- 1Italian National Research Council, Research Institute for Geo-Hydrological Protection (IRPI-CNR Perugia), Perugia, Italy (farhad.bahmanpouri@irpi.cnr.it)
- 2Chair of Hydrology and River Basin Management, Technical University of Munich, Germany
- 3DTU Space, Technical University of Denmark, Kgs. Lyngby, Denmark
- 4Swedish Meteorological and Hydrological Institute, 601 76 Norrköping, Sweden
- 5Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen
River monitoring is of particular importance in river engineering due to decision-making related to protecting life and property from water-related hazards, such as floods and water resources management.
In this direction, three cross-sections (XSs) were surveyed along a 10 km stretch of the Rönne River in Sweden. Ground-truth surface velocity measurements were obtained using an electromagnetic velocity sensor (OTT MF Pro). Additionally, videos captured by a UAS RGB camera were analyzed using both Particle Image Velocimetry (PIV) and Space-Time Image Velocimetry (STIV) techniques (Zhou et al., 2024). The bathymetry data for all cross-sections were recorded by the water penetrating radar.
The Entropy model was applied to the three different selected sites to estimate the two-dimensional cross-sectional velocity distribution by exploiting the available data, with the aim to estimate river discharge. Specifically, the surface velocities and bathymetry data for each section were considered as input for the Entropy model (Bahmanpouri et al., 2022a, b). The phenomenon of the velocity dip induced by the secondary current was also implemented in the estimation of the vertical velocity distribution where, for aspect ratios (river width/flow depth) lower than 5, the maximum velocity was observed below the water surface. Secondary currents result in a vertical shift in momentum, enhancing the turbulence and shear stress near the bed. Finally, the discharge rate was calculated for each cross-section using the mean velocity of the section and the observed flow area. The results highlighted the potential of the combination of the UAS‐Borne Doppler Radar and the theoretical Entropy model to estimate the velocity distribution and flow discharge with high accuracy. The suggested methodology would be of particular benefit in estimating the velocity distribution and flow discharge for inaccessible locations especially during high flow conditions where there are in-situ dangers for operators to measure flow characteristics. The work is funded by the European Union's Horizon Europe research and innovation programme as part of the UAWOS project (Unoccupied Airborne Water Observing System).
Keywords: Entropy, Velocity distribution, Velocity dip, Flow discharge, UAS‐Borne Doppler Radar, Rönne River
Bahmanpouri, F., Barbetta, S., Gualtieri, C., Ianniruberto, M., Filizola, N., Termini, D., & Moramarco, T. (2022). Prediction of river discharges at confluences based on Entropy theory and surface-velocity measurements. Journal of Hydrology, 606, 127404.
Bahmanpouri, F., Eltner, A., Barbetta, S., Bertalan, L., & Moramarco, T. (2022). Estimating the average river cross‐section velocity by observing only one surface velocity value and calibrating the entropic parameter. Water Resources Research, 58(10), e2021WR031821.
Zhou, Z., Riis‐Klinkvort, L., Jørgensen, E. A., Lindenhoff, C., Frías, M. C., Vesterhauge, A. R., ... & Bauer‐Gottwein, P. (2024). Measuring river surface velocity using UAS‐borne Doppler radar. Water Resources Research, 60(11), e2024WR037375.
How to cite: Bahmanpouri, F., Barbetta, S., Hu, X., Zhou, Z., Wennerberg, D., Tarpanelli, A., and Bauer‐Gottwein, P.: Applying the Entropy theory to estimate river flow using the surface velocity by UAS‐Borne Doppler Radar, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4136, https://doi.org/10.5194/egusphere-egu25-4136, 2025.
