Investigating the Effect of Spatial and Temporal Variabilities of Rainfall on Catchment Response

This study investigates the influence of rainfall variability in time and space, as well as the location of storm center, on catchment outflow hydrograph. Synthetic data of over 600 rainfall events were generated for the Walnut Gulch catchment in Arizona using two rainfall generation models. After calibrating the distributed MIKE-SHE rainfall-runoff model for a sub-catchment in the basin, we subsequently used it to simulate the entire catchment behavior by employing the generated synthetic rainfall data with predetermined characteristics. The findings demonstrate that the storm center location has a significant impact on the characteristics of the outflow hydrograph, with closer proximity to the outlet resulting in increased peak magnitude and decreased time to peak. The spatiotemporal resolution of the monitoring network also affects the hydrograph characteristics, particularly the peak magnitude, with lower resolutions leading to underestimation of peak and overestimation of time to peak. The impact of spatial resolution on hydrograph characteristics increases as the correlation of rainfall events in space decreases. However, the effect of rainfall temporal resolution on catchment response remains almost consistent regardless of temporal correlation. Ultimately, the results imply that accurate estimation of the outflow hydrograph requires a monitoring network with relatively high spatial and temporal resolutions.