27:
128:
148:, which can create greater variety in local geomorphology and thus create provision and variety of habitat for instream living organisms. The formation of a log jam against one bank typically concentrates flow in the wood-free portion of the channel, increasing velocity through this section and promoting
199:
of the United States, it has been shown there is a lifecycle of tree growth and river migration, with large trees falling into the channel as banks erode, then staying in place and acting as focal points for log jam formation. These log jams act as hard points, resisting further erosion and channel
155:
The hydraulic and geomorphological effects of log jams are highly dependent on the slope of the river (and thus the potential power of the stream); in steep channels, log jams tend to form channel-spanning steplike structures with an associated downstream scour pool, whereas in large lowland rivers
208:"Logjam" or "log jam" can be used metaphorically to mean "deadlock" or "impasse." It can be used either more literally, to mean a physical impasse, or more metaphorically, to mean an impasse in a process due to differing opinions, legal or technical issues, etc. Here are two example sentences:
89:, which prior to its removal in the 1830s affected between 390 and 480 km (240–300 mi) of the main channel. It has been suggested that such extensive log rafts may have been common in Europe in prehistory. Currently, the largest known log jam is over 3 million tonnes in the
143:
hydraulics by diverting flow towards the bed or banks, increasing flow resistance and creating upstream pools, diverting flow onto the floodplain and damming the channel, causing water to spill over the structure. These altered channel hydraulics change local patterns of erosion and
191:
and promote the formation of stable islands in the river. These stable islands are then prime areas for establishment of seedlings and further vegetation growth, which in turn can eventually provide more fallen trees to the river and thus form more log jams.
74:. Unless they are dismantled by natural causes or humans, log jams can grow quickly, as more wood arriving from upstream becomes entangled in the mass. Log jams can persist for many decades, as is the case with the log jam in Spirit Lake.
50:" is commonly defined to be pieces of wood more than 10 cm (4 in) in diameter and more than 1 m (3 ft 3 in) long.) Log jams in rivers and streams often span the entirety of the water's surface from
172:. These pools also provide refuge for fish during low water levels when other parts of a stream may be nearly dry. Log jams can provide refuge, as velocity shelters, during high-flow periods.
152:
of the riverbed. The formation of channel-spanning log jams can lead to the formation of an upstream pool, water spilling over the structure generating a "plunge pool" immediately downstream.
200:
migration. The areas of floodplain behind these log jams then become stable enough for more large trees to grow, which can in turn become potential log jam anchor points in the future.
58:, or other objects anchored underwater. They can build up slowly over months or years, or they can happen instantaneously when large numbers of trees are swept into the water after
831:"The floodplain large-wood cycle hypothesis: A mechanism for the physical and biotic structuring of temperate forested alluvial valleys in the North Pacific coastal ecoregion"
46:
is a naturally occurring phenomenon characterized by a dense accumulation of tree trunks and pieces of large wood across a vast section of a river, stream, or lake. ("Large
77:
Historically in North
America, large natural "log rafts" were common across the continent prior to European settlement. The most famous natural wood raft is the
187:, fallen trees form log jams when they are deposited on bars; fine sediment is deposited around these log jams, and sprouting seedlings are able to stabilise
26:
175:
It has been suggested that log jams are an aspect of trees acting as ecosystem engineers to alter river habitats to promote tree growth. In dynamic
100:. It contains more than 400,000 caches of wood and stores 3.4 million tons of carbon, equivalent to a year's emissions from 2.5 million cars.
592:
Gurnell, A.M.; Gregory, K.J.; Petts, G.E. (1995). "The role of coarse woody debris in forest aquatic habitats: Implications for management".
54:
to bank. Log jams form when trees floating in the water become entangled with other trees floating in the water or become snagged on rocks,
518:
212:"The presence of an ambulance on the side of the highway created a logjam of rubberneckers who just had to have a look." (more literal).
870:
156:
with low slopes, log jams tend to be partial structures primarily acting to deflect flow with minimal geomorphological change.
399:
349:
275:
168:
habitat. The pools created and sediment deposited by formation of log jams create prime spawning grounds for many species of
63:
677:
Curran, J.C.; Wohl, E.E. (2003). "Large woody debris and flow resistance in step-pool channels, Cascade Range, Washington".
505:
Abbe, T.B.; Montgomery, D.R. (1996). "Large woody debris jams, channel hydraulics and habitat formation in large rivers".
571:
490:
71:
485:
420:
Montgomery, D.R.; Collins, B.D.; Buffington, J.M.; Abbe, T.B. (2003). "Geomorphic effects of wood in rivers".
656:
249:
725:
437:"Wood-Based Carbon Storage in the Mackenzie River Delta: The World's Largest Mapped Riverine Wood Deposit"
712:
Shields, F.D.; Gippel, C.J. (1995). "Prediction of effects of woody debris removal on flow resistance".
20:
435:
Sendrowski, Alicia; Wohl, Ellen; Hilton, Robert; Kramer, Natalie; Ascough, Philippa (16 April 2023).
897:
786:
Gurnell, A.M.; Petts, G.E. (2006). "Trees as riparian engineers: The
Tagliamento River, Italy".
902:
82:
145:
97:
838:
795:
752:
686:
601:
545:
448:
284:
8:
842:
799:
756:
690:
605:
549:
452:
288:
811:
768:
648:
563:
486:"World's biggest cumulative logjam mapped in the N.W.T. — and it stores tons of carbon"
466:
391:
341:
302:
244:
215:"He was called in to try to break the logjam in the negotiations." (more metaphorical).
149:
55:
35:
740:
698:
815:
652:
567:
470:
395:
345:
196:
180:
59:
866:
772:
306:
851:
846:
830:
803:
760:
721:
694:
640:
609:
553:
514:
456:
383:
371:
333:
321:
292:
239:
51:
907:
90:
62:. A notable example caused by a natural disaster is the log jam that occurred in
127:
104:
31:
16:
Accumulation of large wood in a stream or river, preventing movement downstream
891:
533:
387:
337:
176:
132:
519:
10.1002/(sici)1099-1646(199603)12:2/3<201::aid-rrr390>3.3.co;2-1
111:
or the intentional release of large masses of trees into the water during a
613:
184:
558:
461:
436:
112:
234:
225:
140:
108:
78:
19:
This article is about river debris. For the cryptographic exploit, see
829:
Collins, B.D.; Montgomery, D.R; Fetherston, K.L.; Abbe, T.B. (2012).
807:
764:
644:
297:
270:
188:
86:
67:
629:"A dimensionless statistical analysis of logjam form and process"
116:
828:
628:
419:
229:
169:
94:
262:
165:
47:
434:
271:"Large in-stream wood studies: a call for common metrics"
534:"Structure and hydraulics of natural woody debris jams"
594:
591:
422:The Ecology and Management of Wood in World Rivers
531:
183:in Italy, where the dominant tree species is the
122:
889:
532:Manners, R.B.; Doyle, M.W.; Small, M.J. (2007).
372:"A legacy of absence: Wood removal in US rivers"
322:"A legacy of absence: Wood removal in US rivers"
504:
103:Log jams are not to be confused with man-made
711:
785:
507:Regulated Rivers: Research & Management
676:
850:
557:
483:
460:
296:
126:
25:
738:
726:10.1061/(ASCE)0733-9429(1995)121:4(341)
890:
788:Earth Surface Processes and Landforms
745:Earth Surface Processes and Landforms
626:
276:Earth Surface Processes and Landforms
203:
159:
369:
319:
268:
13:
741:"Plants as river system engineers"
14:
919:
491:Canadian Broadcasting Corporation
484:Lamberink, Liny (26 April 2023).
714:Journal of Hydraulic Engineering
873:from the original on 2022-03-23
859:
822:
779:
732:
705:
670:
659:from the original on 2020-02-10
620:
574:from the original on 2020-07-09
402:from the original on 2015-02-17
352:from the original on 2015-02-17
852:10.1016/j.geomorph.2011.11.011
585:
525:
498:
477:
428:
413:
376:Progress in Physical Geography
363:
326:Progress in Physical Geography
313:
123:Effects on river geomorphology
1:
699:10.1016/S0169-555X(02)00333-1
255:
441:Geophysical Research Letters
250:1886 St. Croix River log jam
72:eruption of Mount St. Helens
7:
219:
164:Log jams provide important
10:
924:
269:Wohl, Ellen (April 2010).
228:, a wooden dam created by
21:Logjam (computer security)
18:
538:Water Resources Research
388:10.1177/0309133314548091
338:10.1177/0309133314548091
195:In large rivers in the
867:"Definition of LOGJAM"
739:Gurnell, A.M. (2014).
614:10.1002/aqc.3270050206
136:
39:
130:
98:Northwest Territories
29:
837:. 139–140: 460–470.
627:Dixon, S.J. (2015).
559:10.1029/2006WR004910
462:10.1029/2022GL100913
447:(7): e2022GL100913.
370:Wohl, Ellen (2014).
320:Wohl, Ellen (2014).
843:2012Geomo.139..460C
800:2006ESPL...31.1558G
757:2014ESPL...39....4G
691:2003Geomo..51..141C
606:1995ACMFE...5..143G
550:2007WRR....43.6432M
453:2023GeoRL..5000913S
289:2010ESPL...35..618W
245:Stream restoration
204:Metaphorical usage
160:Effects on ecology
137:
56:large woody debris
40:
794:(12): 1558–1574.
197:Pacific Northwest
181:Tagliamento River
70:triggered by the
60:natural disasters
915:
882:
881:
879:
878:
863:
857:
856:
854:
826:
820:
819:
808:10.1002/esp.1342
783:
777:
776:
765:10.1002/esp.3397
736:
730:
729:
709:
703:
702:
685:(1–3): 141–157.
674:
668:
667:
665:
664:
645:10.1002/eco.1710
639:(6): 1117–1129.
624:
618:
617:
589:
583:
582:
580:
579:
561:
529:
523:
522:
502:
496:
495:
481:
475:
474:
464:
432:
426:
425:
417:
411:
410:
408:
407:
367:
361:
360:
358:
357:
317:
311:
310:
300:
298:10.1002/esp.1966
266:
240:River morphology
923:
922:
918:
917:
916:
914:
913:
912:
898:Aquatic ecology
888:
887:
886:
885:
876:
874:
865:
864:
860:
827:
823:
784:
780:
737:
733:
710:
706:
675:
671:
662:
660:
625:
621:
590:
586:
577:
575:
530:
526:
513:(23): 201–221.
503:
499:
482:
478:
433:
429:
418:
414:
405:
403:
368:
364:
355:
353:
318:
314:
267:
263:
258:
222:
206:
162:
139:Log jams alter
125:
91:Mackenzie River
38:, United States
30:Log jam on the
24:
17:
12:
11:
5:
921:
911:
910:
905:
900:
884:
883:
858:
821:
778:
731:
720:(4): 341–354.
704:
669:
619:
600:(2): 143–166.
584:
524:
497:
476:
427:
412:
382:(5): 637–663.
362:
332:(5): 637–663.
312:
283:(5): 618–625.
260:
259:
257:
254:
253:
252:
247:
242:
237:
232:
221:
218:
217:
216:
213:
205:
202:
179:, such as the
177:braided rivers
161:
158:
124:
121:
32:Quinault River
15:
9:
6:
4:
3:
2:
920:
909:
906:
904:
903:Geomorphology
901:
899:
896:
895:
893:
872:
868:
862:
853:
848:
844:
840:
836:
835:Geomorphology
832:
825:
817:
813:
809:
805:
801:
797:
793:
789:
782:
774:
770:
766:
762:
758:
754:
750:
746:
742:
735:
727:
723:
719:
715:
708:
700:
696:
692:
688:
684:
680:
679:Geomorphology
673:
658:
654:
650:
646:
642:
638:
634:
630:
623:
615:
611:
607:
603:
599:
595:
588:
573:
569:
565:
560:
555:
551:
547:
543:
539:
535:
528:
520:
516:
512:
508:
501:
493:
492:
487:
480:
472:
468:
463:
458:
454:
450:
446:
442:
438:
431:
423:
416:
401:
397:
393:
389:
385:
381:
377:
373:
366:
351:
347:
343:
339:
335:
331:
327:
323:
316:
308:
304:
299:
294:
290:
286:
282:
278:
277:
272:
265:
261:
251:
248:
246:
243:
241:
238:
236:
233:
231:
227:
224:
223:
214:
211:
210:
209:
201:
198:
193:
190:
186:
182:
178:
173:
171:
167:
157:
153:
151:
147:
142:
134:
133:Goodell Creek
129:
120:
118:
114:
110:
106:
101:
99:
96:
92:
88:
84:
80:
75:
73:
69:
65:
61:
57:
53:
49:
45:
37:
33:
28:
22:
875:. Retrieved
861:
834:
824:
791:
787:
781:
748:
744:
734:
717:
713:
707:
682:
678:
672:
661:. Retrieved
636:
633:Ecohydrology
632:
622:
597:
593:
587:
576:. Retrieved
541:
537:
527:
510:
506:
500:
489:
479:
444:
440:
430:
421:
415:
404:. Retrieved
379:
375:
365:
354:. Retrieved
329:
325:
315:
280:
274:
264:
207:
194:
185:black poplar
174:
163:
154:
138:
135:, Washington
105:timber rafts
102:
76:
66:following a
43:
41:
751:(1): 4–25.
131:Log jam in
107:created by
64:Spirit Lake
892:Categories
877:2022-04-30
663:2022-04-30
578:2022-04-30
406:2015-12-01
356:2015-12-01
256:References
235:Great Raft
226:Beaver dam
189:braid bars
146:deposition
79:Great Raft
36:Washington
816:129185856
653:131127480
568:129868907
471:258063526
396:131725942
346:131725942
113:log drive
87:Louisiana
83:Red River
68:landslide
871:Archived
773:55420478
657:Archived
572:Archived
424:: 21–47.
400:Archived
350:Archived
307:16337806
220:See also
95:Canada's
839:Bibcode
796:Bibcode
753:Bibcode
687:Bibcode
602:Bibcode
546:Bibcode
449:Bibcode
285:Bibcode
230:beavers
117:sawmill
109:loggers
81:on the
44:log jam
908:Rivers
814:
771:
651:
566:
469:
394:
344:
305:
170:salmon
812:S2CID
769:S2CID
649:S2CID
564:S2CID
544:(6).
467:S2CID
392:S2CID
342:S2CID
303:S2CID
150:scour
115:to a
166:fish
141:flow
52:bank
48:wood
847:doi
804:doi
761:doi
722:doi
718:121
695:doi
641:doi
610:doi
554:doi
515:doi
457:doi
384:doi
334:doi
293:doi
93:in
85:in
894::
869:.
845:.
833:.
810:.
802:.
792:31
790:.
767:.
759:.
749:39
747:.
743:.
716:.
693:.
683:51
681:.
655:.
647:.
635:.
631:.
608:.
596:.
570:.
562:.
552:.
542:43
540:.
536:.
511:12
509:.
488:.
465:.
455:.
445:50
443:.
439:.
398:.
390:.
380:38
378:.
374:.
348:.
340:.
330:38
328:.
324:.
301:.
291:.
281:35
279:.
273:.
119:.
42:A
34:,
880:.
855:.
849::
841::
818:.
806::
798::
775:.
763::
755::
728:.
724::
701:.
697::
689::
666:.
643::
637:9
616:.
612::
604::
598:5
581:.
556::
548::
521:.
517::
494:.
473:.
459::
451::
409:.
386::
359:.
336::
309:.
295::
287::
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
.jpg)
