Figure 12

The correlation analysis results (a) the Kendall Rank Correlation Coefficient for low frequency components; (b) the Kendall Rank Correlation Coefficient for high frequency components. The higher the value of the Kendall Rank Correlation Coefficient, the higher the correlation between the variables. Therefore, the low frequency components within previous 9 days are all highly correlated with the current low frequency component. The previous average rainfall has high to medium correlation with the rate of the current low frequency component, while the daily rainfall has low to medium correlation with the rate of the current low frequency component. The high frequency component at current time t is moderately correlated with the rainfall at current time and within previous 4 days, while is relatively low correlated with the previous high frequency component.