Author: Salvatore Manfreda

Happy Easter

I would like to wish you all a Happy Easter of Resurrection.

After this long period of difficulties, I hope that this will really be a reborn for a new COVID free life.

A comparison of tools and techniques for stabilising UAS imagery for surface flow observations

This research presents an investigation of different strategies and tools for digital image stabilisation for image velocimetry purposes. Basic aspects of image stabilisation and transformation are presented, and their applicability is discussed in terms of image velocimetry. Seven free-to-use open-source tools (six community-developed and one off-the-shelf) are described and compared according to their stabilisation accuracy, robustness in different flight and ground conditions, computational complexity, ease of use, and other capabilities. A novel approach for fast stabilisation accuracy analysis is also developed, presented, and applied to the stabilised image sequences. Based on the obtained results, some general guidelines for choosing a suitable tool for specific image velocimetry tasks have been obtained. This research also aims to provide a basis for further development or improvement of digital image stabilisation tools, as well as for the analyses of stabilisation impact on image velocimetry results.

How to cite: Robert Ljubičić, Dariia Strelnikova, Matthew T. Perks, Anette Eltner, Salvador Peña-Haro, Alonso Pizarro, Silvano Fortunato Dal Sasso, Ulf Scherling, Pietro Vuono, and Salvatore Manfreda, A comparison of tools and techniques for stabilising UAS imagery for surface flow observations, Hydrology and Earth System Sciences, 2021.

Impact of Flood Control Systems on the Probability Distribution of Floods

Detention dams are one of the most effective practices for flood mitigation. Therefore, the impact of these structures on the basin hydrological response is critical for flood management and the design of flood control structures. With the aim to provide a mathematical framework to interpret the effect of flow control systems on river basin dynamics, the functional relationship between inflows and outflows is investigated and derived in a closed-form. This allowed the definition of a theoretically derived probability distribution of the peak outflows from in-line detention basins. The model has been derived assuming a rectangular hydrograph shape with a fixed duration, and a random flood peak. In the present study, the undisturbed flood distribution is assumed to be Gumbel distributed, but the proposed mathematical formulation can be extended to any other flood-peak probability distribution. A sensitivity analysis of parameters highlighted the influence of detention basin capacity and rainfall event duration on flood mitigation on the probability distribution of the peak outflows. The mathematical framework has been tested using for comparison a Monte Carlo simulation where most of the simplified assumptions used to describe the dam behaviours are removed. This allowed to demonstrate that the proposed formulation is reliable for small river basins characterized by an impulsive response. The new approach for the quantification of flood peaks in river basins characterised by the presence of artificial detention basins can be used to improve existing flood mitigation practices, support the design of flood control systems and flood risk analyses.

How to cite: Manfreda, S., D. Miglino, and C. Albertini, Impact of Flood Control Systems on the Probability Distribution of Floods, Hydrology and Earth System Sciences, https://doi.org/10.5194/hess-2021-47, in review, 2021. [pdf]

VISION: VIdeo StabilisatION using automatic features selection

This project presents the codes and example of the use of one of the algorithms (FAST) used in the automatic feature selection part of the manuscript entitled “A comparison of tools and techniques for stabilizing UAS imagery for surface flow observations”. The “StabilisationFunction.m” is a Matlab function aiming at stabilising videos for image velocimetry analyses in rivers. It is a command-line function without GUI at the moment. An example of how to call the stabilisation function is also provided in the file “ExampleScript.m”. All the codes were written in Matlab R2020a.

CODE: https://doi.org/10.17605/OSF.IO/HBRF2

How to cite: Pizarro, A., S.F. Dal Sasso, S. Manfreda, VISION: VIdeo StabilisatION using automatic features selection, DOI 10.17605/OSF.IO/HBRF2, 2021.

HARMONIOUS deliverables of 2020

This year, COST Action – HARMONIOUS members produced a quite impressive number of results working online. Imagine what we could do without restrictions!
See the following list:
1. Use of UAVs with the simplified “triangle” technique https://lnkd.in/dFQftqY
2. Identifying the optimal spatial distribution of tracers https://lnkd.in/dyEcmzq
3. A geostatistical approach to map near-surface soil moisture https://lnkd.in/dymZzHB
4. Refining image-velocimetry performances for streamflow monitoring https://lnkd.in/dyQzvyc
5. Metrics for the quantification of seeding characteristics https://lnkd.in/gvMBe4c
6. Harmonisation of image velocimetry techniques for river surface velocity observations https://lnkd.in/d-ygHpY
7. An integrative information aqueduct to close the gaps in water observations https://lnkd.in/dfTHZcG
8. Practical guidance for UAS-based environmental mapping https://lnkd.in/dAAuFmf
9. Long-term soil moisture observations over Tibetan Plateau https://lnkd.in/dguKMCE
10. Image velocimetry techniques under low flow conditions https://lnkd.in/dGRwY9Y


#hydrology #environmentalmonitoring #remotesensing #UAS #rivermonitoring

Call for Papers on Advances in Hydrological Monitoring with UASs

We are promoting a new research topic entitled Advances in Hydrological Monitoring with Unmanned Aerial Systems in Frontiers in Remote Sensing.

FRONTIERS IN REMOTE SENSING

Abstract Submission by March 2021
Manuscript Submission by July 2021

This Research Topic, we would like to promote research which explores the contribution that UASs can provide on hydrological observations, understanding of hydraulic and hydrological processes and development of modelling approaches. More specifically, topics of interests are the following:

• Development of new sensors and Unmanned Aerial System configurations devoted to hydrological monitoring;
• Definition of guidelines of the best-practices to improve the overall quality of the final products promoting a consistent use of UASs in hydrology;
• Development of new algorithms able to exploit high resolution observations;
• Development of new methodologies to fill the gap between satellite observation and field data;
• Coupled application of hydrological models exploiting Unmanned Aerial System observations; and
• Linking the Unmanned Aerial System monitoring of hydrological processes to its novel applications in agricultural management, water resources management, early warning systems etc.

Keywords: UAS, Environmental Monitoring, Hydrology, Rivers, Vegetation.

Appunti di Idrologia Superficiale

Da oggi è disponibile la versione e-book del libro “Appunti di Idrologia Superficiale” pubblicato dalla casa Editrice Aracne.

SINTESI: Il testo offre spunti ed approfondimenti sui processi idrologici superficiali e con particolare riferimento all’interazione acqua-suolo tenendo in considerazione anche le esigenze di carattere tecnico-pratico del lettore. Per tale motivo, oltre a proporre dei contenuti di carattere generale sul tema dell’idrologia superficiale, vengono riportate informazioni utili alla caratterizzazione idrologica in differenti contesti del territorio nazionale.

Disponibile al link: Aracne Editrice

Exploring the use of UAVs with the simplified ‘triangle’ technique for soil water content and evaporative fraction retrievals in a Mediterranean setting

Information acquired from Unmanned Aerial Vehicles (UAVs) is frequently used nowadays in a variety of disciplines and research fields. The present study explores for the first time the combined use of UAVs with a newly proposed technique for estimating evaporative fraction (EF) and surface soil moisture (SSM). The investigation is performed in a typical Mediterranean setting, a citrus field with flat topography divided in two plots with different irrigation schemes, in Sicily, Italy, at which ground data acquired during an extensive field campaign in July 2019. Reasonable estimates of both EF and surface wetness were produced, with patterns in agreement to vegetation cover fragmentation, topography, and other site-specific characteristics. Validation shows average error of 0.053 for EF and of 0.040 cm3 cm−3 for SSM. The results are comparable or better to those reported in analogous studies performed in similar areas. This implies that the investigated approach performs well under the semi-arid conditions characterizing the experimental set up. To our knowledge, this study represents the first evaluation of the combined use of the ‘simplified triangle’ with very high-resolution UAV imagery. As such, the findings are of significance regarding the potential future use of the ‘simplified triangle’ approach particularly with very fine resolution imagery such as that provided by UAV for mapping and monitoring EF and SSM in agricultural and natural ecosystems.

Figure: Maps of EF (a) and SSM (b) computed from the ‘simplified triangle’ implementation using the data retrieved with UAV.

How to cite: Petropoulos, G.P., A. Maltese, T. N. Carlson, G. Provenzano, A. Pavlides, G. Ciraolo, D. Hristopulos, F. Capodici, C. Chalkias, G. Dardanelli, S. Manfreda, Exploring the use of UAVs with the simplified “triangle” technique for Soil Water Content and Evaporative Fraction retrievals in a Mediterranean setting, International Journal of Remote Sensing, VOL. 42, NO. 5, 1623–1642, (doi: 10.1080/01431161.2020.1841319) 2021. [pdf]