Preston Gabel, Rivergauge Hardware/Software Engineer
Many thanks to Preston Gabel! Preston has done the majority of the work on this project including the electrical hardware design, Perl and Java software (which required learing Java), and the design and fabrication of the printed circuit board.
May 14, 2003 update. The gauge has had Engineering Release! The guage is in the calibration and quality verification phase now. All hardware and software are running on the bench amd reporting level and temperature data and plotting the results to the www. You can see the output of the system on The Kaweah Rivergauge Page . If all continues to go well the rivergauge is being contemplated for commercial sale. Contact the Kaweah River Page webmaster if you might be interested in this device. Supported platforms might be limited to Linux and Windows 2000 for the time being.
A digital rivergauge in being designed and built from the ground up for installation on the Kaweah River. Such a device could be useful on other rivers, any river with a nearby local residence with internet access. The system is simple in concept and the prototype will be installed on the Kaweah River.
The web based Kaweah rivergauge is projected to be installed on the Kaweah in the Spring of 2003 to provide a more accurate and relevant reading of the actual flow between the East Fork confluence and North Fork confluence. It is intended to output a reading to be that of the water level at Pumpkin Hollow. A convertion to Dinely Bridge gauge height will follow following corelation of the two gauges. Current COE readings at Three Rivers include the North Fork contribution and are generally irrelevant for actual conditions during the North Fork runnoff period. Such a gauge could also be installed easily on the North Fork if I can find a home with a PC and a local ISP account. We'll get the Main Fork gauge up and running, then worry about the North and South Forks. The gauge may or may not run year round unless it can be adequately secured again flood conditions. Kaweah floods tend to move thousands of very big boulders an could be harmful to the underwater portion of the gauge.
Technical Description of Operation:
A regulated and precision power supply provides a stable voltage reference to the internally temperature compensated and calibrated differential strain gauge pressure transducer unit. Hydrostatic pressure is applied to one of the pressure ports while atmospheric pressure is applied to the other pressure port. The differential transducer is neccessary to nullify atmospheric pressure variations that could otherwise add variations of 1 ft of H2O to the reading, resuluting in an inaccurate river reading. Analog voltage output of the pressure transducer is low pass filtered and read by the 8 bit Digital to Analog converter. LSB Raw accuracy is +/- 0.05 inches of H2O over an operating range of 0 to 15 feet of water. The digital data is sent via single wire serial connection to the PC. This serial data is sent a hundred yards over Cat 5 wire to the single wire serial receiver plugged into a COM input of a Personal Computer. Data collection in the PC will be done via code written in the Java programming language with post processing and convertion of the data using the Perl programming language for display as web based graphs. Data averaging is expected to yield a derived accuracy on the order of 12 bits, the equivelent of better than 0.01 foot of H2O. A lookup table will be used to convert the averaged reading to it's equivelent reading at Dinely Bridge, the standard gauge reading for Kaweah recreational flow. Water temperature data will be handled in the same way and will be posted by graph to the Kaweah River Page.
Mechanical configuration places the entire electrical unit in a sealed unit below the water surface with separate rubber tubing providing the paths to the river and atmosphere. Power supply voltage is supplied down the Cat 5 Data cable from the remote PC. The entire unit will be mounted in a secured pipe. A structure capable of withstanding a Jan 1997 flood would be desired but is likely impossible to produce.
Output to the World Wide Web will be automated upload by ftp to the Kaweah River Page. Upload interval will likely coincide with the hourly webcam upload. Raw ASCII data will be made available on the WWW too in the case that someone else wants to generate there own plots.
Photo History of the Design of the Riverguage
Copyright © 2000, 2001, 2002, 2003 by Bill Pooley. All rights reserved.
This page is http://www.c2.com/kaweah/rivergaugeproject.html
Last modified: 05.29.03