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Volume XIV |

Rainfall deficit and excess within Oltenia region, Romania (1961-2020)

Abstract: Temporary rainfall deficit and excess impact both the natural environment and economic activities. Although rainfall does not display significant upward or downward trends in Central and Eastern Europe, global warming is expected to increase variability and associated risks. Thus, determining the annual and seasonal deviations of precipitation amounts at local scale is important in order to establish accurate trends of precipitation deficit and excess. We used 60-year time series (1961-2020) for 15 meteorological stations and a shorter series for one station (i.e., Slatina). The Standardized Precipitation Anomaly (SPA) indicates a predominance of normal years (32-50%), followed by dry and humid years, without an obvious latitudinal and altitudinal differentiation, while De Martonne aridity index (IaDM) emphasizes a latitudinal pattern: predominance of semi-humid years in the southern plain area, humid years in the northern plain area and the Getic Piedmont, very humid years in the Subcarpathians and extremely humid years in the mountains. Water deficit (IsDM < 20mm/°C) mainly affects the plain area during summer and autumn (50-60% of the seasons are arid and semiarid), but also the piedmont, where the share varies between 30 and 35%. Mann-Kendall (MK) test reveals the same pattern for annual values, namely, predominantly negative trends (statistically significant in the southwestern part of the region), which indicate an increase of both aridity and drought, including the higher hilly and mountain area. At seasonal level, autumn is the only period with positive, but not statistically significant trends, while in winter, spring and summer, trends are negative and statistically significant at certain stations. Consequently, drought-associated risks are projected to increase in the near future.