Particle Image Velocimetry PIV and numerical modeling for flow estimation and analysis

In this paper an image-based measuring technique to collect water surface velocities is described. Unlike point-based measurements that require a substantial investment in equipment and field crews, the Particle Image Velocimetry (PIV) approach uses inexpensive video equipment to make digital images of the surface flow. Measurements can be made quickly and with little site preparation. PIV is well suited for shallow areas, where lack of access limits conventional point measurements. Furthermore, PIV is suitable for wetland and marsh waterways that often have velocities below the limit of detection of conventional devices. Numerical models, guided by the PIV measurements, are used to generate two-and three-dimensional flow-fields. This hydrodynamic information can be used to assess restoration strategies and perform water quality analysis in an economical and effective fashion. It can be also used to investigate the short-and long-term response of natural fluvial systems to human influences. As a first step toward validating the proposed methodology, field measurements were collected at Clear Creek near Oxford, IA. USGS Gage 05454220 is located immediately downstream of the reach under investigation. A three-dimensional flow field is produced for this reach using a kinematic numerical model with the PIV surface-flow measurements used as input. Comparison between profiles extracted from the three-dimensional flow field with point-measurements collected in the field showed good agreement. This study demonstrates that the PIV technology coupled with numerical modeling has a potential of being used as a practical alternative …