Abiotic Responses to Wood Wednesday, February 15, 2012 Tim Abbe, PhD, PEG, PHG, Cardno ENTRIX

1. Abiotic Responses to WoodWednesday, February 15, 2012Tim Abbe, PhD, PEG, PHG, Cardno ENTRIX

2. Abiotic: ”Physical rather than biological; not derived from living organisms” … • “Physical” includes: • Hydraulics and Hydrology • surface • subsurface • Sediment transport and deposition • Bedform development (e.g., pools, bars, …) • Landform development (e.g., islands, floodplains, terraces, …) • Cover, surface area, interstitial space within water column. • Chemical (carbon sequestration, nutrient processing, …) • Temperature

3. Wood influences fluvial ecosystems across a wide range of spatial, hydrological, and temporal scales cm km substrate & cover Bedforms & gradients planform & floodplain Base flows Flood flows Moderate flows Q Q Q t t t

4. What is large wood? Let’s start with a definition of trees: Woody plants with stem diameters greater than 0.1 m and heights of at least 6 m. 1000 species in US, 90,000 worldwide. Forests covered over 30% of the earth’s land surface through the Holocene. Currently that is down to about 22%. Wood has been around for ~400 million years and found preserved in rocks all over the earth (Gerrienne 2007, Science)

5. What is large wood? Wood is one part of the physical matter (debris, sediment) that enters stream networks. Just like inorganic sediment, wood can stay in place where it entered (e.g., in-situ) or be transported downstream as either suspended or bedload. Wood is unique from other sediment: it has different density it has different shape it is generally much larger than native bed material the size of trees entering a channel network generally increases downstream, opposite to inorganic sediment

6. let’s take a minute to look at the relative size of wood: The exponential plot we are accustomed…

7. Looking at size more graphically…

8. Looking at size more graphically…

9. Looking at size more graphically…

10. Queets River, 2003 Just to remind us that large trees still are around (albeit at less 5% their original extent)

11. historical context… The ability of riparian trees to influence streams was recognized over a hundred years ago: “The thirsty mountaineer knows well that in every sequoia grove he will find running water, but it is a very complete mistake to suppose that the water is the cause of the grove being there; for, on the contrary, the grove is the cause of the water being there. … a single trunk falling across a stream often forms a dam 200 feet long and ten to thirty feet high, giving rise to a pond …” - John Muir (1878, p.627)

12. The recognition that wood could control riversversusbe controlled by riverswas not limited to the Giant Sequoia, nor uncommon: “A close study of conditions shows that in every instance the current was first deflected by an accumulation of drift, the huge timber of this section serving readily in its formation. … Gravel, sand, and silt collect in the dead water, behind the drift piles, strengthening them and preventing the river from returning to its original bed. Evidences of this action are plentiful…. - Wolff, H.H. (1916) (describing the White River draining Mt Rainier, WA)

13. Abiotic responses to wood: Energy dissipation/shear stress partitioning: reducing sediment transport capacity of a stream reducing erosive capacity of the stream decreasing mean grain size of stream bed increasing textural variability of the bed increasing sediment storage and residence time Flow deflection Wood constricts channel hydraulic geometry which: creates areas of local scour and pool formation redirects streamlines across the channel creates re-circulation areas which trap sediment raises water elevations indreaseshyporheic exchange Impoundments - channel spanning jams creates sediment traps creates aggradational landforms, elevating floodplains can lead to dam-breaks that scour d/s and incise u/s. raise groundwater tables.

14. Stress partitioning and channel form

15. ELJ’s reduce the effective shear stress available for sediment transport, reducing grain size of bed material Bed particle size distribution no ELJ with ELJ D50 of bed decreased almost 5 fold after ELJs were installed. D50(before) = 90 mm, D50 (after) = 19 mm

16. wood occupying only 5% of the stream bed can partition as much as half of the total shear stress (Buffington and Montgomery 1999, WRR 36, 3507-3521, Manga and Kirchner, 2000, WRR 36, 2373-2379) Photo showing what some of our rivers looked like. Olympic Peninsula River (Queets), circa 1913.

17. Effect of reducing D50 :

18. Anabranching river with large amounts of wood Taiya River, Alaska T.Abbe2002

19. Stress partitioning and bank erosion

20. Map illustrating stability of Wooded Banks upon the Mississippi River 1870-1879 Does wood play a factor in bank erosion rates? Central Sacramento River Micheli, E.R., J.W. Kirschner, and E.W. Larsen 2003.

21. maximum 75% tile median 25% tile minimum Eroded area of old and young forest as a percent of total eroded area Abbe et al. 2004

22. Trees that are unlikely to be stable in the channel are unlikely to have any significant influence on the rate of bank eroison.

23. Wood forming stable snags along the shoreline would reduce effective shear stress and lower erosion rates. Missouri River

24. Using engineered wood structures to partition shear stress. Complex timber revetment, stops erosion while creating excellent fish habitat South Nooksack River

25. Physical complexity of channel margins Cover and surface area

26. Jams also dramatically increase surface area and interstitial volume along channel margins: factors influencing biologic processes Meander Jam (1993, Queets River) This type of structure can increase surface area over 10,000 times (Abbe & Brooks 2011).

27. Flow Deflection

28. Distinct types of wood accumulations form depending on the size of the wood & the river; and create distinctive bedforms Bar Apex jams (Abbe & Montgomery 1996, 2003)

29. Flow Deflection Jam (1994, Queets River, WA) site of 7 m pool, deepest in the Queets River in 1993-94

30. Pools in 1l river segment: # perennial pool Year pools cover* 1998 3 0-5 2010 18 25-50 No significant increase in pool area but dramatic increase in #, distribution and cover Approximate % of pool volume with complex cover in water column 18 17 16 15 14 13 11 10 12 9 8 7 6 5 4 3 2 1 70% of ELJs are sustaining perennial pools

31. Flow bifurcation and island formation (anabranching channels) Summer 2001 Fall 2005

32. Elwha gravel bar area has increased with construction of ELJs and channel aggraded.

33. Flow deflection to limit channel migration and establish forest buffers Cispus River ELJ Site B, RM 19 Constructed in 1999, now 13 years old. December 2007

34. Wood Channel Impoundments

35. Wood in steep low-order channels: does it influence sediment & flood routing? Natural Log Steps in Queets and Hoh Basins

36. What about large moderate to low gradient channels? Natural Logjam in Middle Fork Teanaway River circa 1900 East Cascade Mountains, Washington State Source: Russell, I. C. 1909. Rivers of North America. G.P. Putnam's Sons, New York. 327pp. Figure B, Plate XII, page 239.

37. Logjam raise water elevations Overbank flow upstream of logjam on the Deschutes River south of Tumwater, WA.

38. Discontinuous, oblique alluvial surfaces can develop due to the presence of logjams which impound the channel and retain sediment

39. Wood channel impoundments and flood routing

40. Wood in channels reduces downstream flood peaks while spreading out hydrograph – benefiting fish & wildlife while reducing impacts to communities No wood Stage /Discharge Wood time e.g., Anderson 2006

41. Is it sacrilege to ask: is wood a more significant variable controlling channel morphology than Q? Does wood increase the resilience of a stream? This creek remains in excellent condition despite being in an urbanized watershed that sends much more water into the creek: what was once the 100 yr flood now occurs twice a year. The creek’s resilience is entirely due to woody debris and vegetation.

42. Without wood, channels cut down and damaging pipes, bridges, homes and roads. This process also disconnects floodplains and increases downstream flooding

43. Wood channel impoundments and sediment storage

44. The Red River of Louisiana was commonly cited as an example of where wood accumulations were responsible for altering an entire valley – forming lakes 50 km in length and a complex mosaic of bayous that disappeared with the removal of wood from the river. The Red River incised about 5 m shortly after wood removal, making the river un-navigable.

45. Sediment Storage and Logjams Consequences of removing valley jam complex from Colorado River of Texas by U.S. Army Corp of Engineers: Sediment deposited in Matagorda Bay between 1909 and 1941 = 42,809,700 m3 An average sediment discharge of 1,297,264 m3yr-1 Can we learn more about historic changes? How much sediment can we store using wood again?

46. Sediment Storage and Logjams Did removal of the many other logjams around the country also result in sediment delivery to coastal areas (such as Skagit River pictured here)?

47. Hyporheic Changes

48. Pool Depth Affects Summer TemperatureDeeper pools are associated with lower temperatures (Elwha ELJ 1) water surface Degrees Celsius bottom of pool

49. Does subsurface wood alter the subsurface flow, is it capable of raising the water table and forcing perennial conditions that would otherwise be ephemeral? Proposed placement of wood to ‘force’ a perennial system Existing ephemeral low-flow conditions (devoid of wood)

50. Common questions that still come up What was the ‘natural’ or pre-historic wood loading? What function is the wood providing? Will wood increase water surface elevations? Will wood trap sediment and if so, will it cut-off sediment to downstream reaches? Where will mobile wood end up and what will it do? What role did wood have in lakes, estuaries and coasts? How long will it last? (a hydrobiogeochemical question)