ASTM D6145-97(2018)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6145 − 97 (Reapproved 2018)
Standard Guide for
Monitoring Sediment in Watersheds
This standard is issued under the fixed designation D6145; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Soil erosion and resulting sedimentation is the major cause of nonpoint source pollution that
threatens water resources. These impacts include: impaired aquatic habitat; destruction of sport and
commercialfisheriesandshellfisheries;lostreservoircapacityforfloodcontrol,powergeneration,and
storage of potable water supplies; excessive flooding; impaired navigation; aggradation of irrigation
and drainage channels; lost productivity of lands swamped by deposition and infertile overwash;
increased levels of water treatment; lost or declined recreational opportunities; and impaired aesthetic
values. The amount of sediment in a stream can affect channel shape, sinuosity, and the relative
balance between riffles and pools. Excessive sediment in a stream causes a decrease in channel
capacitywhichinturnresultsinmorefrequentandlargeroutofbankfloods.Inadditiontotheadverse
physical effects of sediment loads, many nutrients, pesticides, and heavy metals are sorbed onto fine
sedimentparticleswhichmayresultineutrophicortoxicwaters.Indirecteffectsofincreasedsediment
loads may include increased stream temperatures and decreased intergravel dissolved oxygen levels.
This guide recommends a process for developing and implementing monitoring projects for
sediment in a watershed. It follows Guide D5851 with more specifics applicable to watersheds and
sediment.
These guidelines are presented for use in the nationwide strategy for monitoring developed by the
IntergovernmentalTask Force on Monitoring (ITFM).The nationwide monitoring strategy is an effort
to improve the technical aspects of water monitoring to support sound water-quality decision-making.
It is needed to integrate monitoring activities more effectively and economically and to achieve a
better return of investments in monitoring projects (1).
This guide is offered as a guide for standardizing methods used in projects to monitor and evaluate
actual and potential nonpoint and point source sediment pollution within a watershed. The guide is
applicable to landscapes and surface water resources, recognizing the need for a comprehensive
understandingofnaturallyoccurringandmanmadeimpactstotheentirewatershedhydrologicsystem.
1. Scope 1.2 Sedimentation as referred to in this guide is the
detachment, entrainment, transportation, and deposition of
1.1 Purpose—This guide is intended to provide general
eroded soil and rock particles. Specific types or parameters of
guidance on a watershed monitoring program directed toward
sediment may include: suspended sediment, bedload, bed
sediment. The guide offers a series of general steps without
material, turbidity, wash load, sediment concentration, total
setting forth a specific course of action. It gives advice for
load, sediment deposits, particle size distribution, sediment
establishing a monitoring program, not an implementation
volumes and particle chemistry. Monitoring may include not
program.
only sediments suspended in water but sediments deposited in
fields, floodplains, and channel bottoms.
1.3 This guide applies to surface waters as found in streams
This guide is under the jurisdiction ofASTM Committee D19 on Water and is
and rivers; lakes, ponds, reservoirs, estuaries, and wetlands.
thedirectresponsibilityofSubcommitteeD19.02onQualitySystems,Specification,
1.4 Limitations—This guide does not establish a standard
and Statistics.
Current edition approved Aug. 1, 2018. Published September 2018. Originally
procedure to follow in all situations and it does not cover the
approved in 1997. Last previous edition approved in 2012 as D6145 – 97 (2012).
detail necessary to define all of the needs of a particular
DOI: 10.1520/D6145-97R18.
2 monitoring objective or project. Other standards and guides
The boldface numbers given in parentheses refer to a list of references at the
end of this standard. included in the reference and standard sections describe in
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6145 − 97 (2018)
detail the procedures, equipment, operations, and site selection 3.2.4 measurement, n—determining the value of a charac-
for collecting, measuring, analyzing, and monitoring sediment teristic within a representative sample or in situ determinations
and related constituants. of selected components of riverine, lacustrine, or estuarine
systems.
1.5 Additional ASTM and U.S. Geological Survey stan-
dards applicable to sediment monitoring are listed in Appendix 3.2.5 nonpoint source pollution, n—a condition of water
X1 and Appendix X2. Due to the large number of optional within a water body caused by the presence of undesirable
standards and procedures involved in sediment monitoring,
materials that enter the water system from diffuse locations
most individual standards are not referenced in this document. with no particular point of origin.
Standardsandprocedureshavebeengroupedintheappendices
3.2.6 resource management system (RMS), n—a combina-
according to the type of analyses or sampling that would be
tion of conservation practices identified by the primary use of
required for a specific type of measurement or monitoring.
the land that will protect the soil resource base, maintain
1.6 This standard does not purport to address all of the
acceptable water quality, and maintain acceptable ecological
safety concerns, if any, associated with its use. It is the
and management levels for the selected resource use.
responsibility of the user of this standard to establish appro-
3.2.7 watershed, n—all lands enclosed by a continuous
priate safety, health, and environmental practices and deter-
hydrologic surface drainage divide and lying upslope from a
mine the applicability of regulatory limitations prior to use.
specified point on a stream.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1 This guide is intended to be used in the planning stage
mendations issued by the World Trade Organization Technical
or phase of developing a sediment monitoring program. This
Barriers to Trade (TBT) Committee.
guide is an assembly of the components common to all aspects
of watershed sediment monitoring and fulfills a need in the
2. Referenced Documents development of a common framework for a better coordinated
and a more unified approach to sediment monitoring in
2.1 ASTM Standards:
watersheds.
D1129 Terminology Relating to Water
D4410 Terminology for Fluvial Sediment
4.2 The user of this guide is not assumed to be a trained
D4411 Guide for Sampling Fluvial Sediment in Motion
technical practitioner in the water quality, sedimentation, or
D4581 Guide for Measurement of Morphologic Character-
hydrology fields. The intended users are managers and plan-
istics of Surface Water Bodies (Withdrawn 2013)
ners who need information to develop a water quality moni-
D4823 Guide for Core Sampling Submerged, Unconsoli-
toring program or project with an emphasis in sediment and
dated Sediments
hydrology. Sediment specialists will also find information on
D5851 Guide for Planning and Implementing aWater Moni-
procedures, equipment, methodology, and operations to con-
toring Program
duct a monitoring program.
4.3 This guide is used during the planning process of
3. Terminology
developing, designing, and re-evaluating a sediment monitor-
3.1 Definitions:
ing program.
3.1.1 For definitions of terms used in this standard, refer to
Terminologies D1129 and D4410.
5. Monitoring Purpose
3.2 Definitions of Terms Specific to This Standard:
5.1 A watershed monitoring program for sediment is com-
3.2.1 assess, v—to determine the significance, value, and
prised of a series of steps designed to collect sediment and
importance of the data collected and recorded.
related flow data in order to achieve a stated objective. The
3.2.2 best management practice (BMP), n—a practice or
purposes of monitoring may be several and include: analyzing
combination of practices that are determined by state or
trends, establishing baseline conditions, studying the fate and
area-wide planning agencies to be the most effective and
transport of sediment and associated pollutants, defining criti-
practical means of controlling point and nonpoint pollution.
cal source areas, assessing compliance, measuring the effec-
tiveness of management practices, project monitoring, imple-
3.2.3 hydrograph, n—a graphical representation of the
mentation monitoring, making wasteload allocations, testing
discharge, stage, velocity, available power, or other property of
models, defining a water quality problem, and conducting
stream flow at a point with respect to time.
research.
5.2 Monitoring to analyze trends is used to determine how
water quality or sediment load changes over time. Normally,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
measurements will be made at regular well-spaced time inter-
Standards volume information, refer to the standard’s Document Summary page on
vals in order to determine the long term trend in some
the ASTM website.
sedimentation parameter. Typically the observations are not
The last approved version of this historical standard is referenced on
www.astm.org. taken specifically to evaluate BMPs or management activities,
D6145 − 97 (2018)
water quality models, or water quality standards, although Quality Monitoring Handbook (2), the ITFM reports (1, 3, 4,
trend data may be utilized, in part, for one of these other 5), and EPA Guidelines (6, 7).
purposes.
6. Monitoring Components
5.3 Baseline monitoring is used to characterize existing
sediment or water quality conditions, and to establish a data
6.1 This guide suggests and discusses the following steps in
base for planning or future comparisons. Baseline monitoring
designing a watershed monitoring program for sediment. More
should capture as much of the temporal variations as possible
detail on each step may be found in USDA-NRCS Monitoring
in order to assess seasonal and long term climatic influences
Handbook (2).
upon runoff and sediment yield. In some cases baseline
6.1.1 Identify Need—The first step is to define the need for
monitoring is included as the early stage of trend monitoring.
water quality monitoring. The need statement should include
5.4 Fate and transport monitoring is conducted to determine several components: the potential or real water quality issue
whether sediment and associated pollutants move and where
requiring attention, the potential use impairment or threats, the
they may go. name of the actual water resource(s), and finally the potential
sources that may cause the problem(s) (2). Very often the need
5.5 Sediment monitoring can be used to locate critical
is to identify a water quality problem but in some cases, the
source areas within watersheds exhibiting greater pollution or
need may be to assess the existing water quality whether a
loading potential than other areas.
problem exists or not. An example of a need statement might
5.6 Sediment monitoring may also be used to assess com-
be: “The decline in shellfish in Big Bay is due to accelerated
pliance with water quality management plans or standards.
sedimentation caused by excessive erosion from forestry op-
This is the monitoring used to determine whether specified
erations within the Trout Brook watershed.” Since sediment
water-quality criteria are being met. The criteria may be
may originate or become resuspended from a vast variety of
numerical (quantitative) or descriptive (qualitative).
nonpoint and point sources, the cause(s) of the sediment
problem may be difficult to establish or distinguish unless
5.7 Sediment monitoring may assess the effectiveness of
detailed monitoring plans are implemented.
individual management practices or resource management
systems for improving water quality or, in some cases, may be
6.2 Monitoring Objectives—The second step in developing
used to evaluate the effect of an entire program in a watershed.
a sediment monitoring program is to define the monitoring
Evaluating individual BMPs may require detailed and special-
objectives. The objectives of the monitoring study should
ized measurements made at the practice site or immediately
address the water quality need or problem. An objective
adjacent to the management practice. Monitoring the overall
statement should include an infinitive verb, an object word or
effectiveness of BMPs is usually done in the stream channel
phrase, and some constraints on the objective such as the
and it may be difficult to relate measured values to individual
surface or ground water watershed boundaries and variables to
practices.
monitor. An example of a monitoring objective might be: “To
5.8 Implementation monitoring may assess whether BMPs
determine the effect of implementing best management prac-
were installed or implemented, or if significant land uses tices on sediment concentration or sediment yield in Trout
changes occurred. Typically this activity is carried out as an
Brook.” When several objectives are used, a hierarchical
administrative review or a monitoring of landuse changes. On approach may be used to determine higher priority objectives.
its own, however, implementation monitoring cannot directly
An objective tree can be used to distinguish among several
link management activities to water quality or sediment yield, objectives. To determine how several objectives can be linked,
as no actual sediment or water measurements were taken.
the following question can be asked: “Does the achievement of
objectiveAcontribute directly to the achievement of objective
5.9 Monitoring of water bodies receiving runoff and sedi-
B?”To assess whether objectives are being achieved, objective
ment or other suspended loads can be used to make wasteload
attributes could be determined.These attributes may be binary,
allocations between various point and nonpoint sources. Such
achieved or not, or scaler.
allocations require good knowledge of the individual contribu-
tions from each source.
6.3 Sampling Design—A wide variety of instruments and
techniques have been developed for field measurements of soil
5.10 Sediment monitoring may be used to fit, calibrate, or
erosion, sediment movement, turbidity, and sediment deposi-
test a model for local conditions. Sediment monitoring may be
tion. In general four basic types of studies exist: measurements
used to evaluate samplers, rainfall simulators, runoff collection
of sediment in surface runoff from small experimental plots
devices and other related instruments or devices for research
and field size watersheds, stream sampling of suspended
purposes.
sediment load and bedload, measurements of eroded areas to
5.11 Finally, sediment monitoring may be used to give
determine volume of material removed, and measurements of
adequate definition to a water quality problem or determine
the volume and density of deposited sediment.All four studies
whether a sediment related problem exists.
may also include particle size analyses and chemistry of the
5.12 Guide D5851 provides overall guidance on water sediments and associated pollutants. A statistical experimental
monitoring and provides detailed information on purposes of design should be stated that is consistent with the objectives of
monitoring water quality. Additional information on purposes the monitoring program.Appropriate experimental designs for
of watershed monitoring is provided in USDA-NRCS Water monitoring sediment in motion or suspended sediment could
D6145 − 97 (2018)
include: reconnaissance, plot, single watershed “above-and- 6.3.7 Trend stations are single watersheds monitored over
below,” single watershed “before-and-after,” paired time. A trend is a persistent change in the water quality
variablesofinterestovertime.Itisimportantfortrendanalysis
watersheds, multiple watersheds, and trend stations (2).
thattherenotbegapsinthedataset,thatwaterqualityanalysis
6.3.1 The design selected will dictate most other aspects of
methodsnotchange,thatthehydrologicalcontrolisstable,and
the monitoring project including the study scale, the number of
a causal link can be made between the water quality and
sampling locations, the sampling frequency, and the station
watershed activities. A control trend station is highly recom-
type.
mended where no changes in watershed activities occur during
6.3.1.1 Reconnaissance or synoptic designs may be used as
the trend investigation (2).
a preliminary survey where no data exist or to assess the
6.3.8 In addition to erosion and sediment yield studies from
magnitude and extent of a problem. This type of sampling
plotandfieldsizewatersheds,sedimentinvestigationsinaland
could be used to identify critical source or problem areas as
resource area may require measurements of sediment yield
well. Randomization in sampling locations may be important
from channels, gullies, and other major or critical sediment
for reconnaissance monitoring.
sources. Typical sites may not exist, but sites selected should
6.3.2 Plot designs have been commonly used in agricultural
represent local conditions as nearly as possible. Often these
and forestry experiments for 100 years. Plots are generally
studies require detailed topographic surveys in order to deter-
small areas that allow replication and control on the landscape
mine volumes of material eroded.
of certain variables, such as soil type, slope, and land cover.
6.3.9 Sampling of sediment deposited in stream beds and
Plot studies can utilize natural rainfall events or artificial
valley bottoms is used to provide information on sediment
rainfall simulators (for example, rainulators). Plot studies are
particle size distribution, specific gravity, mineralogy of the
best utilized for evaluating individual BMPs, developing
sediment particles, sediment volumes, effects on benthic
model algorithms, and evaluating specific soil, climatic, and
ecosystems, sorbed toxic chemicals, and nutrients. The most
physiographic variables. Plot designs are generally analyzed
common purpose for sampling sediment deposits in streams is
using analysis of variance (2).
to obtain information on the character of the sediment particles
6.3.3 The single watershed “before-and-after” approach has
that are subject to movement during storm runoff events. This
been sometimes used to compare water quality conditions
information is needed for channel stability analyses, sediment
before an application of BMPs or landuse changes to condi-
transport studies, and assessing the effects of bed scour and
tions after activity has occurred. Generally, this technique is
deposition upon bethic organisms.
not recommended, since the results are confounded with time,
6.3.10 Sampling of reservoir and lake deposits often pro-
and should be avoided. For example, the water quality differ-
vides information on the sediment yield and sediment charac-
ences from year-to-year may be caused by climate differences
teristics of an entire watershed. Most reservoir sedimentation
not the watershed activity or land use management.
studies are directed toward determining the quantity,
characteristics, and distribution of sediment as determined by
6.3.4 The single watershed “above-and-below” design is
used after a watershed practice is in place. Sampling is periodic volumetric surveys of the lake or reservoir. Reservoirs
are normally surveyed to determine rate of sediment buildup
conducted both upstream and downstream from the activity of
interest.Although this design is not as susceptible to the effect and assess remaining useful reservoir life or water storage,
determine sediment yield from a watershed that represents a
of climate as the single watershed design, the differences in
typical landuse pattern in a region or land resource area,
water quality between the two stations may be partly due to
evaluate the effects of watershed protection measures, deter-
inherent watershed differences such as soil type, land gradient,
mine sediment yield of unusually large storms, determine long
geologic materials, or varying watershed runoff characteristics,
term regional sediment yields, provide basic data for planning
or all of these.
and designing reservoirs, monitor quality, and evaluate sedi-
6.3.5 The paired watershed approach uses a minimum of
ment damages. Reservoir sedimentation investigations may be
two watersheds—control and treatment—and two periods of
partofsinglewatershed,pairedwatershed,multiplewatershed,
study—calibration and treatment (8). The control watershed
or trend station study approaches. In addition, determination
serves as a check and provides information on the effects of
and evaluation of reservoir trap efficiencies can be made if
year-to-year climate variations and receives no changes in land
infloworoutflowsedimentmeasurements,orboth,aremadeor
uses or activities during the monitoring study. During
are available.
calibration, the two watersheds are managed or treated identi-
cally and paired water quality data are collected. During the
6.4 Study Scale—The size or scale of the monitoring pro-
treatment period, one watershed is treated with a practice or
gram should be determined. Appropriate scales include: point,
managementsystemwhilethecontrolwatershedremainsinthe
plot, field, and watershed.
original management.
6.4.1 Points are the smallest scale considered for water
6.3.6 The multiple watershed approach involves more than quality monitoring and are characterized by obtaining single
observations. A rain gage, a sediment probe, or a staff gage
two watersheds. Watersheds with treatments already in place
are selected from across the region of interest. Sampling from represents a point sample.
these watersheds is conducted over a period of time. Groups of 6.4.2 Plots are microcosm sampling units which are appro-
likewatershedsaretestedagainsteachothertodeterminewater
priate if the objective is to replicate several treatments or
quality differences (2). activities. Generally, fractional acre (hectare) plots are used to
D6145 − 97 (2018)
study basic erosion rates and edge of plot sediment yield of associated with the water body. Other techniques for selection
various soil cover complexes with various BMPs installed. include ranking the variables of interest, developing correla-
Replicate plots are often required to obtain representative data tions between variables, and determining the probability of
due to such factors as inherent errors in measurement and exceeding a standard (2).
naturalvariationswithinsoilunits.Thenumberofplotsneeded
6.6 Sample Type—Sediments in watersheds may be col-
for a study is a function of the number of treatments applied
lected and measured as either; total water and sediment runoff;
(2). For most experiments, ten or more years of study is
portioned or fractional runoff; grab; composite; integrated; or
requiredinordertocoverthenormalrangeinweatherpatterns.
continuous samples. The type of sample collected is a function
Utilizing rainfall simulators can greatly reduce the evaluation
of the purpose in monitoring, the variables to sample, and
period or allow greater numbers of test to be performed in a
whether turbidity, concentration, total yield or mass is the
short period of time. Detailed information on designing plot
desired outcome.
studies may be found in Ref (9).
6.6.1 Total collection devices are often used on very small
6.4.3 Monitoring on a field scale implies a larger area than
plots where a suitable collection tank large enough to contain
an individual plot. The area of a field is difficult to state
the total runoff (water and sediment) expected in a 24 or 48 h
because it varies greatly in different parts of the United States.
period can be installed (9). Total collection devices are
Field scale monitoring is normally used to determine erosion
normallynotrecommendedbecauserunoffstoragevolumesare
rates and edge of field (mini-watershed) sediment yield from
excessive even for very small drainage areas. Also small plots
tracts of land a few acres (hectares) in size which are
may not be representative of larger complex fields and small
representative of given land resource area under specific land
watershed conditions.
use and management with or without BMPs installed.
6.6.2 Slot type or portioned samplers, which collect a
6.4.4 Watershed scale monitoring is used for most water
known portion of the runoff-sediment mixture, are often better
quality monitoring purposes. One of the most difficult deci-
suited for larger plots and small fields. These samplers are
sions is the watershed size. Generally, size is influenced by
automatic in the sense that no attendant is required during the
stream order, climate, number of landowners, homogeneity in
sampling operation and sampling is continuous during the
land use and physical attributes, and geology (2). If a determi-
runoff event. The samplers provide a storm integrated or
nation of sediment yield from a watershed or river-basin is the
discharge weighted sample for determining sediment yield.
only objective, any size watershed is appropriate, however
Construction, installation and operation details for total collec-
smaller watersheds will require more frequent measurements
tion and slot type samplers can be found in Ref (9).
duetomorerapidandextremetemporalvariationsinrunoff.In
6.6.3 A grab sample is a discrete sample that is taken at a
order to assess the effects of land use, land management, BMP
specific point and time. A series of grab samples, usually
installations,orotheractivities,thesamplingstationsshouldbe
collected at different times or locations in a stream cross-
as close to the activity as possible. This will often dictate the
section, and lumped together, are considered a composite
size of the watershed to be monitored.
sample. Composite samples may be either time-weighted or
flow-weighted. A specific type of a grab sample is a
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