DePlaMar:

Detection of Plastic at Sea

The project DePlaMar analyses the presence of plastics at the Underwater Gardens of la Selva >> (name that S'Agulla has given to the area of the sea bottom at 30-70m deep, located at the header of the Blanes underwater canyon).

The objective is de detection and analysis of plastic (fragments larger than 10cm) with the aid of a drone. In order to evaluate its impact on the environment the following parameters will be taken into account: type, size, colour and density

 

METHODOLOGY

Drone: MAVIC 2 PRO equipped with a Hasselblad camera and recording with 4k quality
Flight altitude: 20m
Camera angle: zenithal
Flight speed: 18-20km/h (display of recordings at half the speed)
Swath: 23'66m
Lineal distance recorded: 56km
Total area recorded: 139ha
Sampling period: autumn 2020

FACTORS TO TAKE INTO ACCOUNT DURING FLIGHTS:
-Suitable meteorological conditions: daylight, little wind and no rain
-Real flight duration: 20 minutes (battery at 30%)
-Do not let battery discharge till 10% because the drone will land automatically, that is, it will fall in the water!
-The mobile phone or tablet used as display during flights only allows to see large and well contrasted objects, such as boats due to the reflections of ambient light
-In the case of encountering birds, the sensors of the device warn of the presence of intrusive objects within the security fight zone of the drone. Stop the drone in the air and let birds wander around, they will eventually go away. During the project there have not been any incidents with birds

RESULTS


A small sample of what we have found with Borinot, the drone of S'Agulla!

CONCLUSIONS

The usage of Borinot (drone MAVIC 2 PRO) has proven to be a powerful tool: it allows the detection of plastic fragments of up to 5cm in optimal meteorological conditions and scan areas of 15ha in only 20 minutes flights.

At the Underwater Gardens of la Selva, the average size of plastics found is 16cm. Most of it was colour white. Also, thanks to the flights, it has been possible to dismiss the presence of areas of accumulation of plastic litter at the sea surface. Plastics were detected more frequently off the Fenals beach (Lloret de Mar)

The overall assessment of the usage of drones for plastic detection at sea surface is good, however it is conditioned to swell and the angle of the solar rays during surveys.

More information in the Project's Report >> and photographs in the annex>>

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