FLOOD00261 - Laserfiche WebLink

Home Browse Search

ll.4 Project Benefits At present the vast major~t). of the tow~ of ~olores lies within the lOa-year floodplain of the Dolores River. ~t the east end of Dolores, near the high school, water would break over Highway 145 and enter the town. Between that breakout p~int and the 4tn Street Bridge thE~re are two additional breakout points for floodwaters. The result is that much of the town would experience flooding from 0 to 2 feet deep, while some of the town would experience floodin~ more than 2 feet deep. Plate 3 showed the likely percent damage to a Structure versus the depth of flooding. hs can be seen from the table, damages in DoloreS would range from 0% of th~, value of a structure (and its contents) ~o about 50%. Mos~ s~ructures would experience damage on the order of 20% ~o 30% during a lOa-year flood. A detailed benefit-cost analysis is beyond the scope of this report. An effort was mad,,,, however, to prepare very general values to determine whether the planning of a flood control project was worth pursuing. The estimation of a\rerage annual flood damages under present conditions was dE!scribed in Section 2.4 of this report. If one accepts ttlat a project designed to the 'OO-yea~ level (wi~:~ f:r'eeboard) will a110\<,1 smell residual damages far ::100C.5 gr'eater than a 100-year ~lood, one can proceed. ~~hese residual aamageS can be s~t;":r.-act.e6 ::rom l::.he ,:0-;:a1 a.ve:.-age annual damages to estimate annual benefi~s attribllt2~le to the project. The next s~ep was ~o calc~:a~e ann~a~ C85~S. ::'~7QV"~~C .._ . _ _ c':' _ annual costs aSS~~e a 50-YEa~ P~OjE=t :i~e, an 8 ~/'2% an~~a: interest rate (per the U.S. Army CO~?S of Enginee~s), ana the costs listed in Tables 3 and 4~ Bese8 on all of ~hese estimates, it appears that average annual bene~its fo~ the north side of the river are over 2 ~imes average annual costs. These general calculatio~s clearly inaica~e that a fll)od control project in Dolores is worth pursuing. -19-