Investigating hydrologic responses to spatio‐temporal characteristics of storms using a Dynamic Moving Storm generator

Abstract

A synthetic storm generator—Dynamic Moving Storm (DMS)—is developed in this study to represent spatio‐temporal variabilities of rainfall and storm movement in synthetic storms. Using an urban watershed as the testbed, the authors investigate the hydrologic responses to the DMS parameters and their interactions. In order to reveal the complex nature of rainfall–run‐off processes, previously simplified assumptions are relaxed in this study regarding (a) temporal variability of rainfall intensity and (b) time‐invariant flow velocity in channel routing. The results of this study demonstrate the significant contribution of storm moving velocity to the variation of peak discharge based on a global sensitivity analysis. Furthermore, a pairwise sensitivity analysis is conducted to elucidate not only the patterns in individual contributions from parameters to hydrologic responses but also their interactions with storm moving velocity. The intricacies of peak discharges resulting from sensitivity analyses are then dissected into independent hydrologic metrics, that is, run‐off volume and standard deviation of run‐off timings, for deeper insights. It is confirmed that peak discharge is increased when storms travel downstream along the main channel at the speed that corresponds to a temporal superposition of run‐off. Spatial concentration of catchment rainfall is found to be a critical linkage through which characteristics of moving storms affect peak discharges. In addition, altering peak timing of rainfall intensity in conjunction with storm movement results in varied storm core locations in the channel network, which further changes the flow attenuation effects from channel routing. For future directions, the DMS generator will be embedded in a stochastic modelling framework and applied in rainfall/flow frequency analysis.

The Effect of Storm Direction on Flood Frequency Analysis

“…In general, the importance of storm direction in the peak flow response depends on the compounding effects of rainfall (e.g., storm extent, speed, duration, and intensity; Marco & Valdés, 1998; Singh, 2005) and watershed (e.g., geometry and river network structure) characteristics (Ayalew & Krajewski, 2017; Perez et al., 2018a). Based on these studies, the relationship between peak flow response and storm properties can be summarized in the following conclusions: (1) The effect of storm direction increases when the storm size is significantly smaller than the watershed size, and (2) the peak flow response tends to increase when the storm travels downstream along the main channel (Gao & Fang, 2019; Volpi et al., 2013).…”

“…From a mechanistic perspective, the role of storm direction in runoff generation has been explored with laboratory experiments (de Lima & Singh, 2003) and rainfall‐runoff modeling in natural and synthetic watersheds (C.‐L. Chang, 2007; Han et al., 2004; Kim & Seo, 2013; Seo & Schmidt, 2013, 2014) forced by real (Lee et al., 2015; Sigaroodi & Chen, 2016; ten Veldhuis et al., 2017) and synthetic (Fang et al., 2019; Gao & Fang, 2019, Nunes et al., 2006) storms. In general, the importance of storm direction in the peak flow response depends on the compounding effects of rainfall (e.g., storm extent, speed, duration, and intensity; Marco & Valdés, 1998; Singh, 2005) and watershed (e.g., geometry and river network structure) characteristics (Ayalew & Krajewski, 2017; Perez et al., 2018a).…”

Unveiling the Evolution of Extreme Rainfall Across Space and Time in a Warming Climate

“…manuscript submitted to AGU's Earth's Future While mounting evidence supports the increase in intensity and frequency of extreme storms in a warming climate, there is a lack of holistic understanding of changes in spatiotemporal patterns of these storms. Such insights about the spatio-temporal pattern of storms are pivotal for accurate flood behavior simulation (Gao & Fang, 2019;Ogden & Julien, 1993;Shah et al, 1996;V. P. Singh, 1997).…”