Severe floods in Nemunas River Delta

The river delta regions are usually most vulnerable to flooding due to small changes in terrain elevation and river – sea interaction. The trends of increased frequency of flooding and an increased duration of the high water events are evident in many regions. In this study, we analyse the most extreme (severe) flood events in the Nemunas Delta region of Lithuania. The study focuses on the causes of floods and their changes over 1926–2016. Analysing specific case studies and comparing them with related studies of other researchers, we present an original interpretation of the variability of flood parameters. The aim of the study is to demonstrate that the analysis of flood events must be based on the identification of the drivers of individual floods. This is especially true for the lower reaches and the delta regions of rivers situated within the North European Plain. Historically, an intense melting of snow appeared to be the main cause of severe flooding in this region. The results of this study, however, show that the situation has rapidly changed over the last 30 years and large areas can be flooded even if the snow water equivalent over the whole basin is relatively low.