Effects of rainfall spatial distribution on the relationship between rainfall spatiotemporal resolution and runoff prediction accuracy

We studied how rainfall spatial distribution affects the relationship between rainfall spatiotemporal resolution and runoff prediction accuracy under real field conditions. We gathered radar rainfall and discharge data for three rainfall events. These rainfall-runoff events were then reproduced using a kinematic wave model. Modeling accuracy was estimated quantitatively using the Nash-Sutcliffe model efficiency coefficient and peak discharge ratio. Normalized root-mean-square error (nRMSE), skewness (S_k), and second scaled spatial moment of catchment rainfall (δ₂) were employed to quantify rainfall spatial distribution characteristics. By relating the accuracy of modeling results to the rainfall spatial characteristics using various rainfall spatiotemporal resolutions, we found that the modeling results converged to a value as the nRMSE, S_k and 1 - δ₂ decreased. That is, rainfall spatial distributions affect the relationship between lower limit of rainfall spatiotemporal resolution for runoff models and runoff prediction accuracy.