Problem B. In reference to the information provided in Problem 16.13, determine the peak flow at...

 

  
 

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Problem B. In reference to the information provided in Problem 16.13, determine the peak flow at location B from drainage area 1 by the NRCS (SCS) TR-55 graphical hydrograph method. In addition to the related material of our textbook, refer to the report "USDA Urban Hydrology Small Watersheds TR-55", which is available from the folder "Manuals and Reports" of our course website and contains detailed information in support of your solution, as needed. 16.13 An urban watershed has a main ditch as shown in Fig. P16.13. Paths from remote points to the main ditch are also indicated. The details of each subarea are listed below. Deter- mine the peak flow at the outlet ditch by the rational method, assuming that the 5-year rainfall intensity is given by 170/(t + 23.0), where t, is in minutes and i in in./hr. Assume shallow concentrated flow through each subarea. Drainage Area Area (acres) Type of Surface Path Length (ft) Slope (%) 1 12.0 Bare surface, C=0.4 AB 1300 6.0 2 13.5 Asphalt paved, C = 0.8 BD 1250 1.5 CD 1420 2.0 3 11.8 Lawn, C=0.3 ED 1800 1.0 4 14.1 Concrete paved, C = 0.9 DG 1510 1.5 FG 1660 2.5 Figure P 16.13 F Main ditch Outlet ditch E Problem B. In reference to the information provided in Problem 16.13, determine the peak flow at location B from drainage area 1 by the NRCS (SCS) TR-55 graphical hydrograph method. In addition to the related material of our textbook, refer to the report "USDA Urban Hydrology Small Watersheds TR-55", which is available from the folder "Manuals and Reports" of our course website and contains detailed information in support of your solution, as needed. 16.13 An urban watershed has a main ditch as shown in Fig. P16.13. Paths from remote points to the main ditch are also indicated. The details of each subarea are listed below. Deter- mine the peak flow at the outlet ditch by the rational method, assuming that the 5-year rainfall intensity is given by 170/(t + 23.0), where t, is in minutes and i in in./hr. Assume shallow concentrated flow through each subarea. Drainage Area Area (acres) Type of Surface Path Length (ft) Slope (%) 1 12.0 Bare surface, C=0.4 AB 1300 6.0 2 13.5 Asphalt paved, C = 0.8 BD 1250 1.5 CD 1420 2.0 3 11.8 Lawn, C=0.3 ED 1800 1.0 4 14.1 Concrete paved, C = 0.9 DG 1510 1.5 FG 1660 2.5 Figure P 16.13 F Main ditch Outlet ditch E