HOMS COMPONENT

DETERMINATION OF STREAM REAERATION COEFFICIENTS BY USE OF TRACERS

1.   Purpose and objectives

     To provide detailed theory and methodology on the performance of gas- dye tracer tests to measure in situ stream reaction coefficients.

2.   Description

     The manual (Kilpatrick and others, 1989) describes the slug injection and constant rate injection methods of measuring gas-tracer desorption. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the non-conservative gas tracer. The manual covers 
planning field tests, methods of injection, sampling, and analysis, and techniques for computing desorption and reaeration coefficients.

3.   Input

     A gas tracer, usually propane and a dye tracer, usually rhodamine WT are injected into the stream concurrently and allowed to mix and disperse with the flow and sampled at two or more sections downstream.

4.   Output

     A reaeration coefficient is computed based on the desorption of the gas tracer relative to the non-desorbing dye tracer.

5.   Operational requirements and restrictions

     Dyes should not be injected into streams in quantities that would result in dye concentrations exceeding 10 micrograms/litre at water-user withdrawal points. Regulations in different countries may control dyes to be used and permitted concentrations.

     Equipment needed: a fluorometer to measure rhodamine WT dye concentrations, a constant injection device for the dye and propane gas (if the constant injection method is used), and access to a laboratory capable of determining propane gas concentrations in the water samples.

     Most of the needed guidance is provided in the manual, however, some knowledge of hydraulics is beneficial to determine the proper sampling technique.

6.   Form of presentation

     Manual, written in English is available (Kilpatrick and others, 1989).

7.   Operational experience

     Extensive use within the United States.

8.   Originator and technical support

     U.S. Geological Survey, Office of Surface Water, Reston, Virginia, USA.

9.   Availability

     From HOMS National Reference Centre for the United States.

10.  Conditions on use

     The manual is available free of charge.

Reference:

Kilpatrick, F. A., Rathbun, R. E., Yotsukura, N., Parker, G. W., and Delong, L. L., 1989, Determination of stream reaeration coefficients by use of tracers: U.S. Geological Survey Techniques of Water Resources Investigations, Book 3, Chapter A18, 52 p.

Last updated: 29 NOV 94)
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