On The Calculation Of The Parallel Bridge Backwater Of Yanguoxia Reservoir

The increasing bridge groups has drawn great attention in recent years. The paper discusses three calculation methods including water surface profile, formula, and mathematic model among a variety of calculation methods and applies them in the calculation of the backwater height of the parallel bridge in the Yanguoxia reservoir located in the main steam of Huanghe River.Hongjiasi section of the yanguoxia reservoir is covered byerosion and deposition terrace with typical qualities of valley such as serious riverbed entrenchment, wideriver bed cross section, narrow and rugged terrain. Based on that, this section is an ideal place for calculating the backwater height of the bridge. In application of the three calculation methods mentioned above, the results are as following:(1) As for thewater surface profile,thetransformation from thetraditional fixed step size algorithm to variable step size algorithmreduced the calculating steps and accumulation of errors Based on this improvement, the bridge group back water height is estimated to be0.80m, which is the maximum value among the results of the three calculations. The reason lies in that the bridgelocated in the reservoir.(2) The results by the D’Aubuioson formula and shaman formula are0.36m and0.24m respectively. There is no big difference between the two results.The difference between the two formulas and the problems in their application are discussed.(3) The result by the mathematic modelvalidated by the academy of the HuangheWater Resources committee is0.35m, which is more accurate.Base on the comparison among those three calculating methods, two formulas in the formulacalculations differ from the mathematic modal due to different perspectives. Nevertheless, their results are quite close to each other and could be used to verify one another. Water surface profile could be the upper control limitin the design of the bridge backwater in the reach within the reservoir and provides the base for caculation of the back water of the bridge group in the Upper Middle main stream of the Huanghe river.