Geographia Technica, Vol 19, Issue 1, 2024, pp. 103-120
EXTREME RAINFALL INTENSITIES AT SUB-HOURLY TEMPORAL SCALE IN DOBRUDJA (ROMANIA)
Adrian IRAȘOC 
, Nicoleta IONAC , Alexandru DUMITRESCU , Andreea BETERINGHE
ABSTRACT: This study presents a statistical analysis of maximum precipitation amounts at different time intervals in Dobrudja - a historical region in Romania, with semi-arid mid-latitude climate, spanning over the entire historical period of measurements available for each weather station taken into consideration. The data provided by the National Meteorological Administration have different time spans for each weather station, starting with 1948 (at Constanţa weather station). Two methodologies were used for data recording: the pluviographs being used during the last century, and the automatic weather sensors, which have been introduced into general use starting with 2008. In this study, a sub-hourly temporal scale was used to estimate extreme rainfalls: 5, 10, 15, 20, 25, 30 minutes. Then, the corresponding evolution trends were calculated over the entire period of reference (1948-present day), with Mann-Kendall and Sen’s slope tests being applied (cases with p-level < 0.05 have been considered statistically significant). The probability for extremely high rainfall amounts to occur in very short periods of time and consequently, the resulting rainfall intensities have also been computed by means of Gumbel distribution. Our findings show that, despite rather scarce rainfall amounts, mostly due to the prevalent mid-latitude semi-arid conditions (the annual rainfall amounts in Dobrudja hardly exceed 400 mm/year), when occurring, they turn into downpours, mounting up to 21 mm in 5 minutes (two events exceed 20 mm) and sometimes 10 mm in one minute (one event).
Keywords: extreme precipitation, rainfall intensity, trend analysis, Gumbel, IDF curves, Dobrudja (Romania).
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