Natural environment

Sediment management at the basin scale

The inclusion of sediment dynamics at basin scale into water resources planning and management could potentially improve the performance of our infrastructures and contribute to a holistic strategy against climate change. This is particularly relevant for hydropower plants’ sustainability since proper siting and management could increase their operational life and contribute to increase the reliability of the renewable energy mix. Increased knowledge will reduce risks and increase the reliability of investments. Sediment dynamics are in particular studied using a combination of field measurements and developing new modelling approaches to reproduce sediment connectivity at basin scale. These tools are used to simulate the impacts of different infrastructures development or climatic forcings scenarios.

Projects: S-MultiStor - Sustainable Hydropower and Multipurpose Storage to meet the Water, Food and Energy SDG's – DUPC II

Main publications
Schwindt S., Franca M.J., De Cesare G. & Schleiss A.J. Analysis of mechanical-hydraulic bedload deposition control measures, Geomorphology, doi: 10.1016/j.geomorph.2017.07.020

Schwindt S., Franca M.J. & Schleiss A.J. Effects of lateral and vertical constrictions on flow in rough steep channels with bedload, Journal of Hydraulic Engineering, doi: 10.1061/(ASCE)HY.1943-7900.0001389

Battisacco E., Franca M.J. & Schleiss A.J. Sediment replenishment: influence of the geometrical configuration on the morphological evolution of channel-bed. Water Resources Research, doi: 10.1002/2016WR019157

Juez C., Battisacco E., Schleiss A.J., & Franca M.J. Assessment of the performance of numerical modeling in reproducing a replenishment of sediments in a water-worked channel. Advances in Water Resources, doi:10.1016/j.advwatres.2016.03.010

Cattapan, A., Paron, P. & Franca, M.J. (2018) Deriving grain size distributions from UAVs images, in: Huismans, Y., Berends, K.D., Niesten, I., Mosselman, E. (2018), The future river: NCR DAYS 2018 Proceedings. Netherlands Centre for River studies publication 42-2018

Khan, U.A., Cattapan, A. & Franca, M.J. (2018) Analysis of sediment transport dynamics in the Piave River basin to define hotspots of geomorphic change, in: Huismans, Y., Berends, K.D., Niesten, I., Mosselman, E. (2018), The future river: NCR DAYS 2018 Proceedings. Netherlands Centre for River studies publication 42-2018

Processes of sediment entrainment, transport and deposition

The sediment dynamics, which includes the transport and the diversity in size of the sediment, are an often neglected but essential linkage in the nexus between water-food-energy and ecosystems. Flow and sediment dynamics are two interlinked key abiotic drivers in riverine ecosystems which can host a large variety of habitats. Sediments are a source of minerals, are agents of transport of nutrients, oxygen, microorganisms, carbon and contaminants, build the landscape morphology (river and coastal stability) and guarantee fluvial connectivity (from the mountains to seas, lakes and oceans). We study sediment processes in laboratory, in the field and with numerical models, using methods to forecast their contribution to short and long term morphological evolution for applications in water resource management, river ecology, river restoration and flood risk assessments. 

Projects

F.Bregoli, Fine sediment and river dynamic, Experienced Water Postdoc Fellowship Program, COFUND - Marie Curie Actions (FP7-PEOPLE-2013-COFUND)
Assessment and modeling of sediment flux and sedimentation in the Mara River and Wetland, Tanzania, characterized by intense fine sediment transport and increasing human pressures on habitat. The work includes field campaigns employing UAV topographic survey, wetland bathymetry, sediment and water discharge measurement.

News
Bregoli F. (2018) Water and sediment: news from the Mara Wetland, Tanzania, AGU Blog The Field. 

Main publications

Juez C., Hassan M. & Franca M.J. The origin of fine sediment determines the observations of suspended sediment fluxes under unsteady flow conditions. Water Resources Research, accepted for publication

Matos J.P., Hassan M., Liu X.X. & Franca M.J. Probabilistic prediction and forecast of daily suspended sediment concentration on the Upper Yangtze River. Journal of Geophysical Research - Earth Surface, 122, doi: 10.1029/2017JF004240

Juez C., Buhlmann I., Maechler G., Schleiss A.J. & Franca M.J. Transport of suspended sediments under the influence of bank macro-roughness. Earth Surface Processes and Landforms, doi: 10.1002/esp.4243.

Bregoli, F.; Crosato, A.; Paron, P; McClain, M. (2018) Morphology, water discharge and suspended load distribution along the Mara River Wetland, Tanzania. NCR Days 2018, Book of abstracts, 136-137, Delft, 8-9 February 2018, Ed: Y. Huismans, K.D. Berends, I. Niesten, E. Mosselman. NCR Publication 42-2018  

Bregoli, F.; Crosato, A.; Paron, P; McClain, M. (2018) Altered sediment flux endangering the habitat of the Mara Wetland, Tanzania. Geophysical Research Abstracts, Vol. 20, EGU2018-14775, EGU General Assembly 2018

River engineering and morphodynamics

Sustainable river engineering can be achieved only by taking into account the river response to interventions on the short and long time. All changes made on water flow and river morphology trigger processes of sediment erosion and deposition in the river channel resulting in river bed and bank alignment adaptation. This inevitably involves also the upstream and downstream river reaches. Alterations of the river morphology manifest rather slowly and are often not taken into account in river engineering projects. However, they may negatively impact river services, such as the draining of flood waters, navigation, infrastructure, etc. The field of study quantifying these processes is called “river morphodynamics”. Riverbed shape, slope and bank alignment become variables and the river is treated as a fully-dynamic system. This allows predicting scours, bars, bank erosion, channel incision and many other phenomena and finding ways to mitigate them.
 
News
 
Main publications
Guillen-Ludena S., Cheng Z., Constantinescu G. & Franca M.J. (2017) Hydrodynamics of mountain-river confluences and its relationship to sediment transport, Journal of Geophysical Research - Earth Surface, 122, doi:10.1002/2016JF004122

Density currents

Density or gravity currents are geophysical flows driven by density differences between two contacting fluids. The either natural or anthropogenic occurrence of gravity currents is of great engineering relevance as it is often related to human and environmental safety. Pollutant spillage or outflows from desalinization plants or industrial cooling systems provoke density currents resulting from differences in both temperature and salinity of water. Turbidity currents resulting from landslide events can travel for long distances in water bodies destroying deep water installations. Additionally, sediment deposition from turbidity currents may, through geological time, form hydrocarbon reservoirs. Sediments deposited by turbidity currents have negative impacts on the sustainable use of reservoirs for hydropower production by clogging bottom outlets and intakes and by reducing reservoir storage. Moreover, buoyancy-driven flows play a key role in the horizontal and vertical distribution of fresh water, oxygen, nutrients, and carbon throughout lakes ecosystems.

Projects
PhD project Contribution of turbitidy currents triggered by bank erosion processes to reservoir sedimentation, student: Patricia Buffon. Funded by Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Ministerio da Educacao, Brazil

Main publications

Zordan J., Schleiss A.J. & Franca M.J. Structure of a dense release produced by varying initial conditions. Environmental Fluid Mechanics, doi: 10.1007/s10652-018-9586-8

Zordan J., Juez, C., Schleiss A.J. & Franca M.J. Entrainment, transport and deposition of sediment by saline gravity currents. Advances in Water Resources, 115, pp.17-32. https://doi.org/10.1016/j.advwatres.2018.02.017

Adduce C. & Franca M.J. Preface to the Special Issue on Environmental Buoyancy-driven Flows, Environmental Fluid Mechanics, 18: 1. https://doi.org/10.1007/s10652-017-9539-7

Pokrajac D., Venuleo S. & Franca M.J. Depth-averaged momentum equation for gravity currents with varying density: coefficient in pressure term, Journal of Hydraulic Research, doi: 10.1080/00221686.2017.1335245

Share

Connect with us

Never miss a thing!