Reconstruction of floods in Poland in the pre-instrumental period (1001-1800)

Abstract

A reconstruction of historical floods in Poland in the 11th–18th centuries was carried out based on a comprehensive database of documentary evidence. For this period, we collected more than 1700 weather notes describing floods. The quality of each source containing weather notes was estimated. Only the most reliable sources were used for the analysis of flood occurrences and their characteristics. For the classification of flood intensity, the two most commonly used propositions for European rivers (Barriendos and Coeur 2004; Brázdil et al. 2006) were used. The origins of floods were evaluated based on the classification presented by Lambor (1954). The results showed that the highest number of floods in Poland in the study period occurred in the 16th century (294 cases). The number of floods in the 11th–15th, 17th, and 18th centuries were 166, 284, and 272, respectively. Most of the floods were recorded in the Oder River basin and Silesia region (western and south-western Poland). The evaluation of the intensity of floods revealed that most of the floods belong to the “above-average, or supra-regional flood” category according to the Brázdil et al. (2006) classification and the “extraordinary” category for the Barriendos and Coeur (2004) classification. The assessment of the main origin of floods demonstrated that rain and its sub-types (torrential, frontal, long-lasting, territorially widespread) constituted the main cause of floods in Poland in the 11th–18th centuries. The findings of this study will improve existing knowledge of historical hydrology in Europe and Poland before the 19th century.  The work was supported by the National Science Centre, Poland, project No. 2020/37/B/ST10/00710.