Measurement Of The Flood Discharge Of A Small-Sized River Using An Existing Digital Video Recording System

Journal of Hydro-environment Research

Ryota Tsubaki 1, Ichiro Fujita 2 and Shiho Tsutsumi 3

1 Department of Civil and Environmental Engineering, Hiroshima University, Kagamiyama 1-4-1, Higashihiroshima, Hiroshima 739-8527, Japan

2 Department of Civil Engineering, Kobe University, Rokkodai, Nada-Ku, Kobe 657-8501, Japan

Abstract

In this study, a closed-circuit television (CCTV) system, installed for surveillance purposes, is utilized to measure the flow rate during a flood. The procedure to determine both the angle and scale-factor of the camera is described. Then, image analysis techniques, namely the direct visual measurement method, Large-Scale PIV (LSPIV) and Space-Time Image Velocimetry (STIV), are applied to the video images recorded by the CCTV camera. The results of these methods and the conventional float measurement are compared. In addition, the accuracy of the respective methods is discussed. A set of low-quality video images of a flood during a thunderstorm that occurred under the dark ambient conditions (midnight) is analyzed using three image-based methods. The transition of the flow rate during the event is successfully estimated.

Reseach highlights

A video surveillance system was utilized for measuring the flow rate during floods.

The procedure to determine camera setting is described.

The results of three methods and the conventional float method were compared.

The accuracy of the respective methods is quantitatively discussed.

Keywords

LSPIV; STIV; Small-sized river; CCTV; River discharge measurement; Float method; Floating debris