Hydrometeorological Analysis of Tropical Storm Hermine and Central Texas Flash Flooding, September 2010

Abstract

Heavy rainfall and flooding associated with Tropical Storm Hermine occurred on 7-8 September 2010 across central Texas, resulting in several flood-related fatalities and extensive property damage. The largest rainfall totals were received near Austin, Texas, and immediately north, with 24-h accumulations at several locations reaching a 500-yr recurrence interval. Among the most heavily impacted drainage basins was the Bull Creek watershed (58 km 2 ) in Austin, where peak flows exceeded 500 m 3 s 21 . Storm cells were trained over the small watershed for approximately 6 h because of the combination of a quasi-stationary synoptic feature slowing the storm, orographic enhancement from the Balcones Escarpment, and moist air masses from the Gulf of Mexico sustaining the storm. Weather Research and Forecasting Model simulations with and without the Balcones Escarpment terrain indicate that orographic enhancement affected rainfall. The basin received nearly 300 mm of precipitation, with maximum sustained intensities of 50 mm h 21 . The Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model was used to simulate streamflow from the event and to analyze the flood hydrology. Model simulations indicate that the spatial organization of the storm during intense rainfall periods coupled with surface conditions and characteristics mediate stream response.

Assessment of the Performance of Satellite-Based Precipitation Products for Flood Events across Diverse Spatial Scales Using GSSHA Modeling System

“…The Texas Hill Country is one of the most flash flood-prone areas of the entire United States due to its flood-prone physiography and susceptibility to extreme precipitation [38,39]. Although not considered among the very humid regions of the U.S., proximity to the Gulf of Mexico allows for extremely moist tropical air masses to reach the Balcones Escarpment where they can be subjected to orographic lift [40]. The region holds or has held several precipitation world records on time scales less than 24 h (USGS 2014).…”

“…All of the storm event accumulations from the Stage IV precipitation record are presented in Figure 2. The hydrometeorology of several of these events has been examined in detail including Furl, Sharif [42] (May 2015 event), Furl, Sharif [40] (September 2010 event), and Sharif, Sparks [36] (November 2004 events). Total accumulations from stage IV data for individual storm events used in the analysis (mm).…”

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

“…To make informed decisions in proactive response to water‐related hazards and risks, it is imperative to fully understand the sensitive nature of hydrologic responses from the spatio‐temporal characteristics of storms. This subject has motivated tremendous research effort undertaken by hydrologists and meteorologists (e.g., Borga, Boscolo, Zanon, & Sangati, ; Furl et al, ; Rozalis, Morin, Yair, & Price, ; Segond, Wheater, & Onof, ; Smith et al, ; Tarolli et al, ; Zhou, Long, Liu, & Smith, ). Therefore, in hydrologic modelling, identifying key elements in rainfall input, such as storm movement and spatio‐temporal variability, is paramount to run‐off calculation.…”

Physically, Fully-Distributed Hydrologic Simulations Driven by GPM Satellite Rainfall over an Urbanizing Arid Catchment in Saudi Arabia

“…Since the hydrological response of a basin is very sensitive to the spatio-temporal variability in various physical attributes of soil, land use, and topography, hydrological models that consider the spatial variability are better suited for accurate flood simulation and predictions [23][24][25]. Distributed hydrologic models can also provide a detailed description of the flood hazard areas, especially in urban catchments [26].…”

“…Sharif et al [29] successfully applied the GSSHA model to evaluate the effect of flood control structures on stream discharge in urbanized watersheds. Furl et al [23] used the model to describe the flood hydrology of a small urbanized basin in Austin, TX. Chintalapudi et al [30] used the GSSHA model to study the effect of land cover changes on peak discharge and runoff volumes with simulations driven by satellite rainfall products.…”