Abstract
Design, operation and management of water resource projects are influenced by the amount of discharge passing through the stream. Discharge at the gauging site is generally estimated by developing single-valued simple rating curves. However, in case of unsteady flows, hysteresis affect is introduced in the stage discharge relationship and as such single-valued rating curves are no longer valid for such situations. The present paper presents a simple spreadsheet-based optimization approach for modelling the hysteresis-affected discharge rating curves. Generalized reduced gradient (GRG) technique has been reported as a reliable tool for handling optimization problems; therefore, in the present paper, it has been applied to estimate discharge for two sites with hysteresis affect based on Jones formula. Comparison of results shows that discharge estimated by GRG technique is as efficient as genetic algorithm and the goodness-of-fit criteria shows that the rating curves obtained by using Jones formula fit the observed data better than single-valued simple rating curves for both the sites considered in the present study. Application of spreadsheet-based GRG optimization technique could prove very helpful to the hydrometric offices.
Highlights
Design and operation of hydraulic structures mainly rely on the amount of discharge reaching these structures
Discharge rating curves were established for two sites that were affected by hysteresis
The rating curve was modelled by single-valued simple rating approach and the Jones formula
Summary
Design and operation of hydraulic structures mainly rely on the amount of discharge reaching these structures. When a flood wave propagates through a river corresponding to same stage higher discharges are observed during rising stage than in falling stages resulting in looped rating curves This affect is popularly known as hysteresis in stage–discharge relationship. The present paper proposes a very simple spreadsheet-based optimization approach to model the hysteresis-affected rating curves. Calibration and validation of results using GRG technique, simple rating curve (Eq 1) and Jones formula (Eq 3) were modelled on spreadsheet. The parameters in simple rating curve and Jones method were estimated using spreadsheetbased optimization technique and genetic algorithm.
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