Author(s): Marian Muste, Danielle Thomas, Ciprian Bacotiu

Linked Author(s): Marian Muste, Danielle Thomas

Keywords: Continuous streamflow monitoring; Slope-area method; Stage-discharge method; Hysteresis; Measurement of unsteady flows;

Abstract: Low-cost pressure transducers equipped with capabilities to transmit the data in real time enable to conveniently measure water surface elevations at remote locations. If a pair a sensors is set up at two close locations on a reach of quasi-uniform flow, the water surface slope can be derived at fast sampling rates. This setup paired with analytical models allows to dynamically monitor both steady and unsteady flows. Described in this paper is the use of direct slope measurements in a simplified form of the slope-area discharge estimation method. The slope-area (SA) method is a discharge estimation approach typically used to determine peak flows occurring during floods. The simplified estimation method, labeled herein as the continuous slope area (CSA), is based on Manning’s equation. The CSA is applied to an actual cross-section geometry obtained from local geodetic survey, an assumed Manning’s roughness coefficient, and the free-surface slope estimated from continuous stage measurements at the ends of the channel reach. The CSA method is evaluated for continuous streamflow measurements in steady and unsteady flows passing through a gaging site located on a small stream (Clear Creek, Iowa, USA). Comparison of the streamflow during several unsteady flows at this site reveals that the CSA method displays loops in the stage-discharge relationship that are not captured by a collocated stage-discharge based gaging station. An additional advantage over the widely-used stage-discharge approach is that the CSA method can be implemented immediately after it is set up as there are no ratings associated with this method.

DOI: https://doi.org/10.3850/38WC092019-1860

Year: 2019