DBPapers
DOI: 10.5593/SGEM2014/B31/S12.062

MODELLING LARGE - SCALE HYDRODYNAMIC MODEL USING HEC-RAS

M . Podhoranyi, T. Kocyan, D. Fedorcak
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-13-1 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 1, 479-486 pp

ABSTRACT
The construction of accurate numerical hydrodynamic models is an important task for flood simulations. Accurate modelling is essential not only for flood simulations but also for detection of events that can cause damage on property or human lives. This work presents a comprehensive methodology for building of hydrodynamic model on large area (approx. 1000 km2). The model was built using 1-D hydrodynamic program HEC-RAS. Study area is Ostravica catchment (827.4 km2). Which is located in the north-east of the Czech republic. The study area was selected on the basis of the accessibility of topographic data and regularly repeated events. The model was subdivided into 24 unique schematizations which were joined with boundary conditions (mainly flow hydrograph or rating curve). Boundary conditions have been obtained from river stations which cover the whole catchment. Manning’s values, contraction and expansion coefficients were applied across the whole domain. Manning roughness coefficient was used in the Manning’s formula for flow calculation in open flow channels. Usual Manning’s value for channels in Czech Republic is 0.035. The values outside the river channel were derived from the land cover layer. Storage areas, bridges and other obstacles were included into hydrodynamic model as well. Calibration and validation were separated tasks and were carried out with separate data. The calibration phase was done using May 2010 flood event and the validation was done using August 2009 flood event. The results of the large-scale hydrodynamic model has shown that relatively good match with real state. Developed model may have following problems: problematic parameterization and to maintain all part on the same level of computational accuracy. The problems related to computational time are strongly depended on available hardware. The calibrated model provides a diagnostic tool for future analyses of flood events. Developed model will be incorporated into the Floreon+ system in the near future.

Keywords: hydrodynamic model, HEC-RAS, flood, modelling