Volume XV |

Temporal rainfall properties at events scale in the Curvature Subcarpathians (Romania)

Abstract: Characteristics of rainfall events (RE) play a determinant role in the hydrologic process in a small catchment (e.g., runoff formation, flood elements), water balance and water resource management. The goal was to investigate temporal rainfall properties at events scale. The study was based on long-term properties of rainfall events (e.g., depths, intensities), recorded in the warm semester (the period between 1 April and 30 September; 1980-2010) at Voinești Experimental Basin (VEB), Romania. Rainfall events values were recorded by a pluviograph, production of the former USSR. The rain gauge is situated at the central place of the VEB (altitude 500 m a.s.l.), in Curvature Subcarpathians. A valuable database with 1852 rainfall events characteristics was created. The depths (mm) and durations (min) of each RE were recorded and rainfall maximum and average intensities (mm/min) were calculated. Rainfall events were characterized by small depth (up to 15.7 mm; up to 90th percentile) ~ 93% and they were concentrated (34.4%) in May. Almost half of RE (48.2%), had short duration (up to one hour) and the smallest depth (95% confidence interval, 3.85–4.56 mm), while those with durations longer than 5 hours (10.5%) were specific the September (22.5%). Regarding maximum intensities of rainfall events, just 16 events exceeding 1 mm/min (0.86%), which denote insignificant occurrence – encountered phenomenon in all months, especially in August – and mild torrential character. Insignificant rainfall events correlations between rainfall parameters were observed. Just “time – depth” correlation has been notable (Pearson’s r: 0.631). Absolute frequency of rainfall events parameters in most cases shows a strong density of smallest interval. These results may have important implications for next runoff plot study.