My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
9665
CWCB
>
UCREFRP
>
Public
>
9665
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
7/14/2009 5:02:37 PM
Creation date
5/20/2009 1:34:57 PM
Metadata
Fields
Template:
UCREFRP
UCREFRP Catalog Number
9665
Author
Schmidt, J. C. and J. B. Box.
Title
Controls on the Longitudinal Distribution of Age-0 Colorado Pikeminnow in the Middle Green River, Colorado and Utah - Draft Report.
USFW Year
2001.
USFW - Doc Type
Logan, UT.
Copyright Material
NO
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
57
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 />11/14/01 draft report, Schmidt and Box <br /> <br />middle Green River has been greatest in reaches that initially had the greatest the largest shoreline <br />complexity. Thus, one impact of channel narrowing is increasing homogeneity of the channel. <br />We eval uated the potential impact of these transformations by predicting the longitudinal <br />distribution of larval fish under a scenario where every reach had the same shoreline complexity. <br />This scenario of geomorphic homogeneity was developed by assigning all reaches the complexity <br />of reach 295265, which has fixed meanders. In these simulations, a cohort of 100,000 fish was <br />introduced into the Green River on 1 day, and we compared the predicted distributions of these fish <br />during the rest of the summer and fall. We used 1992 hydrology in these simulations, and we ran <br />simulations with the cohort entering the Green River on June 26 (day 57), July 6 (day 67), and July <br />16 (day 77). The discharge of the Green River on these three days was 83,55, and 45 m3s-1, <br />respectively. Thus, the June 26 scenario evaluated the role of geomorphic homogeneity in a river <br />descending from medium discharge and the July 16 scenario evaluated the role of geomorphic <br />homogeneityin a river that was nearly at base flow when larval fish enter the Green River. These <br />results were compared with simulations based on shoreline complexity values used elsewhere in <br />this study. <br />Results from these simulations demonstrate the complex interaction between geomorphic <br />organization and river discharge in determining the distribution of larval fish (Fig. 13). The model <br />predicts that more fish are transported into backwaters where complexity is high. Thus, most <br />restricted meandering reaches accumulate more fish than they do if their complexity is changed to <br />that of fixed meanders. The only exception to this situation is reach 265250 where shoreline <br />complexity at low discharge is less than for fixed meanders. Predicted changes due to geomorphic <br />simplification are greatest in early summer and decrease in late summer and fall. <br />The differences in predicted populations of larval fish in restricted meandering reaches are <br />somewhat greater for simulations where the cohort enters the Green River at a higher discharge on <br />an earlier date. The difference between shoreline complexity of restricted and fixed meandering <br />reaches is typically greater at moderate discharge than at low discharge, and thus the scenario of <br />geomorphic homogeneity affects the predicted transport rates into backwaters more at moderate <br />than at low pischarge. Thus, the impact of increasing geomorphic homogeneity would also have <br />been greater if we had evaluated a year with a larger spring flood, such as 1995,Jor our simulations. <br />Late summer distributions of larval fish change in these two simulations in reach 265250, but <br />predicted changes were insignificant elsewhere. <br />The Effect of River Discharge on Predictions of Larval Fish Distribution <br />Releases from Raming Gorge Dam partly determine river flow in the middle Green River. <br />At times, dam releases are delayed so that the cumulative peak flow of the middle Green River does <br />not cause significant over-bank flooding. When dam releases are delayed, the duration of high <br /> <br />15 <br />
The URL can be used to link to this page
Your browser does not support the video tag.