The 1903 flood was undoubtedly one of the most significant floods of the 20th century in Moravia and Silesia. Although systematic observa-tions of water levels had already begun at many gauging sites during this period, it is difficult to convert historical water levels recorded at limnigraph stations into present-day equivalents due to historical territorial changes in terms of politics (Prussia versus the present-day Czech Republic), landscape structure (forest cover in the historical and present-day landscape), morphology (terrain and urban development in the affected areas), and water management conditions (the course of the Opava river channel and the condition of water flumes in 1903 and today). Useful (though not always entirely reliable) sources include historical flood marks, photographic documentation, historical maps and plans, reports in the contemporary press, family chronicles, and the recollections of millers, sawyers, and other craftsmen using water power. These sources form a rather heterogeneous body of evidence, and it is therefore necessary to find ways to verify and combine them. One possible approach is to use these data in GIS-based spatial analyses and subsequently as inputs for rainfall–runoff and hydraulic model-ling. Since the team of the Czech Hydrometeorological Institute (CHMI), together with its partners, had already conducted similar analyses (e.g. during the reconstruction of the 1872 historical flood on Blšanka), they also attempted to apply this approach to the 1903 flood on the Opava river. The results, including a partial uncertainty analysis, are presented in this article.
