Research

Uncertain hydraulic roughness in river models

Short project description

Hydraulic–morphological river models are applied to design measures for purposes such as safety against flooding, navigation and ecological rehabilitation. Much effort has been put into the development of sophisticated numerical model system. These numerical models are all based on a deterministic approach, that is, the results are presented in terms of, for example, water levels, water depths, flow velocities and bed levels at a certain time and location. However, the modelling of river processes involves numerous uncertainties, resulting in uncertain model results. Knowledge of the type and magnitude of these uncertainties is crucial for a meaningful interpretation of the model results and to identify the usefulness of these results in decision making processes.

The explicit analysis of uncertainties in river models is a relatively new research field. In previous years attention has been paid to the methodological question of how to perform uncertainty analysis and to the effect of uncertain river discharge on estimated bed levels in particular (Van der Klis, 2003; Van Vuren, 2005). One of the main sources of uncertainty in modelled water levels is the uncertainty about the hydraulic roughness of the river bed (Chang et al., 1993; Van der Klis, 2003). Uncertain roughness affects the model results in several ways (Van Asselt, 2000; Van der Klis, 2003). Firstly, the roughness as model parameter varies in time and space and secondly, hydraulic roughness can be included in a model in several ways. The choice of this type of modelling affects the model results, thus inducing an uncertainty in the model results.

Knowledge of the type and magnitude of uncertainties in the hydraulic roughness gives insight in the application of hydrodynamic models for flood safety computations. Identification of the main sources of uncertainty in river models will result in knowledge on which uncertainties can be reduced. Therefore, the objective of this research is to quantify the effects of uncertain hydraulic roughness on the results of hydrodynamic river models used for flood safety computations, and assess methods for communication of uncertainties in model results to decision makers.

To reach the objective, an inventory of uncertainties in hydrodynamic models is conducted. The important uncertainties in roughness are quantified and their influence on the model results is assessed to yield the model uncertainty due to uncertain roughness. Finally, methods for communication of uncertain model results are assessed by conducting interviews with decision makers.

Persons involved

drs. Jord J. Warmink (PhD student)

dr. ir. Martijn J. Booij (daily supervisor)

dr. ir. Hanneke van der Klis (daily supervisor)

prof. dr. Suzanne J.M.H. Hulscher (promotor)

Publications [see ‘Publications’ for PDF-file or request free hard copy]

Goedhart, L., 2010. Presentation of uncertainty in model output to decision makers in flood management. MSc-thesis. University of Twente, Enschede.

Warmink, J.J. and Booij, M.J., 2015. Uncertainty analysis in river modelling. In: P. Rowiński and A. Radecki-Pawlik (Eds.), Rivers—Physical, Fluvial and Environmental Processes. Springer, Switzerland, 255-277, ISBN: 978-3-319-17719-9.

Warmink, J.J., Booij, M.J., Van der Klis, H. and Hulscher, S.J.M.H., 2007. Uncertainty in water level predictions due to various calibrations. In: Proc. International Conference on Adaptive and Integrative Water Management (CAIWA), 12-15 November 2007, Basel, Switzerland, 18 pp.

Warmink, J.J., Booij, M.J., Hulscher, S.J.M.H. and Van der Klis, H., 2010. Uncertainty in design water levels due to uncertain bed form roughness in the river Rhine. In: K. Koll, A. Dittrich, J. Aberle and P. Geisenhainer (Eds.), River Flow 2010. Proc. International Conference on Fluvial Hydraulics , 8-10 September 2010, Braunschweig, Germany. Bundesanstalt für Wasserbau, Karlsruhe, 359-366.

Warmink, J.J., Booij, M.J., Hulscher, S.J.M.H. and Van der Klis, H., 2010. Quantification of uncertain bed roughness under design conditions and propagation to the design water levels- a case study for the river Rhine. In: T.B.M.J. Ouarda (Ed.), Proc. 10th International Symposium on Stochastic Hydraulics (Water 2010), 5-7 July 2010, Quebec City, Canada. INRS-ETE, Quebec, 1-8.

Warmink, J.J., Booij, M.J., Van der Klis, H. and Hulscher, S.J.M.H., 2010. Combining different sources of uncertainty of design water level computations in the Dutch river Rhine. In: E. Stouthamer (Ed.), Proc. NCR-days 2010, 4-5 November 2010, Amsterdam, the Netherlands. NCR, Delft, 1-3.

Warmink, J.J., Booij, M.J., Van der Klis, H. and Hulscher, S.J.M.H., 2013. Quantification of uncertainty in design water levels due to uncertain bed form roughness in the Dutch river Waal . Hydrological Processes, 27, 1646-1663.

Warmink, J.J., Janssen, J.A.E.B., Booij, M.J. and Krol, M.S., 2010. Identification and classification of uncertainties in the application of environmental models. Environmental Modelling and Software, 25, 1518-1527.

Warmink, J.J., Straatsma, M.W., Huthoff, F., Booij, M.J. and Hulscher, S.J.M.H., 2013. Uncertainty of design water levels due to combined bed form and vegetation roughness in the Dutch River Waal. Journal of Flood Risk Management, 6, 302–318.

Warmink, J.J., Van der Klis, H., Booij, M.J. and Hulscher, S.J.M.H., 2008. Identification and quantification of uncertainties in river models using expert elicitation. In: A.G. van Os and C.D. Erdbrink (Eds.), Proc. NCR-days 2008, 20-21 November 2008, Dalfsen, the Netherlands, 40-41.

Warmink, J.J. , Van der Klis, H., Booij, M.J. and Hulscher, S.J.M.H., 2009. Quantification of uncertainty sources in a 2D hydraulic model for the river Rhine using expert opinions. Geophysical Research Abstracts, 11, 8627.

Warmink, J.J., Van der Klis, H., Booij, M.J. and Hulscher, S.J.M.H., 2009. Quantification of uncertainties in a 2D hydraulic model for the Dutch river Rhine using expert opinions. In: P.A. Lopez-Jimenez, V.S. Fuertes-Miquel, P.L. Iglesias-Rey, G. Lopez-Patino, F.J. Martinez-Solano and G. Palau-Salvador (Eds.), Environmental hydraulics. Theoretical, experimental and computational solutions. Proc. International Workshop on Environmental Hydraulics, IWEH09, 29-30 October 2009, Valencia, Spain. Taylor & Francis, London, 195-198.

Warmink, J.J., Van der Klis, H., Booij, M.J. and Hulscher, S.J.M.H., 2011. Identification and quantification of uncertainties in a hydrodynamic river model using expert opinions. Water Resources Management, 25, 601–622.