1. Module # 16 Restoring Functions to Streams Through Design
Iowa’s River Restoration Toolbox Level 1 / Base Training

2. Indicators of Geomorphic Instability
Incision/Bedcutting
Channel Filling
Entrenchment/High Streambanks
Lateral Migration
Over Widening
Lack of Habitat
Eroded Banks
Slope Instability

3. Incision/Bedcutting Caused by Excess Shear Stress
Often Triggered by Downstream Straightening of Channel
Will Propagate Upstream
Increases Channel Entrenchment

4. Grade Control - Constructed Riffle

5. Grade Control – Vane Structures

6. Grade Control – Rock & Log Riffle

7. Channel Filling/Aggradation
Caused by:
Excess Sediment Supply
Low Shear Stress
High Width/Depth Ratio
Can Lead to Lateral Migration
Reduces Capacity of Culverts

8. Geomorphic Channel Design Multi-Stage Channel

9. Entrenchment/High Streambanks
Very Significant Indicator of Instability
Results in High Shear Stress
Often Early Stage of Channel Evolution
Results in Excess Sediment Supply

10. Bankfull Bench

11. Toe Wood Protection

12. Fabric Encapsulated Soil Lifts

13. Lateral Migration Often Due to: Slope Adjustment High Sediment Supply
Downstream Channel Straightening
Often Triggers Bank Erosion
Belt Width Considerations

14. Geomorphic Channel Design

15. Over-Widened Streams Cannot Effectively Transport Sediment
Can be High Maintenance Areas
Poor Water Quality/Habitat
Elevated Water Temperatures
Bedrock Bottom Streams Often Overwidened

16. Geomorphic Channel Design

17. J-Hook/Straight Vane

18. Module # 16 Restoring Functions to Streams Through Design
Iowa’s River Restoration Toolbox Level 1 / Base Training