HURRICANES 



that we possessed the means, not for 

 directly altering the large-scale con- 

 ditions that favor the development of 

 hurricanes, but for destroying each 

 hurricane individually during its 

 formative stages, soon after its initial 

 detection. In the hurricane-free world 

 that we would have temporarily cre- 

 ated, the effects of hurricanes on the 

 environment would no longer cancel 

 the other effects and the environment 

 would proceed toward a different 

 state of long-term statistical equi- 

 librium. 



Very likely, the new environment 

 would be more favorable for the 

 natural development of hurricanes 

 than the old one. This would be true 

 if one of the natural effects of hurri- 

 canes is to remove from the environ- 

 ment some of its hurricane-producing 

 potential, as would be expected if 

 the hurricane is an instability phe- 

 nomenon. Perhaps a super-hurricane 

 would then try to form to do the 

 work of the ordinary ones that were 

 suppressed; perhaps it would not. 

 In any event, the task of artificially 

 removing the hurricanes one by one, 

 if such a task can be visualized at all, 



would become even more difficult 

 than it had originally been. 



Beneficial Effects 



The most frequently cited bene- 

 ficial effect of hurricanes is probably 

 the rainfall that they supply to certain 

 areas, with its obvious value to agri- 

 culture. A familiar example of such 

 an area is the southeastern United 

 States, where a fair fraction of the 

 total annual rainfall is supplied by 

 tropical storms. Yet even if this 

 region were deprived of all its hur- 

 ricanes, there would still be ample 

 rainfall left to support other crops 

 not presently raised in this region. 

 This leads us to suggest that the 

 principal beneficial effect of hurri- 

 canes may be to help preserve the 

 climatic status quo — a status quo 

 which the hurricanes themselves have 

 helped to create. 



To appreciate the value of preserv- 

 ing the status quo, let us suppose that 

 two regions of the United States, each 

 possessing a reasonably satisfactory 



climate, could somehow suddenly ex- 

 change climates with one another. 

 The climatic statistics of the United 

 States as a whole would then be 

 unaltered. Yet the average climate of 

 the United States would be worse, 

 because the climate would be "worse" 

 in each of the two regions in question. 

 That is, the new temperature and 

 rainfall regime in each region would 

 presumably be unfavorable to the 

 plant and animal life existing there, 

 especially to the crops, and very 

 likely also to many aspects of human 

 culture. The new climates would 

 favor new flora and fauna, and after 

 a sufficient number of years those 

 in one region might become effec- 

 tively interchanged with those in 

 the other. But during the period of 

 adjustment there would be a net loss. 



Since hurricanes exert a modifying 

 influence on the larger-scale tropical 

 environment, a further effect of hurri- 

 canes is to help preserve the climatic 

 status quo throughout the tropics, 

 even in those areas not frequented 

 by heavy hurricane rains or violent 

 hurricane winds. Here, too, the effect 

 may be beneficial. 



Geomorphological Effects of Hurricanes 



The morphologic changes induced 

 by hurricanes are concentrated along 

 seacoasts and the shores of large 

 estuaries. As they move inland, few 

 major tropical cyclones encounter at- 

 mospheric conditions necessary to 

 maintain their destructive violence 

 for as much as 100 miles. Only 

 rarely are they capable of retaining 

 their structures when crossing land 

 areas, as from the coast of the Gulf 

 of Mexico to New England or to the 

 Canadian border. 



Hurricane Camille (1969) — shown 

 in Figure V-5 — reached the Gulf 

 Coast as the most intense hurricane 

 ever reported, breaking records for 

 barometric depression and wind ve- 

 locities and bringing tragic devasta- 

 tion to the coast of Mississippi. It 



retained its identity for an exceptional 

 distance, causing excessive rainfall 

 and flooding that did considerable 

 damage in West Virginia and south- 

 western Virginia the day after leaving 

 Mississippi. And yet, Camille caused 

 few morphologic changes of any con- 

 sequence. It effected many short- 

 lived, minor physical changes on is- 

 lands in Louisiana and Mississippi, 

 but in comparison with losses in hu- 

 man and animal life and with destruc- 

 tion of property, the physical changes 

 were trivial. 



Effects of Differing Coastal 

 Characteristics 



Morphologic changes resulting 

 from hurricanes depend mainly on 



the physical characteristics of the 

 coasts involved. Three examples will 

 illustrate the relationships: 



Plum Island, Massachusetts, expe- 

 rienced the impact of Hurricane Carol 

 (1954). A detailed line of levels had 

 been surveyed across the marshes 

 behind the island, the coastal dunes, 

 and the island's beach. This survey 

 was completed the day before Carol 

 arrived. On the morning following, 

 the beach was broadened and reduced 

 as a result of wave erosion to a level 

 well below that determined by the 

 instrumental survey. Three days 

 later, however, most of the beach 

 had been restored, and within a few 

 days following its profile had re- 

 turned essentially to its pre-hurricane 

 condition. 



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