Plotting water flow rates in small watercourses by means of an above-water unmanned vehicle in order to find the source of pollutant discharges

The methodology of measuring flow velocities and constructing water consumption curves in waterways in order to find the source of pollutant discharges by the surface unmanned vehicle (unmanned craft – UC) is proposed. The research was carried out on the Pekhorka River in the Moscow region in August-September 2023. The following software and equipment were used: Google Earth Pro, Microsoft Excel, an in-house developed surface drone, a Garmin Striker Cast GPS echo sounder, a water flow sensor based on the Arduino UNO platform with customised enhancements (tail feathering and a built-in plug-in for current velocity determination). Fixation of exceedance of maximum permissible concentrations (MPC) of pollutants in a watershead indicates a violation has occurred. Due to the high degree of water exchange in waterways, the presence of a water sample with exceeded MPC values does not guarantee the detection of a violator. Particularly, if a water consumer is not in the supervision authorities' database, it becomes almost impossible to confirm his guilt without a comprehensive evidence base. If there is a wide network of hydrological monitoring on streams, the issue in the evidence base would be exhaustive, but dependent on the length of the river, frequent installation of hydrological posts is impossible for economic reasons. In such a case, an alternative option to supplement hydrological observations could be the use of a surface unmanned vehicle to take data at any reference station at the operator's discretion. The method of identifying sources of stream pollution using the unmanned ship not only allows to significantly expand the hydrological monitoring network along streams, but also to locate illegal water users by randomly selecting a control node to measure flow velocity and water volume. The large number of registered control nodes can also serve as a basis for the commission of a discharge when an intruder is detected.