Seasonality and multiannual variability of floods: case study from Eastern Poland

Abstract

Nowadays, under increasing climate change effects on the environment, we can observe increasing number of extreme phenomena, including meteorological and hydrological ones. One of such phenomena are floods. The objective of this article is the assessment of basic flood characteristics seasonality in the annual distribution. Analysis were performed based on time series of daily flow values recorded in the years 1951–2014 in three gauging stations located on rivers in Easter Poland, in upper Wieprz catchment. Floods were defined according to TLM algorithm and were assumed to be all cases of flow occurrence exceeding 10% read from FDC (flow duration curve) (Q10). Seasonality was analysed using Markham’s Seasonality Index and Period of Seasonal Concentration, analysis of autocorrelation function (ACF) as well as proposed by the author Seasonal Winter Floods Index. The distribution of floods during year indicates one flood season in year which occurs in the spring.