Treatment Strategies based on Stream Stratification Methodology by W. Barry Southerland Fluvial Geomorphologist, WNTSC, USDA, NRCS

Transcription

1 Treatment Strategies based on Stream Stratification Methodology by W. Barry Southerland Fluvial Geomorphologist, WNTSC, USDA, NRCS Cedar Creek, WA Cedar Creek, WA Asotin Creek, WA 2005: photo by WBS

2 Rationale for this discussion To discuss structure relative to landscape setting: risk and uncertainty To identify treatment strategies Integrative-ness of stream classification

3 Landscape Setting (socio-economic setting) Landscape Setting # of Bridges # of Homes Urban Most Most Highest Risk and Uncertainty (Liability Issues) Urban Fringe More Low to Medium Ag Landscape More Low Density Higher High Meander Migration Free Zone (MMFZ) Least Least Low to potentially high

4 Propensity for Private Landowners to Accept Risks and/or Attributes of Meander Migration Landscape Setting Urban Urban Fringe Propensity to allow Meander Migration Very little, often nonexistence Low, Little tolerance to property loss Structures moving offsite (i.e. Risk) High risk unless property is upstream of a specific outlet such as delta, ocean..etc. High risk unless property is upstream of a specific outlet such as delta, ocean..etc. Ag Landscape Landowners are skeptical but some possibilities e.g. M. Belt Width May be high risk and depending on landowner s position and relationship with others on the stream corridor Meander Migration Free Zone (MMFZ) High Low risk unless the site is located near a high risk setting or specific infrastructure

5 How well attached is your floodplain? Is floodplain attachment within the cards when you consider the stage of channel evolution? Top of Bank Bankfull Stage Water Table

6 Streambank failure (What mode if failure? What it the mechanism?)

7 What is the problem with this? Apex of meander or riffle facet? Very high near bank stress

8 We need better fish habitat Build a bankfull bench with subcritical flow inducers Sub-critical flow inducer Bankfull Bench

9 J-Bar Ranch Case Study Watershed size: 37 m 2 BFQ (Channel forming Q): 70cfs CEM Stage: III with some II BHR inches annual precipitation Photo by WBS, South Fork Asotin CK Photo by WBS, South Fork Asotin CK, 1997

10 Opposite Problems Incised Stream J-Bar - South Fork Asotin Creek 1997 Braided and Aggraded Stream Koch - Asotin Creek Asotin 1997 Photo by WBS, South Fork Asotin CK, 1997 Photo by WBS, Asotin CK, 1997 Lane s balance Q S *d 50 ~ S*Q Lane s balance Q S *d 50 ~ S*Q

11 Goal and Objective Transport bedload in a stable manner while maintaining local deposition and scour (bedload competence) Reduce streambank erosion Re-attach floodplain to provide water table for riparian plants Restore salmonid habitat (steelhead) Increase hyporeic zone

12 Incised Stream Description /97 Photo by WBS, South Fork Asotin CK, 1995 Photo by WBS, South Fork Asotin CK, 1997

13 Meander Reconstruction Rebuilding bankfull channel and floodplain w/i incised system

14 Bankfull channel and floodplains rebuilt. Late fall 1997 before planting

15 After Riparian Plantings

16 1997 G3 Before and After 2002 B4 Six years and two large floods later Pages 5-22 and 5-23 in SCRM

17 1997 Example of Dimensionless Ratio and Regional Bankfull Discharge Based Design 1998 Asotin Ck, WA Photo by WBS, Asotin CK, 1998 Asotin Ck, WA Photo by WBS, Asotin CK, YEARS LATER Asotin Ck, WA

18 Summary of Case Study Cost (1997) $10,200 for meander reconst. Estimate for rip-rap $40,000 Steelhead juvenile population increase 500% Project has been subjected to two floods since implementation: 1998 flood was 6 times bankfull Q Project is nine years old Photo by WBS, Asotin CK, 2005

19 Components of the system 2005, 7 years and three floods later Constructed Log Jam Photo by WBS, Asotin CK, 2005 Photo by WBS, Asotin CK, 2005 Deep pools with riffles, glides, and runs Photo by WBS, Asotin CK, 2005 Photo by WBS, Asotin CK, 2005

20 Asotin Creek Red Counts No Redds Observed at Koch Project in 1997 Total Unaltered Area Treated (altered) Area Redds/Kilometer (9.9 redds/km) unaltered to (17.6 redds/km) treated

21 Underlying principle to design most violated! Structures are built to accommodate the geomorphic system and not visa-versa! Whether you are determined to add wood or rock structure, think system first. Sequoia National Forest Sequoia National Forest

22 Valuable, but Caution Will Robinson! Caution! Lost in Space Robot B9 Applied River Morphology, 1996 and 2001 update These are a generalized rating scheme. These are only meant to provide general direction and not intended to be used separate from a comprehensive fluvial geomorphic and fish habitat analysis and design process.

23 TREATMENT STRATIGIES Do Nothing (it depends on watershed and reach field conditions, and can be generally predicted by stream type). What factors: Is there an excessive sediment supply that will make it easier to erode streambanks than to move sediment. One needs to treat the source of excessive supply, and or remove some of the supply at specific locations causing streambank problems. Is there reach level downcutting and widening as show by CEM that will compromise any work proposed.

24 STRATIGIES (Cont.) Is there sufficient stream belt width room, to allow stream to meander. What will be the continuing off-site effects from this action.

25 Pot. Treat. Opt. Low Banks (<8 ft.) Low Grad. Rosgen Str. Typ. & Simon CEM Stage Simon Rosgen Typical Strategies Typical Practices I Stable C and E Maintain W/S Qw, Os Riparian Spot Treat. Soil Bio. Stakes, facines, Rooted stock Whole Pl.

26 Pot. Treat. Opt. Low Banks (<8 ft.) Simon Stage III Downcutting and Widening Low Gradient Rosgen F and?gc Treatment Strategies Reduce W/S Qw and Qs May need to Raise Ch.; F. P. reconnect; Increase Sin.; Improve Riparian Typical Practice Realign; Grade Ctr.; Soil Bioeng. Only, if With Other Practices

27 Pot. Treat. Opt. Low Banks (<8 ft.) Low Gradient Continued Simon Rosgen Strategies Typ. Treat. Early IV of Widening Following Downcutting F Type Reduce W/S Runoff & Qs; Excavate F. P. & Shape Banks; Toe Protection; No Independent Soil Bio. Minor Grading with Permanent Toe Protect, Than Soil Bioeng., & Whole Plant Transplants

28 Pot. Treat. Opt. Low Banks (<8 ft.) Low Gradient Continued Simon Rosgen Strategies Pot. Treat. IV C, E Maint. W/S Minor grade Widening w/o downcutting Runoff & Qs; Create more F. P, & shape banks toe protect; Improve riparian; No Sin. Soil Bio With Permanent Toe Protect, than assoc. Soil Bioeng. & Whole Plant Transplants

29 Pot. Treat. Opt. Low Banks (<8 ft.) Low Grad Cont. Simon Rosgen Strategies Pot. Treat. Late IV Widening F, Bc Maint. W/S Runoff & Qs; Create more F.P. &Shape Banks; Toe Protect. & Imp. Ripar.; No single Soil Bio. Minor Grading with Permanent Toe Protect; Whatever Soil Bio. Required; & Whole Plnt. Transplants

30 Pot. Treat. Opt.Low Banks (<8 ft.) Low Gradient Continued Simon Rosgen Strategies Pot. Treat. Early V Deposition F, Bc Maint. W/S Runoff & Qs New F.P. Shp Some Bnks. for ToeProtect.; Impv. Rip.; Implement Soil Bio. Minor Grad. With Toe Protect.; Than Whatever Soil Bio. Needed & Whole Plant Transplants

31 Pot. Treat. Opt. Low Banks (<8 ft.) Low Grad Cont. Simon Rosgen Strategies Pot. Treat. Late V Deposition Bc, C, E Maint. W/S Runoff & Qs Shape Some Bnks. For Toe Protect.; Impv. Rip.; Implement Soil Bio Minor Grad. With Toe Protect.; Than Whatever Soil Bio. Needed & Whole Plant Transplants

32 Rosgen Interp. Cross Vane

33 Rosgen Interpretation Structures Example

34 Rosgen Interp. W-WeirW Weir

35 Hoh Vanes w/o hooks 1999 S Durgin Rock Vane

36 Rosgen, 1998

37 Log Vane Photo by W. Barry Southerland, Ohio Creek, CO Photo by W. Barry Southerland, Ohio Creek, CO

38 W - Weirs Wildland Hydrology, 2005 Very Good on systems that involve bridges and large streams with high width Photo by W. Barry Southerland, CO

39 Log Cross Vanes Wildland Hydrology, 2005

40 Log Cover Does it float? If it does what extra design considerations must you consider? Bear Cr. in Willowa Co. OR, FR Log cover has its place when you consider location, stream type, confinement, and so forth but these can be bad-newsbears if not designed properly.

41 Bear Cr. in Willowa Co. OR Log Cover Continued

42 Cross - Vanes South Fork of the Platte River, CO 2005: Photo by W. Barry Southerland Cross Vane Tail out (Glide) Cedar Creek, WA Cedar Creek, WA: Salmon Spawning, 2005 Photo R. Dyrland

43 On smaller streams where a structural practice is compatible with the design and geomorphic stream type consider some Log Spurs cost-effective differences. Log deflectors single wing Log vanes Root wad structure On both large an smaller waterways, understand geotech material needs and how it is integrated in log checking type practices! Ohio Creek, CO, 2005: photo by W. Barry Southerland

44 Beaver Management Willow Creek, CO, 2005 by W. Barry Southerland Willow Creek, CO, 2005 by W. Barry Southerland

45 Restored F channel through beavergation If you choose to use beavergation as a strategy to address incision and to accelerate channel evolution, consider the follow (not all inclusive): Longitudinal profile bust and extreme gradients throughout the entire treatment range. Some initial check may be needed Beaver management and trapping plan Pre-existing vegetative conditions Consultation regarding fish management implications with your local area fish habitat manager. Willow Ck., CO, 2005 by W. Barry Southerland Adjacent land use compatibility issues

46 Root wad and revetments and vanes with wood placement and recruitment Low width to depth ratio pools with excellent cover and complexity Cedar Creek, WA Cedar Creek, WA

47 Thank you! Questions?