VII. Effects Of Transportation Structures On Fluvial Systems
16
VII. 1 VII. Effects Of Transportation Structures On Fluvial Systems A. Riverine Systems 1. Analytical Tools to Evaluate Impacts 2. Single Channel 3. Braided 4. Meandering B. Non-Riverine Systems 1. Alluvial Fans/Distributary Flow 2. Sheet Flow 3. At-Grade Crossings C. Recommended Best Management Practices
description
VII. Effects Of Transportation Structures On Fluvial Systems. A.Riverine Systems 1. Analytical Tools to Evaluate Impacts 2. Single Channel 3. Braided 4. Meandering B.Non-Riverine Systems 1. Alluvial Fans/Distributary Flow 2. Sheet Flow 3. At-Grade Crossings - PowerPoint PPT Presentation
Transcript of VII. Effects Of Transportation Structures On Fluvial Systems
VII. 1
VII. Effects Of Transportation Structures On Fluvial Systems
A.Riverine Systems1. Analytical Tools to Evaluate Impacts
2. Single Channel
3. Braided
4. Meandering
B.Non-Riverine Systems1. Alluvial Fans/Distributary Flow
2. Sheet Flow
3. At-Grade Crossings
C.Recommended Best Management Practices
VII. 2
VII. Effects Of Transportation Structures On Fluvial Systems
A.Riverine Systems1. Analytical Tools to Evaluation Roadway
Impacts:Sediment Transport Function
Qs = W n1.77 V4.32 G0.45 Y-0.3 D50-0.61
Lane’s Relation:
Q S QS D50
Manning’s EquationV (A) = 1.49 n-1 R0.67 S0.5 (W * d)
VII. 3
VII. Effects Of Transportation Structures On Fluvial Systems
A.Riverine Systems2. Single Channel Streams Lateral Impacts
Narrow the Floodplain or Channel
Widen the ChannelPrevent Channel
Movement Vertical Impacts
Base Level Adjustments (+/-)
Analysis
Increase V & D ordecrease upstream
Decrease V & DDecrease Qs
Change Slope (+/-)
VII. 4
VII. 5
VII. 6
VII. Effects Of Transportation Structures On Fluvial Systems
A.Riverine Systems3. Braided Channels Lateral Impacts
Narrow/Widen ChannelCut Off BraidsConcentrate FlowObstruction
Vertical ImpactsBase Level
Adjustments (+/-)
Analysis
Same as single channel Increase Q, V & D Increase Qs
Upstream impacts
Same as single channel
VII. 7
VII. 8
VII. 9
VII. 10
VII. Effects Of Transportation Structures On Fluvial Systems
A.Riverine Systems4.Meandering Streams Lateral Impacts
Prevents Natural Channel Migration
Analysis
Roadway approachChannel training
VII. 11
Rivers
VII. 12
VII. Effects Of Transportation Structures On Fluvial Systems
B.Non-Riverine Systems1. Alluvial Fan Impacts Limit Channel Movement Upstream Channel Location Crossing Alignment Vertical Impacts
Long-Term Aggradation
AnalysisShift fan locationDischarge changes
Cross above apex or below avulsions
Maintenance Induce degradation
VII. 13
VII. 14
VII. Effects Of Transportation Structures On Fluvial Systems
B.Non-Riverine Systems2. Sheet Flow Areas: Culverts Concentrate Flow
Perpendicular Alignment Identify Flow Paths
Vertical Impacts Invert Elevation
Analysis
Induce degradation Downstream and
upstream damages Roadways become
drainage paths
Too low - headcut
VII. 15
VII. Effects Of Transportation Structures On Fluvial Systems
B.Non-Riverine Systems3. At-Grade
Crossings Paved Wide and Flat
Widen or Narrow Channel
AnalysisLower n, Increase VDecrease SDownstream drop
Same as single channel
VII. 16
VII. Effects Of Transportation Structures On Fluvial Systems
C.Recommended Best Management Practices1.Don’t obstruct or narrow main channel
2.Mimic bankfull width and depth
3.Relief culverts
4.Match natural grade
5.Energy dissipation
6. Inspection, maintenance and documentation
