Water Quality Dynamics in a Tidal River With Groins

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Flow Structure through Groins in the Kiso River during a Flood Event

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Estimation of Flood Discharge in a Vegetated River Using Multipoint Water Level Hydrographs

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Surface oscillations in flow past a side cavity using stereoscopic measurement and POD

When a relatively large side cavity is created in an open channel, the influence of vortices in the shear layer and circulatory flow is exerted on the main flow, causing surface oscillations and increased water levels. The mechanism of the oscillation is still not clearly understood because of the complexity of the phenomena. In this research, by using a stereoscopic surface measurement system developed by the authors, time-dependent water surface configurations are successfully measured at a sampling rate of 12 Hz, from which general features of the surface oscillation are made clear for a wide range of Froude numbers. Then, we applied the proper orthogonal decomposition (POD) method to measure results. We found that the surface oscillation can be clearly decomposed into a seiche-like major mode and sub-modes with smaller wavelengths

Analysis of Water Surface Osccilation at Open-Channel Side Cavity by Image Analysys and Large Eddy Simulation

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Stereoscopic measurement of a fluctuating free surface with discontinuities

This paper presents a new innovative method for measuring two dimensional water surface configurations. This method uses a pair of sequential images captured by two high-resolution CCD cameras arranged in a stereo position. The idea of the method is to make the water colour white so that the instantaneous water surface appears like a solid surface with a clear pattern when an irregular pattern of light is projected onto it. It should be noted that this method is suitable to measure waves with small amplitude accurately and at the same time discontinuous surface robustly. At first, we explain the measurement principal and the experimental procedure for obtaining stereo images. Secondly, we examine the measurement accuracy by applying our technique to calibrated wavy plates. In the application of the technique to actual flow fields, we first measure surface waves and ripples generated in a shallow water box, and show that we can trace the propagation of small waves as small as 1mm. In another application, we measure periodic surface fluctuation generated at an asymmetric cavity installed in an open-channel flow, demonstrating robustness of the technique applicable even when a discontinuous surface with wave breaking is presented in the course of the measurement

Unstructured grid generation using LiDAR data for urban flood inundation modelling

Inundation disasters, caused by sudden water level rises or rapid flow, occur frequently in various parts of the world. Such catastrophes strike not only in thinly populated flood plains or farmland but also in populated villages or urban areas. Inundation of the populated areas causes severe damage to the economy, injury, and loss of life; therefore, a proper management scheme for the disaster has to be developed. To predict and manage such adversity, an understanding of the dynamic processes of inundation flow is necessary because risk estimation is performed based on inundation flow information. In this study, we developed a comprehensive method to conduct detailed inundation flow simulations for a populated area with quite complex topographical features using LiDAR data. Detailed geospatial information including the location and shape of each building was extracted from the LiDAR data and used for the grid generation. The developed approach can distinguish buildings from vegetation and treat them differently in the flow model. With this method, a fine unstructured grid can be generated representing the complicated urban land features precisely without exhausting labor for data preparation. The accuracy of the generated grid with different grid spacing and grid type is discussed and the optimal range of grid spacing for direct representation of urban topography is investigated. The developed method is applied to the estimation of inundation flows, which occurred in the river basin of the Shin-minato River. A detailed inundation flow structure is represented by the flow model and the flow characteristics with respect to topographic features are discussed

Impact of the flush discharge from a dam on the biotic and abiotic river environment

River engineeringRiver habitat management and restoratio

Flood Surface Flow Measurement by STIV in Adverse Conditions for Imaging

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Development of a non-intrusive and efficient flow monitoring technique : The space-time image Velocimetry (STIV)

A novel image analysis technique for measuring river surface flow is proposed. When we assume that the brightness distribution of river surface image is convected with the surface velocity, a space-time image for a searching line set parallel to the main flow would indicate velocity information as its image orientation. The new technique, the space-time image velocimetry (STIV), is capable to measure the orientation angle of the pattern using the eigenvalue analysis of the local space-time image. The performance of STIV is compared with the other image analysis technique, the large-scale particle image velocimetry (LSPIV), previously proposed by the authors and it is shown that STIV is an alternative image analysis method for measuring streamwise velocity distributions efficiently