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Enhancing the Monitoring Protocols of Intermittent Flow Rivers with UAV-Based Optical Methods to Estimate the River Flow and Evaluate Their Environmental Status

Drones and Autonomous Vehicles. 2024, 1(2), 10006; https://doi.org/10.35534/dav.2023.10006
Paschalis Koutalakis *    Mairi - Danai Stamataki    Ourania Tzoraki   
Department of Marine Sciences, University of the Aegean, 81100 Mytilene, Greece
*
Authors to whom correspondence should be addressed.

Received: 18 Sep 2023    Accepted: 23 Nov 2023    Published: 27 Nov 2023   

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Abstract

Temporary streams are a key component of the hydrological cycle in arid and semi-arid regions, but their flow is highly variable and difficult to measure. In this paper, we present a novel approach that could be used to assess the flow of temporary streams this allowing to characterize their environmental status. Specifically, we apply the Image Velocimetry (IV) method to estimate surface velocity in temporary streams using Unmanned Aerial Vehicles (UAVs) equipped with optical sensors (IV-UAV method). The IV-UAV method enables the easy, safe and quick estimation of the velocity on the water’s surface. This method was applied in different temporary streams in Lesvos Island, Greece. The results obtained indicate that the IV-UAV can be implemented at low discharges, temporary streams and small streams. Specifically, the water depth ranged from 0.02 m to 0.28 m, while the channel width ranged from 0.6 m to 4.0 m. The estimated surface velocity ranged from 0.0 to 5.5 m/s; thus, the maximum water discharge was 0.60 m3/s for the largest monitored stream of the island. However, there were many occasions that measurements were unable due to various reasons such as dense vegetation or archaeological sites. Despite of this, the proposed methodology could be incorporated in optical protocols which are used to assess the environmental status of temporary streams of Mediterranean conditions. Finally, this would become a valuable tool for understanding the dynamics of these ecosystems and monitoring changes over time.

Keywords

Environmental flow; Intermittent flow; Mediterranean conditions; Optical protocol; Surface velocity; Temporary streams; Unmanned aerial vehicles

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