Laserfiche WebLink
<br />I <br />I <br />I. <br />I <br />I <br />I <br />I <br />I <br />I <br />I. <br />I <br />I <br /> <br />I <br />I <br />I <br />I <br />I. <br />I <br />I <br /> <br />".llIII~ ~. """" <br /> <br />damage relationships based upon them and as such, only infrequently are <br /> <br /> <br />used in flood damage analysis. <br /> <br /> <br />Probably the most important determinate to flood damage, besides <br /> <br /> <br />flood depth, would be velocity. The greater the velocity of the flood <br /> <br /> <br />waters hitting a structure, the greater the damage will be, Some <br /> <br /> <br />structures may be able to withstand velocities of 3 feet per second <br /> <br /> <br />at a depth of 6 feet but increase either slightly and the building could <br /> <br /> <br />be pushed off its foundation. Floating debris will have more of a damag- <br /> <br /> <br />ing affect when high velocities are present. Debris can break windows <br /> <br />and in some cases sever electrical and fuel connections which then can <br /> <br />increase fire risk, The force of moving debris was evident on the out- <br /> <br />side of some of the homes that were left standing after the Big Thompson <br />flood of 1976. <br /> <br /> <br />Various methods have been developed for working velocity into the <br /> <br /> <br />depth-damage relationship. In a study done in the Pacific Northwest <br /> <br /> <br />(U.S.A.C,E" 1974), curves were derived for various building classifica- <br /> <br /> <br />tions that related the point of building collapse to the depth and <br /> <br /> <br />velocity of surrounding floodwater, FIA curves were used up to the point <br /> <br /> <br />of building collapse at which time total loss to both structure and con- <br /> <br /> <br />tents was assumed, The error in this methodology is that the FIA curves are <br /> <br />. based upon all experienced losses, not just to those structures that can <br /> <br /> <br />.withstand velocity. To accurately use the above methodology, FIA's depth- <br /> <br /> <br />damage curves would have to be reworked to exclude all claims in which the <br /> <br /> <br />structure was a total loss due to velocity-depth considerations. An <br /> <br /> <br />analysis of flood insurance claims shows that very few structures suffer <br /> <br />total loss, even one-story structures at depths greater than 10 feet. The <br /> <br />20 <br /> <br />-,--,.,..,..~",,^, ""~._-~ .~ ,"'~,.- <br /> <br />~L <br /> <br />nit' <br />