Sandra Soares Frazao
Recent publications

- Sediment transport under fast transient flow conditions: experimental measurement of the velocity profile, characterisation of the bed shear stress at the interface between the clear-water flow and the moving sediment, determination of the critical shear stress leading to grain entrainment;
- Flood propagation in urban areas: modelling using a porosity-concept;
- Numerical modelling (depth-averaged) of morphological processes in fluvial hydraulics, application to laboratory-scale flows and to larger scales (real cases);
- Scientific cooperation with Haiti about floods: field measurements of topography, bathymetry, water levels and discharge using UAV-based photogrammetry; numerical simulation of flood events including sediment transport and morphological evolution; use of GIS for vulnerability and hazard mapping.

IMMC main research direction(s):
Civil and environmental engineering
Fluid mechanics

geophysical and environmental fluid dynamics
fluvial hydraulics

Research group(s): GCE


PhD and Post-doc researchers under my supervision:

Morphological impact of dam-flushing
Robin Meurice

An important number of dams worldwide face sedimentation issues, leading to a decrease in their reservoir capacity and hence, many difficulties to properly satisfy to their different functions (e.g. water distribution, flood management, hydroelectricity production). To overcome these problems, we can proceed to dam flushing operations, transporting huge amounts of sediment downstream of the dam. Nevertheless, these operations can be harmful to the environment, the living organisms and the human infrastructures if not properly handled. For that reason, this thesis aims at developing a numerical model capable of accurately predicting the sediment deposition downstream of a dam after flushing operations. In order to do so, several mathematical models shall be implemented, among which a two-phase two-layer model, and laboratory experiments shall be run. The numerical model will then be confronted with the data collected from the experiments. Finally, the model will be tested with real-case data collected in situ near Lyon, France.

Numerical and experimental modeling of breaching of earthen embankments
Masoumeh Ebrahimi

Embankments failures can have devastating impacts. Therefore, proper risk assessment requires a

reliable description of the breaching process, flow hydrograph and downstream inundation. In

this project, medium and large‐scale experiments of breaching due to overtopping will be

conducted and monitored using digital imaging techniques. An existing numerical simulation tool

will be improved to represent the whole process, including the flow through the embankment.

Influence of soil saturation on earthen embankments failure by overtopping
Nathan Delpierre

In the current context of climate change and aging infrastructure, the failure of earthen dikes is becoming a
critical issue. Dikes have an essential protection role in flood defense, coastal protection or for the storage of
mining industry waste. The objective of the research is to develop and validate a simulation model to take into
account the effect of
saturation of the dike material on its stability when it is subjected to overtopping flows, which alone cause 34%
of failures (Costa, 1985). For this purpose, a complete simulation model will be developed, taking into account
the internal and external flows as well as the erosion and the consequences on the evolution of the stability of
the dam. The originality of this project lies in the multidisciplinary approach that takes into account the
evolution of the dike both from a hydraulic and hydrogeological point of view (water content, flow velocity and
surface erosion) but also from the point of view of the geomechanics and thus of the intrinsic stability of the
dike. Laboratory experiments will be carried out in order to validate the model experimentally. At this level, the
novelty brought by this project is the control of the evolution of the water content of the dike in real time with
pressure gauges and tensiometers. The acquired data will allow to calibrate the model and to confirm the key
role of the initial saturation in the dam failure.
Finally, based on the critical characteristics defined in terms of dike saturation, a study on large-scale
monitoring techniques will be carried out. In particular, the possibility of using technologies such as
photogrammetry or GPR (Ground Penetrating Radar) to determine the degree of saturation of a soil will be
investigated in the context of dike monitoring.

Floods in urban areas - modelling the interactions between flow and buildings
Charles Ryckmans

Recent publications

See complete list of publications

Journal Articles

1. Delpierre, Nathan; Rattez, Hadrien; Soares Frazao, Sandra. Finite volumes methods for coupled surface-subsurface flows. In: Journal of Hydraulic Research,. (Soumis).

2. Guinot, Vincent; Delenne, Carole; Soares Frazao, Sandra. Self-similar solutions of shallow water equations with porosity. In: Journal of Hydraulic Research, Vol. 61, no. 1, p. 109-119 (2023). doi:10.1080/00221686.2022.2106598.

3. Meurice, Robin; Martínez-Aranda, Sergio; Ebrahimi, Masoumeh; García-Navarro, Pilar; Soares Frazao, Sandra. Laser profilometry to measure the bed evolution in a dam-break flow. In: Journal of Hydraulic Research, Vol. 60, no. 5, p. 725-737 (2022). doi:10.1080/00221686.2022.2059584.

4. Yang, Jiangtao; Shi, Zhenming; Peng, Ming; Zheng, Hongchao; Soares Frazao, Sandra; Zhou, Jiawen; Shen, Danyi; Zhang, Limin. Quantitative risk assessment of two successive landslide dams in 2018 in the Jinsha River, China. In: Engineering Geology, Vol. 304, no.106676, p. 35 (2022). doi:10.1016/j.enggeo.2022.106676.

5. Sergio Martínez-Aranda; Meurice, Robin; Soares Frazao, Sandra; Pilar García-Navarro. Comparative Analysis of HLLC- and Roe-Based Models for the Simulation of a Dam-Break Flow in an Erodible Channel with a 90° Bend. In: Water, Vol. 13, no.13, p. 1840 (2021). doi:10.3390/w13131840.

6. Le, Hoang-Anh; Gratiot, Nicolas; Santini, William; Ribolzi, Olivier; Tran, Duc; Meriaux, Xavier; Deleersnijder, Eric; Soares Frazao, Sandra. Suspended sediment properties in the Lower Mekong River, from fluvial to estuarine environments. In: Estuarine, Coastal and Shelf Science, Vol. 233, p. 106522 (2019). doi:10.1016/j.ecss.2019.106522.

7. Pham Van, Chien; de Brye, Benjamin; de Brauwere, Anouk; Hoitink, A.J.F. (Ton); Soares Frazao, Sandra; Deleersnijder, Eric. Numerical Simulation of Water Renewal Timescales in the Mahakam Delta, Indonesia. In: Water, Vol. 12, no.4, p. 1017 (2020). doi:10.3390/w12041017.

8. Le, Hoang-Anh; Lambrechts, Jonathan; Ortleb, Sigrun; Gratiot, Nicolas; Deleersnijder, Eric; Soares Frazao, Sandra. An implicit wetting–drying algorithm for the discontinuous Galerkin method: application to the Tonle Sap, Mekong River Basin. In: Environmental Fluid Mechanics, (2020). doi:10.1007/s10652-019-09732-7.

9. Soares Frazao, Sandra. Review of imaging-based measurement techniques for free surface flows involving sediment transport and morphological changes. In: Journal of Hydroinformatics, Vol. 22, no.5, p. 958-971 (2020). doi:10.2166/hydro.2020.026.

10. Meurice, Robin; Soares Frazao, Sandra. A 2D HLL-based weakly coupled model for transient flows on mobile beds. In: Journal of Hydroinformatics, Vol. 22, no.5, p. 1351-1369 (2020). doi:10.2166/hydro.2020.033.

Conference Papers

1. Meurice, Robin; Soares Frazao, Sandra. Closing parameters of morphodynamical models without trial-and-error. 2023 xxx.

2. Delpierre, Nathan; Soares Frazao, Sandra; Rattez, Hadrien. Coupled surface and subsurface flows for earthen embankments using finite-volume methods. 2023 xxx.

3. Ebrahimi, Masoumeh; Meurice, Robin; Soares Frazao, Sandra. Application of Depth-Averaged Bedload Finite-Volume Models to a Progressive Embankment Dam-Failure. 2022 xxx.

4. Meurice, Robin; Soares Frazao, Sandra. A Two-Phase/Two-Layer Model for Fast and Heavily Loaded Transient Flows. 2022 xxx.

5. Meurice, Robin; Soares Frazao, Sandra. How to optimize dam-flushes to limit their downstream impacts?. 2022 xxx.

6. Meurice, Robin; Soares Frazao, Sandra. Comparison of coupled and weakly coupled HLLC based finite-volume schemes for dam-break flows on mobile bed. 2021 xxx.

7. Draoui, Insaf; Lambrechts, Jonathan; Legat, Vincent; Soares Frazao, Sandra; Hoitink Ton; Deleersnijder, Eric. Discontinuous Galerkin method for 1D shallow water models. 2021 xxx.

8. Rikkert, Stephanus, J.H.; Cédrine Alleon; Ichrak Khaldi; Salah Shaiek; Kristof, Verelst; Ebrahimi, Masoumeh; Soares Frazao, Sandra. How strong are our levees? Hydraulic analysis based on POLDER2c’s project in situ testing. 2021 xxx.

9. Le, Hoang Anh; Lambrechts, Jonathan; Deleersnijder, Eric; Soares Frazao, Sandra; Gratiot, Nicolas; Ortleb, Sigrun. Numerical modelling of flow dynamics in the Tonle Sap by means of a discontinuous Galerkin finite-element model. In: River Flow 2020, Taylor & Francis Group: London, 2020, 978-0-367-62773-7, p. 1-7 xxx.

10. Draoui, Insaf; Lambrechts, Jonathan; Legat, Vincent; Soares Frazao, Sandra; Hoitink, Ton (A.J.F.); Deleersnijder, Eric. Discontinuous Galerkin method for 1D river flows. In: River Flow 2020, Taylor & Francis Group: London, 2020, 978-0-367-62773-7, p. 1-8 xxx.