A synthesis of space-time variability in multicomponent flood response

Abstract

Catchment flood response consists of multiple components of flow originating from different surface and subsurface layers. This study proposes an extension of Viglione et al. (2010a) analytical framework to represent the dependence of catchment flood response to the different runoff generation processes. The analytical framework is compared to simulations from a distributed hydrologic model. A large number of rainfall-runoff events from three catchments of Tar River basin in North Carolina are used to illustrate the analytical framework. Specifically, the framework is used to estimate three flood event characteristics (cumulative runoff volume, centroid, and "spreadness" of hydrograph) through three corresponding framework parameters: the rainfall excess and the mean and variance of catchment response time. Results show that, under the smooth topographic setups of the study area, the spatial and/or temporal correlation between rainfall and runoff generation are insignificant to flood response; delay in flood response due to runoff generation and routing are of equal importance; the shape of the flood is mainly controlled by the variability in runoff generation stage but with non-negligible contribution from the runoff routing stage. Sensitivity tests show that the framework's main error source is the systematic underestimation of the flood event's centroid and spreadness, while the random error is relatively low.