Flooding is the leading cause of natural disaster losses in many regions worldwide, resulting in more damage than any other natural hazard. In recent decades, climate change has caused significant shifts in the global climate, leading to a rise in extreme weather events’ severity and frequency, such as floods. Szigetköz island, part of the Little Hungarian Plain in Hungary, is particularly significant for observing piping as a failure mechanism that can lead to levee breaches. This susceptibility originates from the area’s geology: a significant gravel layer lies beneath a relatively thin, heterogeneous, poor blanket layer. This paper presents the underseepage analysis based on an analytical method related to hydraulic failure in a specific Szigetköz floodplain area. A series of stability analyses focused on the variations in subsoil conductivity, thickness, and floodwater levels. The results indicated that the risk of hydraulic failure increases as the conductivity ratio increases. Consequently, the impact of the blanket layer thickness becomes less significant. These findings can be applied to other sections of the Szigetköz floodplain area to develop underseepage hazard maps and identify sections susceptible to hydraulic failure.