31:
164:
with a static morphology or frozen equilibrium; on the contrary, the bed moves and adjusts in a dynamic equilibrium with the flow and sediment transport for that particular condition. These phase diagrams are used for two main purposes: i) for prediction of bed states in a known flow and sediment transport condition, and, ii) as a tool for the reconstruction of paleoenvironments from a known bed state or sedimentary structure. Despite the great utility of such diagrams, they are very difficult to construct, making them either incomplete or very hard to interpret. This complexity lies in the number of variables needed to quantify the system.
168:
331:
1155:
362:
402:
132:
rates since for high rates defects maybe washed away and bedforms generally initiated across the entire bed spontaneously. Venditti et al. (2005) report that instantaneous initiation begins with the formation of a cross-hatch pattern, which leads to chevron-shaped forms that migrate independently of
323:
This chart is for general use, because changes in grain size and flow depth can change the bedform present and skip bedforms in certain scenarios. Bidirectional environments (e.g. tidal flats) produce similar bedforms, but the reworking the sediments and opposite directions of flow complicates the
163:
Phase or stability diagrams are defined as graphs that show the regimes of existence of one or more stable bed states. The stability of the bed can be defined when the bedform is in equilibrium and does not change in time for the same flow condition. This invariance over time must not be confused
114:
The defect theory proposes that the turbulent sweeps that are generated in turbulent flows entrain sediment that upon deposition generates defects in a non-cohesive material. These deposits then propagate downstream via a flow separation process, thus developing bedform fields. The origin of the
137:
type between a highly active pseudofluid sediment layer and the fluid above it. In addition, Venditti et al. (2005) imply that there is no linkage between the instantaneous initiation and coherent turbulent flow structures, since spatially- and temporally-random events should lock in place to
150:
in the laminar regime. However, instantaneous process, such as burst and sweeps, which are infrequent at low
Reynolds number but still present, can be the driving mechanisms to generate the bedforms. The generation of bedforms in laminar flows is still a topic of debate within the scientific
119:
give rise to entrainment corridors on the mobile bed, forming grain lineations that interact with the low-speed streaks generating an agglomeration of grains. Once a critical height of grains is reached, flow separation occurs over the new structure. Sediment will be eroded close from the
105:
are omnipresent in many environments (e.g., fluvial, eolian, glaciofluvial, deltaic and deep sea), although there is still some debate on how they develop. There are two separate, though not mutually exclusive, models of bedform initiation: defect initiation and instantaneous initiation.
133:
the pattern structure. This chevron-like structure reorganizes to form the future crest lines of the bedforms. Venditti et al. (2006), based on the earlier model by Liu (1957), proposed that instantaneous initiation is a manifestation of an interfacial hydrodynamic instability of
334:
Bedforms formed in sand in channels under unidirectional flow. Numbers correspond broadly to increasing flow regime, i.e., increasing water flow velocity. Blue arrows show schematically flow lines in the water above the bed. Flow is always from left to
120:
reattachment point and deposited downstream creating a new defect. This new defect will thus induce formation of another defect and the process will continue, propagating downstream while the accumulations of grains quickly evolve into small bedforms.
151:
community, since if true, it suggests that there should be other processes for defect development other than the one suggested by Best (1992). This alternative model for bedform development at low
180:
Typical unidirectional bedforms represent a specific flow velocity, assuming typical sediments (sands and silts) and water depths, and a chart such as below can be used for interpreting
138:
generate the cross-hatch pattern. Moreover, there is no clear explanation of the effect of turbulence in the formation of bedforms since bedforms may also occur under
600:
Best, J. L. (1992). "On the entrainment of sediment and initiation of bed defects: insights from recent developments within turbulent boundary layer research".
171:
Dimensional phase diagram for combined flows. Relationships of combined-flow bed-phases stability fields in a plot of
Oscillatory vs Unidirectional velocity.
30:
1140:
816:
582:
Grass, A. J. (1983). "The influence of boundary layer turbulence on the mechanics of sediment transport". In Sumer, B. M.; Muller, A. (eds.).
142:. It is important to note, that laminar-generated bedform studies used the temporally-averaged flow conditions to determine the degree of
90:
setting. Bedforms are often characteristic to the flow parameters, and may be used to infer flow depth and velocity, and therefore the
782:
758:
134:
1179:
849:
809:
167:
539:
Lu, S. S.; Willmarth, W. W. (1973). "Measurements of the structure of the reynolds stress in a turbulent boundary layer".
116:
719:
Perillo, Mauricio M.; Best, James L.; Garcia, Marcelo H. (2014). "A new phase diagram for combined-flow bedforms".
39:
1158:
802:
370:
181:
972:
205:
349:"Lower plane bed" refers to the flat configuration the bed of a river that is produced in via low rates of
902:
420:
1084:
1079:
330:
87:
155:
rates should explain the generation of defects and bedforms for cases where the flow is not turbulent.
1105:
728:
691:
649:
609:
548:
505:
452:
410:
640:
Venditti, J. G.; Church, M. A.; Bennett, S. J. (2005). "Bed form initiation from a flat sand bed".
139:
377:"Upper plane bed" features are flat and characterized by a unidirectional flow with high rates of
1135:
1089:
564:
521:
378:
350:
290:
152:
129:
55:
35:
1130:
967:
778:
754:
390:
366:
897:
825:
736:
699:
657:
617:
556:
513:
460:
1125:
912:
874:
859:
147:
67:
732:
695:
653:
613:
552:
509:
464:
456:
1115:
982:
932:
884:
844:
839:
621:
386:
496:
Willmarth, W. W.; Lu, S. S. (1972). "Structure of the reynolds stress near the wall".
1173:
1120:
1002:
962:
907:
568:
525:
415:
393:, which are typically subtle streaks on the bed surface due to the high energy flow.
91:
63:
1053:
864:
236:
1069:
1020:
987:
977:
869:
83:
361:
115:
defects is thought to be linked to packets of hairpin vortex structures. These
1074:
1015:
942:
922:
560:
517:
249:
143:
75:
947:
937:
892:
298:
27:
Geological feature resulting from the movement of bed material by fluid flow
680:"On interfacial instability as a cause of transverse subcritical bed forms"
17:
443:
Southard, J B (1991). "Experimental
Determination of Bed-Form Stability".
1043:
917:
704:
679:
661:
382:
66:, the result of bed material being moved by fluid flow. Examples include
773:
Klaus K.E. Neuendorf; James P. Mehl Jr.; Julia A. Jackson, eds. (2005).
740:
1110:
992:
927:
854:
401:
753:
Prothero, D. R. and Schwab, F., 1996, Sedimentary
Geology, pg. 45-49,
1010:
957:
952:
128:
In general, the defect propagation theory plays a bigger role at low
794:
400:
360:
329:
166:
79:
59:
29:
327:
This bed form sequence can also be illustrated diagrammatically:
1048:
262:
71:
43:
798:
1038:
190:
777:. Alexandria: American Geological Institute. p. 382.
483:
Flow, sediment transport and bedforms under combined flows
678:
Venditti, J. G.; Church, M. A.; Bennett, S. J. (2006).
306:
Water in phase with bedform, low angle, subtle laminae
485:(Ph.D.). University of Illinois at Urbana-Champaign.
1098:
1062:
1029:
1001:
883:
832:
365:Parting lineation, from lower left to upper right;
438:
436:
389:. Upper plane bed conditions can produce parting
34:Current ripples preserved in sandstone of the
810:
476:
474:
445:Annual Review of Earth and Planetary Sciences
8:
1141:List of rivers that have reversed direction
768:
766:
817:
803:
795:
703:
595:
593:
673:
671:
635:
633:
631:
432:
82:. Bedforms are often preserved in the
257:Rare, longer wavelength than ripples
231:Flat laminae, almost lack of current
188:water velocity going down the chart.
7:
465:10.1146/annurev.ea.19.050191.002231
622:10.1111/j.1365-3091.1992.tb02154.x
289:Flat laminae, +/- aligned grains (
86:as a result of being present in a
58:that develops at the interface of
25:
1154:
1153:
850:Drainage system (geomorphology)
721:Journal of Sedimentary Research
642:Journal of Geophysical Research
586:. A. A. Balkema. pp. 3–18.
584:Mechanics of Sediment Transport
860:Strahler number (stream order)
1:
481:Perillo, Mauricio M. (2013).
117:coherent turbulent structures
244:Small, cm-scale undulations
271:Large, meter-scale ripples
1196:
541:Journal of Fluid Mechanics
498:Journal of Fluid Mechanics
317:Mostly erosional features
40:Capitol Reef National Park
1149:
561:10.1017/S0022112073000315
518:10.1017/S002211207200165X
371:Canyonlands National Park
275:
217:
182:depositional environments
684:Water Resources Research
124:Instantaneous Initiation
973:River channel migration
1180:Sedimentary structures
903:Bar (river morphology)
421:Sedimentary structures
406:
374:
336:
206:Preservation Potential
172:
159:Bedform phase diagrams
47:
1085:Erosion and tectonics
1080:Degradation (geology)
404:
364:
333:
170:
33:
1106:Deposition (geology)
833:Large-scale features
705:10.1029/2005wr004346
662:10.1029/2004jf000149
411:Churn turbulent flow
405:Megaripple from Utah
775:Glossary of geology
741:10.2110/jsr.2014.25
733:2014JSedR..84..301P
696:2006WRR....42.7423V
654:2005JGRF..110.1009V
614:1992Sedim..39..797B
553:1973JFM....60..481L
510:1972JFM....55...65W
457:1991AREPS..19..423S
212:Identification Tips
98:Bedforms Initiation
1136:Sediment transport
1090:River rejuvenation
1063:Regional processes
407:
391:current lineations
379:sediment transport
375:
351:sediment transport
337:
291:parting lineations
173:
153:sediment transport
130:sediment transport
56:geological feature
48:
36:Moenkopi Formation
1167:
1166:
968:River bifurcation
367:Kayenta Formation
340:Types of Bedforms
321:
320:
176:Bedforms vs. flow
110:Defect Initiation
16:(Redirected from
1187:
1157:
1156:
898:Avulsion (river)
826:River morphology
819:
812:
805:
796:
789:
788:
770:
761:
751:
745:
744:
716:
710:
709:
707:
675:
666:
665:
637:
626:
625:
597:
588:
587:
579:
573:
572:
536:
530:
529:
493:
487:
486:
478:
469:
468:
440:
191:
135:Kelvin-Helmholtz
46:, United States.
21:
1195:
1194:
1190:
1189:
1188:
1186:
1185:
1184:
1170:
1169:
1168:
1163:
1145:
1126:Helicoidal flow
1094:
1058:
1025:
997:
913:Channel pattern
885:Alluvial rivers
879:
875:River sinuosity
828:
823:
793:
792:
785:
772:
771:
764:
752:
748:
718:
717:
713:
677:
676:
669:
639:
638:
629:
599:
598:
591:
581:
580:
576:
538:
537:
533:
495:
494:
490:
480:
479:
472:
442:
441:
434:
429:
399:
359:
357:Upper Plane Bed
347:
345:Lower Plane Bed
342:
283:Upper plane bed
225:Lower plane bed
178:
161:
148:Reynolds number
126:
112:
100:
62:and a moveable
28:
23:
22:
15:
12:
11:
5:
1193:
1191:
1183:
1182:
1172:
1171:
1165:
1164:
1162:
1161:
1150:
1147:
1146:
1144:
1143:
1138:
1133:
1131:Playfair's law
1128:
1123:
1118:
1116:Exner equation
1113:
1108:
1102:
1100:
1096:
1095:
1093:
1092:
1087:
1082:
1077:
1072:
1066:
1064:
1060:
1059:
1057:
1056:
1054:Current ripple
1051:
1046:
1041:
1035:
1033:
1027:
1026:
1024:
1023:
1018:
1013:
1007:
1005:
999:
998:
996:
995:
990:
985:
983:Slip-off slope
980:
975:
970:
965:
960:
955:
950:
945:
940:
935:
933:Meander cutoff
930:
925:
920:
915:
910:
905:
900:
895:
889:
887:
881:
880:
878:
877:
872:
867:
862:
857:
852:
847:
845:Drainage basin
842:
840:Alluvial plain
836:
834:
830:
829:
824:
822:
821:
814:
807:
799:
791:
790:
783:
762:
746:
727:(4): 301–313.
711:
667:
648:(F1): F01009.
627:
608:(5): 797–811.
589:
574:
547:(3): 481–511.
531:
488:
470:
431:
430:
428:
425:
424:
423:
418:
413:
398:
395:
387:suspended load
358:
355:
346:
343:
341:
338:
319:
318:
315:
312:
311:Pool and chute
308:
307:
304:
301:
295:
294:
287:
284:
280:
279:
273:
272:
269:
266:
259:
258:
255:
252:
246:
245:
242:
239:
233:
232:
229:
226:
222:
221:
215:
214:
209:
202:
197:
177:
174:
160:
157:
125:
122:
111:
108:
99:
96:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1192:
1181:
1178:
1177:
1175:
1160:
1152:
1151:
1148:
1142:
1139:
1137:
1134:
1132:
1129:
1127:
1124:
1122:
1119:
1117:
1114:
1112:
1111:Water erosion
1109:
1107:
1104:
1103:
1101:
1097:
1091:
1088:
1086:
1083:
1081:
1078:
1076:
1073:
1071:
1068:
1067:
1065:
1061:
1055:
1052:
1050:
1047:
1045:
1042:
1040:
1037:
1036:
1034:
1032:
1028:
1022:
1019:
1017:
1014:
1012:
1009:
1008:
1006:
1004:
1003:Bedrock river
1000:
994:
991:
989:
986:
984:
981:
979:
976:
974:
971:
969:
966:
964:
963:Riparian zone
961:
959:
956:
954:
951:
949:
946:
944:
941:
939:
936:
934:
931:
929:
926:
924:
921:
919:
916:
914:
911:
909:
908:Braided river
906:
904:
901:
899:
896:
894:
891:
890:
888:
886:
882:
876:
873:
871:
868:
866:
863:
861:
858:
856:
853:
851:
848:
846:
843:
841:
838:
837:
835:
831:
827:
820:
815:
813:
808:
806:
801:
800:
797:
786:
784:0-922152-76-4
780:
776:
769:
767:
763:
760:
759:0-7167-2726-9
756:
750:
747:
742:
738:
734:
730:
726:
722:
715:
712:
706:
701:
697:
693:
690:(7): W07423.
689:
685:
681:
674:
672:
668:
663:
659:
655:
651:
647:
643:
636:
634:
632:
628:
623:
619:
615:
611:
607:
603:
602:Sedimentology
596:
594:
590:
585:
578:
575:
570:
566:
562:
558:
554:
550:
546:
542:
535:
532:
527:
523:
519:
515:
511:
507:
503:
499:
492:
489:
484:
477:
475:
471:
466:
462:
458:
454:
450:
446:
439:
437:
433:
426:
422:
419:
417:
416:Sedimentation
414:
412:
409:
408:
403:
396:
394:
392:
388:
384:
380:
372:
368:
363:
356:
354:
352:
344:
339:
332:
328:
325:
316:
313:
310:
309:
305:
302:
300:
297:
296:
292:
288:
285:
282:
281:
278:
274:
270:
267:
264:
261:
260:
256:
254:Medium to low
253:
251:
248:
247:
243:
240:
238:
235:
234:
230:
227:
224:
223:
220:
216:
213:
210:
208:
207:
203:
201:
198:
196:
193:
192:
189:
187:
183:
175:
169:
165:
158:
156:
154:
149:
146:, indicating
145:
141:
140:laminar flows
136:
131:
123:
121:
118:
109:
107:
104:
97:
95:
93:
92:Froude number
89:
85:
81:
77:
73:
69:
65:
61:
57:
53:
45:
41:
37:
32:
19:
1030:
865:River valley
774:
749:
724:
720:
714:
687:
683:
645:
641:
605:
601:
583:
577:
544:
540:
534:
504:(1): 65–92.
501:
497:
491:
482:
448:
444:
376:
348:
326:
324:structures.
322:
276:
265:/Megaripples
237:Ripple marks
218:
211:
204:
199:
194:
185:
179:
162:
127:
113:
102:
101:
88:depositional
51:
49:
1070:Aggradation
1021:Plunge pool
988:Stream pool
978:River mouth
870:River delta
451:: 423–455.
195:Flow Regime
84:rock record
18:Flow regime
1121:Hack's law
1075:Base level
1016:Knickpoint
943:Oxbow lake
923:Floodplain
427:References
250:Sand waves
186:increasing
144:turbulence
1099:Mechanics
948:Point bar
938:Mouth bar
893:Anabranch
569:124179402
526:121418853
299:Antidunes
1174:Category
1159:Category
1044:Antidune
1031:Bedforms
918:Cut bank
397:See also
383:bed load
381:as both
314:Very low
103:Bedforms
993:Thalweg
928:Meander
855:Estuary
729:Bibcode
692:Bibcode
650:Bibcode
610:Bibcode
549:Bibcode
506:Bibcode
453:Bibcode
200:Bedform
184:, with
74:on the
68:ripples
52:bedform
1011:Canyon
958:Rapids
953:Riffle
781:
757:
567:
524:
335:right.
565:S2CID
522:S2CID
277:Upper
263:Dunes
219:Lower
80:river
78:of a
72:dunes
60:fluid
54:is a
1049:Dune
779:ISBN
755:ISBN
385:and
286:High
268:High
241:High
228:High
70:and
44:Utah
1039:Ait
737:doi
700:doi
658:doi
646:110
618:doi
557:doi
514:doi
461:doi
303:Low
76:bed
64:bed
1176::
765:^
735:.
725:84
723:.
698:.
688:42
686:.
682:.
670:^
656:.
644:.
630:^
616:.
606:39
604:.
592:^
563:.
555:.
545:60
543:.
520:.
512:.
502:55
500:.
473:^
459:.
449:19
447:.
435:^
369:,
353:.
293:)
94:.
50:A
42:,
38:,
818:e
811:t
804:v
787:.
743:.
739::
731::
708:.
702::
694::
664:.
660::
652::
624:.
620::
612::
571:.
559::
551::
528:.
516::
508::
467:.
463::
455::
373:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
