A comprehensive analysis of spatial and temporal variability of extreme precipitation in the Nenjiang River Basin, Northeast China

Better investigation of extreme precipitation in large river basins is important for hydro-meteorological research and water resources management. Based on daily precipitation data from 17 national meteorological stations in Nenjiang River Basin (NRB) during 1959–2011, spatial-temporal characteristics and trends of seven extreme precipitation indices were analyzed in this study using Mann-Kendall non-parametric test and the ensemble empirical mode decomposition (EEMD) method. We found that almost all selected extreme precipitation indices declined in regionally averaged values, except maximum 5-day precipitation amount (Rx5day). Both extreme precipitation indices and their trends demonstrated spatial varieties. Generally, lower basin obtained less extreme precipitation and tended to be drier. But the amount and intensity of extreme precipitation in upper basin, where are more humid, are rising. Extreme precipitation indices presented apparent non-linear process with periodic oscillations of 1.63–1.94a for IMF1 to 25–31a for IMF4. The findings of this study are useful for the management of water resources in NRB, as well as provide reference information for precipitation evolution under climate change in other regions.