Flood Impacts on Critical Infrastructure in a Coastal Floodplain in Western Puerto Rico during Hurricane María

Abstract

Flooding during extreme weather events damages critical infrastructure, property, and threatens lives. Hurricane María devastated Puerto Rico (PR) on 20 September 2017. Sixty-four deaths were directly attributable to the flooding. This paper describes the development of a hydrologic model using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA), capable of simulating flood depth and extent for the Añasco coastal flood plain in Western PR. The purpose of the study was to develop a numerical model to simulate flooding from extreme weather events and to evaluate the impacts on critical infrastructure and communities; Hurricane María is used as a case study. GSSHA was calibrated for Irma, a Category 3 hurricane, which struck the northeastern corner of the island on 7 September 2017, two weeks before Hurricane María. The upper Añasco watershed was calibrated using United States Geological Survey (USGS) stream discharge data. The model was validated using a storm of similar magnitude on 11–13 December 2007. Owing to the damage sustained by PR’s WSR-88D weather radar during Hurricane María, rainfall was estimated in this study using the Weather Research Forecast (WRF) model. Flooding in the coastal floodplain during Hurricane María was simulated using three methods: (1) Use of observed discharge hydrograph from the upper watershed as an inflow boundary condition for the coastal floodplain area, along with the WRF rainfall in the coastal flood plain; (2) Use of WRF rainfall to simulate runoff in the upper watershed and coastal flood plain; and (3) Similar to approach (2), except the use of bias-corrected WRF rainfall. Flooding results were compared with forty-two values of flood depth obtained during face-to-face interviews with residents of the affected communities. Impacts on critical infrastructure (water, electric, and public schools) were evaluated, assuming any structure exposed to 20 cm or more of flooding would sustain damage. Calibration equations were also used to improve flood depth estimates. Our model included the influence of storm surge, which we found to have a minimal effect on flood depths within the study area. Water infrastructure was more severely impacted by flooding than electrical infrastructure. From these findings, we conclude that the model developed in this study can be used with sufficient accuracy to identify infrastructure affected by future flooding events.

Hydrology in the Caribbean Basin

“…The paper "Flood Impacts on Critical Infrastructure in a Coastal Floodplain in Western Puerto Rico during Hurricane María" [4], by Said Mejia Manrique, Eric Harmsen, Reza Khanbilvardi, and Jorge Gonzalez, evaluates the depth and extent of impacts inflicted by floods on critical infrastructures and communities on the Añasco coastal flood plain in Western Puerto Rico in the aftermath of storm Maria. The team developed a numerical model based on GSSHA code that was forced using WRF-based hydro-climate variables to model various flooding scenarios: (1) The use of an observed discharge hydrograph from the upper watershed as an inflow boundary condition for the coastal floodplain area, along with the WRF rainfall in the coastal flood plain; (2) The use of WRF rainfall to simulate runoff in the upper watershed and coastal flood plain; and (3) the use of bias-corrected WRF rainfall.…”

Water and Energy Balance Model GOES-PRWEB: Development and Validation

“…The U.S. Forest Service and the National Integrated Drought Information System (NISDIS) uses soil moisture, soil saturation, and rainfall deficit information from the model for their bi-monthly reports in Puerto Rico and the USVI. Soil saturation from the model was recently used in a Hurricane María flood modeling study in western Puerto Rico ( [67]).…”

The global long-term effects of storm surge flooding on human settlements in coastal areas

“…By using a multivariate grid-cell-level-fixedeffects panel regression model at a resolution of 0.1 • , we analyze the responses of the populations in LECZ to storm surge flooding depth globally and regionally. We also investigate whether there are heterogeneous impacts of storm surge in terms of urban versus rural populations, as urban area infrastructure may be particularly vulnerable through impacts on drainage systems, electricity grids, and schools [34,35]. Furthermore, urban poor people tend to be overexposed to flood damage while for rural populations abundant land in rural areas can reduce their exposure [36][37][38].…”