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<br />, <br /> <br />. <br /> <br />1(14 <br /> <br />HYDRAULIC ENGINEERING '94 <br /> <br />Il'or tht! Il;l Mt!dlO site, the ratio is 3. <br /> <br />The compuwd f obtained from STARCAL program was compared to Figure <br />7 of the Aquirre-Pe paper (990) which shows plots of RlDliQ vs. f for several <br />differt:nl resist.ance equations for mountain streams. This graph shows an fofO.25 <br />for an W()/iIl af6.a. The computed fwas 0.20. The same approach was used for the <br />upper reaches of the Vigil Ditch. The f converted from the n obtained in the RMS <br />calibration was 0.17. The fcomputed from the graph was 0.12. <br /> <br />The equivalent sand grain roughness (k.) was also computed from the converted <br />f at the El Media site using the Colebrook.White relationship for open ch..noels. <br />'fhe k.obtained for the site was 0.8. This compares well to the value of 0.5 derived <br />in the Thompson-Campbell equatillll tThorne ct. al., 1985). When this value is <br />used in their equation the computl..-t:1 f is 0.17. This relationship also compares <br />favorably to the RMS calibration using STARCAL. <br /> <br />CONCLUSIONS <br /> <br />The STARCAL program was used to calibrate the Manning's n coeffici~nl <br />for 3 reaches in the Rio Grande basin with steep gradients and large roughness <br />elements. The Manning's n coefficlents obtained from t.he prfl~H am were converted <br />to Ilarcy.Weisbach friction factors. These results were C(IH1i,ared to resist.ance <br />equutions developed by Bathurst (1978) and the Thompson~ Campbell equation <br />presented in Thorne and Zevenbergen (1986). The Darcy Weisbach friction factors <br />obtained from bolh method. compared very favorably. The STARCAL program can <br />be used in steep gradient streams to obtain the frictional resistance oithe reach. <br /> <br />REFERENCES <br /> <br />Aguirre.Pe. J. and Fuentes, R., 1990, "Resistance to Flow in Steep Rough <br />Slreams", J. of Hydraulic Engine.'. ,,,g, ASCE, 116 OJ), pp 1374-1385. <br /> <br />Bathurst, James C., 1978, "Flow Resistance of Large-Scale Roughness". <br />J. of Hydraulic Engineering, ASCE, 104 (2), pp 1587-1603. . <br /> <br />Fullerton, W. T., 1992, 'Manning'S n.Value Calibration, letter report prepared <br />by FLO Engineering for the Albuquerque Projects Office. <br /> <br />Klumpp, C.C. and Baird, D. C. 1993, .Calibration of Manning's Roughness <br />for a River Reach", Proceedings of Hydraulic Engineering 1993, ASCE, VoL I, pp <br />1073-1078. <br /> <br />Thorne, C. R. and Zevenbergen, L. W., 1985. "}I~stimating Mean Velocity in <br />Mountain Rivers, Journal of Hydraulic Engineering, Vol. 111 (4), pp 612-623. <br /> <br />1. <br /> <br />- <br /> <br />FR)CTJON FACTORS-RIO GRANDE <br /> <br /> <br />Figure I . l..ocat.ion of Manning's N Calibration Sites <br /> <br />Rio Grande at EI Medio <br /> <br />Calibrated Manning's N = 0.05 <br /> <br />Elevation em) <br />1,758.5 <br />1,758 <br />1,751.5 <br />1,757 <br />1,756.5 <br />1,756 ----.- . ----.....- -----. <br />0.0 50.0 100.0 150,0 <br />, . Distance downstream (m) <br />ComPIII'lIIIQn o{mea&u~d and ail'Rulat.ed <br />water eurf.ce elwauOll8 for. diacbarp. <br />of 12 cu. mf" SeptembeT 1993 <br /> <br />-~-$o:.. <br />--~i..:C--_i <br /> <br />- .--'.. <br /> <br />-- .--.. <br />200.0 <br /> <br />. <br /> <br />105 <br /> <br />Thalweg <br />-. . <br />Measured <br />-+. <br />Simulated <br />-0 <br /> <br />250.0 <br /> <br />Figure 2: ~ Water surface profiles at EI Medio for Manning's n calibrations <br />