ASTM D5924-18

Standard Guide for Selection of Simulation Approaches in Geostatistical Site Investigations

SIGNIFICANCE AND USE
4.1 This guide is intended to encourage consistency and thoroughness in the application of geostatistical simulation to environmental, geotechnical, and hydrogeological site investigations.  
4.2 This guide may be used to assist those performing a simulation study or as an explanation of procedures for qualified nonparticipants who may be reviewing or auditing the study.  
4.3 This guide should be used in conjunction with Guides D5549, D5922, and D5923.  
4.4 This guide describes conditions for which simulation or particular simulation approaches are recommended. However, these approaches are not necessarily inappropriate if the stated conditions are not encountered.
SCOPE
1.1 This guide covers the conditions that determine the selection of a suitable simulation approach for a site investigation problem. Alternative simulation approaches considered here are conditional and nonconditional, indicator and Gaussian, single and multiple realization, point, and block.  
1.2 This guide describes the conditions for which the use of simulation is an appropriate alternative to the use of estimation in geostatistical site investigations.  
1.3 This guide does not discuss the basic principles of geostatistics. Introductions to geostatistics may be found in numerous texts including Refs (1-3).2  
1.4 This guide is concerned with general simulation approaches only and does not discuss particular simulation algorithms currently in use. These are described in Refs (4-6).  
1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.  
1.6 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.

General Information

• Status: Published
• Publication Date: 14-Jul-2018
• ICS: 07.060 - Geology. Meteorology. Hydrology
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.01 - Surface and Subsurface Investigation

Relations

• Replaces: ASTM D5924-96(2010) - Standard Guide for Selection of Simulation Approaches in Geostatistical Site Investigations
• Effective Date: 15-Jul-2018
• Refers: ASTM D5549-19 - Standard Guide for Contents of Geostatistical Site Investigation Report
• Effective Date: 01-May-2019
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D5922-96(2010) - Standard Guide for Analysis of Spatial Variation in Geostatistical Site Investigations
• Effective Date: 01-May-2010
• Refers: ASTM D5923-96(2010) - Standard Guide for Selection of Kriging Methods in Geostatistical Site Investigations
• Effective Date: 01-May-2010
• Refers: ASTM D653-09 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Jan-2009
• Refers: ASTM D653-08a - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Dec-2008
• Refers: ASTM D653-08 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Nov-2008
• Refers: ASTM D653-07f - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 15-Dec-2007
• Refers: ASTM D653-07e - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Nov-2007
• Refers: ASTM D653-07d - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2007
• Refers: ASTM D653-07c - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Jul-2007
• Refers: ASTM D653-07b - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-May-2007
• Refers: ASTM D653-06 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Nov-2006

Overview

ASTM D5924-18: Standard Guide for Selection of Simulation Approaches in Geostatistical Site Investigations provides a framework to facilitate consistency and thoroughness when selecting geostatistical simulation techniques for site investigations. Developed by ASTM International, this guide helps environmental, geotechnical, and hydrogeological professionals choose suitable simulation approaches to model spatial variability in soils, rocks, and fluids. The standard is widely used for both conducting and reviewing simulation studies, supporting quality and transparency in site assessment and decision-making.

Key Topics

ASTM D5924-18 covers a range of critical considerations and terms for choosing simulation methods in geostatistical site investigations:

• Simulation vs. Estimation
  • Estimation methods like kriging create 'smoothed' maps, whereas simulation maintains the natural variability of measured attributes, which is essential for dynamic modeling.
  • Simulation is preferred when it is crucial to reflect in-situ variability, such as in groundwater flow modeling.
• Types of Simulation Approaches
  • Conditional vs. Nonconditional: Conditional simulations honor actual sampled data; nonconditional focus only on statistical properties.
  • Indicator vs. Gaussian: Indicator approaches are suited for binary/categorical data or situations emphasizing extreme values. Gaussian simulations are typical for continuous variables unless indicator coding is necessary.
  • Single vs. Multiple Realizations: Multiple simulations are essential for uncertainty analysis and Monte Carlo studies.
  • Point vs. Block Simulation: Selection depends on whether spatial averaging (support) matches the samples or needs to be modeled over larger blocks or regions.
• Practical Guidance
  • The guide outlines conditions under which specific simulation types are appropriate, without prescribing a fixed methodology, encouraging the integration of professional judgment.
  • The guide is not algorithm-specific but helps select suitable general simulation concepts based on investigation goals and data structure.

Applications

This standard has broad relevance across multiple fields that require spatial data assessment and risk-based analysis:

• Environmental Site Investigations
  • Mapping contaminant distribution and supporting remedial decision-making by accurately simulating spatial heterogeneity.
• Geotechnical Studies
  • Modeling subsurface variability for infrastructure design, slope stability, or ground improvement planning.
• Hydrogeological Modeling
  • Simulating hydraulic property fields for groundwater flow and transport modeling, where preserving true spatial randomness is critical for prediction reliability.
• Auditing and Review
  • Enables third-party reviewers or regulators to assess whether simulation studies follow consistent, robust frameworks for spatial data analysis.

By following ASTM D5924-18, professionals can ensure that simulation approaches are justified, scientifically sound, and tailored to specific project needs-enhancing both the accuracy and defensibility of site characterization results.

Related Standards

ASTM D5924-18 is designed to be used in concert with related ASTM guides to provide a comprehensive approach:

• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D5549: Guide for the Contents of Geostatistical Site Investigation Report
• ASTM D5922: Guide for Analysis of Spatial Variation in Geostatistical Site Investigations
• ASTM D5923: Guide for Selection of Kriging Methods in Geostatistical Site Investigations

These related standards offer definitions, reporting guidance, spatial analysis techniques, and recommendations for kriging approaches, complementing the simulation selection principles described in ASTM D5924-18.

---

Keywords: geostatistical simulation, site investigation, spatial variability, environmental simulation, conditional simulation, indicator simulation, kriging, ASTM D5924-18.

Standards Content (Sample)

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: D5924 − 18
Standard Guide for
Selection of Simulation Approaches in Geostatistical Site
Investigations
This standard is issued under the fixed designation D5924; 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
Geostatistics is a framework for data analysis, estimation, and simulation in media whose
measurable attributes show erratic spatial variability yet also possess a degree of spatial continuity
imparted by the natural and anthropogenic processes operating therein. The soil, rock, and contained
fluids encountered in environmental or geotechnical site investigations present such features, and their
sampled attributes are therefore amenable to geostatistical treatment. Geostatistical simulation
approaches are used to produce maps of an attribute that honor the spatial variability of sampled
values. This guide reviews criteria for selecting a simulation approach, offering direction based on a
consensus of views without recommending a standard practice to follow in all cases.
1. Scope a given professional service must be judged, nor should this
document be applied without consideration of a project’s many
1.1 This guide covers the conditions that determine the
unique aspects. The word “Standard” in the title of this
selection of a suitable simulation approach for a site investi-
document means only that the document has been approved
gation problem. Alternative simulation approaches considered
through the ASTM consensus process.
here are conditional and nonconditional, indicator and
1.6 This international standard was developed in accor-
Gaussian, single and multiple realization, point, and block.
dance with internationally recognized principles on standard-
1.2 This guide describes the conditions for which the use of
ization established in the Decision on Principles for the
simulation is an appropriate alternative to the use of estimation
Development of International Standards, Guides and Recom-
in geostatistical site investigations.
mendations issued by the World Trade Organization Technical
1.3 This guide does not discuss the basic principles of
Barriers to Trade (TBT) Committee.
geostatistics. Introductions to geostatistics may be found in
numerous texts including Refs (1-3). 2. Referenced Documents
1.4 This guide is concerned with general simulation ap- 2.1 ASTM Standards:
proaches only and does not discuss particular simulation D653 Terminology Relating to Soil, Rock, and Contained
algorithms currently in use. These are described in Refs (4-6). Fluids
D5549 Guide for The Contents of Geostatistical Site Inves-
1.5 This guide offers an organized collection of information
tigation Report (Withdrawn 2002)
or a series of options and does not recommend a specific
D5922 Guide for Analysis of Spatial Variation in Geostatis-
course of action. This document cannot replace education or
tical Site Investigations
experienceandshouldbeusedinconjunctionwithprofessional
D5923 Guide for Selection of Kriging Methods in Geostatis-
judgment. Not all aspects of this guide may be applicable in all
tical Site Investigations
circumstances. This ASTM standard is not intended to repre-
sent or replace the standard of care by which the adequacy of
3. Terminology
3.1 Definitions:
This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rock
and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
Characterization. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 15, 2018. Published August 2018. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2010 as D5924–96(2010). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5924-18. the ASTM website.
2 4
The boldface numbers in parentheses refer to a list of references at the end of The last approved version of this historical standard is referenced on
the text. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5924 − 18
3.1.1 For definitions of common technical terms used in this 4.3 This guide should be used in conjunction with Guides
standard, refer to Terminology D653. D5549, D5922, and D5923.
3.2 Definitions of Terms Specific to This Standard: 4.4 This guide describes conditions for which simulation or
particular simulation approaches are recommended. However,
3.2.1 conditional simulation, n—a simulation approach
these approaches are not necessarily inappropriate if the stated
where realizations of the random function model are con-
conditions are not encountered.
strained by values at sampled locations.
3.2.2 drift, n—in geostatistics, a systematic spatial variation
5. Selection of Simulation Approaches
of the local mean of a variable, usually expressed as a
5.1 Simulation Versus Estimation—A common objective of
polynomial function of location coordinates.
geostatistical site investigations is to produce a two- or
3.2.3 field, n—in geostatistics, the region of one-, two- or
three-dimensional spatial representation of a regionalized vari-
three-dimensional space within which a regionalized variable
able field from a set of measured values at different locations.
is defined.
Such spatial representations are referred to here as maps.
Estimation approaches, including all forms of kriging, yield
3.2.4 indicator variable, n—a regionalized variable that can
maps that exhibit a smoothing effect, whereas simulation
have only two possible values, zero or one.
approaches yield maps that preserve the spatial variability of
3.2.5 kriging, n—an estimation method where sample
the regionalized variable.
weights are obtained using a linear least-squares optimization
5.1.1 If mapped values of the regionalized variable are
procedure based on a mathematical model of spatial variability
required to provide an estimate of actual values at unsampled
and where the unknown variable and the available sample
points, then an estimation approach such as kriging is appro-
values may have a point or block support.
priate.
3.2.6 nonconditional simulation, n—a simulation approach
5.1.2 If mapped values of the regionalized variable are to
where realizations of the random function model are uncon-
preserve the spatial variability of values at unsampled points,
strained by sample data.
then simulation rather than estimation should be used.
3.2.7 nugget effect, n—the component of spatial variance
NOTE 1—Preservation of in-situ spatial variability is important if
unresolved by the sample spacing and the additional variance
mapped values of the regionalized variable are to be entered in a
due to measurement error. numerical model of a dynamic process, and therefore, simulation should
generally be used. For example, mapped values of transmissivity to be
3.2.8 point, n—in geostatistics, the location in the field at
entered in a numerical model of groundwater flow should be generated by
which a regionalized variable is defined. It also commonly
simulation (7). However, if the numerical process model is insensitive to
spatialvariationsoftheregionalizedvariable,thenanestimationapproach
refers to the support of sample-scale variables.
may also be used.
3.2.9 realization, n—an outcome of a spatial random func-
5.2 Conditional Versus Nonconditional Simulation—
tion or a random variable.
Geostatistical simulation methods are able to produce maps of
3.2.10 regionalized variable, n—a measured quantity or a
a regionalized variable that honor values observed at sampled
numerical attribute characte
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5924 − 96 (Reapproved 2010) D5924 − 18
Standard Guide for
Selection of Simulation Approaches in Geostatistical Site
Investigations
This standard is issued under the fixed designation D5924; 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
Geostatistics is a framework for data analysis, estimation, and simulation in media whose
measurable attributes show erratic spatial variability yet also possess a degree of spatial continuity
imparted by the natural and anthropogenic processes operating therein. The soil, rock, and contained
fluids encountered in environmental or geotechnical site investigations present such features, and their
sampled attributes are therefore amenable to geostatistical treatment. Geostatistical simulation
approaches are used to produce maps of an attribute that honor the spatial variability of sampled
values. This guide reviews criteria for selecting a simulation approach, offering direction based on a
consensus of views without recommending a standard practice to follow in all cases.
1. Scope
1.1 This guide covers the conditions that determine the selection of a suitable simulation approach for a site investigation
problem. Alternative simulation approaches considered here are conditional and nonconditional, indicator and Gaussian, single and
multiple realization, point, and block.
1.2 This guide describes the conditions for which the use of simulation is an appropriate alternative to the use of estimation in
geostatistical site investigations.
1.3 This guide does not discuss the basic principles of geostatistics. Introductions to geostatistics may be found in numerous
texts including Refs (1-3).
1.4 This guide is concerned with general simulation approaches only and does not discuss particular simulation algorithms
currently in use. These are described in Refs (4-6).
1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course
of action. This document cannot replace education or experience and should be used in conjunction with professional judgment.
Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace
the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied
without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the
document has been approved through the ASTM consensus process.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
Characterization.
Current edition approved May 1, 2010July 15, 2018. Published September 2010August 2018. Originally approved in 1996. Last previous edition approved in 20042010
as D5924–96(2004).D5924–96(2010). DOI: 10.1520/D5924-96R10.10.1520/D5924-18.
The boldface numbers in parentheses refer to a list of references at the end of the text.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5924 − 18
D5549 Guide for The Contents of Geostatistical Site Investigation Report (Withdrawn 2002)
D5922 Guide for Analysis of Spatial Variation in Geostatistical Site Investigations
D5923 Guide for Selection of Kriging Methods in Geostatistical Site Investigations
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 conditional simulation, n—a simulation approach where realizations of the random function model are constrained by
values at sampled locations.
3.1.2 drift, n—in geostatistics, a systematic spatial variation of the local mean of a variable, usually expressed as a polynomial
function of location coordinates.
3.1.3 field, n—in geostatistics, the region of one-, two- or three-dimensional space within which a regionalized variable is
defined.
3.1.4 indicator variable, n—a regionalized variable that can have only two possible values, zero or one.
3.1.5 kriging, n—an estimation method where sample weights are obtained using a linear least-squares optimization procedure
based on a mathematical model of spatial variability and where the unknown variable and the available sample values may have
a point or block support.
3.1.6 nonconditional simulation, n—a simulation approach where realizations of the random function model are unconstrained
by sample data.
3.1.7 nugget effect, n—the component of spatial variance unresolved by the sample spacing and the additional variance due to
measurement error.
3.1.8 point, n—in geostatistics, the location in the field at which a regionalized variable is defined. It also commonly refers to
the support of sample-scale variables.
3.1.9 realization, n—an outcome of a spatial random function or a random variable.
3.1.10 regionalized variable, n—a measured quantity or a numerical attribute characterizing a spatially variable phenomenon
at a location in the field.
3.1.11 simulation, n—in geostatistics, a numerical procedure for generating realizations of fields based on the random function
model chosen to represent a regionalized variable.
3.1.12 smoothing effect, n—in geostatistics, the reduction in spatial variance of estimated values compared to true values.
3.1.13 spatial average, n—a quantity obtained by averaging a regionalized variable over a finite region of space.
3.1.14 support, n—in geostatistics, the spatial averaging region over which a regionalized variable is defined, often
approximated by a point for sample-scale variables.
3.1 Definitions of Other Terms—Definitions: For definitions of other terms used in this guide, refer to Terminology D653 and
Guides D5549, D5922, and D5923. A complete glossary of geostatistical terminology is given in Ref (7).
3.1.1 For definitions of common technical terms used in this standard, refer to Terminology D653.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 conditional simulation, n—a simulation approach where realizations of the random function model are constrained by
values at sampled locations.
3.2.2 drift, n—in geostatistics, a systematic spatial variation of the local mean of a variable, usually expressed as a polynomial
function of location coordinates.
3.2.3 field, n—in geostatistics, the region of one-, two- or three-dimensional space within which a regionalized variable is
defined.
3.2.4 indicator variable, n—a regionalized variable that can have only two possible values, zero or one.
3.2.5 kriging, n—an estimation method where sample weights are obtained using a linear least-squares optimization procedure
based on a mathematical model of spatial variability and where the unknown variable and the available sample values may have
a point or block support.
3.2.6 nonconditional simulation, n—a simulation approach where realizations of the random function model are unconstrained
by sample data.
3.2.7 nugget effect, n—the component of spatial variance unresolved by the sample spacing and the additional variance due to
measurement error.
3.2.8 point, n—in geostatistics, the location in the field at which a regionalized variable is defined. It also commonly refers to
the support of sample-scale variables.
The last approved version of this historical standard is referenced on www.astm.org.
D5924 − 18
3.2.9 realization, n—an outcome of a spatial random function or a random variable.
3.2.10 regionalized variable, n—a measured quantity or a numerical attribute characterizing a spatially variable phenomenon
at a location in the field.
3.2.11 simulation, n—in geostatistics, a numerical procedure for generating realizations of fields based on the random function
model chosen to represent a regionalized variable.
3.2.12 smoothing effect, n—in geostatistics, the reduction in spatial variance of estimated values compared to true values.
3.2.13 spatial average, n—a quantity obtained by averaging a regionalized variable over a finite region of space.
3.2.14 support, n—in geostatistics, the spatial averaging region over which a regionalized variable is defined, often
approximated by a point for sample-scale variables.
4. Significance and Use
4.1 This guide is intended to encourage consistency and thoroughness in the application of geostatistical simulation to
environmental, geotechnical, and hydrogeological site investigations.
4.2 This
...