APPENDIX A: COMPUTER PROGRAM BWL0SS1 

 Estimation of Economic Losses as a Function of Wave Height 



Program purpose 



1. The program BWL0SS1 is intended to aid planners of coastal struc- 

 tures which provide protection from wave attack by deriving an empirical math- 

 ematical expression relating a given level of economic losses to the responsi- 

 ble incident significant wave height. This loss function can be used to de- 

 fine the "without-project" condition with respect to the incremental economic 

 benefits provided by artificial wave protection. The program optionally pro- 

 vides an estimate of expected annual economic losses due to wave attack, given 

 the coefficients of an Extremal Type I cumulative probability distribution 

 function of significant wave heights for the site. 



Program capabilities 



2. BWL0SS1 is written in FORTRAN IV as implemented on the Honeywell 

 DPS-8 mainframe system at the US Army Engineer Waterways Experiment Station 

 (WES). A BASIC version written for the IBM PC is also available. The least 

 squares method is applied to historical data on economic losses associated 

 with the significant wave heights of the storms that caused the losses. A 

 loss function is derived from the following form: 



[, . /<"s-".o>] 



$L(H ) = $L Li - e ^ ^^ J (ftl) 



s max 



where 



$L(Hg) = economic losses as a function of significant wave height Hg 



$L = maximum conceivable economic loss from wave attack (at any 

 intensity) 



A = site-specific coefficient derived by regression 



Hr = maximum significant wave height for which economic losses are 

 negligible 



3. The regression requires at least one point for H^ , $L(Hg) , but 

 it can deal with up to 100. The coefficient A is presented along with the 

 nonlinear correlation coefficient and the sum of the square residuals. A ta- 

 ble of residuals is optionally presented. Losses can be optionally predicted, 

 given a specific significant wave height, or the significant wave height 



A1 



