Effect of rainstorm structure on runoff
Description
Figures, Table and appendix for the article "Effect of rainstorm structure on runoff" Rainfall-infiltration-runoff interactions are highly sought-after, because forecasted climatic changes may increase flood and erosion risks. The main question arising in this context is why the increase in extreme rainfall events is not always translated into an increase in flood events. To answer this question, it is necessary to investigate the effects of temporal distribution of rainfall intensities during rainfall events, and of antecedent water content in the soil profile, on runoff generation and accumulation. This study shows how temporal patterns of individual rainstorms affect runoff formation under different antecedent soil water content conditions. We simulated the runoff outcome of rainfall time series characterized by different statistical moments (mean, standard deviation and skewness) on a Mediterranean loamy soil. The results show that ponding time and time to peak runoff decreased with mean rainfall rate and standard deviation, and increased with storm skewness and as the soil profile was drier. Also, total runoff increased with the mean rainfall rate standard deviation of temporal distribution of storm intensity. However, maximal total runoff was obtained for storms with temporal distribution skewness close to zero, and as the antecedent soil water content was higher. This was even more pronounced when the storm was characterized by high maximal rainfall rate. The overall result was that runoff coefficient increased with mean rainfall rate and standard deviation but was not affected by skewness. Peak runoff was highly correlated to maximal rainfall rate, and time to peak runoff, to time to maximal rainfall rate.