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PhD Defence Matthijs Gensen | Discharge and water level uncertainty in bifurcating rivers

Discharge and water level uncertainty in bifurcating rivers

Due to the COVID-19 crisis the PhD defence of Matthijs Gensen will take place (partly) online.

The PhD defence can be followed by a live stream.

Matthijs Gensen is a PhD student in the research group Marine and Fluvial Systems (MFS). His supervisor is prof.dr. S.J.M.H. Hulscher from the Faculty of Engineering Technology (ET).

Accurate predictions of water levels, discharges and their uncertainties are essential for flood risk management of rivers. Previous studies on the accuracy of water level predictions have only been performed for single-branch rivers. The aim of this thesis is to quantify water level uncertainties in a bifurcating river system. This is achieved by both hydraulic modelling and by data analysis.

The thesis shows that the bifurcation balances out water level variations between the branches. Such variations may originate from uncertainties in hydraulic roughness of the river bed or from changes in the geometry through human intervention. The physics of a bifurcation thus significantly affect system-wide water levels and water level uncertainties, and therefore need to be accounted for to accurately estimate water levels and discharges. Observations of discharges and water levels are required for accurate hydraulic modelling and for data analysis, but errors in such observations may limit the accuracy of the hydraulic models and of the data analysis. Methods have been proposed to be able to decrease this limitation.