DISSECTING AND CLASSIFYING THE IMPACTS OF HISTORIC HURRICANES ON ESTUARINE SYSTEMS J.C. Stevenson1 and M.S. Kearney2 1 University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, MD 21613 2 Department of Geography, University of Maryland, College Park, MD 20742 ABSTRACT particularly in the upper portions of the estuary. This situation differs sharply from hurricanes or Since the Great Hurricane of 1667 hit tropical storms, such as Agnes, which had high Chesapeake Bay, many have tried to describe the precipitation and runoff in the upper watershed but impacts caused by these destructive storms. Other weak winds and storm surge. Such differences than Hurricane/Tropical Storm Agnes in 1972, highlight the need for additional analyses of however, only sporadic efforts have assessed the historical storms. many changes that can occur during and after these tropical visitors pass. One problem is that INTRODUCTION hurricanes vary widely in their impact, both temporally and spatially. Not only is wind strength Along with the New World, Christopher important, but also the path that the winds take over Columbus made another startling discovery: the watershed can prove crucial in their impact. To hurricanes. He appears to have encountered his first analyze hurricane impacts more systematically, a hurricane in 1493, with an additional three during simple classification system is proposed that his Caribbean voyages. The Spanish were the first accounts for the three main forcing functions or to introduce the Caribbean Indian word for the drivers that can significantly change estuaries. severe tropical storms to Europe, but it took the The first driver emanates from the storm’s English a century to understand fully the fury of precipitation and consequent runoff, which can these storms. cause massive flushing of the watershed and a Hurricanes have captured our imagination and freshet in the upper reaches of an estuary. Winds terror at least since 1609 when the wreck of the and waves, which can alter shorelines and disrupt Sea Venture off Bermuda inspired William normal estuarine stratification processes, constitute Shakespeare to write The Tempest. In a more the second driver. The third driver is the surge scientific context, hurricanes are extreme high- associated with low-pressure systems as these energy events. While such storms are generally rare systems move over the Bay, potentially transporting in a given area, they can obliterate structures in oceanic organisms far up the Bay, overwhelming their path and profoundly affect estuarine wetlands, and spilling salt water into normally non- ecosystems. One of the earliest well-documented saline uplands. By categorizing each of the drivers hurricanes in Chesapeake Bay occurred in 1667 into high, medium, and low impacts for hurricanes, when a huge storm with 12-ft (3.7-m) surge was three main categories of storms are shown to have noted in a dispatch from Virginia to London [1]: affected the Chesapeake Bay in the 20th century Sir, having this opportunity, I cannot but with as many as 27 different combinations of wind, acquaint you with the relation of a very strange storm surge, and precipitation. For example, Isabel tempest which hath been in these parts with us is a storm in which winds and runoff remained called a hurricane which had began August 27th comparatively weak, but surge was high, and continued with such violence, that it overturned K.G. Sellner (ed.). 2005. Hurricane Isabel in Perspective. Chesapeake Research Consortium, CRC Publication 05-160, Edgewater, MD. 167 many houses, burying in the ruines much goods to climb to the top of their houses to keep and many people, beating to the ground such as themselves above water. The waves carried all the were any wayes employed in the fields, blowing foundations of the Fort at Point Comfort into the many cattle that were near the sea or rivers, into river and most of furnished and garrison with it... them, whereby unknown numbers have perished, The nearest computation is at least 10,000 houses to the great afflication of all people, few having blown down, all the Indian grain laid flat on the escaped who have not suffered in their persons or ground, all the tobacco in the fields torn to pieces estates, much corn was blown away, and great and most of that which was in the houses perished quantities of tobacco have been lost, to the great with them. The fences about the corn fields were damage of many, and utter undoing of others. either blown down or beaten to the ground by trees Neither did it end here, but the trees were torn up which fell upon them. by the roots, and in many places whole woods The description indicates that the storm could blown down so that they cannot go from plantation have been a Category 3 or even possibly a 4 on the to plantation. The sea, by the violence of the wind, Saffir-Simpson scale when it hit the lower Chesa- swelled twelve feet above its usual height drowning peake. Curiously, there appears to be no direct the whole country before it, with many of the mention of the 1667 event in the official records inhabitants, their cattle and goods, the rest being of colonial Maryland [4]. The only 17th-century forced to save themselves in the mountains nearest reference to a hurricane in Maryland notes another adjoining, while they were forced to remain many hurricane, which apparently occurred in 1670 [5]. days together in great want. In fact, the 1667 hurricane may have headed in- It now appears likely that this was the same land, missing tidewater Maryland and then hurricane that eight days before passed over recurving sharply eastward, since a severe storm Barbados and left most houses standing [2]. The was noted on Manhattan Island shortly thereafter. damage was so extensive in Virginia, however, that Whatever the exact track of the storm, the Secretary of State of the Colony, Thomas Maryland planters eventually benefited because the Ludwell, who lived at Rich Neck on Archer’s storm devastated production in Virginia. Creek, related the following in a letter to Lord Consequently, the price of tobacco, which had been Berkeley of Stratton, a favorite of King Charles II slumping, rose for a brief period. This differential [3]: response is due in part to the localized area of high this poore country is now reduced to a very winds that occurs around the inner eye wall, as miserable condition by a continental course of well as localized surge and rainfall that may differ misfortune. On the 27th of August followed the most dramatically over a 200-mile-long ecosystem, such dreadful Hurry Cane that ever the Colony groaned as Chesapeake Bay. under. It lasted 24 hours, began at North East and The differences in precipitation, wind, and went around northerly till it came to west and so it surge not only vary based on the intensity of came to Southeast where it ceased. It was hurricanes (now classified by the Saffir-Simpson accompanied with a most violent rain but no scale), but also due to the direction that such storms thunder. The night of it was the most dismal time I approach the Bay. Obviously, hurricanes that ever knew or heard of, for the wind and rain raised approach an estuarine system from the seaward so confused a noise, mixed with the continued side have a higher probability of surge than cracks of failing houses...The waves were hurricanes that approach from the landward impetuously beaten against the shores and by that direction. In addition, because of the counter- violence forced and as it were crowded into all clockwise circulation patterns of hurricanes in the creeks, rivers and bays to that prodigious height northern hemisphere, the area on the right side of that it hazarded the drowning of many people who the approaching storm is more likely to have a lived not in sight of the rivers, yet were then forced higher storm surge. 168 Table 1. The ten heaviest rains in Virginia from tropical A = 0–10 ft (0–25.4 cm), P Class B = 1–20 ft (25.4– cyclones and their remnants. 50.8 cm), and P Class C >20 ft (>50.8 cm). Total Rainfall Dates Location WIND 297.00" (68.58 cm) 8y/19 —20/196 Nelson Count Since the Saffir-Simpson scale is now widely 159.77" (50.22 cm) 1o1/02 —07/198 2 NE Montebell used to describe the potential impacts of hurricanes and tropical storms, the same cut-off points are used 198.13" (46.05 cm) 9n/14 —16/199 Yorktow for the proposed classification, while condensing them into three classes (Table 2). 196.57" (42.09 cm) 9s/14 —16/199 Newport New Mercifully, the Chesapeake Bay has not yet experienced any recorded hurricanes in the W Class 126.00" (40.64 cm) 6y/17 —24/197 Chantill C range. This lack of extremely strong storms is due to the relative protection afforded from the 194.30" (36.32 cm) 9y/14 —16/199 James Cit south by the North Carolina landmass and the fact 164.30" (36.32 cm) 9h/05 —09/199 Tom’s Branc that storms approaching more directly from the east usually have less energy because they have passed 124.18" (36.02 cm) 6e/17 —24/197 Centrevill over cooler Mid-Atlantic water before moving ashore. Temperatures of the North Atlantic Ocean 164.17" (35.99 cm) 9E/05 —09/199 Luray 5 S have been rising faster than any other ocean since the mid-1950’s [6], however, increasing the 123.60" (34.54 cm) 6s/17 —24/197 Big Meadow probability that the Bay will experience a W Class C hurricane in the future.