Highwater Mark Collection after Post Tropical Storm Dorian and Implications for Prince Edward Island, Canada

Donald E. Jardine,Adam L. Fenech,Xiuquan Wang

doi:10.3390/w13223201

Abstract

Prince Edward Island (PEI), Canada has been experiencing the consequences of a rising sea level and intense storms on its coasts in recent years. The most recent severe event, Post Tropical Storm Dorian (Dorian), began impacting Prince Edward Island on 7 September 2019 and lasted for over 20 h until the morning of 8 September 2019. The measurement of highwater marks (HWM) from the storm was conducted between 25 September and 25 October 2019 using a high precision, survey grade methodology. The HWM measured included vegetation lines, wrack lines, beach, cliff, and dune morphological features, and tide gauge data at 53 locations in the Province along coastal areas that are exposed to high tides, storm surge, high winds, and wave runup. Photos were taken to provide evidence on the nature of the HWM data locations. The data reveal that Dorian caused extensive coastal floods in many areas along the North and South Coast of Prince, Queens and Western Kings Counties of Prince Edward Island. The floods reached elevations in excess of 3.4 m at some locations, posing threats to local infrastructure and causing damage to natural features such as sand dunes in these areas. The HWM data can provide useful information for community and emergency response organizations as plans are developed to cope with the rising sea level and increased frequency of highwater events as predicted by researchers. As Dorian has caused significant damage in several coastal areas in PEI, better planning using an enhanced storm forecasting and coastal flood warning system, in conjunction with flood stage values, could possibly have reduced the impacts of the storm in the impacted areas. This could help enhance public understanding of the potential impacts in local areas and how they can prepare and adapt for these events in the future.

Highlights

Prince Edward Island is located on the Atlantic Coast of Canada in the Gulf of the St
Hurricane Dorian, a storm originating in the south-central Atlantic Ocean near the Lesser Antilles, started tracking toward North America as a category 5 Hurricane when it hit the Bahamas as the most powerful tropical cyclone on record to ever strike
Watermarks were measured with a Trimble Geo7X survey grade dual frequency receiver connected to a Networked Real Time Kinematic (NRTK) GPS tracking system with integrated 3G cellular modem to enable connection to Cansel’s Can-Net Network of base stations to provide real time corrections with vertical accuracies in the 2 to 15 cm range, which is dependent on satellite connections and configuration [11]

Summary

Introduction

Hurricane Dorian (see Figure 2), a storm originating in the south-central Atlantic Ocean near the Lesser Antilles, started tracking toward North America as a category 5 Hurricane when it hit the Bahamas as the most powerful tropical cyclone on record to ever strike. As one of the most powerful hurricanes recorded in the Atlantic Ocean with 1 min sustained winds peaking at 295 km/h (185 mph), Hurricane Dorian’s resultant damage was catastrophic, flattening most structures or sweeping them to sea, causing 70 fatalities and leaving at least 70,000 people homeless. Hurricane Dorian slowly made its way from the Bahamas, along the eastern seaboard of the USA, and made landfall in Nova Scotia at suppertime on 7 September, being reclassified from a category 2 Hurricane to a

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