Dynamic Modeling of Surface Runoff and Storm Surge during Hurricane and Tropical Storm Events

Abstract

Hurricane events combine ocean storm surge penetration with inland runoff flooding. This article presents a new methodology to determine coastal flood levels caused by the combination of storm surge and surface runoff. The proposed approach couples the Simulating Waves Nearshore model and the Advanced Circulation (ADCIRC) model with the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) two-dimensional hydrologic model. Radar precipitation data in a 2D hydrologic model with a circulation model allows simulation of time and spatially varied conditions. The method was applied to study flooding scenarios occurring during the passage of Hurricane Georges (1998) on the east coast of Puerto Rico. The combination of storm surge and surface runoff produced a critical scenario, in terms of flood depth, at this location. The paper describes the data collection process, circulation and hydrologic models, their assemblage and simulation scenarios. Results show that peak flow from inland runoff and peak flow due to storm surge did not coincide in the coastal zone; however, the interaction of both discharges causes an aggravated hazardous condition by increasing flood levels beyond those obtained with storm surge penetration only. Linking of storm surge and hydrologic models are necessary when storm surge conditions occur simultaneously with high precipitation over steep and small coastal watersheds.

Defining Flood Zone Transitions in Low‐Gradient Coastal Regions

“…Across Puerto Rico, Hurricane Maria produced over 760 mm of rain and up to 3 m of storm surge. These types of coastal flood events can affect the livelihood of resource-rich coastal communities (Rueda et al, 2017) and point to the need to consider the combined effects of rainfall excess and storm surge (Wahl et al, 2015).…”

“…Deterministic models of storm surge and rainfall runoff have been combined in a geographic information system framework to quantify their combined hazard and exposure (Thompson & Frazier, ). Other numerical modeling studies have shown that the combined effects of freshwater river discharge and rainfall runoff, including their timing, increase the magnitude of inland flooding (Chen & Liu, ; Ray et al, ).The integration of hydrodynamic and hydrologic models have resulted in more accurate simulations of peak water levels, extent of inland flooding, and surge recession during tropical cyclones (Bacopoulos et al, ; Silva‐Araya et al, ).…”

Baroclinic Coupling Improves Depth‐Integrated Modeling of Coastal Sea Level Variations Around Puerto Rico and the U.S. Virgin Islands

“…These improvements could help refine flood risk warning metrics in operational forecast models particularly if coastal sea levels are close to a flood tipping point. Furthermore, while the effects of wind waves (Joyce et al, ) and compound flooding (Silva‐Araya et al, ) that were not considered here are particularly critical to PRVI, both of these processes are dependent on background sea levels which have improved representation through baroclinic coupling. In future work we aim to combine wind waves and hydrological coupling effects into the analysis, and extend the 2DDI‐BC model to mild‐sloped wide‐shelved areas such as the U.S. Atlantic and Gulf Coasts, where climatic and oceanographic variability is larger than in the Caribbean, to more thoroughly assess its capabilities and limitations.…”

“…The 2DDI‐BT models can simulate a large proportion of such coastal sea level variations by accounting for the barotropic response to astronomical and meteorological forcing (Carrére & Lyard, ). Also, while yet to be implemented into operational forecasting, 2DDI‐BT ADCIRC models have been coupled to hydrological models to account for rainfall and river flooding effects in a number of studies (Bacopoulos et al, ; Dresback et al, ; Van Cooten et al, ), including most recently in PRVI (Silva‐Araya et al, ). However, the effects of seasonal warming and cooling cycles, baroclinically driven ocean currents, upwelling events, and fresh‐saline water interactions cannot be accounted for.…”

Storm Surge Propagation and Flooding in Small Tidal Rivers during Events of Mixed Coastal and Fluvial Influence

“…In other locations where storm surge can be larger and the tidal range is smaller, these results indicate that the impacts of storm surge will be felt much further upstream. For example, along the Gulf Coast of the United States, which is considered microtidal (tidal range <1 m) [53], hurricanes and tropical storms can create surges of 5 m or more (Hurricane Katrina had surges of 7-10 m [54]). In locations like this, we would anticipate coastally driven water levels to propagate further up a tidal river, making the need for integrated modeling even more important than that of the San Francisco region.…”