Drone usage for Rivers

What´s beneath the following flow pattern ? Drone zenithal view subsequently vectorized with LSPIV. You´ve got it; just this groyne when submerged flow begins !

A rather complex process, which can lead to spectacular images of  mixing eddies. Practical questions like: what´s the mixing length, the influence of each stream speed and width,  and how do they  change along the interface,  can be derived for simple cases with math models.

A good example of sun glitter while the drone raises and films oriented towards the sun, however it can be helpful to determine a correlation between surface reflectance and roughness, and related flow speed.

Drones make easier to recognize surface speed patterns and debris storage areas in order to   clean up  plastic litter , as this image of Alcala de Ebro groynes shows. See more at  The Ocean Clean Up project and https://doi.org/10.3390/rs11172045

This is a particular village  30 Kms upstream Saragosse along the Ebro river, Google-Map , where we can observe a riverine island with its typical confluence pattern, and our computer LSPIV  video processing:

Shallow flows with relatively transparent water, captured  by 4K camera drones and filtered by computer, can help to define the bathymetry without more expensive data acquisition. See this example nearby "Sotos del Ebro, Alfaro".

Tests at Castejon de Ebro: Checking heights for look angles, fields of view and resulting flow resolution around Castejon railway bridge, during the dry season . This is a key reach for monitoring the Ebro river during flood periods.

State of the art technique is available at this IAHR publication: https://iahr.org/Portal/News/News%20-%20Latest%20issue%20of%20Hydrolink%20on%20Drone%20Special%20is%20now%20published.aspx

4K images dozen of meters above water surface allow for tracking the flow speed in this confluence, the change in velocity determines the driving forces (Newton´s 2nd Law) and the prediction of effects and control measurements. Drone videos and further image processing are affordable tools for real scale studies.

4K  Images during this year first rise, flights were stable and the resolution pretty much fine.

Limitations, accuracy, Ground Control Points support, Structure from Motion, what can be done at the moment ? Latest research available at:  https://www.mdpi.com/journal/drones/special_issues/DroTop

No wind, clear sky, and all dry for the moment. As you can guess ... the first drill is to fly below the bridge, go and return !

Testing a DJI Mavic 2 Zoom to feel familiar with stable heights, angles and video parameters, although January is usually windy at Saragosse and wind speeds over 10 m/s are not secure, as happens now; current wind speed map provided by darksky.net .