Influence of East and South Asian summer monsoons on runoff in the monsoon region of East China

The Variable Infiltration Capacity (VIC) model and the Mann-Kendall with LOWESS test are employed to evaluate the influence of East Asian summer monsoon (EASM) and South Asian summer monsoon (SASM) on runoff in the monsoon region of East China. The spatial variation of runoff coefficients in the region is also examined. The results indicate that the EASM-influenced area is much larger than the SASM-influenced area. EASM shows positive relationships with runoff in most area between Yangtze River and Songhua River, while negative EASM-runoff relationships are found in partial area of the South China. SASM shows positive and negative relationships with runoff in South China and partial areas of the upper Yangtze River basin, respectively. Moreover, the results indicate remarkable spatial disparities in runoff coefficients: it is a larger value for the Southeast Coast and the Yangtze River basin, and lower for the Yellow River and Haihe River basins. Understanding the relationships between EASM/SASM and the runoff has important implications in predicting the hydrologic change and water resources management in East China.