Flood risk in past and future: A case study for the Pawtuxet River's record-breaking March 2010 flood event.

Soroush Kouhi,Isaac Ginis,Matthew Lewis,Malcolm Spaulding,Rozita Kian,M Reza Hashemi

doi:10.1111/jfr3.12655

Soroush Kouhi, Isaac Ginis + Show 4 more

Open Access

https://doi.org/10.1111/jfr3.12655

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Abstract

In March 2010, a sequence of three major rainfall events in New England (United States) led to a record-breaking flooding event in the Pawtuxet River Watershed with a peak flow discharge of about 500-year return period. After development of hydrological and hydraulic models, a number of factors that played important roles in the impact of this flooding and other extreme events including river structures (reservoirs, historical textile mill dams, and bridges) were investigated. These factors are currently omitted within risk assessments tools such as flood insurance rate maps. Some management strategies that should be considered for future flood risk mitigation were modeled and discussed. Furthermore, to better understand possible future risks in a warmer climate, another extreme flood event was simulated. The synthetic/hypothetical storm (Hurricane Rhody with two landfalls) was created based on the characteristics of the historical hurricanes that severely impacted this region in the past. It was shown that while the first landfall of this hurricane did not lead to significant flood risk, the second landfall could generate more rain and flooding equivalent to a 500-year event. Results and the methodology of this study can be used to better understand and assess future flood risk in similar watersheds.

Highlights

River flooding is a major cause of catastrophic loss in the United States and around the world
Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS), Hydrologic Engineering Center's River Analysis System; USGS, United States Geological Survey lead to errors in estimation of discharge; this uncertainty cannot be addressed by adjusting the parameters of rainfall-runoff model
Due to similarities of this case study and other watersheds in the northeast of the United States and elsewhere, these results will be of interest of flood management researchers and decision makers

Summary

| INTRODUCTION

River flooding is a major cause of catastrophic loss in the United States and around the world. Trends in average and extreme precipitation due to climate change can affect the flood risk It is not clear how these factors can change the estimated flood risk (e.g., 500 and 100 years) which are used in FEMA FIRMs. In the Eastern United States, in addition to winter and spring storms, wet hurricanes can lead to major inland flooding. As this figure shows, after the late 1960s, the frequency of flooding, the frequency of multiple floods over a given year, and severity of floods have been increasing during the past decades. Results from the cited study predict an increase in the number of extreme precipitation events, more frequent flooding, and more severe flooding for the time period 2020–2099.

| METHODOLOGY

| RESULTS AND DISCUSSION

| CONCLUSIONS