My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
7405
CWCB
>
UCREFRP
>
Public
>
7405
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
7/14/2009 5:02:30 PM
Creation date
5/22/2009 5:23:32 PM
Metadata
Fields
Template:
UCREFRP
UCREFRP Catalog Number
7405
Author
Bain, M. B., ed. 1990.
Title
Workshop Synopsis,
USFW Year
Ecolog
USFW - Doc Type
U.S. Department of the Interior,
Copyright Material
NO
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
51
PDF
Print
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
Show annotations
View images
View plain text
<br />34 BIOLOGICAL REPORT 90(5) <br /> <br />Considerations in Applying IFIM to Warmwater Streams1 <br /> <br />by <br /> <br />John M. Nestler <br /> <br />u.s. Army Engineers Waterways Experiment Station <br />CEWES-ES-Q <br />3909 Halls Ferry Road <br />Vicksburg, Mississippi 39180 <br /> <br />Increased diversion of riverine flows in the south- <br />eastern United States for irrigation, municipal, and <br />industrial water supply has resulted in an increased <br />awareness of the importance of adequate instream <br />flows for protecting and maintaining riverine fishes. <br />One of the most commonly employed means of <br />assessing the effects of river water diversion on <br />warmwater streams is the U.S. Fish and Wildlife <br />Service's Instream Flow Incremental Methodology <br />(IFIM). Because the methodology was originally <br />developed for coldwater streams, a number of fac- <br />tors should be considered in applying the IFIM to <br />warm water streams. Some primary considerations <br />include differences in hydrology, channel geometry, <br />and biology between coldwater and warmwater <br />systems. <br />The hydrograph of cold water streams used to <br />develop the IFIM is heavily influenced by snow- <br />melt or groundwater recharge, which tends to <br />result in long-term gradually varying flow condi- <br />tions. In contrast, warmwater streams are more <br />influenced by rain runoff and can, therefore, ex- <br />hibit complex hydrologic patterns that reflect <br />daily, synoptic, or seasonal influences. Consequently, <br />simple hydrologic variables, such as mean or <br />median monthly flow (commonly used to describe <br />coldwater streams), may not be as relevant to <br />aquatic biota in warmwater systems. Indeed, vari- <br />ability in the hydrograph and concomitant varia- <br />tions in habitat may be important features of these <br />ecosystems, required for organic matter transport, <br />nutrient cycling, or successful completion of life <br />stages. <br /> <br />IThe conclusions and interpretations presented in this paper were <br />based on research conducted under the auspices of the Envi- <br />ronmental and Water Quality Operations Studies and Environ- <br />mental Impact Research Program of the U.S. Army Corps <br />of Engineers by the Waterways Experiment Station. Permis- <br />sion was granted by the Chief of Engineers to publish this <br />information. <br /> <br />Channel morphometry in the coldwater stream <br />systems used to develop the IFIM was usually sim- <br />ple, composed primarily of pool-riffle complexes, <br />and variety in habitat conditions (depth, velocity, <br />and substrate) was more limited than in warmwater <br />systems. In contrast, many warm water streams <br />have compound channels and may include back- <br />waters, sloughs, braided channels, snags, and other <br />channel features that make habitat conditions within <br />these systems more difficult to describe using cross <br />sections and relatively simple hydrologic methods. <br />The biology of many cold water biota (primarily <br />salmonids) is well known and documented. Many <br />studies have been performed that describe salmonid <br />habitat requirements in terms of substrate and <br />channel flow conditions. In contrast, the biology of <br />warmwater aquatic biota is less known and often <br />undocumented in terms of variables used in in- <br />stream flow studies. In fact, even the term warm- <br />water biota may be misleading because it implies the <br />existence of a distinct category of aquatic biota <br />restricted to warmwater stream ecosystems. In <br />reality, there may be any number of warmwater <br />"biotic assemblages." <br />Coldwater and warmwater stream ecosystems <br />differ substantially in species number. Small- and <br />medium-sized coldwater streams are usually char- <br />acterized by a relatively small number (1 to 10) of <br />fish species and usually include only one or two sport <br />fishes. It is usually not difficult to identify a target <br />species or life stage to serve as the focal point of <br />the study. In contrast, a warmwater stream of <br />similar size may have 30 or 40 species of fishes, with <br />several of them having commercial or sport-fishing <br />importance. Consequently, it is often difficult to <br />identify a suitable target species for the analysis. If <br />the habitat requirements of a large number of <br />species are evaluated, then assessment of impact is <br />complicated because each life stage may have <br />substantially different flow optima. <br /> <br />J <br />
The URL can be used to link to this page
Your browser does not support the video tag.