388:
31:
125:
544:. By employing inconsistent approaches to the study period of the mean sea level during the establishment of the two datums, the mean sea levels for the mainland and Tasmanian datums are highly likely to contain some degree of error relative to the true mean sea level value. This neglection of the differences in ocean's time-mean dynamic topography between the creation of Australian Height Datum (mainland) and Australian Height Datum (Tasmania) resulted in a distinct offset between the height of the mainland and Tasmania
481:
horizontal). While this systematic error is relatively insignificant for the design of “small-scale engineering projects” that use local heights, the north–south slope is very influential on the design of “large-scale studies” that span larger distances across the country. The north–south slope is primarily due to the fact that the
Australian Height Datum was taken as the fixed mean sea level of 30 tide gauges around Australia over a 2-year period, ignoring the natural variations in
485:. The National Mapping Council of Australia chose to use this ‘mean sea level’ approach to minimise the use of negative heights, that are quite problematic for surveyors and engineers, near coastal areas where most of the population resides. By utilising the mean sea level approach, the creation of the Australian Height Datum neglected the significant influence the ocean's time-
170:
respective State
Surveyors-General. The council's first meeting held discussions between the respective state authorities about the need to have a unified national scheme for surveying and mapping of Australia. Upon the meeting's completion, members of the National Mapping Council of Australia unanimously agreed that the Director of National Mapping,
222:. Through the linear adjustment of 757 primary levelling sections across the Australian National Levelling Network, while simultaneously "holding 30 tide gauges fixed at their mean sea level values", the Australian Height Datum was determined and then adopted by the National Mapping Council of Australia in July 1971.
437:
was assigned a value of 0.000 m. Zero condition equations between Port MacDonnell and the other 29 stations’ sea level data were then utilised to hold the mean sea level at 0.000 m across the entire national tide gauge network, while the primary and secondary levelling records within the
Australian
272:
and record the readings in a level book. By employing this strategy, the levelling parties were able to achieve an average of 35 km of primary levelling each day. One-way levelling involved adopting this outlined methodology in only one direction, while two-way levelling also would repeat this
539:
the vertical height of 0.000m over the year of 1972. This method deviates from the method employed to determine the mean sea level used to create the mainland
Australian Height Datum, which was taken across the period from 1966 – 1968 for 29 of the tidal gauges and 1957-1960 for the single tidal
217:
made additional funds available to the
Director of National Mapping to employ private contract surveyors to speed up the surveying effort. By 1970, the consolidation of levelling and tide gauge data from these collective surveying operations resulted in the formation of a 97,320 km "single
455:
during the 1970s, the
Australian Height Datum was constructed using a lower standard of spirit-levelling equipment and techniques to ensure completion in the shortest possible period of time. For example, approximately 80% (76520 km) of the primary levelling contributing to the Australian
169:
approved the formation of the
National Mapping Council of Australia in 1945 with a primary objective of planning and managing the nation's topographic mapping activities. The inaugural National Mapping Council consisted of the Director of National Mapping, the Commonwealth Surveyor General and
569:
of these distortions does not lend itself to any distinct trends. Moreover, the utilising gravimetric quasigeoid models to “practically” eliminate the impact of the ocean's time-mean dynamic topography does not minimise the extent of these regional distortions. For these reasons, the regional
254:
Five different observing authorities contributed to primary levelling sections in the
Australian National Levelling Network that were used to determine the Australian Height Datum, each utilising their own levelling parties that conducted a combination of one-way and two-way levelling. These
480:
in the
Australian Height Datum's horizontal surface of approximately 1.5m from the North coast to South coast of Australia. This tilt is quite problematic, as it invalidates the major assumption in using the Australian Height Datum: the datum surface has a gradient of zero (i.e. perfectly
514:
heights provide a far greater limit of reading that the magnitude of the spirit-level errors in the
Australian Height Datum, the AUSGeoid09 model is able to “practically” eliminate the north–south error when converting GNSS readings to Australian Height Datum heights.
438:
National Levelling Network were simultaneously adjusted to fit this model. In doing so, the Australian Height Datum surface was derived and officially adopted in 1971 as the benchmark to which all new vertical height measurements in Australia are referenced to.
505:
have all contributed to the formation of a distinct 1.5m North-South slope within the Australian Height Datum. In order to counteract this slope, the AUSGeoid09 gravimetric quasigeoid model has been introduced to determine Australian Height Datum heights from
420:
to Port Kembla (1,150 km). Sea level observations were conducted on an hourly basis from 1 January 1966 to 31 December 1968 for 29 of the designated tidal gauges, and from 1 January 1957 to 31 December 1960 for the single tidal gauge at
556:
In addition to the north–south slope, numerous other regional distortions within the Australian Height Datum have been identified across the state of Western Australia. The largest of these non-linear distortions are present across the
255:
levelling parties consisted of two drivers of separate vehicles, as well as one instrument man who would alternate between the cars as they "leap-frog along the levelling route". This strategy involved the instrument man taking both a
446:
Since the inception of the Australian Height Datum in 1971, numerous deficiencies, distortions, offsets and other errors have been identified and examined using newer technologies. Due to Australia's desperate need for a surveying
263:
staff reading, before being driven by one of the drivers, past the other driver's stationary car, to the next set-up position to take the next set of reading. The two drivers’ responsibility was to hold the
411:
coastline was also collected in order to derive the Australian Height Datum. The distances between each successive tidal gauge varied significantly around the country, with the smallest interval between
273:
again in the opposite direction to improve the accuracy of the readings. The following outlines the cumulative contribution of the levelling parties for their respective observing authority:
121:, newer technologies have uncovered numerous deficiencies, offsets and distortions within the Australian Height Datum, leading to discussions about defining a new Australian vertical datum.
456:
National Levelling Network was completed by private contractors during the 10-year period from 1960 to 1970. Since then, significant errors have been identified including the north–south
205:, commenced the Australian Levelling Survey by levelling 4,800 km of the mainland. By 1960, 20,800 km of controlled levelling had been completed with the addition of the
596:
179:
246:
of the original, ‘primary’ levelling data spanning 97,320 km, combined with more recent, ‘supplementary’ levelling data spanning 80,000 km.
1318:
230:
The Australian Height Datum is the vertical height of 0.000m established within the Australian National Levelling Network (ANLN), through taking the
174:, would be tasked with the coordination of local, state and Commonwealth authorities in order to execute mapping activities across the entire of the
153:
were carried out by professional surveyors for construction and mapping purposes using only local or state-based vertical datums. The execution of
531:
adjustment of seventy-two levelling sections across the Tasmanian state, while simultaneously assigning the mean sea level of two tidal gauges at
1316:
Featherstone, W. E.; Filmer, M. S. (2008). "A new GPS-based evaluation of distortions in the Australian Height Datum in Western Australia".
1343:
1071:
1178:
Featherstone, W. E.; Kirby, J. F.; Hirt, C.; Filmer, M. S.; Claessens, S. J.; Brown, N. J.; Hu, G.; Johnston, G. M. (2010).
391:
This map illustrates the positions of the 30 tide gauges used in the determination of the Australian Height Datum (mainland)
1108:
35:
Example of a surveying expedition in the 20th Century similar to those undertaken to complete the Australian Height Datum.
507:
948:. Canberra, Australia: The Australian Survey Office, Commonwealth Department of Administrative Services. pp. 1–2.
1353:
101:
work conducted by numerous state and territory authorities across the country, and was corrected to align with the
1368:
1358:
1348:
46:
1104:"Detecting spirit-levelling errors in the AHD: recent findings and issues for any new Australian height datum"
562:
202:
97:
to which all height measurements are referred. The Australian Height Datum is an amalgamation of decades of
413:
171:
1000:"The north-south tilt in the Australian Height Datum is explained by the ocean's mean dynamic topography"
891:. Canberra, Australia: Department of Minerals and Energy and Division of National Mapping. pp. 1–11.
545:
239:
1373:
779:
633:
1244:"A Re-Evaluation of the Offset in the Australian Height Datum Between Mainland Australia and Tasmania"
906:
511:
387:
1363:
574:“present in the spirit-levelling observations” during the creation of the Australian Height Datum.
482:
243:
628:
486:
214:
260:
109:
positioned around the entire coastline. While it remains the published vertical datum for all
175:
94:
277:
Primary Levelling contributions to the Australian Height Datum by each Observing Authority
213:
state authorities. To assist mining companies with the search for oil during the 1960s, the
1257:
1117:
1011:
714:
642:
601:
558:
30:
8:
541:
194:
162:
1261:
1121:
1015:
718:
646:
124:
1291:
1221:
1184:
1151:
748:
676:
565:
regions. Unlike the well-defined and measurable north–south tilt across the state, the
461:
408:
269:
206:
154:
1283:
1213:
1155:
1143:
1077:
1067:
1039:
967:
926:
838:
796:
740:
668:
566:
198:
1295:
818:
774:
752:
680:
527:) is considered as a separate datum to the Australian Height Datum, consisting of a
1273:
1265:
1225:
1203:
1193:
1133:
1125:
1029:
1019:
922:
918:
834:
830:
792:
788:
730:
722:
702:
658:
650:
494:
477:
98:
1243:
726:
219:
1269:
654:
430:
190:
218:
homogenous network" of primary levelling spanning the entire country, named the
1248:
1103:
502:
448:
434:
417:
231:
102:
90:
1278:
1208:
1198:
1179:
1138:
1129:
1034:
735:
663:
433:
tidal gauge station was selected to be the “nominal origin” and the station's
1337:
1287:
1217:
1147:
1081:
1043:
930:
842:
800:
744:
672:
571:
528:
468:
of 26 cm, as well as regional distortions throughout Western Australia.
51:
158:
129:
1061:
703:"Yet more evidence for a North-South slope in the Australian Height Datum"
1024:
999:
265:
166:
114:
184:
426:
404:
256:
210:
106:
490:
400:
150:
118:
110:
524:
465:
422:
775:"Australian height datum and standard datum in New South Wales"
536:
532:
498:
452:
133:
61:
457:
235:
889:
THE ADJUSTMENT OF THE AUSTRALIAN LEVELLING SURVEY 1970 -1971
551:
416:
to Camp Cove (128 km) and the largest interval between
1177:
946:
Conversion of A.C.T level datums to Australian Height Datum
570:
distortions throughout Western Australia are attributed to
429:. Once all the tidal data was collected and processed, the
819:"The National Mapping Council of Australia—forty years on"
629:"Three viable options for a new Australian vertical datum"
144:
518:
501:
where tide gauges are positioned, and an amalgamation of
441:
548:, estimated to be between −61 mm and +48 mm.
149:
Prior to the creation of the Australian Height Datum,
1180:"The AUSGeoid09 model of the Australian Height Datum"
185:
The Australian National Levelling Network (1945–1971)
966:. Perth, Australia: Department of Spatial Sciences,
886:
1315:
1241:
1101:
997:
626:
1319:Journal of the Royal Society of Western Australia
249:
1335:
1059:
395:
234:of 30 tide gauges along the entire Australian
964:An examination of the Australian Height Datum
268:, while the instrument man would operate the
165:, to such a great extent that Prime Minister
1066:(Second ed.). Boston, MA: Springer US.
887:Roelse, A.; Granger, H.; Graham, J. (1975).
700:
201:state authorities, with assistance from the
1242:Filmer, M. S.; Featherstone, W. E. (2012).
1102:Filmer, M. S.; Featherstone, W. E. (2009).
998:Featherstone, W. E.; Filmer, M. S. (2012).
627:Filmer, M. S.; Featherstone, W. E. (2012).
225:
29:
1277:
1207:
1197:
1137:
1033:
1023:
734:
662:
552:Regional distortions in Western Australia
508:Global Navigation Satellite System (GNSS)
493:around the country. Spatial variation of
93:for Australia, and thereby serves as the
79:The Australian National Levelling Network
471:
386:
123:
1004:Journal of Geophysical Research: Oceans
904:
816:
161:heavily exposed the lack of Australian
145:The National Mapping Council (pre-1945)
89:was introduced in 1971 as the official
1336:
1311:
1309:
1307:
1305:
1237:
1235:
1173:
1171:
1169:
1167:
1165:
1097:
1095:
1093:
1091:
961:
519:The Australia Mainland-Tasmania offset
157:across the Australian mainland during
1055:
1053:
993:
991:
989:
987:
985:
983:
981:
979:
977:
882:
880:
878:
876:
874:
872:
772:
451:and accurate topographic mapping for
442:Deficiencies, offsets and distortions
220:Australian National Levelling Network
1109:Australian Journal of Earth Sciences
957:
955:
943:
900:
898:
870:
868:
866:
864:
862:
860:
858:
856:
854:
852:
812:
810:
768:
766:
764:
762:
696:
694:
692:
690:
622:
620:
591:
589:
587:
238:during the period of 1966–1968. The
1302:
1232:
1162:
1088:
13:
1050:
974:
14:
1385:
1060:Brinker, R.; Minnick, R. (1995).
952:
895:
849:
807:
759:
687:
617:
584:
1344:1971 establishments in Australia
128:An old tide gauge positioned at
117:operations performed throughout
937:
923:10.1080/00050326.1973.10440669
835:10.1080/00690805.1985.10438299
793:10.1080/00050326.1975.10440774
363:First, Second and Third Order
250:Primary levelling observations
178:; an activity later named the
1:
727:10.1080/14498596.2006.9635076
577:
523:The Australian Height Datum (
203:Royal Australian Survey Corps
139:
1270:10.1080/01490419.2011.634961
701:Featherstone, W. E. (2006).
655:10.1080/14498596.2012.679248
180:Australian Levelling Survey.
7:
476:The North-South Slope is a
396:Mean sea level observations
16:Vertical datum of Australia
10:
1390:
707:Journal of Spatial Science
634:Journal of Spatial Science
1199:10.1007/s00190-010-0422-2
1130:10.1080/08120090902806305
597:"Australian Height Datum"
289:
281:
75:
67:
57:
45:
40:
28:
23:
497:, freshwater outflow in
460:of 1.5m, offset between
330:Hydro-Electric Authority
244:least squares adjustment
226:Measurements methodology
1354:Government of Australia
970:. pp. 1–10, 31–32.
905:Lambert, B. P. (1973).
817:Lambert, B. P. (1985).
489:on the fluctuations in
487:mean dynamic topography
189:From 1945 to 1955, the
105:observations of thirty
87:Australian Height Datum
24:Australian Height Datum
1369:Surveying of Australia
1359:Geography of Australia
1063:The Surveying Handbook
962:Filmer, M. S. (2010).
483:sea-surface topography
407:positioned around the
392:
283:Primary Levelling Type
136:
1349:Australian inventions
773:Blume, P. H. (1975).
472:The North-South Slope
390:
127:
1025:10.1029/2012jc007974
602:Geoscience Australia
559:Goldfields-Esperance
340:Original and Second
290:Observing Authority
176:Australian continent
1262:2012MarGe..35..107F
1122:2009AuJES..56..559F
1016:2012JGRC..117.8035F
911:Australian Surveyor
780:Australian Surveyor
719:2006JSpSc..51....1F
647:2012JSpSc..57...19F
409:Australian mainland
278:
163:topographic mapping
155:military operations
41:General information
1279:20.500.11937/15509
1209:20.500.11937/23487
1185:Journal of Geodesy
1139:20.500.11937/33679
1035:20.500.11937/13616
907:"National mapping"
736:20.500.11937/39721
664:20.500.11937/20186
491:sea surface levels
462:Australia mainland
453:mining exploration
393:
365:Two-Way Levelling
342:One-Way Levelling
276:
215:Federal Government
207:Northern Territory
199:Western Australian
172:Frederick Johnston
137:
1374:Maps of Australia
1073:978-1-4615-2067-2
968:Curtin University
944:Daly, P. (1972).
567:linear regression
403:data from thirty
385:
384:
296:State Authorities
151:levelling surveys
83:
82:
76:Reference Network
1381:
1328:
1327:
1313:
1300:
1299:
1281:
1239:
1230:
1229:
1211:
1201:
1175:
1160:
1159:
1141:
1099:
1086:
1085:
1057:
1048:
1047:
1037:
1027:
995:
972:
971:
959:
950:
949:
941:
935:
934:
902:
893:
892:
884:
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814:
805:
804:
770:
757:
756:
738:
698:
685:
684:
666:
624:
615:
614:
612:
610:
593:
495:sea level change
478:systematic error
449:vertical control
310:National Mapping
279:
275:
266:levelling staffs
242:is based upon a
99:spirit levelling
68:Date Established
33:
21:
20:
1389:
1388:
1384:
1383:
1382:
1380:
1379:
1378:
1364:Vertical datums
1334:
1333:
1332:
1331:
1314:
1303:
1240:
1233:
1176:
1163:
1100:
1089:
1074:
1058:
1051:
996:
975:
960:
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942:
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815:
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771:
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688:
625:
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595:
594:
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554:
521:
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431:Port MacDonnell
398:
326:Snowy Mountains
252:
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191:New South Wales
187:
147:
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36:
17:
12:
11:
5:
1387:
1377:
1376:
1371:
1366:
1361:
1356:
1351:
1346:
1330:
1329:
1301:
1256:(1): 107–119.
1249:Marine Geodesy
1231:
1192:(3): 133–150.
1161:
1116:(4): 559–569.
1087:
1072:
1049:
973:
951:
936:
917:(2): 163–167.
894:
848:
829:(2): 112–115.
806:
758:
686:
616:
582:
581:
579:
576:
553:
550:
546:datum surfaces
520:
517:
503:ocean dynamics
473:
470:
443:
440:
435:mean sea level
418:Point Lonsdale
397:
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232:mean sea level
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103:mean sea level
91:vertical datum
81:
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49:
43:
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9:
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3:
2:
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1362:
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1350:
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1339:
1326:(2): 199–206.
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583:
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573:
572:random errors
568:
564:
561:and northern
560:
549:
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543:
538:
534:
530:
529:least-squares
526:
516:
513:
510:readings. As
509:
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499:harbour areas
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316:Department of
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240:datum surface
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27:
22:
19:
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1107:
1062:
1007:
1003:
963:
945:
939:
914:
910:
888:
826:
822:
787:(1): 11–21.
784:
778:
710:
706:
641:(1): 19–36.
638:
632:
609:21 September
607:. Retrieved
600:
555:
522:
475:
445:
405:tidal gauges
399:
364:
341:
335:Contractors
329:
328:
325:
320:the Interior
319:
318:
315:
309:
308:
305:
299:
298:
295:
285:
282:
253:
229:
188:
159:World War II
148:
130:Fort Denison
86:
84:
58:Unit of
18:
1010:(C8): n/a.
823:Cartography
414:Port Kembla
306:Division of
167:Ben Chifley
115:engineering
107:tide gauges
47:Unit system
1338:Categories
713:(2): 1–6.
578:References
427:Queensland
300:(Combined)
261:fore sight
257:back sight
211:Queensland
140:Background
1288:0149-0419
1218:0949-7714
1156:129898464
1148:0812-0099
1082:852789601
1044:0148-0227
931:0005-0326
843:0069-0805
801:0005-0326
745:1449-8596
673:1449-8596
563:Kimberley
540:gauge at
401:Sea level
381:47,862.5
369:21,529.0
358:19,613.5
352:23,590.0
236:coastline
195:Victorian
119:Australia
111:surveying
95:benchmark
71:July 1971
1296:53474023
753:53571234
681:56168131
525:Tasmania
466:Tasmania
375:3,064.2
349:4,203.8
1258:Bibcode
1226:3818132
1118:Bibcode
1012:Bibcode
715:Bibcode
643:Bibcode
542:Karumba
423:Karumba
1294:
1286:
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1154:
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1080:
1070:
1042:
929:
841:
799:
751:
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679:
671:
605:. 2014
537:Burnie
533:Hobart
378:479.7
372:332.3
346:697.0
134:Sydney
62:height
52:metric
1292:S2CID
1222:S2CID
1152:S2CID
749:S2CID
677:S2CID
458:slope
270:level
1284:ISSN
1214:ISSN
1144:ISSN
1078:OCLC
1068:ISBN
1040:ISSN
927:ISSN
839:ISSN
797:ISSN
741:ISSN
669:ISSN
611:2020
535:and
464:and
355:0.0
286:(km)
259:and
209:and
197:and
113:and
85:The
1274:hdl
1266:doi
1204:hdl
1194:doi
1134:hdl
1126:doi
1030:hdl
1020:doi
1008:117
919:doi
831:doi
789:doi
731:hdl
723:doi
659:hdl
651:doi
512:GPS
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1324:91
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