinate location

can be useful for locating oneself during interpretation. If possible, differentially corrected GPS coordinates for the center of the target panels should be

collected. Accurate coordinate locations aid in registering and entering data

into a GIS.
16
17

IV. Interpreting and Analyzing Aerial Photos

Once photos have been acquired, local BLM staff, State or NSTC personnel, or

contracted facilities can perform interpretation; however, interpretation is best performed by someone familiar with the local vegetation and ecosystem characteristics.

A. Involving Others in Analysis

1. Using Local BLM Staff

Photo interpretation and data analysis should be performed at the local Field

Office level by resource specialists familiar with vegetation and management

activities on the site. Interdisciplinary involvement in interpretive analysis

will provide a broader perspective. State and Field Office remote sensing

expertise should also be called upon, when available. Contacts should be

made with any Federal, State, and local agencies who may have an interest in

the area under consideration. These contacts may contribute expertise in

analysis, existing data, or financial assistance for a data-sharing project.

2. Requesting NSTC Assistance

Optical photo interpretation equipment is sensitive, fragile, and difficult to

move. Such interpretation equipment is available at the NSTC for use by

BLM Field Office personnel. Facilities and staff from the NSTC remote

sensing staff are also available to help field personnel with analysis. Generalized

interpretation can be accomplished at NSTC, followed by verification

assistance from specialists in the field.

3. Contracting for Analysis

Educational institutions, consulting firms, and other Government agencies

may offer interpretation and analysis capabilities. For instance, the Environmental Protection Agency (EPA) facility in Las Vegas, Nevada, has cooperated with BLM offices in past years. This type of cooperation varies from

performing the analysis and documenting the results to simply making their

facilities available for a BLM work session.

B. Initiating Interpretation

Input into a GIS requires transferring interpretations from aerial photos to a stable

map base. If GIS input is not the ultimate goal, and information is to be used

only to calculate approximate acreage of riparian-wetland vegetation, photo

mensuration procedures should be used (see section IV.B.5).
18

1. Preparing the Photos

a. Delimiting the Effective Area

During the interpretation process it is important to analyze only the

"effective area" of each photo. Generally, the effective area is the central

portion of the photo and includes overlap and sidelap from adjacent photos

(Figure 3). The effective area serves two purposes. It defines the area of

least geometric distortion in the photo and it allows the interpreter to

delineate and classify the features in a project area once and only once,

eliminating inefficient and multiple interpretations that could occur if a

larger area on the overlapping photo were to be interpreted. The drawing

of the effective area on every photo can be a tedious and protracted process, a discussion of which is beyond the scope of this technical reference.

Crisco (1988) provides detailed information regarding effective area

delineation.

b. Preparing Overlays

Interpretations should be compiled on clear mylar overlays, thus allowing

the photos to be preserved for other applications. A clear mylar overlay

(9-x 9-inch) should be attached to each frame to be interpreted, and a finepoint permanent marking pen should be used to carefully annotate each

side fiducial mark observed on the photo. The identification format (photo

labeling) is then transferred from each photo so that it can be easily

reregistered if the overlay becomes detached. The identification format

Figure 3. Effective area.

Effective area of

photo 1-3-8 and 1-3-9 60% overlap

Line of flight

1-3-9

1-3-8
19

includes the date of the photography, agency, scale, project code, and

frame number (roll-flight-exposure number) as shown in Figure 4.

Figure 4. Sample identification format.

2. Selecting the Minimum Mapping Unit

A minimum mapping unit (MMU) should be selected prior to photo interpretation. The MMU serves as a guide for all future polygon delineation and

mapping. For example, a 1-acre MMU would be equivalent to a 0.1-inch

square at 1:24,000 scale. Although very small features and individual plants

are discernible on large-scale aerial photos, a reasonable mapping unit must be

selected. The interpreter must keep in mind that the delineations will be

reduced in size significantly when the data is transferred to the map base. To

assist in interpretation, a template depicting the MMU at the intended scale

should be constructed to use as a guide during interpretation. Sample MMU

templates are provided in Appendix A.

Larger riparian-wetland areas can be portrayed as polygons on a 1:24,000-scale

map base. However, the majority of BLM streams have riparian-wetland

communities that are quite small and cannot be portrayed with polygons at a

scale of 1:24,000. This complicates the use of detailed riparian-wetland data

within a GIS. Features that are too small to portray with an MMU as a polygon

at the final map scale can be compiled as line or point data. Line segments must

be described and defined. Appropriate attributes must be assigned to features

when they are input into a GIS. For example, a red line segment represents a

width of less than 100 feet. This information, along with line length and map

scale, determines line segment acreage. Spot symbols need to be defined in

terms of area. For example, spot symbols represent areas less than .5 acre. GIS

feature design and descriptions are discussed at length in Technical Reference

1737-7, Procedures for Ecological Site Inventory—With Special Reference to

Riparian-Wetland Sites (Leonard et al. 1992). These procedures are easily

adapted to any GIS input procedure, but should be defined prior to map transfer.

Identification 6-15-90

format

Fiducial mark

BLM 5 ID-90-CI 1-3-8
20

3. Developing a Vegetation Analysis Framework

If vegetation analysis is part of the defined project, a vegetation analysis

framework should be developed prior to interpretation. This framework

describes the characteristics of the dominant and mixed riparian-wetland

communities to be encountered and delineated. As interpretation proceeds,

the framework is modified as needed. Appendix B provides an example of a

vegetation analysis framework that was used in 1986 during a work session in

Nevada and found to be adequate for that environment. Resource specialists are

urged to review this framework and create their own based on local requirements.

The framework should include defined criteria for the classes that are selected.

The previously selected MMU should be used for interpretations. Delineations

should be confined to the riparian-wetland area and interpretation kept within

the effective area.

4. Analyzing the Photos

Each information layer should be compiled on a separate overlay. For example,

stream channels on recent photos often show much change from the older

7 1/2-minute topographic maps. Stream channels, therefore, are compiled on

one overlay to monitor stream channel movement, while vegetation interpretations are compiled on a separate overlay. Separating the data layers allows

ease in map transfer and subsequent digitization.

Photo interpreters should use the best available optical equipment during the

initial stages of the project. A zoom transfer scope allows interpretations to be

directly compiled from photo to map base. If this equipment is not available,

a two-step process is required. Stereoscopic viewing of prints is helpful,

particularly in determining relative heights of tree and shrub species. Aerial

photographs can be obtained as paper prints or positive film transparencies.

Although paper prints are commonly used in the field, it is strongly recommended

that film transparencies be used with adequate back lighting for interpretation

because they provide a finer resolution image. Visual analysis using

transparencies under stereo magnification has proven to be of great value.

While interpreting the photo, it is best to proceed from the dominant or purer

types of communities to the more difficult mixed communities. Using the

MMU template as a guide for polygon delineation, each vegetation type

should be systematically identified. To develop interpretive consistency, all of

one type should be delineated at the same time. Jumping around creates

confusion in interpretation. Photo 7 in Appendix D shows interpretations on a

portion of Tabor Creek, NV.

Use of supporting ground photography is encouraged, as are field visits. If

aerial photography was contracted, the ground data that was collected when

targeting was accomplished (see section III.B.4) should be used. Photo

interpretation is a confidence-building exercise and it is important to use all
21

available supporting data. Although the first several photos take longer,

experience has shown that photo interpreters increase their speed and efficiency

once confidence is gained.

When analysis is complete, interpretations can be transferred to a standard

map base. Once transfer is completed, the compilation can be entered into a

GIS. Once input into a GIS, future monitoring, change detection, and analysis

can be achieved quickly (see section IV.C).

If input into GIS is not required, and the dominant use of the data is to gather

tabular information concerning approximate acreage, photo mensuration is

possible.

5. Using Photo Mensuration

After the photo preparation and interpretation processes are complete, it is

possible to tabulate acreage directly from the photos. This process is called

photo mensuration. The resulting acreage figures are approximations; this

method is far less accurate due to the lack of a controlled map base. Photo

mensuration is more accurately calculated on interpretations that have been

carefully transferred to a map base.

a. Determining Photo Scale

The contracted photo scale, which is normally annotated in the identification format on each photo, is not the actual photo scale. When severe

elevation changes occur within any flight line, the actual photo scale

varies considerably and affects the mensuration results. The actual scale

on any given photo is calculated using a known ground distance. On

large-scale photos, this distance is obtained between the target sets that are

placed before the flight (see section III.B.3). On smaller scale photos,

calculation is commonly made by measuring a distance between two

photo- and map-identifiable features (Crisco, 1988). An average scale for

the flight line can then be determined for mensuration purposes.

Photo scale (PS) is the ratio of photo distance (PD) to ground distance

(GD). All values must be converted to the same unit of measure.

Example: The ground distance between targets A and B is 400 feet. The

photo distance between the same targets A and B is 2 inches. What is the

photo scale?

Photo Scale = 1:2,400

PD

GD = PS

2" (PD)

400' x 12" (GD) = = –•

•

–• 2" (PD) •

4,800" (GD)

1"

2,400"

2"

2"
22

Photo scale is expressed as a ratio: 1 inch on the photo represents 2,400

inches on the ground. Once the photo scale is determined, the descriptive

scale is easily calculated. The descriptive scale shows how many feet on

the ground are equivalent to 1 inch on the photo. In this example, the

descriptive scale is figured as follows:

Descriptive Scale: 1"=200'

b. Calculating Acreage

There are several methods for determining acreage. These methods may

be used directly on the photo, but are more accurate if used on a controlled

map base once the interpretations have been transferred.

Many Field Offices have access to digital planimeters that allow direct

calculation of acreage when the photo scale is entered. Additionally,

portable digital planimeters can be rented on a daily basis at a reasonable

cost.

If the project area is small, the dot grid and manual methods are costefficient alternatives (Crisco 1988). Acreage calculation can be determined with most GIS software packages, once the interpretations are

digitized.

As the data is assembled, it should be recorded on a vegetation analysis

framework form (Appendix B). The data can be recorded by photo number, and subsequent tabulation by other subdivisions (e.g., allotment,

ownership, stream segment) is possible if desired.

C. Capturing Data for GIS Input

1. Determining the Map Base

If data is primarily to be used to create a map of riparian-wetland cover types

and may ultimately be used in a GIS, map base considerations are critical.

The standard base for BLM resource management applications is the USGS

7 1/2-minute, 1:24,000-scale topographic map or orthophoto quadrangle.

Stable base mylar provides the most accurate digitizing base and should

always be used in place of paper print products.

2. Transferring Data to the Map Base

Aerial photos contain displacement and distortion and do not provide map

accuracy for measuring purposes. Photo analysis should be followed by

transfer of the detail onto a map base to provide input for a GIS. This process

–•

•

1"

2,400" 12" = 1"

200'
23

prevents duplication of effort in future monitoring and supports baseline data

acquisition for ecosystem-based management activities.

To begin map transfer, the vegetation analysis framework, the map base MMU

template (i.e., 1:24,000), and the GIS compilation guidelines discussed in

section IV.B.2 should be used. The interpretations from the photos should be

carefully compiled onto a stable base orthophoto. Detail is easier to transfer

from an aerial photo to an orthophoto because both have photo-identifiable

features in common. If orthophotos are not available, 7 1/2-minute topographic maps can be used as a base. Discrete boundaries of the lines and

polygons, along with appropriate labels, should be transferred to the base map.

If the finished compilation overlay is to be mechanically scanned, the compilation method for producing the most efficiently scanned overlay should first

be determined. For example, black lines with blue attribute labels are easier

to scan and edit than numerous color classes.

Once interpretations are transferred to the map base, the manual photo mensuration technique can be used to acquire acreage figures, which is more accurate

than direct mensuration off the photos. If the area is large and the desired

result is analysis in a GIS, alternate data capture methods are more efficient.

3. Capturing Data in a GIS

Once the data has been compiled on a stable map base, it is ready to enter into

a GIS. A local GIS specialist should be consulted to determine the most

efficient method of input. Manual digitizing on a tablet is commonly used.

Heads-up digitizing from a digital orthophoto is also a common method of

input. Scanner technology is popular, although it is somewhat costly. A drum

scanner is available for use at NSTC.
24
25

V. Using Remote Sensing for Field Applications

Methods and standards for managing riparian-wetland areas have been established

within BLM’s technical reference series (TR 1737) on riparian area management.

Remote sensing techniques can be applied in virtually all types of riparian-wetland

management. Inventory and monitoring are more traditional uses of remotely sensed

data. However, aerial photography can also assist in assessing functionality, determining classification, and improving management planning processes. The table in

Appendix C provides suggestions on how to use remotely sensed data for riparianwetland management applications. Suggested scales and film types are also given.

Actual scale and film selection should be determined by the intended use and size of

the area. Resource specialists may find that other scales or film types are adequate

for their applications.

A. Inventorying and Monitoring Riparian-Wetland Areas

Remote sensing techniques have long been used to inventory and monitor riparianwetland areas. Using the appropriate date, scale, and film, riparian-wetland

vegetation can be interpreted and measured using methods described in section

IV. Small-scale photos give a general overall perspective of the area, including

the geomorphology, landform, drainage pattern, and watershed area and condition.

Aerial photos can be used to determine channel sinuosity, channel confinement,

and valley width, and provide a more accurate basis for analysis than topographic

maps. Stereoscopic photo interpretation, along with physiographic analysis of a

7 1/2-minute topographic map, allow preliminary ecological typing. Initial

assessment of vegetative bank protection and water sedimentation can be performed

using medium- or large-scale aerial photos. Vegetation association and phase can

be identified using aerial photos, as discussed in-depth in Technical Reference

1737-3, Inventory and Monitoring Riparian Areas, (Myers 1989). Certainly tree

canopy, herbaceous cover, and to some extent, age distribution of woody dominant

species can also be identified using aerial photos at an adequate scale.

Technical Reference 1737-8, Greenline Riparian-Wetland Monitoring (Cagney 1993),

discusses methods that can utilize large-scale (1:2,400) color infrared photography.

The Forest Service General Technical Report 47, Monitoring the Vegetation Resources

in Riparian Areas (Winward 2000), offers additional, updated information on this

topic. Recommended transect length is a minimum of 726 feet along the greenline.

At 1:2,400 scale, 1 inch on the aerial photo represents approximately 200 feet on

the ground. With color infrared film, vegetation composition can be differentiated

along the transect. In fact, resolution at that scale is better than 1 foot. After field

checks have been conducted, interpretations can be used to support the baseline data.

The most easily detected change in a riparian-wetland area is a reduction in foliar

cover and an increase in bare soil. This change may be obvious upon inspection

of the baseline (initial) photo compared with monitoring photos taken 5 to 10

years later. The cause of the change may be answered only by on-the-ground

inspection. The photos offer an opportunity to monitor the extent of change, but

not necessarily the cause.
26

Once baseline data is established, a monitoring plan should be initiated for those

areas in need of more intense scrutiny. Videography is especially well suited for

quick damage assessment, but resolution is much lower than conventional aerial

photography.

1. Acquiring Photos for Monitoring

The same considerations outlined for the original aerial photography contract

should be used to plan subsequent flights for monitoring purposes. Area

selection, season and time of day, film type, scale, specifications, procurement,

and ground targeting requirements should follow the same criteria as the

original project. Flight maps used in the previous project should be referred to

in designing the subsequent flights. The idea is to create conditions as close

to those of the previous flight as possible. Although not mandatory, using the

same conditions greatly simplifies interpretation.

2. Analyzing Photos for Monitoring

The old and new aerial photos over the riparian-wetland area, along with

smaller scale photos of the watershed, should be compared visually. From this

comparison, critical areas can be evaluated and apparent changes occurring on

nonstudy areas can also be detected and documented. One of the important

advantages of a photo-based monitoring system over entirely ground-based

study is the ability to expand the area that can be evaluated.

It is anticipated that several key areas will already be selected prior to having

the area reflown. These sites should be closely evaluated. Interpretation and

analysis should again be performed on these key areas and results compared.

It is important to remember that critical steps performed during the initial

baseline interpretation are essential for monitoring the areas. In addition, if

the visual comparison yielded further areas of change, a reinterpretation may

be appropriate. Once photo interpretation and analysis are complete, the

probable causes of change should be investigated.

B. Determining Classification

As with inventory and monitoring, remote sensing brings an added dimension to

the classification process, which is discussed in Technical Reference 1737-5,

Riparian and Wetland Classification Review (Gebhardt et al. 1990). Possibly the

greatest benefit is the overall perspective that is provided with smaller scale

imagery. Using a broad approach allows limiting factors in the landscape to

manifest themselves. Emphasis should be placed on using the remotely sensed

data as a prerequisite to the classification itself.

Technical Reference 1737-7, Procedures for Ecological Site Inventory—With Special

Reference to Riparian-Wetland Sites (Leonard et al. 1992), describes a process

that looks at the interaction between soils, climate, hydrology, and vegetation for

riparian-wetland resources and uplands. This highly interdisciplinary activity
27

lends itself well to using remote sensing techniques. Using appropriate imagery

of the area under study, each interdisciplinary team member can relate their

perspective of the study area. After initial team observations are made, individual

study can be undertaken to determine such things as vegetation composition and

acreage, canopy cover, bare soil, locations for gathering hydrologic information,

present vegetation as compared with previous historical photos, open water

surface area, soil and surface geology characteristics, and general watershed

quality.

C. Assessing Functionality

Considerable effort has been expended to inventory, classify, restore, enhance,

and protect riparian-wetland areas. The following technical references define a

structured interdisciplinary activity that assists resource specialists in determining

the condition of riparian-wetland areas on public lands:

TR 1737-9, Process for Assessing Proper Functioning Condition (Prichard et

al. 1993)

TR 1737-11, Process for Assessing Proper Functioning Condition for Lentic

Riparian-Wetland Areas (Prichard et al. 1994)

TR 1737-15, A User Guide to Assessing Proper Functioning Condition and

the Supporting Science for Lotic Areas (Prichard et al. 1998)

TR 1737-16, A User Guide to Assessing Proper Functioning Condition and

the Supporting Science for Lentic Areas (Prichard et al. 1999)

Although riparian-wetland areas are small in comparison to the vast acreage of

public lands, assessing the condition of all these areas is an extensive effort.

Aerial photos can assist in the initial planning for functionality assessment.

Remotely sensed data can be beneficial in determining existing condition, potential

condition, resource values, planned actions, and monitoring requirements.

Aerial photos can be used to assist in completing the reporting tables shown in

these technical references to define riparian-wetland management objectives.

Riverine miles, acreage, and preliminary determination of functioning condition

can be assessed using remotely sensed data. Initial trend can be assessed using

historical photos. Given the appropriate scale and film type, aerial photos can

significantly reduce field time and overall evaluation efforts.

Technical Reference 1737-12, Using Aerial Photographs to Assess Proper Functioning Condition of Riparian-Wetland Areas (Prichard et al. 1996), provides detailed

explanations and procedures for using aerial photography to assess condition.
28

D. Supporting Other Management Techniques

Grazing management, as discussed in Technical References 1737-4, Grazing

Management in Riparian Areas (Kinch 1989), and 1737-14, Grazing Management

for Riparian-Wetland Areas (Leonard et al. 1997) can be enhanced by using

remotely sensed data to develop alternative strategies. Using historical photos,

range conservationists are able to ascertain how management strategies used over

the years have impacted the land. Heavily grazed riparian-wetland areas and

uplands are generally quite obvious on aerial photos and are stark evidence to

mismanagement of the public lands. Color infrared photos exhibit the seasonal

and topographic aspects of range suitability and carrying capacity. Used in

allotment planning, aerial photos assist in planning livestock access points, pasture

design, and riparian-wetland protection.

Technical Reference 1737-6, Management Techniques in Riparian Areas (Smith

and Prichard 1992), discusses methods to achieve specific goals and objectives in

riparian-wetland management. The basic management unit for these techniques is

the watershed. Small-scale aerial photos and satellite imagery are excellent tools

for becoming familiar with a watershed. They allow a broader perspective than

on-site observation and present a more comprehensive picture than a topographic

map. Some of the management techniques that are enhanced by using aerial

photos include:

Fencing: Exclosures are areas that are easily distinguished on an aerial photo.

Aerial photos may be used to measure and determine the amount of fencing

required and to determine acreage associated with fenced areas.

Prescribed burns: Aerial photos can assist in prescribed burn planning. Topography and fuel characteristics are features easily identified from photos. Fire breaks

and control lines can be determined. Digital image processing techniques have

been used in the past to create fire fuels map products for states in the Western

U.S. These products, produced at a small scale, determine fuel type and burn

characteristics using remotely sensed satellite data.

Forestry practices: Forest management traditionally uses remote sensing techniques for planning, inventory, and monitoring.

Mineral activities: Mineral activities offer extensive opportunities to develop

areas of new riparian-wetland vegetation. Aerial photos and satellite imagery

provide the capability to detect surface disturbance as well as healthy plant vigor.

Change detection and monitoring activities in mining areas are excellent

applications for remote sensing techniques in either a digital or manual environment.
29

Structures: Physical structures are placed in watersheds to control erosion or

degradation of a site. Aerial photos assist in planning the placement of those

structures in addition to monitoring the effects of those structures in the future.

Most failures result from trying to apply a technique that worked well for one site

without realizing that the new site is different. This mistake can be avoided by

using small-scale imagery, which allows the surrounding landform, soils, and

watershed to be studied to determine the possible effectiveness of the plan.

Beaver management: Beaver can be used to naturally transform pioneer woody

vegetation into physical features that result in the expansion of floodplain, riparianwetland community structure, diversity, and productivity (Dickinson 1971).

Beaver activity is uniquely evident on aerial photos. Types of adjacent woody

vegetation can also be identified by aerial photos (Parsons and Brown 1978).

Bank stabilization: Streambank stabilization efforts are aided by the use of

historical photos for change detection purposes. Natural erosive components of

the surrounding landscape can help determine the potential of the area.

Recreation planning: In recreation planning, determining riparian-wetland

values is extremely important. The entire ecosystem should be taken into consideration. Photos can be used to develop future trail systems, plan site design to

minimize vehicular impacts to riparian-wetland areas, evaluate adjacent uplands

for potential hazards to human concentrations, and determine floodplain extent.

Road construction: Road construction planning should always incorporate the

use of aerial photos to help determine impacts to adjacent riparian-wetland areas.

Landform, vegetation inventory, flood potential, and watershed analysis are just a

few components that can be studied from an aerial perspective.
30
31

VI. Summary

Remote sensing techniques provide valuable information for riparian-wetland area

management. Aerial photos and satellite imagery can be used to establish baseline

data on which future management is based.

The first step in acquiring aerial photo baseline data is to define the objective of the

project, and to select the appropriate scale and film type to meet that objective. Then

research is conducted to determine whether photos with the desired specifications

exist.

Contracting for aerial photography is an option if appropriate photos for the area of

interest are not available. Planning for a contract involves selecting the area; determining the season, time of day to fly, and film type; and selecting the scale. Prior to

the flight, ground targets are placed to provide ground reference for determining

photo scale, and vegetation data is collected on-site for use during analysis.

Once the photos have been acquired, interpretation can be accomplished by local

BLM staff, State or NSTC personnel, or contracted photo interpreters. Interpretation

procedures consist of preparing photos, determining a minimum mapping unit

(MMU), developing a vegetation analysis framework, and analyzing photos. Photo

mensuration derived directly from the photos is possible on smaller projects or when

approximate measurements are acceptable.

If data is to be used for analysis purposes in a GIS environment, interpretations are

transferred to a stable map base from the photos. After transferring data to an

orthophoto, digitization into a GIS is possible.

Remote sensing techniques allow resource specialists to monitor an area when field

conditions do not allow on-site visits. Changes in management strategies for riparianwetland areas, which are characteristically highly responsive to modifications, are

easily monitored at specified intervals. Remotely sensed data can also be used in

determining classification, assessing functionality, and supporting other management

techniques addressed in the Riparian Area Management technical reference series.

To ensure that specific objectives are met, projects involving remote sensing must be

carefully designed and executed. The NSTC remote sensing staff is available to

provide support and assistance at each stage of the project.
32
33

Literature Cited

Aldrich, R.C. 1979. Remote sensing of wildland resources: A state-of-the-art review.

General Technical Report RM-71. USDA Forest Service, Rocky Mountain

Research Station, Fort Collins, CO. 56 pp.

Anderson, V.J. and P.J. Hardin. 1992. Infrared photo interpretation of non-riparian

wetlands. Rangelands: 14(6) 334-337.

Batson, F.T., P.E. Cuplin, and W.A. Crisco. 1987. Riparian area management: The use

of aerial photography to inventory and monitor riparian areas. TR 1737-2. Bureau

of Land Management, BLM/YA/PT-87/021+1737, Denver, CO. 16 pp.

Cagney, J. 1993. Riparian area management: Greenline riparian-wetland monitoring.

TR 1737-8. Bureau of Land Management, BLM/SC/ST-93/001+1737, Denver, CO. 45 pp.

Crisco, W.A. 1988. Interpretation of aerial photographs. USDI, BLM/YA/PT-88/

001+1268, Denver, CO. 41 pp.

Dickinson, N.R. 1971. Aerial photographs as an aid in beaver management. N.Y. Fish

and Game J. 18(1):57-61.

Gebhardt, K., S. Leonard, G. Staidl, and D. Prichard. 1990. Riparian area management: Riparian and wetland classification review. TR 1737-5. Bureau of Land

Management, BLM/YA/PT-91/002+1737, Denver, CO. 56 pp.

Keating, Jr., J.B. 1993. The geo-positioning selection guide for resource management.

Technical Note 389. Bureau of Land Management, BLM/SC/PT-93/002+9160,

Denver, CO. 64 pp.

Kinch, G. 1989. Riparian area management: Grazing management in riparian areas.

TR 1737-4. Bureau of Land Management, BLM/YA/PT-89/021+1737, Denver,

CO. 48 pp.

Leonard, S., G. Staidl, J. Fogg, K. Gebhardt, W. Hagenbuck, and D. Prichard. 1992.

Riparian area management: Procedures for ecological site inventory—with special

reference to riparian-wetland sites. TR 1737-7. Bureau of Land Management,

BLM/SC/PT-92/004+1737, Denver, CO. 135 pp.

Mereszczak, I., J. Colmer, J. Oden, J. Almy, M. Hoppus, P. Ishikawa, Jr., H.

Lachowski, J. Ward, and A. Oslin, Ph.D. 1990. Riparian area management: What

can remote sensing contribute? Engineering Management Series EM 7140-19.

USDA, Forest Service, Washington, DC.

Myers, L.H. 1989. Riparian area management: Inventory and monitoring riparian areas.

TR 1737-3. Bureau of Land Management, BLM/YA/PT-87/002+1737, Denver,

CO. 79 pp.
34

Parsons, G.R. and M.K. Brown. 1978. An assessment of aerial photography interpretation for recognizing potential beaver colony sites. In: Trans. N.E. Sect. TWS,

35th N.E. Fish & Wildlife Conference, White Sulphur Springs., WV. Pages 181-184.

Prichard, D., H. Barrett, J. Cagney, R. Clark, J. Fogg, K. Gebhardt, P. Hansen,

B. Mitchell, and D. Tippy. 1993. Riparian area management: Process for assessing

proper functioning condition. TR 1737-9. Bureau of Land Management, BLM/

SC/ST-93/003+1737, Denver, CO. 60 pp.

Prichard, D., C. Bridges, S. Leonard, R. Krapf, and W. Hagenbuck. 1994. Riparian

area management: Process for assessing proper functioning condition for lentic

riparian-wetland areas. TR 1737-11. Bureau of Land Management, BLM/SC/

ST-94/008+1737, Denver, CO. 46 pp.

Prichard, D., P. Clemmer, M. Gorges, G. Meyer, and K. Shumac. 1996. Riparian area

management: Using aerial photographs to assess proper functioning condition of

riparian wetland areas. TR 1737-12. Bureau of Land Management, BLM/RS/

ST-96/007+1737, Denver, CO. 52 pp.

Prichard, D., J. Anderson, C. Correll, J. Fogg, K. Gebhardt, R. Krapf, S. Leonard,

B. Mitchell, and J. Staats. 1998. Riparian area management: A user guide to

assessing proper functioning condition and the supporting science for lotic areas.

TR 1737-15, Bureau of Land Management, BLM/RS/ST-98/001+1737, Denver,

CO. 136 pp.

Prichard, D., F. Berg, W. Hagenbuck, R. Krapf, R. Leinard, S. Leonard, M. Manning,

C. Noble, and J. Staats, 1999. Riparian area management: A user guide to assessing

proper functioning condition and the supporting science for lentic areas.

TR 1737-16. Bureau of Land Management, BLM/RS/ST-99/001+1737, Denver,

CO. 109 pp.

Smith, B. and D. Prichard. 1992. Riparian area management: Management techniques

in riparian areas. TR 1737-6. Bureau of Land Management, BLM/SC/PT-92/

003+1737, Denver, CO. 44 pp.

Winward, A. 2000. Monitoring the vegetation resources in riparian areas. General

Technical Report RMRS-GTR-47. U.S. Department of Agriculture, Forest Service,

Rocky Mountain Research Station, Ogden, UT. 49 pp.
35

Appendix A

Minimum Mapping Unit Templates
36

255 acres

1"= 3,333'

1:40,000

Scale

1"

1 acre

10 acres

91.8 acres

871'

436'

100'

50'

1"= 2,000'

1:24,000

1"

1 acre

10 acres

23 acres

1742'

871'

50'

25'

1"= 1,000'

1:12,000

1"

1 acre

10 acres

436'

100'
37

12.9 acres

1742'

871'

50'

25'

1"= 750'

1:9,000

Scale 1"

1 acre

10 acres

436'

100'

5.7 acres

1742'

871'

50'

25'

1"= 500'

1:6,000

1"

10 acres

436'

100'

1 acre

3.7 acres

1742'

871'

50'

25'

1"= 400'

1:4,800

1"

5 acres

436'

100'

1 acre
38
39

Appendix B

Sample Vegetation Analysis Framework
40

Riparian-Wetland Plant Community Photo Analysis Form

(can be attached on photo or overlay when complete)

Site Name

Photo Number

Date

Interpreter

Dominant Species Groups

1. Herbaceous Vegetation - Minimum Mapping Unit (MMU) is 1 acre. Herbaceous vegetation is dominant and comprises 75% or more of the ground cover.

Shrubs and trees may be present but amount to less than MMU.

1____________acres

2. Shrubs - MMU is 1 acre. Shrubs are dominant and comprise 75% or more of

canopy. Trees and herbaceous vegetation may be present but amount to less

than MMU.

2____________acres

3. Trees - MMU is 1 acre. Trees 10 feet high are dominant and comprise 75% or

more of canopy. Shrubs and herbaceous vegetation may be present but

amount to less than MMU.

3____________acres

4. Riparian-Wetland Vegetation - Scarce or absent. A linear measurement of the

length of stream where there is an absence of riparian-wetland vegetation in

MMU amounts. If less than 200 feet in length, disregard and include in other

types (dominant or mixed).

4____________acres

Mixed Communities

MMUs of mixed types are 1 acre. Tree, shrub, or herbaceous vegetation less than

75% cover with a lesser amount of one or two other groups included in a mixed

community.

5. Shrub/herbaceous vegetation 5____________acres

6. Tree/herbaceous vegetation 6____________acres

7. Tree/shrub 7____________acres

8. Tree/shrub/herbaceous vegetation 8____________acres

Total riparian-wetland ____________acres
41

Appendix C

Remote Sensing Application Guide

 for Riparian-Wetland Management
42

General Comments

1) The Scale column indicates suggested scales only. Appropriate scale selection is

dependent on the size of the area under consideration. Larger or smaller scales

may be used for the applications listed, but may create more interpretive work for

the analyst. Scale selection should be carefully determined based on the area of

consideration and the intended use.

2) Scale column abbreviations represent the following:

L = Large scale (1:2,400 to 1:12,000)

M= Medium scale (1:15,840 to 1:30,000)

S = Small scale (< 1:30,000)

3) The Film Type column indicates suggested film types only. In many instances,

other film types are also appropriate for the applications listed.

4) Film Type column abbreviations represent the following:

B = Black and white

C = Natural color

I = False color infrared

S = Satellite imagery

5) The following table provides examples of various remote sensing applications that

can be used in riparian-wetland management. This list of applications is by no

means inclusive.
43

Remote Sensing Application Guide for

Riparian-Wetland Management*

Film

 Task/Application Scale Type Comments

Project Planning

Synoptic view S B/I/S Provides an overall perspective of the area;

general condition, limiting factors, watershed delineation; ecoregion

delineation.

Linear miles S B/C/I Derived from descriptive scale.

Area identification S B/C/I /S Locating areas in need of further

examination; defining reaches; identifying

field inventory sites.

Geomorphology/landform S C Slope, aspect, relief.

Drainage pattern S B

Inventory Technical References 1737-2**; 1737-3

Riparian-wetland M I Springs, seeps, wet meadow as habitat

type related to the associated vegetation.

Vegetation

Acreage determination L C/I Interpretations should be transferred to an

orthophoto for map accuracy calculation.

The photo scale needed is dependent on

the size of the riparian-wetland areas to be

measured.

Density L I Cottonwoods, willows.

Reproduction L I Young trees, but not seedlings.

Structure L C Height of vegetation.

Streambank shade L C

Streambank stability L I Associated with vegetation composition.

Species composition L I Cottonwoods, willows.

Percent cover L I Trees, shrubs, herbaceous, bare soil.

Hydrology

Stream width M C

Floodplain M C

Streambed silt M I

Stream channel stability M C

& movement

Channel sinuosity S C/I Photos often identify current channel

patterns better than older 7 1/2-minute

topographic maps.
44

Film

Task/Application Scale Type Comments

Soils

Soil determination M B/C Assists in identifying and recording soil

information.

Soil characteristics M B/C

Setting & associated M C Slope, aspect, relief, wetness.

land features

Classification Technical References 1737-5; 1737-7

Potential M B/C/I Compare historical photography to

determine past management practices.

Limiting factors S C Look at a larger area to determine

possible factors effecting riparian-wetlands

in the area of interest.

Field site planning S C/I Use to identify locations for gathering

vegetation, hydrology, and soils data.

General watershed quality S C/I Provides broad perspective of watershed.

Surface geology S C

Open water surface area M C/I Scale depends on size of water body.

Acreage determination L C/I See Inventory section.

Assessing Functionality Technical References 1737-9; 1737-11;

1737-12; 1737-15; 1737-16

Planning

Existing condition L I Scale is dependent on the size of the

riparian-wetland area.

Potential condition L I Use historical photography to assess.

Resource values M C/I Beaver dams, waterfowl habitat; evaluate

surrounding ecovalues.

Management technique M C/I See Management Planning section.

planning

Monitoring — — See Monitoring section.

Preliminary assessment M I Use smaller scale imagery to assess a

of functionality large area, then focus on areas that

appear to need further investigation.
45

Film

Task/Application Scale Type Comments

Reporting tables

Riverine/miles S I General assessment.

Riverine/nonriverine acres S I General assessment.

Functional condition M I General indicators.

Trend M C/I General indicators using historical

photography.

Management Planning Technical References 1737-4**; 1737-6;

1737-14

Grazing M C/I Allotment planning applications.

Ecosystem-based S C/I Provides a synoptic view of an area.

evaluation

Project planning Aerial photos are important ancillary data

that should be examined prior to any

management decision.

Exclosures M C

Prescribed burns M C/I

Physical structures M C

Streambank stabilization M C

Road construction M C

Mineral activities M C

Recreation planning M C

Monitoring Technical References 1737-2**; 1737-3;

1737-8** and General Technical Report 47.

All applications that are listed in the

Inventory section apply to monitoring.

Trend — — Monitoring should attempt to replicate

previous scale and film type as closely as

possible.

* This table is not intended as an all-inclusive list of applications for riparian-wetland management.

** This publication is out of print. Copies may be available in libraries.
46
47

Appendix D

Aerial Photo Samples
48

Photo 1a

Photo 1b

Photo 1a is a portion of a natural

color aerial photo of Texas Creek,

Colorado, acquired October 14,

1976, at approximately 1:15,840

scale (i.e., 1 inch represents 1,320

feet). The arrow in the aerial shot

indicates the gravel bar and bare

ground seen in Photo 1b, which is

a ground shot of the same area.

Photo 1b depicts on-the-ground

conditions for Texas Creek in

September 1976. The gravel bar

and bare ground are obvious

indicators of a nonfunctional

stream.
49

Photo 2a

Photo 2b

Photo 2a is a portion of a color

infrared aerial photo of Texas

Creek, Colorado, acquired July 9,

1983, at approximately 1:24,000

scale (i.e., 1 inch represents

2,000 feet). The photo shows

evidence of revegetation along

the streambank, and the gravel

bars are no longer evident.

Photo 2b shows Texas Creek in

June 1978 in a functional — at

risk condition. Management

actions were changed in 1977 to

reverse the trend of Texas Creek

and allow the area to progress

towards its capability and

potential.
50

Photo 3a

Photo 3b

Photo 3a is a portion of a NAPP

color infrared aerial photo of

Texas Creek, Colorado, acquired

September 29, 1988, at approximately 1:40,000 scale (i.e., 1 inch

represents 3,333 feet). The arrow

indicates taller vegetation, as

seen in Photo 3b of the same

area, as well as a higher spectral

response from the healthy vegetation along the streambank.

Photo 3b is a ground shot of

Texas Creek in July 1987, showing the area in Properly Functioning Condition (PFC).
51

Photo 4 is an enlargement of the NAPP color infrared aerial photo (Photo 3a) of Texas

Creek, Colorado, to approximately 1:24,000 scale.

Photo 4
52

Photo 5 is a portion of a color infrared aerial photo of Muddy Creek, Wyoming, acquired

August 17, 1993, at approximately 1:3,000 scale (i.e., 1 inch represents 250 feet).

Photo 5
53

Photo 6a is a portion of a color

infrared aerial photo of the Blackfoot

River, Idaho, acquired August 2, 1993,

at approximately 1:4,800 scale (i.e., 1

inch represents 400 feet). The arrows

indicate where ground targets (panels) are visible. Targeting should be

annotated on topographic maps,

along with distance between targets

and dominant vegetation information.

The box shown on a portion of a

1:24,000-scale topographic map (6b)

corresponds to the area shown in the

aerial photo.

Photo 6a

6b
54

Photo 7 is a portion of a color infrared aerial photo of Tabor Creek, Nevada, acquired

July 16, 1984, at approximately 1:2,400 scale (i.e., 1 inch represents 200 feet).

Interpretations were compiled on clear mylar overlays registered to the fiducial marks on

the photo.

Photo 7
55

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Revision to September 1994 version

Pam Clemmer

BLM/ST/ST-01/002+1737

(formerly BLM/SC/ST-94/005+1737)

January 2001

RIPARIAN AREA MANAGEMENT TR 1737-10

The Use of Aerial Photography to Manage Riparian-Wetland Areas

U.S. Department of the Interior

Bureau of Land Management

National Science and Technology Center

P.O. Box 25047

Denver, CO 80225-0047

This technical reference was originally produced as an enhanced version of RIPARIAN AREA MANAGEMENT TR 1737-2,

The Use of Aerial Photography to Inventory and Monitor Riparian Areas. This document is a revision to its original version

published in September 1994.

This technical reference provides basic information, concepts, and procedures associated with using

aerial photography to establish baseline data for effective management of riparian-wetland areas.

Suggestions for the use of various scales of photography, guidance for acquiring aerial photography,

and general procedures for conducting a vegetation inventory are included.

• Aerial photography • Wetlands

• Remote sensing • Monitoring

• Riparian area management

64 + covers
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The mention of trade names or commercial products does not constitute endorsement or recommendation for use

by the Federal Government.
60