UAVs for Hydrologic Scopes: Application of a Low-Cost UAV to Estimate Surface Water Velocity by Using Three Different Image-Based Methods

Abstract

Stream velocity and flow are very important parameters that must be measured accurately to develop effective water resource management plans. There are various methods and tools to measure the velocity but, nowadays, image-based methods are a promising alternative that does not require physical contact with the water body. The current study describes the application of a low cost unmanned aerial vehicle that was selected in order to capture a video over a specific reach of Aggitis River in Greece. The captured frames were analyzed by three different software (PIVlab, PTVlab, and KU-STIV) in order to estimate accurately the surface water velocity. These three software also represent three different image-based methodologies. Although there are differences among these three methods, the analysis produced similar trends for all. The velocity ranged between 0.02 and 3.98 m/s for PIVlab, 0.12 and 3.44 m/s for PTVlab, and 0.04 and 3.99 m/s for KU-STIV software. There were parts, especially in the existing vegetation, where differences were observed. Further applications will be examined in the same or different reaches, to study the parameters affecting the analysis. Finally, the image-based methods will be coupled with verification measurements by a current meter to produce more rigorous results.

Riverine Plastic Litter Monitoring Using Unmanned Aerial Vehicles (UAVs)

“…In the future, the aerial images obtained with the presented protocol could provide the basis for, e.g., velocity data, by using them as a basis for PIV measurements. Several papers have previously been published implementing such PIV techniques based on aerial images in outdoor environments [33][34][35][36]. This could significantly increase the accuracy and spatial resolution of velocity measurements.…”

Real-Time Measurement of Flash-Flood in a Wadi Area by LSPIV and STIV

“…The utilization of natural tracers and water turbid current conditions can minimize the effects of sun reflection and enhance the estimated velocity results [15]. Various research studies have investigated the performance of various image-based methods in humid environments, such as LSPIV, Particle Tracking Velocimetry (PTV), and STIV [7,16].…”

“…The STIV technique is dependent on surface textures, which include surface flow waves, brightness, and color variation, to measure surface flow velocity. This technique uses sequential frames over time changing with specified spacing in the search lines set parallel to the flow direction [15,16]. The main concept of this technique is extracting the brightness and texture information, which is called the image intensity distribution (IID), from sequentially recorded frames passing over the segment lines [17,18].…”

Discharge Estimates for Ungauged Rivers Flowing over Complex High-Mountainous Regions based Solely on Remote Sensing-Derived Datasets

“…River flow monitoring with satellite remote sensing is an emerging discipline attractively increasing scientific interest [13,[19][20][21]. In terms of providing better spatial flow monitoring, this method is more appropriate than in-situ methods [6].Apart from the various hydrological modeling approaches, there is another more recent indirect methodology that uses Unmanned Aerial Vehicles (UAVs) to estimate water discharge by combining water level and velocity [22][23][24]. Moreover, river discharge can be also estimated using satellite radar altimetry of monitoring riverbeds [9,25], interferometric synthetic aperture radars (InSAR) [26,27], and passive microwave radiometers [28].…”

“…Apart from the various hydrological modeling approaches, there is another more recent indirect methodology that uses Unmanned Aerial Vehicles (UAVs) to estimate water discharge by combining water level and velocity [22][23][24]. Moreover, river discharge can be also estimated using satellite radar altimetry of monitoring riverbeds [9,25], interferometric synthetic aperture radars (InSAR) [26,27], and passive microwave radiometers [28].…”