Using Storm Transposition to Investigate the Relationships between Hydrologic Responses and Spatial Moments of Catchment Rainfall

Abstract

The dependence between spatiotemporally varied rainfall and watershed hydrology has long been recognized and studied using either synthetic or real storms/watersheds. To examine the relationship, the authors apply the storm transposition technique to reposition three historical storm events over the Brays Bayou watershed in Houston, Texas. Transposing various storms generates a large variety of rainfall-runoff scenarios that exhibit distinct patterns in peak discharge and runoff volume. Furthermore, the authors use spatial statistics (termed spatial moments) to characterize catchment rainfall relative to the geometry of channel network and interpret the identified patterns in hydrologic responses. This study uses multivariate linear regression to quantitatively represent the relationship between peak discharge (dependent variable) and spatial moment of catchment rainfall (independent variables). The dispersion of catchment rainfall is found to influence the patterns in peak discharge; as catchment rainfall becomes more concentrated, the inverse correlation between peak discharge and the flow distance of catchment rainfall centroid becomes more pronounced. The insights gained from this study will benefit future research in hydrologic analyses and prediction of rainfall-induced hazards, especially determining critical factors in the hydrologic responses during natural disasters such as Hurricane Harvey in 217.