Visual Awareness on Surface Flow Measurement

Flow velocity is one of the key factors in hydrology. Considering workers on-site safety, non-contact methods have become the major approach for flow velocity measurement. Although particle image velocimetry (PIV) is a primary non-contact approach, which has been developed and improved since 1991, hydraulics experts are still required to be involved in the initial setting for PIV measurement. Without the initial setting executed by PIV experts, the uncertainty derived from surface flow that has varied features may cause inaccurate measurement. For these reasons, we proposed a surface flow measurement method that takes advantage of human visual awareness to measure flow velocity. People can mark the flow features on images using the measurement tool we developed to acquire flow velocity. We recorded two flow videos under different flow conditions and measured flow velocity using the developed method. The measurements established the feasibility of using the method.