Assessment of flash flood susceptibility potential in Moldavian Plain (Romania)

Concentration of time (Tc) is a frequently used parameter in the evaluation of the hydrological response of different sizes hydrographic basin in case of rainfall events. The present study is innovative, because it has created an index that identifies the small‐sized hydrographic basins that are exposed to the risk of flooding. The Moldavian Plain is an area located in the northeast of Romania where the local population is frequently affected by floods and flash floods caused by heavy rainfall events. The main purpose of the current study is to identify the settlements located in the small‐sized hydrographic basins, which are associated with low concentration times and powerful surface runoff. The empirical method was applied in order to calculate the Tc for rainfall water, for each drainage basin, for a time class less than 6 hr. Calculations of the runoff water were also done for a theoretical extreme precipitation event, corresponding to the 1% occurrence probability. A total number of 312 basins were identified that are smaller than 30 km2, out of which 112 have Tc of less than 6 hr. These basins, in particular, pose flood risk for 12.4% of the villages and towns in the study area.