Real-time discharge measurement in tidal streams by an index velocity

Abstract

Discharge measurement in a tidal stream is always a difficult task. Owing to the complex flow conditions, discharge measurement in tidal streams has to be finished quickly, and must be highly efficient in order to yield an accurate measurement of real-time discharge. Measuring the discharge of tidal streams is done in three steps: (1) establishing the stage and cross-sectional area relation, (2) estimating the index velocity by using a velocity distribution equation based on the probability concept, (3) establishing the relationship between the index and mean velocities. Then the cross-sectional area and mean velocity can be estimated by the gage height and index velocity, respectively. The discharge of tidal streams is computed as the product of the cross-sectional area and mean velocity. The velocity distribution of the Taipei Bridge and Guan-du Bridge in the Tanshui River were established and analyzed to demonstrate the use of discharge measurement by index velocity for estimating the discharge of this tidal stream. The results reveal no large difference between the discharges measured by the conventional methods and the index velocity. This pilot study proposed a cost-effectiveness and efficient method. It is an easy, quick, and accurate model for measuring the real-time discharge of a tidal stream. It makes automatic, real-time, and continuous monitoring of the discharge in a tidal stream become possible.

Revisiting hysteresis of flow variables in monitoring unsteady streamflows

“…These methods combine assumed velocity profiles in the vertical or spanwise directions with directly acquired velocities (Hidayat et al, 2011;Kästner et al, 2018;Nihei & Kimizu, 2008;Nihei & Sakai, 2006). An increasingly popular hybrid approach is based on the principle of maximum entropy (Chiu & Chen, 2003) as adopted by Morse et al (2010) and Chen et al (2012). Finally, it is recommended to continue investigating the performance of the IVRC method when used in steady and unsteady flows (Jackson et al, 2012;Le Coz et al, 2008;Muste & Lee, 2013) as well as assessing the accuracy using rigorous uncertainty analyses (e.g.…”

An expanded rating curve model to estimate river discharge during tidal influences across the progressive-mixed-standing wave systems

“…As of 2011, 470 stations operated and maintained by the USGS employed the index velocity method [23]. Other studies have also used the index velocity method, or similar scaling relationship [25,26].…”

Reconstruction of Tidal Discharges in the St. Lawrence Fluvial Estuary: The Method of Cubature Revisited

“…Continuous measurements can alternatively be acquired by vertically (uplooking) or horizontally (side‐looking) deployed ADCPs (Hidayat et al, ; Hoitink et al, ; Le Coz et al, ; Levesque & Oberg, ; Nihei & Kimizu, ; Ruhl & Simpson, ). In these cases, discharge may be inferred based on the index velocity method (Chen et al, ; Healy & Hicks, ; Ruhl & Simpson, ), the velocity profile method (Le Coz et al, ), or a combination of the two (Hoitink et al, ; Sassi et al, ). Noncontact methods, such as large‐scale particle image velocimetry (Daigle et al, ; Muste et al, ) and radar wave scattering (Costa et al, ), also provide new means for surface velocity and flow measurements.…”