Application of Image Technique to Obtain Surface Velocity and Bed Elevation in Open-Channel Flow

Abstract

The frequency of droughts and floods is increasing due to the extreme climate. Therefore, water resource planning, allocation, and disaster prevention have become increasingly important. One of the most important kinds of hydrological data in water resources planning and management is discharge. The general way to measure the water depth and discharge is to use the Acoustic Doppler Current Profiler (ADCP), a semi-intrusive instrument. This method would involve many human resources and pose severe hazards by floods and extreme events. In recent years, it has become mainstream to measure hydrological data with nonintrusive methods such as the Large-Scale Particle Image Velocimetry (LSPIV), which is used to measure the surface velocity of rivers and estimate the discharge. However, the unknown water depth is an obstacle for this technique. In this study, a method combined with LSPIV to estimate the bathymetry was proposed. The experiments combining the LSPIV technique and the continuity equation to obtain the bed elevation were conducted in a 27 m long and 1 m wide flume. The flow conditions in the experiments were ensured to be within uniform and subcritical flow, and thermoplastic rubber particles were used as the tracking particles for the velocity measurement. The two-dimensional bathymetry was estimated from the depth-averaged velocity and the continuity equation with the leapfrog scheme in a predefined grid under the constraints of Courant–Friedrichs–Lewy (CFL). The LSPIV results were verified using Acoustic Doppler Velocimetry (ADV) measurements, and the bed elevation data of this study were verified using conventional point gauge measurements. The results indicate that the proposed method effectively estimated the variation of the bed elevation, especially in the shallow water level, with an average accuracy of 90.8%. The experimental results also showed that it is feasible to combine the nonintrusive imaging technique with the numerical calculation in solving the water depth and bed elevation.

Flow Measurement Methods in Small Tributaries of the Teles Pires River, Southern of the Amazon Hydrological Region

“…There are several methods for quantitative and qualitative water monitoring. Some of these methods are intrusive, as they depend on the direct contact of the equipment with water [6,15,16], and other methods are considered non-intrusive, such as remote sensing techniques [17,18], terrestrial images [19], and Internet of Things (IoT) technology [20][21][22][23], which do not require physical contact with the object of study (water). These non-intrusive methods have been gaining ground towards the Industrial Revolution 4.0 due to the diverse possibilities of applications in quantitative and qualitative water monitoring, soil management, and monitoring, which contribute to the adequate management and treatment of natural resources [20][21][22][23][24][25].…”

Mathematical Modelling in Energy Measurement Production of Water Tap Flow

“…Currently, many flow rate water measurement tools are available on the market. Still, most are provided for measuring flow rate in a crosssection of pipes because the velocity of water is a parameter that can represent the amount of water discharge [9], i.e., multiplying it by the cross-sectional factor of the measuring area.…”

River Flow Measurements Utilizing UAV-Based Surface Velocimetry and Bathymetry Coupled with Sonar

“…Sonars can reach large depth penetration while optical remote sensing methods are most suitable for shallow waters [67]. Recently, Lin et al ( 2022) applied the LSPIV method on shallow waters (circulated flume) while the two-dimensional bathymetry in laboratory conditions was estimated from the depth-averaged velocity and the continuity equation with the leapfrog scheme in a predefined grid under the constraints of Courant-Friedrichs-Lewy (CFL) [68]. Various UAV-based systems (with sonars or not) have been developed for nearshore or marine bathymetry monitoring [69,70].…”