Technical Note 438

Upland Soil Erosion Monitoring and Assessment:

An Overview

 June 2011
Suggested citation:

Ypsilantis, W.G. 2011. Upland soil erosion monitoring and assessment: An overview. Tech Note 438. Bureau of Land

Management, National Operations Center, Denver, CO.

Production services provieded by:

Bureau of Land Management

National Operations Center

Information and Publishing Services Section

P.O. Box 25047

Denver, CO 80225

BLM/OC/ST-11/001+7100 
Upland Soil Erosion Monitoring and Assessment:

 An Overview 

Bill Ypsilantis

Bureau of Land Management

Environmental Quality and Protection

Washington, DC

Technical Note 438

June 2011

Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 iii

Acknowledgments

The author expresses appreciation to the following U.S. Department of the Interior (USDI) and 

U.S. Department of Agriculture (USDA) individuals for providing review comments for this 

publication.

Pete Biggam, USDI National Park Service

Lisa Bryant, USDI Bureau of Land Management

Randy Davis, USDA Forest Service

Jeff Herrick, USDA Agricultural Research Service

Ed Horn, USDI Bureau of Land Management 

Mike “Sherm” Karl, USDI Bureau of Land Management

Neffra Matthews, USDI Bureau of Land Management

Dan Muller, USDI Bureau of Land Management

Tom Noble, USDI Bureau of Land Management

Mike Pellant, USDI Bureau of Land Management

Jim Renthal, USDI Bureau of Land Management

Chris Smith, USDA Natural Resources Conservation Service

Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 v

Table of Contents

Abstract......................................................................................................................................... 1

Introduction.................................................................................................................................. 3

Soil Erosion Processes and Mitigation ........................................................................................... 5

Water Erosion.................................................................................................................... 6

Wind Erosion.................................................................................................................... 7

Design Considerations for Erosion Monitoring and Assessment.................................................... 9

Erosion Monitoring and Assessment Methods............................................................................. 13

Visual Indicators of Erosion............................................................................................. 13

Watershed Cover ............................................................................................................. 14

Remote Sensing Cover..................................................................................................... 16

Silt Fence Catchments ..................................................................................................... 18

Erosion Bridge................................................................................................................. 20

Erosion Plots ................................................................................................................... 21

Close-Range Photogrammetry ......................................................................................... 23

Cesium-137..................................................................................................................... 25

References ................................................................................................................................... 27

Appendix 1: Erosion Monitoring Methods Comparison Table .................................................... 35

Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 1

Abstract

Soil erosion monitoring and assessment are important tools in determining impacts from land 

management practices. Various methods have been used by the Bureau of Land Management 

to monitor soil erosion. This technical note is intended to aid resource specialists in evaluating 

techniques for monitoring and assessing upland soil surface erosion, other than gully erosion. A 

brief discussion of erosion processes is incorporated in this document. Highlighted monitoring 

techniques include visual indicators of erosion, watershed cover, remote sensing cover, silt 

fence catchments, erosion bridge, erosion plots, close-range photogrammetry, and cesium-137. 

An overview, brief discussion on procedure, advantages and disadvantages, and data analysis 

considerations are summarized for each monitoring technique. Listed references provide more 

detailed information about each technique and instructions on implementing erosion monitoring 

techniques.

Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 3

Introduction

The Bureau of Land Management (BLM) manages more than 245 million acres of public 

lands, primarily located in 12 western states including Alaska. The soil, vegetation, climate, and 

geomorphology across BLM-managed lands vary drastically. For example, the Alaskan tundra has 

permafrost soils; lichens, mosses, sedges, and dwarfed shrub vegetation; very cold, dry weather with 

most precipitation falling as snow; and hummocky, nearly level terrain. The conifer rainforests of the 

Pacific Northwest have well-weathered soils on steep mountain slopes that contrast with the deserts 

of the Southwest, which have a very dry, hot climate, aridic soils, and sparse shrubby vegetation.

The demand for data that provides reliable measures regarding the health of public land has 

increased in recent years. Surface condition is often used as a land health indicator and can be used 

to identify areas that need additional monitoring. Monitoring techniques that measure changes in 

rates of erosion can be very useful to land managers.

This BLM technical note is intended to aid resource specialists in evaluating and selecting 

techniques for monitoring and assessing upland soil surface erosion. To apply one of these 

techniques, refer to the provided reference material for specific procedures. Qualitative monitoring 

methods provide land managers and resource specialists with cost-effective techniques for 

determining the present status and indicators of apparent trend for one or more natural resources. 

Qualitative monitoring methods can be conducted on extensive acreage in a relatively short time 

and can indicate where resource problems may be occurring. More intensive monitoring methods 

provide more detailed, quantitative information about the condition and trend of one or more 

natural resources. 

Soil erosion costs the United States between $30 and $44 billion annually (Morgan 2005; 

Pimental et al. 1995). These costs represent: losses in food and fiber production; replacement of 
4 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

lost soil nutrients by increased fertilizer use; increased 

road, dam, and other infrastructure maintenance costs; 

decreased water storage capacity of the soil, which can 

result in increased irrigation requirements; repairs from 

increased flooding; lost recreational opportunities due 

to reduced water quality, air quality, and wildlife habitat 

degradation; and erosion prevention measures. Although 

erosion is an important natural process on public lands, 

when accelerated by human-induced activities, erosion 

can have substantial impacts on the productivity and 

use of that land. Additional impacts from erosion on 

public lands include loss of wetlands and riparian areas, 

vegetation community conversion to undesirable states, 

reduced plant productivity, increased susceptibility to 

weed invasion, and reduced water and air quality. Erosion monitoring is needed to identify potential problem 

areas and document erosion rates that are predictive of, 

or exceed, a critical threshold that could permanently 

degrade the land or cause serious offsite impacts, such as 

sedimentation.

Various techniques have been used by the BLM and 

other land management agencies to monitor surface 

erosion. Most techniques currently used are site specific 

and involve a resource specialist visiting the site and 

observing visual indicators of erosion or making direct 

measurements of erosion or erosion indicators, such as 

percent cover. Remote sensing is an emerging technology that can be used to monitor erosion over extensive 

acreage. Thus, erosion monitoring can be conducted at 

multiples scales to document the impacts of past management activities and catastrophic natural events, such 

as wildfire (Corwin et al. 2006). Scale refers to both the 

spatial and temporal variability in soil erosion.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 5

Soil Erosion Processes and Mitigation

Erosion is the wearing away of the land surface by running water, wind, ice, 

or other natural or anthropogenic agents that abrade, detach, and remove 

geologic parent material or soil from one point on the earth’s surface and 

deposit it elsewhere, including such processes as gravitational creep (Soil 

Science Society of America 2001). Geologic or natural erosion occurs under 

natural environmental conditions and geologic processes. Accelerated erosion 

is erosion in excess of natural rates, usually as a result of anthropogenic 

activities (Soil Science Society of America 2001). Major environmental 

disturbances, such as wildfire resulting from human changes in the natural 

fire processes, can also accelerate erosion. 

There are many prudent land management practices that will help reduce 

erosion. Examples of these practices include maintaining adequate plant, 

litter, and biological soil crust cover to protect a watershed; diminishing 

soil compaction; maintaining soil aggregate stability (the amount of stable 

aggregates against flowing water); applying good road building practices; 

reducing catastrophic wildfire conditions; and managing off-highway vehicle 

use. Other practices include concurrent reclamation of areas disturbed by 

mining and energy development, designating skid trails for timber harvest, 

proper road maintenance, and implementing sound livestock grazing 

management practices.

Guidance documents outlining these land management practices include 

each state’s rangeland standards and guidelines for livestock grazing 

management on BLM lands; standards for public land health and guidelines 

for recreation management on BLM lands for some states (e.g., Utah and 

Colorado); Grazing Management Processes and Strategies for RiparianWetland Areas, TR 1737-20 (Wyman et al. 2006); the Forest Practices Act 

for each state; Surface Operating Standards and Guidelines for Oil and Gas 

Exploration and Development (USDI and USDA 2007); and many others.
6 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

Accelerated erosion can result in onsite impacts, such 

as loss of soil productivity, and offsite impacts, such as 

sedimentation. Water erosion, runoff, and sediment 

delivery to streams are interrelated. For example, 

increases in runoff result in increased sheet, rill, and 

gully erosion, which results in increased sediment 

delivery to streams. Wind erosion and mass soil 

movement can also deliver sediment to streams as well 

as have major impacts on air quality.

Water Erosion

Surface water erosion processes are controlled by the 

intensity, timing, and duration of rainfall events and 

the size of raindrops; snowmelt runoff volume and 

timing; surface soil texture, structure, and organic 

matter content; soil depth and hydraulic conductivity; 

soil compaction; slope steepness and length; and 

watershed cover (Morgan 2005). Total cover is the 

most important management-related factor affecting 

water erosion, but plant basal cover and spatial 

distribution of plants is also important (Herrick et al. 

2005). Plant basal cover is resistant to rill and splash 

erosion. Large gaps in spatial distribution of plants 

can result in increased runoff and rilling, as well as 

increased wind speed, which causes greater wind 

erosion. Arid and semiarid lands in the western 

United States, which constitute the majority of 

lands managed by the BLM, are vulnerable to 

erosion and subsequent degradation because of 

a combination of factors, such as low vegetation 

cover, steep slopes, often shallow and rocky soils 

with low organic matter content, low infiltration 

rates, and infrequent but high-intensity 

thunderstorms.

Several models, such as the Water Erosion 

Prediction Project (WEPP) and the Revised 

Universal Soil Loss Equation (RUSLE), are 

available for predicting water erosion rates on rangeland 

and forest ecosystems. WEPP is a process-based, 

continuous simulation erosion prediction model that is 

applicable to hillslope erosion processes and simulation 

of the hydrologic and erosion processes on small 

watersheds. Various interfaces have been developed 

for WEPP, including several U.S. Forest Servicederived interfaces, such as Disturbed WEPP, WEPP 

Road, Erosion Risk Management Tool (ERMiT), 

Fuel Management Erosion Analysis (FuME), and 

a geospatial interface, GeoWEPP. WEPP interfaces 

have been extensively used for calculating rill and 

interill erosion on forest and rangeland ecosystems. 

Improvements to the WEPP model are being developed 

for rangeland use by the Agricultural Research Service 

(Spaeth et al. 2006; Wei et al. 2008). RUSLE is 

an erosion prediction model that was developed as 

an improvement on the empirical model USLE. It 

was originally developed to determine impacts of 

agricultural practices on erosion but has been adapted 

for application on forests and rangeland. RUSLE has 

some application limitations for some uses, such as 

postfire erosion prediction, since it only calculates 

average annual erosion.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 7

Upland water erosion occurs on land that is upslope 

from any stream channels, rivers, lakes, or other water 

bodies. It can be classified by the type of erosion that 

occurs.

• Sheet, splash, or interill erosion is the removal of a 

fairly uniform layer of soil from the land surface by 

raindrop splash or runoff water.

• Rill erosion happens as a result of concentrated 

overland flow that creates small channels up to a 

few inches in depth. The width and spacing of these 

channels will depend on soil properties (e.g., texture 

and structure) and management practices (e.g., 

tillage, roads, or trails).

• Gully erosion creates, in a comparatively short time 

period, relatively narrow channels that can be 1–2 

feet to as much as 75–100 feet in depth (Harvey et 

al. 1985). Severe gully erosion can, to a considerable 

extent, limit most uses on an effected hillslope. 

There are no universal and only a few local predictive 

models available for gully erosion. Gully erosion is 

very sensitive to increases in runoff and concentration 

of water flow across the landscape. Beyond reference 

to Technical Reference 1734-6 (Pellant et al. 2005), 

techniques for assessing or monitoring gully erosion 

are not discussed in this technical note.

Wind Erosion

Wind erosion occurs when wind speed exceeds the 

critical threshold; thus, surface soil particles are 

no longer held in place. Wind velocity at the soil 

surface varies greatly depending on wind patterns in 

a particular area and obstructions to wind created 

by uneven landform surfaces, plants, and other 

obstructions. Snow cover and high surface soil moisture 

reduce vulnerability of soil to wind erosion.

Soil texture, organic matter content, calcium carbonate 

reaction, and size and durability of soil surface 

aggregates largely determine the susceptibility of soil 

to wind erosion (Soil Survey Staff 1996). The poorly 

aggregated medium and finer sand soils are the most 

susceptible to wind erosion, and well-aggregated silty 

clay loams and silts are the least susceptible to soil 

blowing. Soil particles larger than 1 millimeter can 

roll on the ground during high wind storms; particles 

between 0.1 and 1 millimeter will bounce along the 

ground; and particles less than 0.1 millimeter can 

become airborne and travel long distances. Airborne 

particles can result in air quality problems, such as 

reduced visibility and increases in PM10 or PM2.5

particulates in the air. Airborne particulate matter that 

is 10 microns and smaller, and especially 2.5 microns 

and smaller, can get into the lungs and cause respiratory 

ailments in humans.

Adequate watershed cover is critical on soils susceptible 

to wind erosion. Also, wind erosion on undisturbed 

rangeland soils is generally reduced by the presence of 

biological, physical, or chemical crusts on the surface 

(Chow and Watson 1997). Disturbance can break up 

those crusts and greatly increase susceptibility to wind 

erosion. Two widely used wind erosion models are 

available, the Wind Erosion Equation (WEQ) and the 

Wind Erosion Prediction System (WEPS), but both 

are applicable only to cropland. There are currently 

no models that predict wind erosion on rangeland. 

However, WEQ and WEPS may be applied to bare, 

devegetated rangeland sites, such as after a severe fire.
8 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

This is an example of naturally occurring rill erosion on a highly erodible soil.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 9

Design Considerations for Erosion Monitoring and 

Assessment

The most basic consideration regarding erosion monitoring is to determine if it is actually needed. 

Is it required in a management plan either for quantifying a specific, anticipated impact or as 

an indicator of land health? Is it necessary to ensure compliance with a rule or regulation, such 

as water quality standards or required road construction practices? Can it provide a measure 

of the effectiveness of a planned management activity or mitigation? Will it provide a required 

performance measure, such as trend in upland condition? Will the monitoring answer the question 

that needs to be answered in the given timeframe? Does assessment indicate a potential erosion 

problem that needs to be monitored to determine if management objectives are being met?

Assessment is the process of estimating or judging the value or functional status of ecological 

processes in a location at a moment in time (Pellant et al. 2005). Monitoring is the orderly 

collection, analysis, and interpretation of resource data to evaluate progress toward meeting 

management objectives (Pellant et al. 2005).

The management objectives of any plan or project are the keys to its success. They articulate how 

issues will be resolved and how overall goals will be achieved. They represent a level of agreement 

among all the parties to the plan. They should be clear, measurable, and attainable. Consequently, 

the design of the monitoring plan should 1) flow smoothly from the objectives and 2) focus on 

selection of the best technique for determining if the actions taken to meet the objectives are 

succeeding (Elzinga et al. 1998; Herrick et al. 2005; Jackson et al. 1985a).

If erosion monitoring is being conducted over a large area, the next step is to stratify your landscape 

into monitoring units. These monitoring units should have similar management or land use 

characteristics and similar soil-landscape-ecological site characteristics. Next, you should try to 

predict the effects of current management on the monitoring units. Important considerations 

include legal requirements, resource use conflicts, threats to soil stability, and ecosystem drivers 

that could cause accelerated soil erosion (Jackson et al. 1985a). An on-the-ground assessment using 

methodology, such as those outlined in Technical Reference 1734-6 Interpreting Indicators of 

Rangeland Health, Version 4 (Pellant et al. 2005), may also be used to identify potential erosion 

problems. Based on risk of undesirable effects, you should determine which of the stratified units 

need to be monitored. Then select your monitoring indicators, such as cover or bare ground, or 
10 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

directly measure an indicator such as erosion. This 

step would not apply if you were monitoring the 

effectiveness of a specific erosion control structure.

Based on how the data will be used, determine the 

number of monitoring plots, transects, or sites and 

the frequency of your monitoring. Determine how 

statistically valid the data needs to be. Factors that 

will influence statistical validity and reliability include 

the method used to determine monitoring site 

locations (random, stratified random, or subjective), 

biases of the monitoring method, adherence to data 

collection standards, data collection from controls or 

comparison sites, number of replicate sample sites, 

overall number of samples collected, and use of the 

appropriate statistical test (Herrick et al. 2005; Jackson 

et al. 1985a; Schreuder et al. 2004). Also answer the 

following questions. What are the resource values at 

stake? What legal requirements must be met? How 

many measurements are needed to detect change with 

a reasonable degree of certainty? You are then ready to 

select your specific monitoring locations.

Erosion monitoring should be conducted at a location 

most representative of a watershed or portion of a 

watershed, such as an allotment, forest management 

area, energy development area, or off-highway 

vehicle area. Key areas already selected for allotment 

monitoring or other monitoring may not be the 

best location for soil erosion monitoring. Erosion 

monitoring should be conducted as part of the overall 

monitoring strategy for a field office. The soil and 

vegetation types of the monitoring site need to be 

identified in order to help determine departure from 

natural erosion rates, resilience of the soil resource, 

and other factors. This is especially important if a 

comparison area that has not been impacted by past 

management or land use practices is not available or 

will not be monitored. The erosion plot or transect 

should be contained within one soil type and/or 

ecological site. The location of the monitoring site 

should be recorded by using a global positioning system 

(GPS) unit. It is also helpful to take digital photos of 

the monitoring plot or transect.

Most water erosion occurs as a result of extreme 

precipitation events (Poesen et al. 1996). Monitoring 

studies need to last long enough to capture these events. 

Thus, soil erosion monitoring and data collection 

should be conducted for at least 3 years in order to 

draw any general conclusions.

The actual method selected for monitoring should be 

based on the amount of accuracy and precision needed 

for the monitoring data, ability to detect a difference, 

method cost, time requirements for conducting the 

method, amount of time needed for monitoring, 

and availability of qualified personnel to conduct the 

monitoring, analyze the data, and report the results.

Monitoring data should be recorded carefully in the 

field to avoid data errors. If the field data set is recorded 

on paper, it should be transferred to a standard database 

to preserve a permanent electronic copy. Currently, 

the BLM does not have a standard agency database for 

erosion or other monitoring data, but a commercial 

off-the-shelf database or spreadsheet should be used to 

preserve the data. This allows data to be easily retrieved, 

analyzed, and shared with others. The analysis method 

should be part of the monitoring plan, widely accepted 

by the scientific community, and applicable to the 

monitoring goals. For example, if assessing impacts or 

monitoring a prescribed burn using cover data, you 

should select an erosion model, such as WEPP, that 

predicts erosion for specific storm years rather than one 

that predicts average annual erosion.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 11

BLM geographer Neffra Matthews (bottom) and BLM physical scientist Tom Noble take a series of photos so they can use close-range 

photogrammetry methods to create three dimensional surface information to help quantify effects from rapidly increasing off-highway vehicle (OHV) 

use in the Dry Creek Extreme OHV Area.
12 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 13

Erosion Monitoring and Assessment Methods

Visual Indicators of Erosion

Background

The relative degree of erosion can be estimated by observing certain visual signs, such as pedestals, 

rills, litter movement, flow patterns, deposition, wind-scoured blowouts, and gully features. Visual 

indicators provide a qualitative assessment of erosion. Section 4180 of the BLM Manual directs 

the BLM to develop rangeland health standards in consultation with Resource Advisory Councils 

and evaluate the health of public lands. In addition, BLM Handbook H-4180-1 provides 

guidance stating that standards must conform to the four fundamentals of rangeland health, 

including watershed function. Indicators of watershed function generally include visual indicators 

of erosion.

Procedure

Along with Soil Surface Factors, visual indicators were commonly used to measure erosion in the 

1970s and early 1980s as described in the Erosion Condition Classification System (Clark 1980). 

Some of these indicators are currently used as part of the rangeland health assessments and are 

described in Technical Reference 1734-6 Interpreting Indicators of Rangeland Health, Version 

4 (Pellant et al. 2005). When rangeland health assessment is conducted using guidance from the 

technical reference, the ecological site for the assessment location is determined; the present status 

of erosion-based indicators is compared with the reference condition status of these indicators; 

and the departure differences are recorded on reference sheets (Pellant et al. 2005).

Advantages and Disadvantages

Major advantages of using visual indicators include 1) a relatively quick process, 2) many 

observations can be made during a field trip, and 3) potential erosion problems that require sitespecific monitoring can be identified.

The major disadvantages of using visual indicators are that 1) this method is subjective, and many 

judgment-based decisions must be made, 2) there can be variation among ratings by different 
14 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

observers if adequate training is not provided, 3) the 

ratings can vary based on the timing of observations 

relative to when a major storm occurred, 4) the 

ecological site must be known, and a reference sheet 

is required, and 5) this technique needs to be used by 

knowledgeable, experienced personnel. Interpreting 

Indicators of Rangeland Health, Version 4 (Pellant 

et al. 2005) states that the qualitative protocol 

they describe is not to be used to monitor land or 

determine trend.

Data Analysis

Visual indicators of departure from reference 

conditions are recorded on the data sheets for the 

rangeland health assessments. Departures from 

reference ratings are recorded for each of the 

indicators, and a summary rating is recorded for 

soil and site stability, hydrologic function, and 

biotic integrity. Sites that indicate potential erosion 

problems should be red flagged so future quantitative 

monitoring can be conducted or so mitigating 

measures can be implemented to correct the problem.

Watershed Cover

Background

Watershed cover protects soil from the erosional forces 

that initiate soil loss. Each ecological site has its own 

potential cover that should be used as a reference 

to determine departure from the natural range of 

variability. Current ecological sites may not include 

plant cover information. In this case, the information 

may need to be collected from a reference site. 

Monitoring cover is needed to quantitatively determine 

the impact that land management activities and natural 

disturbances (such as wildfire and drought) have on 

watershed conditions. Changes in cover are sensitive to 

management actions but can be difficult to interpret 

due to the wide amplitude of natural variation created 

by annual climate fluctuations. For trend comparisons 

in herbaceous-dominated plant communities, basal 

cover is the most stable since it does not vary as much 

due to climatic fluctuations or current-year grazing 

(Cooperative Extension Service et al. 1999). However, 

canopy or foliar cover is more closely correlated to 

raindrop erosion.

Canopy cover is the percent of ground covered by a 

vertical projection of the outermost perimeter of the 

natural spread of plant foliage. Small openings within 

the canopy are included as part of canopy cover. Foliar 

cover is similar to canopy cover, but small openings 

within the canopy are not included. This is effectively 

the area that is protected from raindrops. Canopy gaps 

affect wind erosion by increasing wind velocity at the 

soil surface and rill erosion by increasing concentrated 

overland flow of runoff (Herrick et al. 2005). Thus, 

the canopy gap intercept method can provide useful 

information about soil erosion susceptibility that is not 

indicated by total cover measurements alone.

Procedure

Cover changes are most accurately monitored using 

permanent plots or transects that are periodically 

revisited. Cover can be quantitatively measured using 

the step-point method, line-point intercept method, 

line intercept method, gap intercept method, methods 

using the points on a frequency frame, photo plots, 

or other methods (Cooperative Extension Service 

et al. 1999; Herrick et al. 2005). The canopy gap 

intercept method provides an indication of the extent 

to which plant cover is aggregated or dispersed. Cover 

can also be estimated using techniques such as the 

Daubenmire method. Using a quadrat frame, such 
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 15

as with the Daubenmire method, to estimate cover 

is not recommended by some authors (Floyd and 

Anderson 1987; Kennedy and Addison 1987). Other 

authors believe it to be a reasonably accurate method of 

determining cover (Bonham et al. 2004; Daubenmire 

1959; Hanley 1978; Stohlgren et al. 1998). Each of 

the other methods has advantages and disadvantages 

that should be taken into consideration. Cover can be 

expressed as ground cover, basal cover, canopy cover, or 

foliar cover, depending on the monitoring objective.

A laser point frame has been recently developed that 

can accurately measure cover (VanAmburg et al. 2005). 

It is constructed from aluminum alloy and has a T-bar, 

telescoping legs, and a main tube that contains 10 

equally spaced lasers and electrical components. When 

the instrument is turned on, 1-millimeter diameter red 

laser dots, which are easily seen in sunlight, are projected 

directly downward, and the cover category is identified 

for each dot. Test results indicated a relatively high 

correlation (r+0.62-0.81) between cover data collected 

using the laser point frame and a magnetic (standard) 

point frame (VanAmburg et al. 2005). Material 

costs for the laser point frame were about $700, and 

development and construction costs were $926.

Advantages and Disadvantages

Advantages include the fact that quantitative 

measurement of cover is objective, repeatable, 

rapid, relatively simple to perform, and can be done 

simultaneously with rangeland condition and trend 

monitoring. Changes in cover can also be tied easily to 

livestock and wildlife management objectives. A study 

measuring shrub cover showed that 1) the line-point 

intercept method required about half the time in the 

field than the line intercept method and less time 

in the office, 2) the line intercept method provided 

better results than the line-point intercept method for 

species with low cover (3 percent or less), and 3) the 

two methods provided similar results and precision for 

species with higher cover (Heady et al. 1959). When 

estimating cover, the advantages of using techniques 

such as the Daubenmire method are that it is simple 

and rapid to use.

The disadvantage of measuring or estimating cover is 

that 1) it is an indirect indicator of erosion, 2) canopy 

and foliar cover are difficult to interpret due to the 

natural variation created by annual climate fluctuations, 

3) monitoring needs to be done at a similar time of 

year, and 4) monitoring should be done during a rest 

period from livestock grazing. In addition, cover can be 

overestimated using step-point and frequency methods. 

The line intercept method is not well adapted for 

measuring cover on single stem species, dense grass, 

litter, or gravel with less than 1⁄2-inch diameter. The 

step-point method can be highly biased in vegetation 

that makes it difficult to pace in a straight line. The 

line point and line intercept methods take more time 

than the step-point method. The disadvantage of 

estimating cover using the Daubenmire frame is that 

it is not intended for plants greater than 1 meter in 

height, and if data are summarized using the midpoints 

for the cover classes, precision will be lowered over 

time. Ocular cover estimates using large plots are 

subject to observer bias and require extensive training 

and repeated comparisons with measured data and the 

results of other observers.

Data Analysis

The resource specialist can use cover data in several 

ways. One way is to compare the trend of cover data 

for the same plot from one monitoring cycle to the 

next. If canopy cover is included, the data would ideally 
16 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

be corrected for annual climate fluctuations. Methods 

to make these corrections are not currently available. 

Changes in basal cover may be more easily compared. 

Canopy or foliar cover does correlate better with 

raindrop erosion though. The climate data may also 

be compared to the cover of the reference condition 

for the same ecological site. To determine how much 

impact the change in cover has on water erosion, the 

cover data could be entered into an erosion model 

such as WEPP or RUSLE2. The other input factors for 

WEPP or RUSLE will need to be collected for the site. 

The U.S. Forest Service WEPP interface is the quickest 

and easiest version of the model to make erosion 

calculations. GeoWEPP is a geospatial interface that 

can be used to predict erosion on a watershed scale.

Remote Sensing Cover

Background

Remote sensing can be defined as broadly as “the 

acquisition of information about an object without 

being in physical contact with it” (Elachi and van Zyl 

2006). A much more narrow definition is “the sensing 

of the Earth’s surface from space by making use of the 

properties of electromagnetic waves emitted, reflected 

or diffracted by the sensed objects, for the purpose 

of improving natural resources management, land 

use and the protection of the environment” (United 

Nations 1986). Remote sensing, in the context used 

in this section of the technical note, includes any 

data collected remotely from the ground, aircraft, 

or satellites, including ground-based and aerial 

photographs and satellite imagery. Cover monitoring 

is well adapted to remote sensing frameworks at both 

a fine and coarse spatial scale and using various scales 

of imagery. Fine scale refers to small spatial extent, and 

coarse scale refers to broad spatial extent.

Procedure

Photography may be taken from the ground, speciallyequipped airplanes, helicopters, balloons, tethered 

blimps, kites, or radio-controlled model planes. 

Stereoscopic ground-based and aerial photographs 

are routinely taken in black and white panchromatic, 

black and white infrared, color visible, color infrared, 

and multiband types. High resolution groundbased and aerial photos are appropriate for fine-scale 

cover monitoring. QuickBird and IKONOS images 

and other single band and multispectral imagery 

may also be used for fine-scale cover monitoring. 

Imagery should be of fine enough resolution to detect 

total cover changes as accurately as ground-based 

measurements. New advances in ground-based (Booth 

et al. 2004; Booth et al. 2005; Booth et al. 2006b; 

Booth et al. 2006) and low-altitude (Blumenthal et 

al. 2007; Booth and Cox 2006; Booth and Cox 2008; 

Booth and Tueller 2003; Seefeldt and Booth 2006; 

Sivanpillai and Booth 2008) remote sensing may give 

us the ability to accurately measure bare ground and 

perhaps other cover indicators. Resolution up to 1 

millimeter has been obtained from low-altitude aerial 

imagery captured at a height of 100 meters (Sivanpillai 

and Booth 2008). Some ground-truthing may still be 

required though for low-altitude acquired imagery. 

In the past, costs for contracting image capture, 

processing, and classifying data have been relatively 

high, but they have recently been substantially 

reduced.

Many recent advances in technology have occurred. 

Booth and others (Blumenthal et al. 2007; Booth and 

Cox 2006; Booth and Cox 2008; Booth and Tueller 

2003; Seefeldt and Booth 2006; Sivanpillai and Booth 

2008) have done considerable testing using low-level 

flights with an ultralight plane to acquire imagery 
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 17

for cover change detection in Wyoming. Slaughter 

et al. (2008) are testing the use of unmanned aerial 

vehicles to acquire remotely sensed data for rangeland 

cover monitoring in New Mexico. Homer et al. 

(2008) have tested a predictive model to extrapolate 

QuickBird imagery training data to Landsat imagery 

in southwest Wyoming. Several of these projects have 

been conducted on BLM-administered lands and/or 

supported with BLM funding.

Multispectral imagery that is taken from a satellite 

at regular intervals and archived, such as Landsat, 

ASTER, and MODIS, is appropriate for coarse-scale 

cover monitoring. As an example, Robinove (1981) 

reported Landsat images to be effective in monitoring 

arid regions. These images would be appropriate for 

regional monitoring efforts. Each image covers a large 

area in a single view, and sampling could be done on 

a regional scale. Ground-truthing or training data 

using high-resolution imagery would be required for 

cover monitoring using multispectral imagery taken 

from a satellite. Contracting costs for processing and 

classifying multispectral data are moderate.

Some countries are much further advanced in the use 

of remote sensing for inventory and monitoring 

than the United States. Case in point, methods were 

developed in Australia to use Landsat TM imagery 

to estimate ground cover and identify trends in 

land condition, both spatially and temporally, in 

Queensland’s rangelands (Taube et al. 2001).

Combining information from high- and low-altitude 

sensors appears to offer an optimal path for developing 

a practical system for cost-effective, data-based 

rangeland monitoring and management (Booth and 

Tueller 2003; Sivanpillai and Booth 2008).

Advantages and Disadvantages

The advantages of remote sensing are that it allows 

for extensive, unbiased, economical cover sampling; 

and the measurements, especially when done by 

computer image analysis, have the potential to reduce 

the human-judgment factor. Booth and Tueller 

(2003) proposed that data collection through remote 

sensing appears the most logical approach to acquiring 

appropriately distributed information over large areas 

in short time periods and on random sites far removed 

from easy ground access. Compared to ground-based 

cover monitoring, fewer people are required to do the 

monitoring, and besides cover, considerable additional 

inventory or monitoring data can be obtained from 

the images. When using satellite-based remote sensing 

images, the same image can be reacquired at regular 

intervals. The electronic images are also permanently 

available for additional analysis using different 

techniques or evaluating different features.

One disadvantage is that multispectral data is surrogate 

data. This presents spatial relationships and spectral 

reflectance properties rather than direct measurements 

of an indicator. Thus, ground-truthing is still needed 

with our current capabilities and for the foreseeable 

future. In addition, some vegetation types, such as 

fine-textured, annual grasses or forbs, do not lend 

themselves to accurate cover detection using remote 

sensing. Liability and safety are also of concern when 

acquiring remote sensing data from low-level flights of 

manned aircraft.

Data Analysis

Analysis of the raw, remotely sensed data is a major 

workload unless the process is automated. Fortunately, 

recent developments in automating the data analysis 
18 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

have greatly reduced the workload (Booth and Cox 

2008). The process can now be automated to the 

point that the analysis selects the significant level of 

change of albedo (spectral reflectance) to be displayed 

(Booth and Cox 2008; Robinove 1981). Once this 

is complete, data analysis of the significance of cover 

data changes will be similar for both ground-based 

and remotely sensed data. The main difference will be 

that coarse-scale cover data could be used for regional 

analysis. As described previously in the data analysis 

section under watershed cover, erosion prediction 

models can be used to convert the cover data into 

erosion rates.

Silt Fence Catchments

Background

Silt fences have been used to control surface erosion 

from highway and other construction projects for 

decades. They allow water to pass through while trapping sediment. Silt fences can also be used as an easy-toinstall, low-cost way to measure hillslope water erosion.

Procedure

Silt fences are placed in locations where they can collect 

erosion from a contributing area defined by natural 

or manmade features. Contributing areas should not 

exceed 21,000 square feet (Robichaud and Brown 

2002). Dissmeyer (1982) recommends that the land 

slope be representative of the area being managed and 

not less than 3 percent. Silt fences are not designed 

to measure erosion rates in continuous flowing water 

channels, such as first-order streams.

The silt fence is installed at the base of the plots with 

suitable silt fence fabric and wooden or metal stakes 

to secure the material upright 18 to 30 inches above 

ground level. It is important to bury the bottom of the 

silt fence fabric below the ground surface to prevent runoff and sediment from escaping under the silt fence. Robichaud and Brown (2002) recommend sprinkling red 

chalk over the ground to define the boundary between 

the native ground surface and deposited sediment. 

The silt fence is cleaned out periodically to obtain 

reliable measurements of erosion. Dissmeyer (1982) 

suggests using a flagged grid, an elevation bench mark, 

and surveying equipment to determine the volume of 

sediment trapped behind the silt fence. Silt fences will 

last up to 3 to 5 years. The mean trap efficiency of a 

properly installed silt fence has been measured at 93 

percent the first year on a storm-by-storm basis and 92 

percent the second year when only measured at the end 

of the runoff season (Robichaud et al. 2001).

Advantages and Disadvantages

The advantages of silt fences are 1) they are relatively 

economical compared to some methods (e.g., erosion 

plots), 2) they can be installed with a small field crew, 

and 3) they can be maintained at various time intervals. 

They also provide a good visual means of the amount 

of hillslope erosion to nontechnical stakeholders 

(Dissmeyer 1982).

The disadvantages are that 1) runoff and sediment may 

knock over or overtop the silt fence, 2) if not properly 

installed, runoff water may undercut the silt fence so 

that sediment is lost, 3) it is time consuming and arduous to dig out and measure the collected sediment, 4) 

the contributing area must be accurately measured, and 

5) the silt fences only last up to 3 to 5 years. Livestock 

and wildlife can also knock over the silt fence. Lastly, if 

event sediment correlations are needed, the silt fences 

should be cleaned out after every major event.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 19

Data Analysis

The volume or weight of sediment that is removed 

from the silt fence is measured periodically. This 

volume is divided by the acreage of the contributing 

area to obtain an erosion rate for the time period 

between cleanouts. The erosion rate can then be 

converted into tons/acre/year.

Bob Brown, hydrologist with the U.S. Department of Agriculture Forest Service, repairs a silt fence after the 2003 Myrtle Creek Fire on the Idaho 

Panhandle National Forest. The silt fences in this area were used to measure the effectiveness of straw mulch, hydromulch, and natural needle cast 

on reducing erosion after the fire.
20 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

Erosion Bridge

Background

The erosion bridge is an easy-to-use, inexpensive tool to 

estimate water or wind erosion in the field. The erosion 

bridge is a 4-foot aluminum masonry level placed on 

two fixed support pins that remain in the ground the 

length of the monitoring study. The distance to the soil 

surface is measured at 10 fixed points along each bridge 

by pins that are lowered to the ground surface. These 

measurements are used to calculate the average change 

in soil surface elevation.

Procedure

Sampling locations and orientation of the sampling 

bridge should be randomly selected within the area to 

be monitored (Blaney and Warrington 1983). Each 

sampling location should be accurately recorded with a 

GPS so it can be plotted as a data point. Two rebar are 

driven deep enough into the ground to remain stable 

and spaced so that the erosion bridge is level when 

mounted on the rebar. The modified masonry level is 

taken to the field and mounted on the rebar at each 

monitoring site. The level has 10 equally spaced holes 

drilled into the upper and lower flanges. A 2-foot metal 

pin is placed through each hole. The pins are lowered 

to the ground surface, and the distance is measured 

at each point (Blaney and Warrington 1983; Ranger 

and Frank 1978; Shakesby 1993). Measurements can 

be made to the nearest millimeter. A 1-millimeter 

reduction in soil depth represents about 5 tons per 

acre. Repeat measurements for each pin during each 

monitoring visit; these measurements indicate the 

This erosion bridge is being used to determine the amount of wind erosion at a wildfire site in Idaho two years after the burn.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 21

change in soil surface elevation and thus erosion 

or deposition. Sampling is repeated at desired time 

intervals to determine the erosion rate.

Advantages and Disadvantages

The advantages of the erosion bridge are that it is 

an inexpensive, rapid, and unbiased method for 

monitoring erosion. However, the plot location and 

orientation must be randomly selected to avoid bias.

The disadvantage of the erosion bridge is that the 

rebar can move if disturbed by humans, vehicles, or 

animals, or as a result of frost heave which renders the 

measurements meaningless. In addition, the pins are 

rather thin and somewhat flexible, so if they do not 

fall on the exact same spot, the measurement will not 

be accurate. The erosion bridge only works in shrub 

interspaces. Also, the area sampled and the number of 

sampling points is rather small, so numerous sampling 

plots would need to be established on a hillslope to 

ensure that an accurate representation of hillslope 

erosion is obtained. Ideally, samples should be taken 

at several points up and down the hillslope when 

determining water erosion.

Data Analysis

These data are used to calculate the average change in 

the soil surface elevation. This can then be converted 

into erosion rates. T-statistics can be used to calculate a 

confidence interval for the mean, compare a measured 

mean with a standard value, or compare the values of 

two measured means (Blaney and Warrington 1983).

Erosion Plots

Background

Erosion plots can be used as an accurate monitoring 

technique for estimating differences in annual runoff 

and soil erosion. Plots 50-feet long by 10-feet wide, 

collection tanks, and cumulative mechanical stageheight counters are used to construct the plots.

These erosion plots were used to estimate sediment production from water erosion events on mixed grass rangeland in eastern Montana. 
22 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

The plots are replicated, and the pairing provides a control. The plots can be paired for grazed and ungrazed 

conditions, treated and untreated plots for restoration 

project monitoring, or other impact analysis.

Procedure

Jackson et al. (1985b) describe a procedure for 

construction and instrumentation of paired runoff 

and soil-loss monitoring plots. Plots 50-feet long by 

10-feet wide are constructed in pairs to collect runoff 

and sediment. The side and upper border are wooden 

planks set into the soil and supported by surveyor 

stakes. The lower border is a standard metal rain gutter 

set into the soil with its upper edge at ground level. 

The rain gutter is placed at an angle to the slope with a 

slight drop and ensures movement of sediment through 

the gutter. A length of angled roof edging is placed 

above the gutter and attached so that it overhangs the 

gutter edge; this provides a stable runoff surface into 

the gutter.

The gutter collects water and sediment that is 

transported to a collection trough via a downspout. 

The collection tank is a 100- or 200-gallon oval stock 

watering trough. The water level in the tank is recorded 

by a mechanical float counter that will cumulatively 

measure increases in stage. Thus, evaporation losses 

will not affect the readings. The counter is read yearly, 

along with the measurement of the volume of sediment 

collected. Plots should be located in close proximity 

to each other to ensure that they have the same 

slope, aspect, soil, precipitation, and ecological site 

characteristics.

Advantages and Disadvantages

The advantages of using erosion plots are 1) long-term 

runoff and erosion rates are measured, 2) these plots 

correspond to the standard 0.01 acre plot unit used 

to develop soil-loss parameters for the Universal Soil 

Loss Equation, 3) they are accurate at the plot scale 

if no losses occur from the plot or collection tank, 4) 

replication plots can be established, 5) control plots 

can be established, and 6) data can be compared using 

statistical techniques and analyzed using RUSLE, 

WEPP, or other common erosion models. If no losses 

occur from the plot or collection tank, erosion plots 

can also be used to validate erosion prediction models, 

such as WEPP and RUSLE2.

The disadvantages of using erosion plots are 1) 

equipment failures, including loss of runoff and 

sediment along the plot borders, overtopping of the 

collection tank, and potential livestock or wildlife 

damage to the plots, 2) the chance of improper site 

selection or plot installation, 3) difficulty in finding 

duplicate site conditions for the erosion plots, 4) 

potential rodents burrowing under the plot borders 

can result in loss of runoff and sediment, 5) wind 

erosion is not measured by this technique, 6) relatively 

high installation and maintenance costs, and 7) the 

effect of the plot borders on erosion processes. Erosion 

measured from small plots can underestimate or 

overestimate the erosion occurring on a hillslope scale 

(Boix-Fayos et al. 2006; Taube et al. 2001). A couple 

factors could cause underestimates. For one, the upper 

plot border could reduce overland flow within the 

plot. Also, erodible material could be exhausted within 

the plot. Overestimates can result from the fact that 

the disturbances along the plot border may increase 

detachable material, and the upper plot border reduces 

soil deposition within the plot (Boix-Fayos et al. 2006).

Data Analysis

If only one plot is established, regression can be 

used to quantify change in erosion and runoff over 
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 23

time. However, no significant trend over time can be 

established. If two or more plots are established, but a 

control is not established, probability statements can 

be established to a change over time, and confidence 

limits can be created for sediment yield or runoff for 

any given year or group of years. However, change 

over time cannot be related to management actions. If 

two or more plots are established for both the control 

and management-impacted areas, statistical analysis 

can be done for probability, and confidence and 

management implications can be determined (Jackson 

et al. 1985b).

Close-Range Photogrammetry 

Background

Close-range photogrammetry is an excellent method 

for capturing detailed information about erosion on 

plots ranging in scale from 1 square meter up to an 

entire hillslope. The software creates a digital terrain 

model with grid spacings of 1–2 millimeters and can 

detect vertical elevation changes with submillimeter 

accuracy on smaller plots. This methodology is 

especially effective for monitoring erosion on areas 

that will remain devoid of vegetation, such as roads, 

off-highway vehicle trails, and construction sites. This 

method is also appropriate for measuring sediment 

that accumulates in a sediment trap that is designed to 

monitor erosion in a catchment basin.

Procedure

Close-range—also referred to as terrestrial or groundbased—photogrammetry is defined as that having 

a distance of less than 300 meters from camera to 

object (Matthews et al. 2006). A calibrated camera 

is used to capture x, y, z coordinate data in a series of 

oblique orientation, overlapping photographs that 

are taken of the subject area with circular reference 

targets, circular coded targets, and an object of known 

dimension placed within the target area (Matthews 

2008; Ypsilantis et al. 2007). One or more permanent, 

fixed points is also needed as a reference for elevation. 

For larger size plots, three or four reference elevation 

points are needed. The reference points consist of 

bedrock or rebar driven deep enough in the ground to 

remain stable, with the top slightly below the ground 

surface so that they will not be disturbed and do not 

present hazards to recreational users. The rebar location 

is recorded with a GPS, and a GPS unit and metal 

detector are used to relocate them for subsequent plot 

measurement. This is an emerging technique with 

image processing expertise that is currently available 

from the BLM National Operations Center (NOC). 

Photos can be taken by field personnel and processed 

by the NOC’s photogrammetry personnel.

Laptop computers with PhotoModeler® or 3DM 

Analyst software (ADAM Technology, Australia) can 

be used to create digital terrain models that consist 

of a closely spaced grid with thousands of x, y, z 

data points (Matthews 2008; Ypsilantis et al. 2007). 

Using the photos taken of the monitoring plot or 

hillslope, the software creates a mosaic based on 

sophisticated automated recognition of coded targets 

and similar ground features between photos. Initial 

photo processing can be done in the field within a 

few minutes of downloading the digital photo images. 

The three-dimensional digital terrain datasets are then 

analyzed in ArcGIS using ArcMap and ArcScene. A 

tin surface is created and converted to a grid, and a 

hillshade is generated from the grid for each dataset 

(Matthews 2008; Ypsilantis et al. 2007). To determine 

changes in elevation of soil surface features, the surface 

grids created from initial sampling data are compared 

to data taken during a later sampling period.
24 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

Dennis Murphy, BLM soil scientist (retired), captures a series of overlapping images to create a digital terrain model of the Falcon Road Open 

Off-Highway Vehicle Area. Close-range photogrammetry can be used to determine changes in soil surface features by comparing the surface grids 

created from initial sampling data to data from later sampling periods.
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 25

Advantages and Disadvantages

The advantages of the methodology are 1) erosion can 

be directly measured to a high level of accuracy for 

a variety of plot sizes, from 1 square meter up to an 

entire hillslope, in a quick, efficient manner, 2) the cost 

of field equipment is low, 3) thousands of data points 

are collected for each plot, 4) the ability to drive rebar 

control points below the ground surface eliminates risk 

of disturbance and risk of safety hazard for recreation 

vehicle users, 5) detailed maps of the spatial pattern of 

soil erosion are produced for the entire hillslope, and 6) 

the photos and derived data sets are permanently stored 

electronically. This methodology could also be used to 

validate erosion models.

The disadvantages are 1) the processing software needed 

for larger size plots is currently expensive, 2) vegetation 

can obscure the ground surface and reduce the ability 

to make measurements on that portion of the site, 

and 3) there are few current sources of the expertise to 

conduct this monitoring. Another disadvantage is that 

any movement of litter, rocks, or other objects on the 

ground surface will be interpreted by the software as a 

soil loss and gain. This can bias the results of the analysis 

unless those data points are removed from the data set. 

Fortunately, erroneous data points can be removed from 

the data set during processing.

Data Analysis

ArcGIS software is used to determine cut and fill and 

surface subtractions for the surface grids within the 

monitoring plots or hillslope. The net soil loss or gain 

volume is divided by the area to determine loss or 

gain per area or tons per acre of erosion. Close-range 

photogrammetry can be used to determine soil loss 

and gain rates to subcentimeter accuracy for hillslopes 

and submillimeter accuracy for 1 square meter plots. 

The ADAM Technology 3DM software quickly and 

efficiently processes the digital photogrammetry 

data for a project. The close-range photogrammetry 

methodology has promising potential application for 

directly measuring erosion caused by a variety of soil 

disturbing activities.

Cesium-137

Background

Cesium-137 has been widely used over the past few 

decades to monitor soil erosion. Cesium-137 is an 

artificial radionuclide with a half-life of approximately 

30 years. It was globally distributed by the deposition 

(mostly by rainfall) of fallout from atmospheric nuclear 

weapons tests in the mid-1950s through the mid1960s (Cambray et al. 1989; Carter and Moghissi 

1977; Playford et al. 1993; Ritchie et al. 2003). Once 

cesium-137 reached the soil surface, it strongly and 

quickly adsorbed onto the exchange sites of the soil 

particles and was essentially nonexchangeable in most 

environments (Cremers et al. 1988; Ritchie et al. 

2003; Tamura 1964). Physical processes of water and 

wind erosion are usually the dominant factors moving 

cesium-137-tagged soil particles between and within 

landscapes (Ritchie and McCarthy 2003; Ritchie and 

McHenry 1990).

Procedure

Soil core samples are collected from the study area and 

from undisturbed reference sites that are assumed to 

have little erosion or deposition. Cored samples can be 

sliced to show the depth distribution of cesium-137. 

Samples are air-dried or ovendried and sieved through 

a 2-millimeter mesh. Subsamples are packed into 

Marinelli beakers or small plastic pots and analyzed 

with a gamma-ray spectrophotometer. Identification of 
26 Technical Note 438 Upland Soil Erosion Monitoring and Assessment: An Overview

cesium-137 loss and gain for each sampled location is 

made by comparison with the measurement from the 

reference sites. Estimates of soil erosion/deposition for 

each sample site can be made using various models, 

such as the cesium-137 profile distribution model 

(Walling and He 1999; Walling and He 2001).

Advantages and Disadvantages

The main advantage of using cesium-137 for erosion 

monitoring is that it is suitable for long-term erosion 

studies at a watershed or landscape scale (Bernard 

and Laverdiere 2001; Ritchie and McHenry 1990). 

Variations in erosion and deposition over a hillslope 

or within a catchment are possible. Cesium-137 also 

has potential for the study of source areas of sediment 

and sediment routing on hillslopes (Loughran 1989). 

Other advantages are that cesium-137 data can be used 

to estimate wind erosion when applied to a large area 

(Sac et al. 2008), only a single sampling trip to the 

field is required, and cesium-137 allows a sampling 

strategy to provide any spatial resolution required 

(Ritchie 2001).

The main disadvantage is that cesium-137 is not 

suitable for relatively short-term monitoring of the 

effect of management actions on erosion rates, which is 

the information needed by land management agencies, 

such as the BLM. Also, laboratory analysis costs for 

numerous samples would be potentially expensive.

Data Analysis

Estimates of soil erosion or deposition for each sample 

site can be made by using various models, such as the 

cesium-137 profile distribution model (Walling and He 

1999; Walling and He 2001). Indepth descriptions of 

other models used for estimating soil loss or deposition 

are provided by Walling and He (1997) and Walling 

and Quine (1990).
Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 27

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Upland Soil Erosion Monitoring and Assessment: An Overview Technical Note 438 35

Appendix 1: Erosion Monitoring Methods Comparison Table

METHOD Direct 

measurement 

or indirect 

indicator

Spatial scale Relative cost 

and rapidity

Relative 

accuracy and 

reliability

Applicable 

to water and 

wind erosion

Appropriate 

monitoring or 

assessment 

application

visual indicators of 

erosion 

indirect indicator local, regional, 

and national

inexpensive and 

rapid

qualitative, can 

vary between 

observers

both land health 

assessment, 

erosion over 

short- and longterm time periods 

indicated

watershed cover indirect indicator local inexpensive, 

rapidity depends 

upon specific 

method used 

but can be time 

consuming

quantitative, 

estimated cover 

can vary between 

observers, climate 

impacts canopy 

cover

both condition and 

trend monitoring, 

effectiveness 

and postfire 

monitoring, 

indicates current 

susceptibility to 

erosion

remote sensing 

cover

indirect indicator local and regional inexpensive and 

rapid

Accurate except 

for fine-textured 

grasses and forbs, 

reliable

both condition and 

trend monitoring, 

effectiveness 

and postfire 

monitoring, 

indicates current 

susceptibility to 

erosion

silt fence 

catchments

direct 

measurement

local moderate expense, 

time consuming to 

clean out

accurate 

if properly 

constructed and 

maintained

water only effectiveness 

and postfire 

monitoring

erosion bridge direct 

measurement

local inexpensive and 

rapid

accurate if 

undisturbed, 

reliability depends 

upon number of 

samples taken

both effectiveness 

and postfire 

monitoring

erosion plots direct 

measurement

local moderately 

expensive and 

time consuming 

to install and 

maintain

accurate and 

reliable if properly 

installed and 

maintained

water only effectiveness 

and postfire 

monitoring, longterm studies

close-range 

photogrammetry

direct 

measurement

local software 

expensive, very 

rapid

very accurate and 

reliable

both effectiveness 

and postfire 

monitoring, longterm studies

cesium-137 direct 

measurement

local and regional lab analysis 

expensive if 

numerous samples 

collected, rapid

accurate and 

reliable

both long-term studies 

evaluating erosion 

during past 40+ 

years

The mention of company names, trade names, or commercial products does not constitute endorsement or 

recommendation for use by the Federal Government.