Laserfiche WebLink
Maxwell Mine <br /> Purgatoire River Flow Estimations <br /> Regional Analysis Method <br /> 1 ) Yearly peak flows of gaged water stations along the <br /> Purgatoire River were obtained from the United States <br /> Geological Survey. These records , of the same river <br /> drainage in question at the Maxwell Mine , satisify the <br /> requirement that the gaged watersheds should be <br /> climatically and physically similar to the ungaged <br /> watershed at the mine . Additional data for the Ciruela <br /> Canyon drainage comes from the Soil Conservation <br /> Service to suppliment data from the USGS because of the <br /> short times of record of the Stonewall station on the <br /> Purgatoire . <br /> 2) Frequency lines for each gaged watershed were <br /> constructed numerically and the flows estimated for the <br /> 100-yr ( 3) and 50-yr (2%) return periods . The <br /> frequency lines are Cumulative Distribution Curves of a <br /> log-normal plot of the probility vs . flow. The <br /> flow is then approximated from the curve for the <br /> desired return frequencies for each gaged watershed . <br /> 3) The Peak Flow vs. Watershed Area for a given return <br /> period , as calculated above , is then fit to a log curve <br /> by a least squares fit method . <br /> 4) These curves then predict the expected flow for any <br /> watershed of a given area for the desired return' <br /> period . Only the 100-yr and the 50-yr return periods <br /> were calculated therefore a frequency plot of the <br /> Maxwell (design) watershed was not constructed . <br /> 5) Because the State Highway Department estimates <br /> predicted a lower flow ( 13 ,000 cfs vs . 15 ,700 cfs) <br /> further error estimates were felt to be unnecessary as <br /> the high value would provide for a certain margin of <br /> safety. <br />