Analysis of precipitation extremes related to agriculture and water resources sectors based on gridded daily data in Romania

Climate change is one of the most frequent topics in climatic literature over the last three decades. One of the significant concerns with a potential change in climate is that extreme events will occur with a higher frequency. This paper focuses on spatial distribution and changes that occurred in extreme precipitation indices in Romania over a 53-yr period: 1961–2013. Gridded daily precipitation data have been used at a spatial resolution of 0.1° × 0.1° (about 11 km × 11 km). A set of 14 indices established by the Expert Team for Sector-Specific Indices for agriculture and water resources sectors has been calculated. They are both frequency and intensity indices: four are fixed threshold indices (R10, R20, CDD, and CWD), four are station-related thresholds (R95p, R99p, R95pTOT, R99pTOT), and six indices were detected without using a threshold (Rx1day, Rx3days, PRECPTOT, SDII, SPI, SPEI). The study’s main finding is that most of the indices registered increasing trends but not statistically significant at the country level. The only exceptions are the drought-related indices (CDD, SPI, and SPEI), for which we found a dominant decreasing trend. In the northern half of the country, increasing trends were prevailing, and in the southern one, those decreasing registered a broader spatial coverage. SPI and SPEI recorded mainly significant changes: SPI trends are almost equally divided between increasing and decreasing. For SPEI, more than 70% of the country was characterized by a significant decrease.