Short course for UNIVERSIDAD NACIONAL DE INGENIERIA January 26-29, 2016
Planning and Design for Rehabilitation of Rivers Using Large Wood Metodología para Reforestar Ríos Degradados por Actividades Humanas usando Técnicas de Bioingeniería
11.0 Monitoring and adaptive management for large wood projects
Course overview Day I (Jan 26)--Foundational topics • Review of information resources (design handbooks and spreadsheets) for large wood • Is wood appropriate for your site?—criteria for screening (Planning) • Three design approaches • Key issues for large wood design
Day 2 (Jan 27)—Designing large wood structures • Case study I—Little Topashaw Creek, Mississippi • Design life for wood structures/selection of design event or condition
Day 3 (Jan 28)—Risk, uncertainty and construction • Sensitivity and Monte Carlo analyses
• Constructability assessment • Case study II—Trinity River, California • Monitoring
Day 4 (Jan 29)--Field trip
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• Introductions
• Types of wood structures • Findings of recent research on drag and lift coefficients • “Road testing” selected design spreadsheets
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• All projects need some monitoring • Monitoring may be very intensive and costly, but it also may be low effort and cheap • Monitoring required for “organizational learning” • Monitoring required for adaptive management • The best monitoring is based on BACI design
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Key points for project monitoring
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• • • •
Uncertainty A “stitch in time” Risk to infrastructure Learning…refinement of technique • Reduce liability • Certify benefits • Certify compliance
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Why monitor?
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Why NOT monitor • When you do not have a good answer to, “What is the question we are trying to answer?” • When you do not have a scientifically defensible plan (BACI, experimental design, etc.) • When resources are better directed toward another (less common) project or site • When you have $$ for data collection, but inadequate funds or personnel to screen data, filter data, reduce data, archive data, analyze data, assess impacts/effects and report results
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• Really, monitoring should be designed to test an hypothesis
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• Fate of structures • Response of channel • Forcing signal….water (precip/discharge), sediment, wood inputs • Habitat quality • Biological response • Invertebrates • Fish • Riparian vegetation
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What to measure?
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• Has structure changed size? • Has structure increased in height and size by adding material? • Is there any vertical settling? • What is extent of water flow through the structure? • Has stream orientation changed or is there any danger of structure abandonment or flanking? • Has bank erosion occurred?
Abbe et al. 2005
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What to measure (or observe)?
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8
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How to measure • Visual observation • Photos • Check form(s) • GPS
• Wood tags/RFID • Stream gaging • • • •
Full blown gaging with rating curves Pressure transducers to record stage Sediment gaging ($$$$) Wood flux?
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• Drones • Webcams
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Little Topashaw Creek Cross Section 23 95
Elevation, m MSL
94
Preconstruction
Postconstruction
93 92 91 90 89 88 87 0
Cross section 23 shortly after construction on 23 Aug 2000
5
10
15
20
25
Distance from Left Bank, m
Thalweg Profiles, Little Topashaw Creek Preconstruction Postconstruction
Elevation, m MSL
90
30
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86 35
88
10 86 3,500
Cross section 23 on 24 Jan 2001. Note fresh deposition at toe of left bank.
3,000
2,500
2,000
Distance upstream f rom mouth, m
1,500
Upstream 150
Treated Reach
Downstream
100
50
0
150
Fall
100
50
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Spring
0
Upstream
Treated Reach
Downstream
Before debris addition (1999) After debris addition (2001)
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LITTLE TOPASHAW CREEK TOPOGRAPHY AT STUDY BEND
93 92 91 90.5 90
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89.5 89 88.5 88 87.5 87 86.5
PRECONSTRUCTION (2000)
POSTCONSTRUCTION (2001)
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86
0
20
40
60
80
Data Collected • At 30% bankfull, after 90% bankfull test • Photogrammetry used to collect bed elevations before and after • Point gages used to read water surface elevations to the nearest 0.001 ft. • SonTek 2D FlowTracker acoustic Doppler velocimeter was used to collect velocity measurements Kendra Russell, USBoR, Denver
Potential Juvenile Chinook Habitat Kendra Russell, USBoR, Denver
Configuration 1: Triangular LW
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Biological sampling
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Monitoring riparian vegetation
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Centrarchids, % of total catch by number 18 16 14 12 10 Before After
8 6 4 2 0 Upstream
Within modified reach
Downstream Shields Engineering, LLC
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Bank stability
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How to measure • Laser • RTK/GPS • LiDAR
• Wood samples • Density • Other?
• Local hydraulics (next) • Scour
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• Surveying
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1000 500 0 -500 -1000 18-Jan-01
19-Jan-01
inside debris structure
20-Jan-01 outside LWDS
21-Jan-01
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Velocity, mm/s
1500
20
As built (2000)
After one year (2001)
No. of structures
72
68
Mean crest elevation above bed, m
2.1 + 0.5
2.5 + 0.6
Length,m
13.9 + 3.9
10.2 + 4.2
Width, m
5.3 + 1.9
6.0 + 2.3
No. of structures with anchors
58
55
Estimated portion of structure buried, %
31 + 28
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Durability of structures
21
22
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Debris Structures Depress Current Velocity at Baseflow 120 80 40 0 0
1
2
3
4
5
Time (h) Downstream reach without large woody debris structures Study reach--with large woody debris structures
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Concentration ppb
Rhodamine Dye Concentration vs Time after Injection
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Aquatic Habitat Effect of LWDS on Aquatic Habitats Upstream Treated reach Treated reach Downstream
After
Downstream 0
20
40
60
80
Mean Water Depth at Baseflow, cm
Effect of LWDS on Aquatic Habitats Upstream Treated reach
•Mean water depth doubled within the treated reach. Depth was halved upstream and remained unchanged downstream .
Before
Treated reach
After
Downstream Downstream 0
2
4
6
8
10
Mean Water Width at Baseflow, m
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• Mean water width increased 16% downstream, 17% within, and decreased by 25% upstream from the treated reach.
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Before
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• All projects need some monitoring • Monitoring may be very intensive and costly, but it also may be low effort and cheap • Monitoring required for “organizational learning” • Monitoring required for adaptive management • The best monitoring is based on BACI design
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Key points for project monitoring
25