TREATING RIVERS RIGHT & EXAMPLES OF BEST USE OF WOOD IN RESTORATION

Transcription

1 TREATING RIVERS RIGHT & EXAMPLES OF BEST USE OF WOOD IN RESTORATION James Mac Cartney, TU River Restoration Specialist John Braico, MD, NY Council Resource Mgr Grassroots Trustee 1

2 Great Trout Streams are no accident! Natural Streams and Rivers are: - self sustaining carpenters of their own edifices & - creators of all aquatic habitat 2

3 Natural Steams key concepts Unimpeded natural processes generate stable stream patterns or types (A-G,1-6)according to the laws of physics while interacting with the landscape Consequence: complex physical systems formed are perfectly suited to all the life found there (i.e, they evolved to fit!) 3

4 Common Types of Trout Streams (grossly simplified!) Hi Gradient (4-10%): torrents (A) Medium Gradient (2-4%) (B) step pools, riffle/run dominant (B) (2-4%), G (gullies), D Low-Medium gradient(< 2%): classic riffle/pool (C), ( F ), braided (D) Low gradient (<< 2%): highly meandering (spring creeks, meadow) (E) (protect) 4

5 What s a good trout stream? Stable Form: low W/D, stable banks, short steep riffles & deep runs, deep flat pools (or step pools), gravelly glides, BHR = 1 (all essential features) Ample Habitat ( abundant LWD & larger rocks bank/bed) => Roughness (& is not embedded with sand) For fish of all stages & sizes For insect life -- For flow diversity/scour/deposition Good riparian zone (>1 Wbkfl, 2-3x ) rooted banks, canopy, energy inputs from leaves, source of LWD recruitment, easily accessed flood plain for sediment deposition, energy control, flood attenuation, ground water Healthy Water: Cold clean consistent flows, + chemistry 5

6 Healthy Mountain Stream great trout water note: roughness, riparian zone 6

7 Starting Upstream (mod gradient B ) riffle run pool glide 7

8 Stable Streams have: Intact watersheds, full access to fxnl floodplain & consistent flow patterns Hardly change at all when monitored over many decades Even when subjected to massive flows Changes in width is measured in fractions of inches/ major flood event! (Not in feet or yards!) 8

9 Stable reference E. Br. Ausable (glide, riffle, run) 6 days post Irene 9

10 E. Br. Ausable (Irene + 6) 10

11 Restoration is NOT: Patching an ailing stream system Plugging in a device to meet a local fisheries objective or just shoring up a failing bank, NOT: Just improving the fishing Just stabilizing banks Just reducing flood impacts Just creating pools NB: Streams are unforgiving only fools rush in! 11

12 Instead: Restoration Aims to Return a disturbed stream system (reach level) to healthy functioning condition modeled after nature & natural stream processes: With Stable channel size & form W, D, A, meander pattern, profile, roughness/substrate With good connection to a fxnl floodplain With a healthy riparian zone (50 min or more) With overall -- Healthy biologic, geomorphic, hydraulic & water quality functional status 12

13 Stream Restoration an evolution from Keyholes to Systems Biologists adult habitat fixes ( s) Classic habitat devices ( 50/50 at best) Engrs move water from pt A->pt B ( s) Trapezoidal channels to contain & transport water Geomorphologists: maintain stability while moving sediments (1980 s early 2000 s) Rosgen & others Functional Integrated Systems ( 05 now): Meet all functions: Form, Processes & Biologic needs 13

14 2012 Functional Restoration EPA underpinning by lower levels + dynamic interplay between: Level 5 Biologic Fxns (fish,bugs,micro) Level 4 Physio-Chemical Fxns (WQ) Level 3 Geomorphic (transport Sed & LWD) Level 2 Hydraulic Fxns (water in channel) Level 1 Hydrologic Fxns (water to channel) underpinned by: Climate, Geology & land use 14

15 So Restoration Requires: Finding out what s going on? Accurate Analysis Accurate Diagnosis Simple screening more complex What is driving it? Why? Where it s heading? worsening, shifting, or recovery Answers give best options to recover stability help fishery (including limiting factor analysis) 15

16 Streams provide optimal habitat All life stages of fish: egg, alevin, fry, YOY, adult Riffle, run, pool, glide, backwater, shallows, LWD All life stages of invertebrates: insect, crustacea (egg, larval, nymphal, adult) Riffle, run, pool, glide, backwater, shallows, LWD, detritus, leafy inputs For best outcomes, include everything 16

17 Key objectives in geomorphic restoration Right size (W, D, W/D, Area) Full connection to floodplain (low bank at or near floodplain/bkfl elevation) Min FPr width: B = 2x W C = 4x W E= 20x W Right slopes: riffles, runs, pools, glides Able to transport all bedload (input = output) Good hyporrhehic zone, not embedded Good bed & bank roughness Riparian buffer: ideally 6x Wbkfl (not less 50 ) 17

18 Modeling after nature: reference reach Match valley & stream types Use measured ratios related to bankfull width from the reference reach applied to the disturbed stream Ensure that restored channel handles bankfull flows & bedload in = bedload out Use native materials 18

19 Use of wood in restoration/habitat Roughening banks & riparian zone Sediment deposition & Scour Flow deflection (Log Vanes) Disrupt helical flows (Log Jams, Toe Wood) Habitat fish & bugs Toe Wood, Log Jams Narrowing over- wide channels (Toe Wood, Root wads, Log vanes) 19

20 Log Vanes Designed to roll energy away from bank & so stop erosion (typical use on bends) degree angle to bank, extending 1/3 of channel width, pointing upstream & sloping 6-8 deg from bankfull to thalweg Cheap, local materials, simple to install, durable Construction sequence 20

21 1 st bend: lay out 3 log vanes to deflect energy from bank, deepen + habitat 21

22 Trench in 4-6% grade & 25 degr 22

23 Tack on filter fabric to anchored vane 23

24 Tips & butts anchored & braced 24

25 Add river cobble to fill in ramp face 25

26 3 completed vanes: check current shifts, where would trout lie? 26

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29 Root Wads 15 log with 10 root fan & DBH set in deep trench on footer log, with root fan perpendicular to flow, anchored & buried so much of root fan is submerged all flows No longer recommended for bank stabilization Best current uses: To roughen margins (2007 USFS) To narrow channel (2008 USFWS) As part of Toe Wood Structure (2008 Rosgen) 29

30 Battenkill VT: dimension, pattern, profile, riparian zone all OK. Deficit: boundary roughness Solution: anchored LWD 5X Trout population 30

31 Anchored Rootwad Battenkill VT 31

32 Rootwads to narrow a low flow channel & improve sinuosity Use alternate sides at 45 deg angle pointing upstream Half entrench log & root fan into bed extending back to ~.5 bankfull at bank Brace & anchor with boulders Problems none to date Yield very good to excellent (Irene tested!) Cheap! 32

33 Adding root wads for habitat & improving w/d ratio in over wide habitat poor reach (rock anchors) 33

34 Just upstream 43 rootwads added to alternate sides (trout # 3X or more) 34

35 Toe Wood Structure Remarkably effective on eroding bends Great instant habitat trout, bugs, all fish Low cost ~ $40 - $50/ LF if free local materials Very durable (even to large flood events) Placed low, kept wet, good access to a bankfull bench to reduce local flood energy on bank Looks natural Caveats follow specs, lots of ballast, revegetate, consider log vanes at both ends 35

36 Bends 1 & 4: adding 1140 of Toe Wood Structure in front of bank 36

37 Logs laid 10 on center with footers, braces & rock ballast 37

38 Next: skidder hauls in tree tops 38

39 Then hay or coir mat laid on tree tops/brush _I_ to bank, then gravel or soil 39

40 Then live willow poles, coir mat, more soil 40

41 2nd TWS: Roughness, narrowing => bank resiliency, Habitat, sediment transport, reconnect to flood plain 41

42 2 nd & 3 rd Toe Wood Structures 42

43 2 weeks post 2 nd flood 1140 intact 43

44 2 nd TWS post 10 floods 44