Skip to main content
padlock icon - secure page this page is secure

AN EXAMPLE OF IN-STREAM PEAK FLOW REDUCTION TARGETS BASED ON HABITAT AND GEOMORPHIC INDICES

Buy Article:

$9.50 + tax (Refund Policy)

Hydrology is such a strong determinant of benthic habitat structure that flow regime can be a very strong predictor of benthic macroinvertebrate health. In sand and gravel bed streams, peak flow control targets based on surface sediment median grain size (D50) mobilization thresholds can function as surrogate targets for benthic habitat and macroinvertebrate health in highly impacted or urban streams. In the present example, we found it was also reasonable to assume that the peak flow associated with the D50 mobilization threshold is probably indicative of pre-development bankfull peak flow. For this analysis, the bankfull event, defined as the event doing the most work on an annual basis to move sediment, was assumed to be the 1.5-year recurrence interval rain event. The peak flow target for the bankfull event is set at the threshold of motion for the existing surface sediment D50. This threshold is based on the ratio of applied shear stress to the shear stress at the estimated threshold of motion using a Shields number approach.

At a moderately entrenched reach of the urbanized Millers Creek in Ann Arbor, Michigan, macroinvertebrate sampling since 1995 has consistently yielded low species variability. Because this tributary of the Huron River has such as steep gradient, particularly in relation to regional averages, the expected variation of species is very high. This disparity emphasizes the extent of habitat degradation. Meeting the bankfull peak flow target here requires a reduction of more than 90% of existing peak flows. The probability of significant bed mobilization for the bankfull event on any given day has risen by two orders of magnitude, from 0.14% to 6.5%, since development of the watershed. Before development, bed mobilization was likely occurring once every year or every other year and but can now occur as many as twelve (or more) times per year. With the implementation of proposed improvements in the watershed the frequency could be reduced to six times per year. Getting back to pre-development flows, based solely on implementing watershed improvement practices, is not feasible. These changes in peak flow recurrence intervals are similar to the results from a Wisconsin watershed evaluated between the period of 1960 and 1998 when the watershed was transformed from primarily agricultural and undeveloped land to a built-out condition (Novotny, et.al., 2001).
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 01 January 2004

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more