1、Designation: D 6106 97 (Reapproved 2004)Standard Guide forEstablishing Nomenclature of Ground-Water Aquifers1This standard is issued under the fixed designation D 6106; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers a series of options but does notspecify a course of action. It should not be used as the solecriterio
3、n or basis of comparison and does not replace or relieveprofessional judgement.1.2 This guide contains instructions and suggestions forauthors of ground-water (hydrogeologic) reports in assigningappropriately derived and formatted aquifer nomenclature.Discussed are the water-bearing units that may r
4、equire nameidentification, which are, ranked from largest to smallest,aquifer system, aquifer, and zone. Guidance is given onchoosing the source of aquifer names, those are from lithologicterms, rock-stratigraphic units, and geographic names.1.3 Included are examples of comparison charts and tablest
5、hat can be used to define the hydrogeologic framework.Illustrations of eleven different hypothetical aquifer settings arepresented to demonstrate the naming process.1.4 Categories of items not suggested as a source of aquifernames are reviewed because, although they should be avoided,they occur in p
6、ublished documents. These categories are thefollowing: time-stratigraphic names, relative position, alpha-numeric designations, depositional environment, depth of oc-currence, acronyms, and hydrologic conditions.1.5 Confining units are discussed with the suggestion thatthese units should not be name
7、d unless doing so clearlypromotes an understanding of a particular aquifer system.Suggested sources of names for confining units correspond tothose for aquifer names, which are lithologic terms, rock-stratigraphic units, and geographic names.1.6 It is suggested that in reports that involve hydrogeol
8、ogy,the author should consider first not naming aquifers (see 6.2).1.7 Format and expression styles are assessed along with thegeneral cautions related to name selection of aquifers andconfining units.1.8 This guide is a modification of a previously publishedreport (1).21.9 This guide offers an orga
9、nized collection of informationor a series of options and does not recommend a specificcourse of action. This guide cannot replace education orexperience and should be used in conjunction with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This guide is no
10、t intended to represent orreplace the standard of care by which the adequacy of a givenprofessional service must be judged, nor should this guide beapplied without consideration of a projects many uniqueaspects. The word “Standard” in the title of this documentmeans only that the document has been a
11、pproved through theASTM consensus process.2. Referenced Documents2.1 ASTM Standards:3D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 1129 Terminology Relating to WaterD 5409 Guide for Set of Data Elements to Describe aGround-Water Site; Part TwoPhysical DescriptorsD 5434 Guide for Fie
12、ld Logging of Subsurface Explora-tions of Soil and RockD 5474 Guide for Selection of Data Elements for Ground-Water Investigations3. Terminology3.1 Definitions: Except as discussed as follows, all defini-tions are in accordance with Terminologies D 653 and D 1129.The following terms are examined in
13、detail in order to clarifythe method of assigning nomenclature to the aquifers andassociated units:3.2 IntroductionAquifers do not lend themselves to brief,neat, and simple definitions; therefore, a flexible hierarchy ofterms is used in these guidelines. The terms that are used forwater-yielding roc
14、ks from largest to smallest are: aquifersystem (2), aquifer (3), and zone (4). Confining units (3) arediscussed because of the stratigraphic relationship with thewater-bearing units.1This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rockand is under the direct responsibility of
15、Subcommittee D18.21 on Ground Water andVadose Zone Investigations.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1997. Last previous edition approved in 1997 as D 6106 - 97e1.2The boldface numbers in parentheses refer to the list of references at the end ofthis stan
16、dard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO
17、 Box C700, West Conshohocken, PA 19428-2959, United States.3.2.1 Parallelism between the hierarchy of terms for water-yielding rocks and rock-stratigraphic terms, namely, aquifersystem (group), aquifer (formation), and zone (member),should be avoided because water-yielding rocks can cross theboundar
18、ies of geologic units or constitute only part of ageologic unit. The scale of the study also may determine thebest usage. For example, at the local scale, an aquifer systemcould be defined totally within a single formation, and at theregional scale, a formation or group could be totally within andon
19、ly a part of a single aquifer or an aquifer system. Again, theguidelines for aquifer nomenclature must remain flexible tomeet a variety of hydrogeologic scales and settings.3.2.2 A discussion of the terms aquifer, aquifer system,zone, and confining unit is provided here to give authors acommon refer
20、ence base. Although complete agreement onthese definitions has not been achieved, the terms are adequateto transfer knowledge from authors to readers of reports. It isnot the purpose of these guidelines to formally redefine theterms or to define new terms to take their place.3.3 Definitions of Terms
21、 Specific to This Standard:3.3.1 aquifer, nThis term probably has more shades ofmeaning than any other term in hydrology (5), see TerminologyD 653. It can mean different things to different people anddifferent things to the same person at different times.3.3.1.1 DiscussionMeinzer (5) defined an aqui
22、fer as “arock formation or stratum that will yield water in sufficientquantity to be of consequence as a source of supply is called anaquifer, or simply a water-bearing formation, water-bearingstratum,orwater-bearer. It is water-bearing, not in the sense ofholding water, but in the sense of carrying
23、 or conveying water.”3.3.1.2 Lohman and others (3) refined Meinzers definitionof an aquifer as “a formation, group of formations, or part of aformation that contains sufficient saturated permeable materialto yield significant quantities of water to wells and springs.”3.3.1.3 Both of these definition
24、s imply that the aquifer isbounded by or is included within the formation(s) (or stratum),but the concept of the aquifer extending across formationalboundaries is not indicated explicitly. In many local studiescovering a few tens to a few hundred square miles, the aquiferand the formation may be the
25、 same. In these studies, fewproblems may exist in defining the aquifer. However, since thelate 1970s, studies of regional aquifers that may cover hun-dreds of thousands of square miles have been made under theRegional Aquifer-System Analysis (RASA)4Program. Resultsfrom several of the RASA studies ha
26、ve shown that regionalaquifers may include numerous formations and rock types andthat the aquifers cut across formational and lithologic bound-aries so that no one formation is completely representative ofthe aquifer.3.3.1.4 In studies of regional scope, the shape and theboundaries of the permeable
27、rocks that form the aquifer havegreater importance to understanding the flow system than dothe individual formational boundaries. A definition that placesless emphasis on the formal term formation (6) and more onpermeable rocks has merit. For example, aquifer is defined inthe Glossary of Geology (7)
28、 as “a body of rock that issufficiently permeable to conduct ground water and to yieldeconomically significant quantities of water to wells andsprings.”3.3.1.5 Regardless of the fine points in any definition,delineating permeable rocks should be the major goal ofhydrogeologists in mapping and descri
29、bing an aquifer. By thesame token, detailed knowledge of the stratigraphic units andpost-depositional processes, such as solution, cementation,folding, and faulting, are essential in determining where theboundaries of the aquifer are located and in understanding theflow system. In addition, hydrauli
30、c properties (hydraulic con-ductivity and storage coefficient) throughout the aquifer usu-ally are not determined directly but are estimated by indirectmeans, such as aquifer tests, analyses of drill cuttings andcores, borehole geophysical logging, and surface geophysicalsurveys.3.3.1.6 In many situ
31、ations, hydrologic estimates and ex-trapolations can be made on the basis of rock type alonewithout any determination of hydrologic properties. For ex-ample, a wide-spread, thick clay separating two sand unitstentatively could be designated as a confining unit on the basisof geologists logs and bore
32、hole geophysical logs alone with-out any hydrologic data.3.3.2 aquifer system, nPoland and others (2) define anaquifer system as “a heterogeneous body of intercalatedpermeable and poorly permeable material that functions re-gionally as a water-yielding hydraulic unit; it comprises two ormore permeab
33、le beds (aquifers) separated at least locally byaquitards (confining units) that impede ground-water move-ment but do not greatly affect the regional hydraulic continuityof the system.”3.3.2.1 DiscussionThe definition could be more general ifthe term aquifers were used in place of permeable beds. Be
34、dimplies a single stratigraphic unit, whereas, the individualaquifer could include or cross many beds.3.3.2.2 Confining unit should be used instead of aquitardbecause the definition of confining unit is broad enough toinclude varying degrees of leakiness.3.3.2.3 The hierarchy of aquifer and aquifer-
35、system namesmay not always be consistent in practice. Because of differ-ences in scales of investigations, individual aquifers may becombined into a single aquifer system, which may be only apart of another aquifer system over a larger area. Authors havethe responsibility to explain these relationsh
36、ips clearly withcomparison charts and descriptions in the text.3.3.3 confining unit, nconfining bed was defined by Lo-hman and others (3) as “ . . . a term which will now supplantthe terms aquiclude, aquitard, and aquifuge in reports of theU.S. Geological Survey and is defined as a body of imperme-a
37、ble material stratigraphically adjacent to one or more aquifers.In nature, however, its hydraulic conductivity may range fromnearly zero to some value distinctly lower than that of theaquifer. Its conductivity relative to that of the aquifer itconfines should be specified or indicated by a suitable
38、modifier,such as slightly permeable or moderately permeable.”4RASA, Regional Aquifer-System Analysis Program, a systematic study of anumber of regional ground-water systems that represent a significant part of thewater supply of the United States. These studies are managed by the WaterResources Divi
39、sion of the U.S. Geological Survey.D 6106 97 (2004)23.3.3.1 DiscussionAlthough the Lohman and others (3)definition of confining bed is descriptive and should be used,the term confining unit is more general and appropriate thanconfining bed, especially where more than a single bed makesup the confini
40、ng unit.3.3.3.2 The term bed is not correct usage for a thicksequence of stratigraphic units that could be of member orformation rank. Bed is particularly inappropriate when used forintrusive igneous rocks beneath an aquifer. The term bed has aformal definition in the 1983 North American Stratigraph
41、icCode (6) and should not be used in definitions of aquifernomenclature.3.3.3.3 Many confining units are leaky and in some areas,under natural conditions, may contribute significant amounts ofwater to the aquifers they confine, and even larger quantities ofwater as heads are lowered in the aquifer b
42、y pumping. In areaswhere withdrawals from aquifers have caused large declines inhead, considerable amounts of water may be derived fromwater stored in the confining unit.3.3.3.4 Poland and others (2) retained the terms aquicludeand aquitard in their definitions related to studies of themechanics of
43、aquifer systems and land subsidence due to fluidwithdrawal. An aquiclude was defined as a body of saturatedbut relatively impermeable material that is characterized byvery low values of leakance (the ratio of vertical hydraulicconductivity to thickness) and transmits negligible interaquiferflow.3.3.
44、3.5 An aquitard is a saturated poorly permeable bed thathas values of leakance that range from relatively low torelatively high. Where an aquitard is sufficiently thick, it mayform an important ground-water storage unit.3.3.3.6 The general term confining unit is preferable toaquitard, aquiclude, and
45、 aquifuge, as recommended by Lo-hman and others (3).3.3.3.7 Estimation of the leakiness of the confining unitshould be discussed if this hydrologic information is available.3.3.4 erathem, na geologic time term, used in this guide,is defined as the largest formal chronostratigraphic unit gener-ally r
46、ecognized, next in rank above system; the rocks formedduring the era of geologic time, such as the Mesozoic Erathemcomposed of the Triassic System, the Jurassic System, and theCretaceous System (7).3.3.5 zone, nthe term zone may be used to subdivide anaquifer for the purpose of delineating a particu
47、lar hydrologiccharacteristic that is not typical of the entire aquifer. Forexample, the Fernandina permeable zone is a high-permeability subunit of the Lower Floridan aquifer (4). Thezone consists of vuggy, locally cavernous limestone and istraceable for as much as 100 miles in coastal Georgia andFl
48、orida. The permeability of the zone greatly exceeds that ofmost of the Lower Floridan aquifer.3.4 Terms to Be AvoidedThe use of terms that are in-tended to be synonymous with aquifer or aquifer system shouldbe avoided. Terms, such as hydrofer or aquiformation shouldnot be used in lieu of aquifer; aq
49、uigroup should not be used inplace of aquifer system.3.4.1 The term aquifer may be less precise than we wouldlike, but it has been used and accepted widely in the hydrologicliterature since it was defined originally.3.4.2 Coining new terms for aquifer and aquifer system thateither are synonyms or defined with slightly different meaningis not an advancement. It only creates confusion especiallyamong people who are not hydrogeologists. Use of the termaquiformation also infers an equivalence between aquifer andformation that is not always correct.4. Significance and Use4.1 A
