The potential of a seismic flowmeter for mountain streams

Abstract

There is a need for the development of a streamflow gauging technique that is
focussed towards mountain streams. A method of continuously gauging the flow of mountain streams with a vertical component geophone utilising the seismic vibrations generated by the turbulent tumbling water has been investigated at four sites, three in North Wales and one in the state of New York. By logging the power of the seismic vibrations in the optimum frequency range for the site it is possible to monitor streamflow and its fluctuations. Each stream would require individual calibration, although a method of calibration has not been established. It has been found that in general the relationship between the power of the seismic vibrations and flow exhibits three gradients: the first represents the flows in which the vibrations are more susceptible to noise; the second represents the increase in the power of the vibrations with increasing flow, as more rocks become incorporated into the stream generating tumbling water, until the relationship plateaus as the rocks become submerged; and
the third arises from the combined effect of streamflow and bed load transport being detected by the geophone. The discharge at which these gradient changes occur is site specific. Noise can arise in the vibrations from natural and cultural sources and can be both transient and more continuous in nature. Whilst a method for removing the transient noise has been developed, a method for compensating for the continuous noise needs to be established. The effect of noise on the vibrations and the issue of calibration do not make the technique commercially viable for quantitative streamflow assessment at present. However, the technique could be used as a flood warning system.

Date of Award	Jan 2009
Original language	English
Awarding Institution	Bangor University
Sponsors	European Social Fund
Supervisor	Jim Bennell (Supervisor)