Importing HEC-2 Data Into HEC-RAS

Click to edit Master title style,Click to edit Master text styles,Second Level,Third Level,Fourth Level,Fifth Level,L-1621/Klipsch98,*,Importing HEC-2 Data Into HEC-RAS,What you need to know,1,L-1621/Klipsch98,Not all HEC-2 options have a parallel in HEC-RAS,Computation of Mannings,n,values from high watermarks.,Archiving (AC),Free format (FR),These options are ignored by the importer, so data sets which contain them can still be imported.,Some HEC-2 options,are,available, but are not imported,Split flow,Vertical variation of Mannings,n,values,Storage outflow for HEC-HMS,What you should know first,2,L-1621/Klipsch98,All imported data should be reviewed carefully for accuracy and completeness, especially.,Special bridges (SB) and culverts (SC),Normal bridges (X2, BT),Encroachments and floodway determination (X3, ET),Ineffective flow areas (X3),Channel improvements and modifications (CI),How the HEC-2 cross sections are,Identified,By river mile or station?,By an arbitrary numbering scheme?,Are the section ID numbers increasing from downstream to upstream?,Are there duplicate section ID numbers?,3,L-1621/Klipsch98,The Import Process Step 1,Create a new project ,4,L-1621/Klipsch98,Give your new project a title and a unique file name ,Confirm your title and file name,5,L-1621/Klipsch98,The Import Process Step 2,After a new project has been opened, select,Import HEC-2 data, from the,F,ile,menu.,6,L-1621/Klipsch98,Select the HEC-2 file to be imported,Tell HEC-RAS how to identify the cross sections as they are imported,7,L-1621/Klipsch98,Use the Geometry and Steady Flow Editors to review the imported data*.,The note below will appear whenever an HEC-2 data set that contains bridge or culvert data is imported. This is a reminder that bridges and culverts are not handled in the same way in HEC-RAS as they are in HEC-2. You will need to check that the data has been interpreted correctly.,8,L-1621/Klipsch98,Computational Differences between HEC2 & HEC-RAS,Cross Section Conveyance Calculations,Critical Depth Calculations,Bridge Hydraulics,9,L-1621/Klipsch98,Cross Section Conveyance Calculations,HEC-RAS Method: subdivisions at n-value break points.,n,1,n,2,n,3,n,4,A,1,P,1,A,2,P,2,A,ch,P,ch,A,3,P,3,K,lob,= K,1,+ K,2,K,ch,K,rob,= K,3,10,L-1621/Klipsch98,HEC-2 Method: subdivisions at every ground point.,n,1,n,2,n,3,n,4,A,2,P,2,A,3,P,3,A,ch,P,ch,A,6,P,6,K,lob,= K,1,+ K,2,+ K,3,+ K,4,K,ch,A,4,P,4,A,5,P,5,A,7,P,7,A,1,P,1,A,8,P,8,K,rob,= K,5,+ K,6,+ K,7,+ K,8,11,L-1621/Klipsch98,To choose the conveyance subdivision method to use, select,Steady Flow Analysis,from the,S,imulate,menu:,12,L-1621/Klipsch98,Select,Conveyance Calculations,from the,O,ptions,menu of the Steady Flow Analysis editor,And select your method,13,L-1621/Klipsch98,Critical Depth Calculations,HEC-RAS,Parabolic Method,Secant Method,Used if parabolic method,Does not converge.,Finds a value at the top of a levee or at an ineffective flow elevation.,HEC-2,Parabolic Method,Uses first local minimum it finds.,14,L-1621/Klipsch98,To choose, first select,Critical Depth Computation Method,from the,Options,menu of the Steady Flow Analysis,editor:,Then select the method:,15,L-1621/Klipsch98,Bridge Hydraulics,HEC-RAS,4 Low Flow Methods,Energy,Momentum,Yarnell,WSPRO,2 Independent High Flow Methods,Energy,Pressure &/or Weir,HEC-2,2 Low Flow Methods,Normal (Energy),Special (,Yarnell,),2 High Flow Methods dependent upon,Low Flow Method,Energy,Pressure & Weir,16,L-1621/Klipsch98,HEC-2s Special Bridge Method Low Flow,HEC-RAS,All methods (including,Yarnells,) use actual bridge geometry to determine flow area,Each pier is defined and located individually,Bridge opening is determined by geometry.,HEC-2,Trapezoidal approximation,of bridge opening used to determine flow area,Single,equivalent width,pier centered within trapezoid,Net flow area input for pressure flow.,17,L-1621/Klipsch98,HEC-2s Special Bridge Method Pressure Flow,HEC-RAS,Fully submerged or upstream-only submerged.,Bridge opening based on geometry.,Weir profile is the union of the cross section and bridge deck.,HEC-2,Fully submerged condition assumed,Net flow area input for pressure flow.,Weir profile is defined by BT or X2 data not cross section.,18,L-1621/Klipsch98,HEC-2s Normal Bridge Method,HEC-RAS,Piers are defined separate from the deck or ground.,The deck data must have a spatial relationship to the cross section(s) but need not match ground points.,HEC-2,Piers were defined as part of the cross section data or deck data.,Each BT data point was required to match a cross section GR point.,19,L-1621/Klipsch98,Culvert Hydraulics,HEC-RAS,Wide variety of shapes available:,Box,Pipe,Arch,Pipe,Low & High Profile,ConSpan,Ellipse,Vertical,horizontal,Multiple culverts of different shapes and sizes can be placed at a single crossing.,HEC-2,2 Shapes available:,Box,Pipe,Multiple barrels of only one shape and size can be used at a single crossing.,20,L-1621/Klipsch98,Floodway Determination,HEC-RAS,Methods 1-3,Method 4,0.01 ft. accuracy,Method 5,Optimizes for Water Surface or Energy or Both.,Floodway determination is independent of blocked obstructions.,HEC-2,Methods 1-3,Method 4,Parabolic Interpolation,Method 5,Optimizes for a change in Water Surface,Method 6,Optimizes for a change in Energy,X3 encroachments override ET floodway determination.,21,L-1621/Klipsch98,What can HEC-RAS do that HEC-2 cannot?,Mixed Flow,Multiple Openings,Momentum computation at bridges and junctions,Complex,dendritic,streams and looped networks,Blocked Ineffective Areas,Normal Ineffective Areas at any station,Blocked Obstructions,Levees,Inline and Lateral weirs and gated spillways,Geometric cross section interpolation,22,L-1621/Klipsch98,