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2.4.2 Scalinq based of contributory area relative to lake size <br /> 1. The contributory area for each lake group relative to the total area of the lake group contributory <br /> area was assumed to be proportional to the area of each individual lake relative to the total lake <br /> area for the lakes in Phase 2. Since the total land area for Phase 2 could be measured/estimated, <br /> the amount of area draining to each lake could be approximated. <br /> Contributory Area for Lake X _ Area Lake X <br /> Eq. 2.4-2a <br /> Total area of Watershed Phase 2 Total Area of Phase 2 Lake <br /> ➢ Solve for Contributory Area for Lake X <br /> 2. The hydrograph for each lake and design storm was scaled from the hydrograph for lakes 1-2-3 <br /> based on their contributory area (from step 1), thus assuming the ratio of developed/undeveloped <br /> area as well as runoff coefficients etc. to be the same in Phase 2 as in Phase 1 Stage 1. <br /> Contributory Area for Lake X _ Hydrograph Value Lake X <br /> Eq. 2.4-2b <br /> Contributory Area for Lake 1-2-3 Hydrograph Value Lake 1-2-3 <br /> ➢ Solve for Hydrograph Value Lake X <br /> The scaling factors for each of the lakes in Phase 2, received by using the above described method, are <br /> shown in Table 2-4 below. <br /> Table 2-4: Scaling based on Contributory Area Relative to Lake Size <br /> Lake Scaling factor based on Contributory <br /> Area Relative to Lake Size <br /> 14 0.402 <br /> 15 0.204 <br /> 16 0.136 <br /> 17 0.248 <br /> 18 0.254 <br /> 19 0.157 <br /> 20 0.425 <br /> 21 0.224 <br /> 22 0.546 <br /> 23 0.197 <br /> 24 0.835 <br /> 25 0.434 <br /> River Islands Phase 2 Stormwater Mitigation Rev 2 16 1� <br /> PACE <br />