Natural Channel Design Based Restoration & Enhancement

Final BMP for Urban and Suburban Streams

Introduction

• Overview of the Author

• Intent of the Presentation– Briefly Introduce Natural Channel Design (NCD) – Highlight NCD as an essential part of effective

watershed management

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Watershed Management

• Comprehensive Watershed Management Concept– Holistic– Involves Diverse Stakeholders and Diverse Interests

Quality of Life, Public Access and Enjoyment of Natural Resources

– Needed in Order to Meet Increasing Financial ConstraintsCo-participation through Volunteerism, Capital Funding, and O&M

– Needed in Order to Meet Increasing Environ. DemandsTMDLs, NPDES, Source Water Protection, Mitigated Dredging

– Review Example InitiativesNCD an Essential Part of Watershed Management

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Natural Channel Design

• Stream Restoration and Enhancement Design based upon the Science of Fluvial Geomorphology (study of river-related landforms)– Analog

Assigns dimensionless ratios to define plan and vertical forms for stability

– EmpiricalUtilizes empirical data to establish predictive formulas that define

function– Analytical

Process based equations that define river function

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Natural Channel Design

• Streams Work to Achieve “Dynamic Equilibrium” in Response to Hydrological and Sediment Loading Characteristics – Minimum Total Work– Most Efficient Planform is a Sine-Generated Meander Pattern (minimal

directional change)– Most Efficient Vertical Form is a Cyclical Pattern of Riffles, Runs,

Pools, and Glides that corresponds to the Meander Pattern– Stable Cross-Section would include a Thalweg (low point), Baseflow

Channel, and a Dominant Discharge Channel (Bank-full Channel)– Discuss Current Example

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Sediment as an Asset and Liability

• A Dynamically Stable Channel will Move within the Bankfull Width without Degrading or Aggrading the Channel Section

• Sediment is Needed and is Naturally Conveyed in a Stable EcoSystem– Needed for Aquatic habitat

• Excessive Sediment Load can Cause Harm Environmentally– EPA Recognizes Sediment Loading as a Pollutant Discharge– Sediment Loading Potentially Correlated to Bacteria Loading and

Possibly Other Pollutants– Increased Dredging/Material Handling Costs

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Best Management Practices

• NPDES Phase I and Phase II MS4 Permits Address Point Source Discharges in to the Waters of the United StatesBMPs are focused on “end of the pipe” solutions

• On-Site Low Impact Development Techniques are being Applied as BMPs in WatershedsRequires Long Term and Wholesale Application

• Stream Restoration through NCD would Impact TMDL Compliance and Increase Water Quality

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Conclusion

• Watersheds Should be Managed Comprehensively and NCD should be Considered as part of the Management Team’s Tool Box to:– Meet Stream Requirements– Reduce Watershed Management Costs– Increase the Quality of Life in a watershed

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TWDB NCD Study

• KBR is Currently Preparing a Study for the State of Texas that Evaluates the Construction Costs and Feasibility of Applying NCD throughout Texas Compared to the Costs of Traditional Erosion Control Techniques.

• If anyone would like to be Notified when this is Published, Please come by and let me know today or e-mail me at eric.hall1@kbr.com

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