Northwest Environmental Training Center (NWETC)

The Ecological Significance of High Flows on Alluvial Rivers



This dynamic and hands-on course provides an introduction to the science of flood dynamics and why they are important to stream and river ecology. High flows flush organic matter from the channel, maintain channel geometry by transporting sediment, form new channels by geomorphic processes, and provide essential conditions for fish migration and spawning.

Over the course of this two-day workshop, attendees will learn methods for developing specific high flow recommendations based on streamflow frequency, magnitude, duration, and seasonality, and discuss how these flows vary with different hydrologic regimes and flow influences such as water storage reservoirs, hydroelectric dams, municipal appropriations, and other water uses. Day 1 will be spent in the classroom, and Day 2 will be spent in the field.

The field day will include a close-up review of stream habitat improvement projects in the area and visiting habitat projects that are using natural materials to complement restoration of high flows. These projects are excellent examples of the ecological significance of restoring high flows. More details on the field trip will be posted as they become available.

Environmental professionals must understand High Flows because regulatory agencies, public utilities, water users, fish and wildlife groups, and others develop environmental flow requirements to protect and restore fish and wildlife habitat in streams and rivers. Recent advances in instream flow science document the importance of protecting and restoring high flows in setting environmental flow requirements. Attendees will gain valuable insights on the analysis, regulation, and importance of high flow hydrology.

The material is designed to be accessible to those new to the field and also to enhance the knowledge of experienced planners, engineers and biologists.

After completing this course, participants will be able to:

  • Review proposals for instream flow recommendations that include high flow components
  • Discuss and present alternatives for high flow recommendations based on stream or river system characteristics
  • Participate in interdisciplinary analyses of high flows
  • Understand how to develop recommendations for preserving or restoring high flows based on magnitude, duration, and frequency criteria.

California Department of Public Health, CDPH, Approved for contact hours

Registration: *Reduced tuition is available for Native American tribes, government employees, nonprofits, students and NAEP, NEBC, NWAEP members. You may register online or by calling the Northwest Environmental Training Center at (425) 270-3274.
Course Materials:

Attendees will receive a course manual containing workshop proceedings and reference material.

Intended Audience:

Environmental professionals, planners, engineers, consultants, public officials, decision-makers, and others using instream flow assessments for water resources allocation, development, and related environmental studies. Environmental management personnel from public utilities, resource agencies, and fish and wildlife groups will benefit from this course, as will members of citizen's organizations who want to gain greater understanding of the role of instream flows in protecting and restoring fish and wildlife habitat.

Course Topics

High Flows and High Flow Functions on Streams and Rivers
Hydrographs, hydrologic regimes, ohwm, and different kinds of floods
water quality, geomorphology, and connectivity
High Flows and geomorphic processes
Ecological significance of Specific high flows
Focus on riparian zones, side channels, floodplains, and hyporhea
High flows, salmonid growth, and survival (Jose C.)
flood scour and flood-induced mortality (Jose C.)

Environmental Flow Requirements
Importance of spawning, incubation, rearing, and migration flows (Jose C.)
Introduction to Instream Flow Council issues and policies for state programs

Tools of the Trade, part I
Hydrologic analysis for magnitude, duration, and frequency, and seasonality
Introduction to IFIM, PHABSIM, and MesoHABSIM
TNC's Environmental Flow Allocation and Statistics Calculator
Streamstats for ungaged sites

Tools of the Trade, part II
LIDaR, Airborne Remote Sensing, and Aerial Photography for channel mapping
the importance of verification, calibration, and field observations
Negotiations for multipurpose recommendations

Summary, Field Work Discussion
Geomorphic and Biologic Response to Flood Disturbance
Instream Flow Negotiations and Recommendations

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