Verification of the peak flow rates of the July 1997 flood in the upper and middle Odra river

Abstract

Aim of the study This paper presents a verification of peak discharges (maximum flow) of the great flood that took place in July 1997 on the Odra (Oder) river, for the section between Racibórz and Słubice. Material and methods The carried out analysis included a review of hydrological and morphological data, GIS analysis, extensive hydrodynamic two-dimensional modelling, and determination of rating curves for gauging stations. Results and conclusions It has been found that previously published peak discharges for the 1997 flood need to be altered to a significant extent. For instance, the maximum discharge in Wrocław is estimated to have reached ca. 3900 m3 ∙ s–1 versus 3640 m3 ∙ s–1 as previously believed, while for the upstream Nysa Kłodzka station, the maximum discharge estimate had to be raised from 3530 m3 ∙ s–1 to 4300 m3 ∙ s–1. On the other hand, for the section below Ścinawa station, the peak discharges were significantly overestimated, even by 1000 m3 ∙ s–1, which is up to 50% of the actual flow. The determined values are hydrologically and hydraulically consistent, i.e. following the law of flow continuity, considering tributary supplies, flood bank breaches, and retention capacity of the river valley.

Keywords

• the Odra river
• the July 1997 flood
• peak discharge
• rating curve
• 2-D hydrodynamic modelling