Storm Surge

Pius Lee

Storm surge causes inundation of large swaths of coastal land. Eleven years ago, storm surge from Hurricane Sandy havocked large damages in New York (NY) and New Jersey (NJ). Today, some of those destructions are still noticeable and remain unrepaired. Until now, a stunning $71 Billion price tag has been accumulated to clean up and recover from the aftermath of Sandy in NY and NJ. The price tag is still increasing and counting. The devastations of storms in coastal areas are mainly caused by wind and water. Water damages are often at least an order of magnitude more costly than wind damages. In terms of casualties, flood-related deaths are much higher than those associated with wind-blown accidents in coastal storms. Hurricane Katrina ravaged large damages in New Orleans and its vicinity in late August 2005. They were largely attributable to floods. Hurricane Katrina drowned more than 1800 people as a result of sudden flooding in their living quarters seeking shelters or in transportation vehicles. Many of such losses were instantaneous, horrendous and heart-breaking as whole families and communities were wiped out in a short time due to being ignorant about the approaching threat from the sea.

Credit: NOAA

Rising Sea Water

A storm surge is defined as the amount of time which averaged sea water rise due to the impacts of a storm. It includes: the rise of sea water due to a low atmospheric pressure system in association with the storm, as well as water rise induced by wind-drag. The former is called the barometric sea rise. Under normal circumstances, the barometric rise of seas should not exceed one meter. The sum of sea water rises attributable to a storm surge and a coinciding astronomical tide is called a storm tide. The factors determining the maximum sea water rise include: astronomical tide, wave height, wind-drag surge, and the coast-line funneling effects. Each of these has the potential to be the leading factor for sea water rise. Storm gust driven waves in an energetically excited sea state can be many meters high. Therefore on top of the storm tide, these battering waves excited by the storm add much higher destruction potentials. In layman terms the total maximum high water mark in a storm is also called a “storm surge”. Hereafter, I use this layman definition instead of the technical one in the beginning of this paragraph.

Credit: NOAA

Colossal Losses

In recent memory, the most devastating storm surge disaster happened on April 29 1991. A large storm surge hit the Bay of Bengal in southern Bangladesh. In that fateful event, a storm land-fall coincided with an astronomical tide amounting to a huge maximum storm surge of 10 meters. Many people died in acute drowning. Thousands more died in the following weeks of cholera and dysentery due to unsafe drinking water resulted from the flood. Over 100,000 people died as a result of that single fateful storm surge.

In the U.S. the two most costly single natural disasters in recent years were both storm surge related: (1) A 6 meters storm surge associated with Hurricane Katrina in September 2005 land-falled near New Orleans, LA, and (2) A 5 meters storm surge during Hurricane Sandy on October 29, 2012 land-falled near Atlantic City, NJ. The former suffered the largest casualties. The latter suffered the largest monetary expenses for property and real estate repairs and compensations.

A Stealthy killer

The danger and harm of a storm surge is its suddenness and its large geographical extent. One can think about the devastation of a storm surge in terms of its suddenness and widespread intrusion as a tsunami hitting a coastal city. Hurricanes are the strongest type of storms. It has a sustained wind, defined as steady wind continually for at least 2 minutes, exceeds 120 km per hour (75 miles per hour). Hurricanes are formed over oceans with warm Sea Surface Temperatures (SST). Under warm sea surface temperature conditions, specifically speaking, when the SST surpasses the hurricane genesis threshold of 26-degree Celsius, the oceans are capable of brewing hurricanes. Due to the spinning of the Earth, hurricanes swirl counterclockwise in the Northern Hemisphere, and swirl clockwise in the Southern Hemisphere.

The Great Wave off Kanagawa  Katsushika Hokusai  (1760–1849)

El Niño

Recently, the National Oceanic and Atmospheric Administration (NOAA) of the U.S.A. has forecasted an active El Niño year for 2023-2024. This would mean bad news for the hurricane season of the U.S.A.  For the Atlantic Hurricanes the El Niño occurrences make the storms stronger and more frequent. The Pacific Hurricanes are also affected. El Niño occurrences cause more severe and frequent torrential deluge and storm surges in certain regions around the tropics and subtropics. This is mainly due to the abnormally high SST during an El Niño cycle.  

An El Niño occurrence in a year usually means poor fishery catches for the following few years. Warmer water usually means fewer nutrients in the sea water. The El Niño devastation is not confined to economy and food security but also extends also to extreme weather and storms. The recent severity of hurricanes and storm surges could be partially attributed to the active El Niño cycles. This finding was confirmed by more accurate records for SST measurements amassed by satellite observations. Although in an El Niño cycle, the abnormally warm surface peaks around December, the abnormally “warmer than usual” SST in the Southeastern Pacific Ocean lingers on for months that follow, influencing a hurricane genesis. As a matter of fact, the entire fall season lies within the official hurricane season of the U.S.A. from June 1st to November 30th. Therefore one should not romanticize the gorgeous crispy days of autumn lest being caught off-guard against hurricanes.

Although elevated, this house in North Carolina could not withstand the 15 ft (4.5 m) of storm surge that came with Hurricane Floyd (1999)
(Credit: NOAA)

Cities at Risk

Storm surge is a threatening dilemma for many large metropolitan centers along the coastlines of the various continents. Herein are a few well-known large coastal metropolitan centers with a low lying topology. The following large cities are merely meters above the sea if any at all: {U.S.A} Miami (1 m); New Orleans (2 m); Atlantic City (2 m); Boston (6 m); New York (10 m), {Asia} Osaka (1 m); Hong Kong (4 m); Jakarta (3 m); Mumbai (6 m); Bangkok (8 m), {Europe} Amsterdam (-2 m); Hamburg (8 m); and Toulon (8 m). If one studies the storm-flood insurance policies of the real estate of these cities, he will find the common lament of high flood-zone insurance premiums. In some cases it is cost-prohibitive to rehabilitate infrastructures damaged by previous floods. For instance, in the aftermath of Hurricanes Katrina and Sandy, their respective affected cities of New Orleans and New York have many damaged structures. They were unrepairable as no flood-zone insurance was granted. It signaled that rebuilding is financially prohibitive.

Many of these cities are predicted to become submerged in the sea in accordance with the United Nations Intergovernmental Panel on Climate Change (IPCC) forecast. It is forecasted that in 2100 the sea would have risen another 84 centimeters respective to today’s level. This potentially record shattering storm surges aggravated with the IPCC projected sea rise render developers to thinking twice to rebuild or build along low-lying coasts. I personally think brute force levee enlargements have its limits. Even the Afsluitdijk dyke in the Netherlands cannot be indefinitely enlarged — Besides the Great Wall of China, the Afsluitdijk dyke is the only other man-made structure visible from the moon with the unaided eyes. The 32-kilometer long 12 meters tall dyke between the provinces of Noord-Holland and Friesland protects a large part of the Netherlands against flooding.

The Great Wall of China at Jinshanling (Credit: Wikipedia)
Surge barrier of the Oosterscheldekering (credit: Wikipedia)

God Treasures Us

To mitigate the dilemma of losing land to the sea, a carbon trade concept can be applied. Investment to rebuild can be better spent to reallocate. Nonetheless, the storm surge dilemma is far more complicated than carbon trade. Heritage and identity are ingrained in man. Culture and tradition matter according to where people lived through the generations. Reallocating people is not the same as reallocating carbon dioxide emissions. No wonder the term “climate change” becomes a magic wand igniting controversies and conflicts all across the world in every walk of life. I personally reject the doomsday notion of “climate change” as change has been the only constant since Day One in Genesis. What man needs to do is to humble ourselves before our Maker. We can find peace and comfort in our merciful and loving Maker: “The LORD sits enthroned over the flood; the LORD sits enthroned as king forever. May the LORD give strength to his people! May the LORD bless his people with peace! ” (Psalm 29:10-11)

Author: Pastor Dr. Pius Lee is the Director of the Development Division of NYSTM. Pastor Lee previously worked in the National Oceanic and Atmospheric Administration. (NOAA) where he was selected the winner of the Administrator’s Award for NOAA’s Air Pollution Forecasting Group in 2020.

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