The use of time-averaged gauge height and discharge estimates is a standard procedure in stream-gauging practice. However, the assumptions made in this procedure fail to apply when the changes in stage during the gauging are large or vary in direction. Such conditions prevail with measurement of streams under tidal influence and the ISO standard describes two methods which can be applied in this gauging environment Urban and small rural streams often have the characteristic of rapidly varying stage during flood flows and more accurate methods of gauging these streams are needed.
This paper reviews the situation and provides a description of a method which has been in limited use at the University of New South Wales. The method is a graphical computational technique which affords the user much valuable information of the flow regime occurring at the selected gauging station and aims to improve the accuracy of gauging of fast rising and falling streams.