HYPOTHETICAL HURRICANE ("HYPOHURRICANE") . A representation of a hurricane, 

 with specified characteristics, that is assumed to occur in a particular 

 study area, following a specified path and timing sequence. 



TRANSPOSED — A hypohurricane based on the storm transposition principle, 

 assumed to have wind patterns and other characteristics basically com- 

 parable to a specified hurricane of record, but transposed to follow a new 

 path to serve as a basis for computing a hurricane surge hydrograph that 

 would be expected at a selected point. Moderate adjustments in timing or 

 rate of forward movement may also be made, if these are compatible with 

 meteorological considerations and study objectives. 



HYPOHURRICANE BASED ON GENERALIZED PARAMETERS— Hypohurricane estimates 

 based on various logical combinations of hurricane characteristics used in 

 estimating hurricane surge magnitudes corresponding to a range of prob- 

 abilities and potentialities. The STANDARD PROJECT HURRICANE is most 

 commonly used for this purpose, but estimates corresponding to more severe 

 or less severe assumptions are important in some project investigations. 



STANDARD PROJECT HURRICANE (SPH)~A hypothetical hurricane intended to 

 represent the most severe combination of hurricane parameters that is 

 reasonably characteristic of a specified region, excluding extremely rare 

 combinations. It is further assumed that the SPH would approach a given 

 project site from such direction, and at such rate of movement, to produce 

 the highest HURRICANE SURGE HYDROGRAPH, considering pertinent hydraulic 

 characteristics of the area. Based on this concept, and on extensive 

 meteorological studies and probability analyses, a tabulation of "Standard 

 Project Hurricane Index Characteristics" mutually agreed upon by repre- 

 sentatives of the U. S. Weather Service and the Corps of Engineers, is 

 available. 



PROBABLE MAXIMUM HURRICANE—A hypohurricane that might result from the 

 most severe combination of hurricane parameters that is considered 

 reasonably possible in the region involved, if the hurricane should 

 approach the point under study along a critical path and at optimum rate 

 of movement. This estimate is substantially more severe than the SPH 

 criteria. 



DESIGN HURRICANE — A representation of a hurricane with specified charac- 

 teristics that would produce HURRICANE SURGE HYDROGRAPHS and coincident 

 wave effects at various key locations along a proposed project aline- 

 ment. It governs the project design after economics and other factors 

 have been duly considered. The design hurricane may be more or less 

 severe than the SPH, depending on economics, risk, and local 

 considerations . 



IMPERMEABLE GROIN. A groin through which sand cannot pass. 



INDIAN SPRING LOW WATER. The approximate level of the mean of lower low 

 waters at spring tides, used principally in the Indian Ocean and along the 

 east coast of Asia. Also INDIAN TIDE PLANE. 



INDIAN TIDE PLANE. The datum of INDIAN SPRING LOW WATER. 



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