Geographia Technica, Vol 21, Issue 1, 2026, pp. 127-144
SUB-HOURLY PRECIPITATION EXTREMES IN ROMANIA AND THEIR LONG-TERM TEMPORAL TREND
Adrian IRAȘOC 
, Nicoleta IONAC , Andreea BETERINGHE , Alexandru DUMITRESCU
ABSTRACT: Sub-hourly precipitation extremes represent a critical aspect of climate variability, particularly in regions prone to convective storms. This study analyzes the climatology and trends of extreme short-duration rainfalls in Romania, by using high-resolution precipitation data from 107 weather stations. We computed five sub-hourly precipitation indices (Rx5min, Rx10min, Rx20min, Rx30min, and Rx1hr) and assessed their temporal trends by using the Mann-Kendall test and Theil-Sen’s slope estimator. Our results reveal substantial spatial variability in extreme sub-hourly precipitation amounts, with values mounting up to 29.3 mm in 5 minutes and 106.3 mm in one hour. Significant increasing trends are observed in several regions, particularly in areas influenced by Mediterranean cyclones and cut-off low-pressure systems. However, decreasing trends are also present, notably in the Curvature Subcarpathian Hills, where foehn effects may suppress convective activity. These findings highlight the importance of high-resolution precipitation data for understanding extreme rainfall trends, as sub-hourly indices exhibit distinct patterns as compared to daily-scale analyses. Given Romania’s vulnerability to flash floods, the observed intensification of short-duration precipitation requires enhanced flood risk management and adaptation strategies.
Keywords: Sub-hourly precipitation; Heavy rainfall; Pluviograph, Trend analysis
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