Adverse Health Outcomes Following Hurricane Harvey: A Comparison of Remotely-Sensed and Self-Reported Flood Exposure Estimates

Abstract

Remotely sensed inundation may help to rapidly identify areas in need of aid during and following floods. Here we evaluate the utility of daily remotely sensed flood inundation measures and estimate their congruence with self-reported home flooding and health outcomes collected via the Texas Flood Registry (TFR) following Hurricane Harvey. Daily flood inundation for 14 days following the landfall of Hurricane Harvey was acquired from FloodScan. Flood exposure, including number of days flooded and flood depth was assigned to geocoded home addresses of TFR respondents (N = 18,920 from 47 counties). Discordance between remotely-sensed flooding and self-reported home flooding was measured. Modified Poisson regression models were implemented to estimate risk ratios (RRs) for adverse health outcomes following flood exposure, controlling for potential individual level confounders. Respondents whose home was in a flooded area based on remotely-sensed data were more likely to report injury (RR = 1.5, 95% CI: 1.27-1.77), concentration problems (1.36, 95% CI: 1.25-1.49), skin rash (1.31, 95% CI: 1.15-1.48), illness (1.29, 95% CI: 1.17-1.43), headaches (1.09, 95% CI: 1.03-1.16), and runny nose (1.07, 95% CI: 1.03-1.11) compared to respondents whose home was not flooded. Effect sizes were larger when exposure was estimated using respondent-reported home flooding. Near-real time remote sensing-based flood products may help to prioritize areas in need of assistance when on the ground measures are not accessible.

Keywords: Hurricane Harvey; adverse health outcomes; disaster recovery; flood exposure assessment; remote sensing; self‐reported versus remote‐sensed flood exposure.

Figure 1

Study area as defined by counties of residence of Texas Flood Registry respondents. The map shows the percentage of respondents in each county or Census tract that reported their home to be flooded following Hurricane Harvey landfall. The main map shows the county‐level percentage of reported home flooding, and the enlarged map shows the same information at the Census tract level.

Figure 2

Discordance between respondent‐reported home flooding and remotely‐sensed home location flooding. Discordance determined at address level were aggregated as hexagons (area of 8,750 km2). Hexagons that contained less than five respondents are color coded with gray (NA) to protect identifiable information.

Figure 3

Risk ratio for association between self‐reported symptoms/injury/hospitalization and exposure to floods determined using flood map or respondents' self‐report (home flooding, other homes in the block flooded, and water contact).

Figure 4

Risk ratio for association between flood depth/number of days of flooding/distance to flood waters determined using flood map and the self‐reported injury/symptoms. Reference category for flood depth and number of days is 0 (non‐flooded); and reference category for flood distance was “>1,100 m” (far away from flood). The outcome hospitalization was not analyzed due to sparse records (<15) in some combinations of the binary outcome and exposure categories.