Spatial Variability and Periodicity of Precipitation in the Middle Reaches of the Yellow River, China

Rainfall is one of the most important reasons causing the soil erosion in the Loess Plateau. The precipitation across the most severely eroded areas in middle reaches of the Yellow River (MRYR), China, was investigated by analyzing the precipitation of flood season (P-f) and precipitation of main flood season (P-mf) from 26 meteorological stations during the period from 1958 to 2013. The empirical orthogonal function (EOF), ensemble empirical mode decomposition, and Hurst exponent are used to detect spatial, multiscale characteristics of periodicity and trend for precipitation. The results show that there exist quasi-3-and quasi-6-year interannual periods and quasi-11-and quasi-28-year interdecadal scale periods for P-f and P-mf. However, periodical features in most of the study area are not statistically noticeable. Moreover, first EOFs indicated precipitation was affected by the large-scale circulation patterns, and the spatial patterns of the second EOFs indicated an obviously north-south gradient in the MRYR, whereas the third EOFs displayed east-west patterns. Hurst exponent analysis indicates that precipitation in P-f and P-mf will continue the current trends in the future. These findings can provide important implications for ecological restoration and farming operations across the study region.