My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
WSP01392
CWCB
>
Water Supply Protection
>
Backfile
>
1001-2000
>
WSP01392
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/26/2010 12:30:49 PM
Creation date
10/11/2006 10:22:32 PM
Metadata
Fields
Template:
Water Supply Protection
File Number
8240.200.10.B
Description
UCRBRIP - Riverine Fish Flow Investigations
Basin
Colorado Mainstem
Date
6/1/2000
Author
CDOW
Title
Riverine Fish Flow Investigations 2000
Water Supply Pro - Doc Type
Publication
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
102
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 />I <br />I <br />I <br />I <br />I <br />I. <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />When calculating a GPS position, vertical distance is the hardest to accurately <br /> <br />calculate due to the relative position of the satellites, errors introduced by the atmosphere, and <br /> <br />method by which the receiver calculates universal time. Because the errors in bathymetry <br /> <br />mapped by GPS and sonar represent the sum of the errors in the sonar and GPS data, it is very <br /> <br /> <br />important to use a very high quality GPS system. The GPS system used in this study was a <br /> <br /> <br />Javad Oddessy LlIL2 RTK GPS with Glonass and Multi-path reduction options turned on. <br /> <br /> <br />This system has a published vertical accuracy of I 5mm +/- 1.5 ppm. As a quick test of the <br /> <br />accuracy of the system in the field, a single point was surveyed repeatedly at a rate of about <br /> <br />once per minute. The point was located approximately I km from the base station and the <br /> <br />standard deviation of the elevations was 0.002 meters which suggests that the positions gained <br /> <br />from the GPS were good to +/- 5mm. <br /> <br />The sonar unit used was an ODOM Hyrographic Systems, Hydrotrac - Single <br /> <br />Frequency, Portable Survey Sounder. This unit used a 200kHZ frequency with a published <br /> <br />accuracy of Icm +/- 1% of depth and an outputresolution of Icm. No detailed study was <br /> <br />made to verify the accuracy of the sonar unit due to time constraints and the difficulty of <br /> <br />making such detenninations in a river system. However, the Hydrotrac outputs depth in <br /> <br />realtime to a screen which is visible to the user and by watching the realtime output of data <br /> <br />when the boat was still or in a section of river with plainbed features, it was possible to <br /> <br />visually verify that the readings did not generally vary by more than I cm. <br /> <br />One of the greatest hindrances to using sonar to map the channel bottom is that there is <br /> <br />a minimum depth requirement. In order for the sonar to get a reading off the bottom of the <br /> <br />channel, the transducer must have at least half a meter of water underneath it. The transducer <br /> <br />was located approximately 15cm underwater as to give room to roll and minimize air <br /> <br />entrainment under the transducer head making it difficult to gather bathymetric data in areas <br />shallower than 75cm. <br /> <br />]5 <br />
The URL can be used to link to this page
Your browser does not support the video tag.