Analysis of River Flow Velocity Measurement Using the Large Scale Particle Image Velocimetry Method

Large-scale particle image velocimetry (LSPIV) can analyze river flow velocity measurement. LSPIV can be performed using either a UAV or terrestrial photogrammetry, but it is important to understand the river flow velocity measurement results from both methods. This study examines the river flow velocity measurement of the Mungkung River water flow in the Mungkung Bridge, Sragen Regency, using an unmanned aerial vehicle (UAV) and terrestrial photogrammetry. The velocity of river water flow will be measured using the Large Scale Particle Image Velocimetry (LSPIV) method and orthorectification with the RIVeR application. UAV orthorectification at each height of 20 m, 30 m, and 50 m. The results of measuring the velocity of river currents using the UAV LSPIV method obtained a range of results between 0.1 and 0.7 m/s with a flight height of 20 meters, 0-0.7 m/s at a UAV flight height of 30 meters, and 0.0-0.8 m/s with a UAV flight height of 50 meters, while terrestrial photogrammetry has a velocity value with a range of value variations of 0-0.7 m/s. Meanwhile, preliminary validation measurement obtained a river flow velocity of 0.393 m/s, and the River Basin Organization of Bengawan Solo River data using a current meter produced a velocity value of 0.375 m/s.