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. . . LINC DFP split flow reach span from the Upper Reach to the Lower Reach which required the 'hard wiring' of discharges in both Upper and Lower Reach models in order to properly account for the flow in the main channel and the flow path. The original 1994 UPPERQ model utilized the JP'.5 (JP card, Field 5) field in HEC-2 to estimate the amount of LINC DFP discharge returning to the main chmmel over Lincoln Avenue. The original 1994 UPPERQ model set the JP.5 field equal to 87, assuming that out of the total LINC DFP discharge (QlOO = 403 cfs) 87% or 351 cfs would be returning to the main chmmel over Lincoln Avenue. When the 403 cfs was inserted into the LINC DFP model [LINC.DAT], the computed 100-year discharge passing over Lemay Avenue was actually 4 cfs thereby indicating that almost 100% (4 cfs / 403 cfs = 99%) of the LINC DFP discharge returned to the main chmmel over Lincoln Avenue during thl~ 100-year event. Therefore, in the CE100Q06 model the JP.5 field was set to 100, eliminating the effective assumption that 4 cfs remains in the LINC DFP east of Lemay Avenue. A comparative summary of the duplicate and corrected FEMA 10-, 50-, 100-, and 500- year water surface profiles is presented in Table 5.2. A comparative summary of tht: duplicate and corrected FEMA 10-, 50-, 100-, and 500-year discharge profiles is presented in Appendix D.l. Within the study reach, the corrected effective 100-year water surface elevations match the duplicate effective water surface elevations everywhere except at Cross Section AM:221702 where a decrease of -004 feet was noted. Minor decreases (004 feet or less) in the 10-, 50-, and 100-year water surface elevations between the corrected condition and the duplicat1e effective condition were noted typically between the upstream side of Lemay Avenue (Cross Section AM:221702) and the Mulberry Street Bridge (Cross Section AN:222452). The differences in 10-, 50-, and 100-year water surface elevations between the corrected and duplicate conditions are attributed to premature truncation of the upstream study limit associated with the analyses for the 1999 Timberline LOMR. The corrected effective 500-year floodplain analyses combined DEL506 and the DEU506 models into the CE500Q06 model. Differences between the corrected and duplicate 500-year water surface elevations occurred between: a) the Tinmath Diversion Dam and Mulberry Street and b) Cross Sections AP:224597 and 229997 (the B.N.R.R. Bridge). The 500-year water surface differences between the Tinmath Diversion Dam and Mulberry Street are attributed to correcting two errors associated with the analysis for the 1999 Timberline LOMR: . Premature truncation of the upstream study limit; and . Utilization of the full base flow QT value (23,000 cfs) instead of a computed discharge value (20,141 cfs) reflecting spills to the LINC and LEMA YDS divided flow paths. COFC2003-l0 Oxbow FINAL LOMR.doc 5.2 ANdERSON CONsulTiNG E,'lGiNEERS, INC.