BMP Design Aids w w w. t r a n s p o r t a t i o n . o h i o . g o - PowerPoint PPT Presentation

BMP Design Aids w w w. t r a n s p o r t a t i o n . o h i o . g o v 1

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 2

Training Intent Introduction and overview of various design aids (equations and programs) Not a detailed training on how to use each one w w w. t r a n s p o r t a t i o n . o h i o . g o v 3

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 4

Rational Method For peak flow rate only Q = CiA Q: flow rate (cfs) C: coefficient of runoff i: rainfall intensity (in/hr) Based on time of concentration Sheet flow, shallow concentrated flow, and open channel or pipe flow A: tributary area (ac) w w w. t r a n s p o r t a t i o n . o h i o . g o v 5

Rational Method Q = CiA C: w w w. t r a n s p o r t a t i o n . o h i o . g o v 6

Rational Method w w w. t r a n s p o r t a t i o n . o h i o . g o v 7

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 8

Manning’s Equation (0.15 for Vegetated Biofilter) w w w. t r a n s p o r t a t i o n . o h i o . g o v 9

Manning’s Equation w w w. t r a n s p o r t a t i o n . o h i o . g o v 10

Manning’s Equation Program or Spreadsheet Calculation Use bisection method (trial and error) Inputs: Channel geometry and slope Manning’s roughness coefficient Flow rate Results: Normal depth Velocity w w w. t r a n s p o r t a t i o n . o h i o . g o v 11

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 12

Discharge Equations Orifice flow Weir flow w w w. t r a n s p o r t a t i o n . o h i o . g o v 13

Orifices Orifices w w w. t r a n s p o r t a t i o n . o h i o . g o v 14

Weir Orifice w w w. t r a n s p o r t a t i o n . o h i o . g o v 15

Orifice Flow w w w. t r a n s p o r t a t i o n . o h i o . g o v 16

Weir Flow L&D Vol. 2, 1102.3.4 w w w. t r a n s p o r t a t i o n . o h i o . g o v 17

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 18

ODOT CDSS CDSS is a hydraulic design software developed by ODOT C – Culvert Design D – Ditch Design SS – Storm Sewer Design w w w. t r a n s p o r t a t i o n . o h i o . g o v 19

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 20

SCS Curve Number Technical Release 55 (TR-55) Technical Release 20 (TR-20) Urban Hydrology for Small Watersheds Determines runoff depth (inches) Combines with unit hydrograph theory Produces runoff hydrographs Peak flow and total volume w w w. t r a n s p o r t a t i o n . o h i o . g o v 21

SCS Curve Number CN: depth of runoff abstracted Total P – Abstracted P = Runoff Depth Runoff Depth * Area = Runoff Volume NRCS unit hydrograph gives runoff volume a shape (distribution over time) Produces a full runoff hydrograph Runoff Flow Rate Time w w w. t r a n s p o r t a t i o n . o h i o . g o v 22

SCS Curve Number w w w. t r a n s p o r t a t i o n . o h i o . g o v 23

SCS Curve Number w w w. t r a n s p o r t a t i o n . o h i o . g o v 24

SCS Curve Number Analyses that require a full hydrograph Pre vs. post volumes (CSO areas) Routing a design storm through a detention basin, bioretention cell, or infiltration trench Still gives peak flow rate, but will likely be slightly different from Rational Method w w w. t r a n s p o r t a t i o n . o h i o . g o v 25

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 26

Hydrograph and Pond Routing Programs Many different programs Different inputs Different calculations Different limitations Know your tool before you use it w w w. t r a n s p o r t a t i o n . o h i o . g o v 27

Common Hydraulics and Hydrology Software Options • •Hydraflow Express Basic Pipe or Open •Bentley CulvertMaster Design Channel Capacity •Bentley FlowMaster Calcs. Calculations •Urban Drainage HY22 • Basin Inlet/Outlet •HY-8, ODOT CDSS • Peak Flow and HGL • •HEC-1 Steady/Unsteady Flow • •HEC-HMS Open Channels HEC • •HEC-2 Some Sediment •HEC-RAS Transport/Quality •GEO-RAS • Often used in FEMA Floodplains • •HydraFlow Hydrographs Normal Gravity Sewer, Detention Pond Design Simple • •HydraFlow Storm Sewers Hydrology and Hydraulics Combined Stormwater • •Bentley StormCAD Rational/TR-55/SCS Hydrology • •Bentley PondPack Manning’s/Orifice/Weir Hydraulic Calcs. Routing Models • •HydroCAD Some Quality Calculations Available • •EPA SWMM Complex Drainage Systems that have: Robust •Bentley CivilStorm • tail water, reverse flow, pump stations, surface flooding Stormwater •AutoDesk SSA • Horton/Green-Ampt Hydrology •PCSWMM • Routing Models Hydrodynamic and Kinematic Wave Hydraulic Calcs. •XP SWMM • Detailed Quality Calculations Available

PondPack and HydroCAD Inputs for runoff hydrograph Area Curve number, land use, or runoff coefficient Time of concentration Design storm frequency Produces runoff hydrograph Then route that hydrograph into your BMP w w w. t r a n s p o r t a t i o n . o h i o . g o v 29

PondPack and HydroCAD Inputs for BMP Stage vs storage curve (elevation vs. volume) Inputs for BMP discharge Elevation vs. Volume Stage vs. depth curve 800 799 Each outlet 798 Elevation (ft) 797 WQ orifices 796 795 Weirs, catch basin grates 794 793 Overflow weirs 0 0.10.20.30.40.50.60.70.80.9 1 1.11.21.3 Discharge pipe Volume (ac-ft) Downstream constraints (tailwater) w w w. t r a n s p o r t a t i o n . o h i o . g o v 30

PondPack and HydroCAD Two types of analyses Hydrograph routing Drawdown analysis Split event into many short pieces and calculate: Volume entering Volume leaving Volume and depth in basin w w w. t r a n s p o r t a t i o n . o h i o . g o v 31

PondPack and HydroCAD Make sure you have all of the potential discharge conveyances Make sure the BMP storage information in the model matches the design sheets Make sure the modeled discharge conveyance characteristics match the design sheets and site, including tailwater Make sure the results make sense w w w. t r a n s p o r t a t i o n . o h i o . g o v 32

Equations / Programs Rational Method Manning’s Equation Outlet Discharge Equations ODOT CDSS SCS Curve Number Hydrograph and Pond Routing Programs USGS StreamStats w w w. t r a n s p o r t a t i o n . o h i o . g o v 33

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Equations / Programs Rational Method Peak flow rate only Manning’s Equation Flow conditions (velocity and depth) at a given flow rate Outlet Discharge Equations Flow rate at a given outlet shape and hydraulic head ODOT CDSS Hydraulic design of culverts, ditches, and storm sewers SCS Curve Number Full runoff hydrograph (flow rate over time and full storm volume) Hydrograph and Pond Routing Programs Full hydrograph, detention, peak flow rate, and draw down analyses USGS StreamStats Peak design storm flow rates as well as other stream statistics w w w. t r a n s p o r t a t i o n . o h i o . g o v 36

Questions ? Jon Prier, P.E. jonathan.prier@dot.ohio.gov 614-644-1876 w w w. t r a n s p o r t a t i o n . o h i o . g o v 37