Flood Analysis of Scioto River Using HEC-RAS/GIS

Converting HEC-2 Data for

HEC-RAS /ArcView GIS Analysis and Inundation Mapping

(A pilot using Big Darby Creek )

1873 flood of Athens1873 flood of Athens

No Exact Record Available

1907 flood - the highest known flood

The estimated peak discharge was 50,000 cfs

The Joseph Herrold Home Before and After the 1913 The Joseph Herrold Home Before and After the 1913 Flood Flood

Before... Before...

Joseph Herrold home after the flood of 1913Joseph Herrold home after the flood of 1913

Flood on March 11, 1964 Flood on March 11, 1964 - Ohio University, Athens - Ohio University, Athens

A height of 24.18 feet was recorded on the gage station

Pre-processing

• USGS 1:24,000 DLGs

• AVRas Pre-processing Function– TIN creation (temporary from DLGs)– Preparing required themes in ArcView GIS

• Bank lines

• Center line - require a line between banks

• Flow lines - direction of the flow

– X-sections digitized from surveying maps

Pre-processing (cont.)

• Digitizing provided X-sections using Arc/Info• Conversion to ArcView GIS• Labeling stations for X-sections

Pre-processing

• Creating the HEC-RAS import file (*.geo) using AVRas– Temporary TIN

– Center line

– Bank lines

– Flow lines

– X-Sections

41

39

38.5

3635

34

3331

292827

26

2524.8

2322

2120.4

1918

17

1514

13

11

109.7

8

•HEC-2 X-sections •Preprocessed X-sections

Geo-referenced X-sections

Importing GIS and HEC-2 Data

• Separately import GIS geometry file (*.geo) and HEC-2 data

• Adjust GIS geometry file according to HEC-2 data– Ground elevations

– X-section lengths

• Run an Avenue script to export X-sections into ArcView GIS– Program written by Nan Shi

– Generate two shapefiles - X-sections and elevation points

• Adjust new X-sections referencing streams in GIS

Cross-Section Cleaning

• Cross-sections lengths adjusted by HEC-2 data

• Position verified by USGS data

• Flow length verified by HEC-2 data

Digitized Adjusted

Final DEM Production

• Point elevation data (original HEC-2 data)

• Topographical elevation data (USGS data)

• New TIN created for flood plain delineation

New DEM

HEC-RAS

• Adding parameters– Manning’s‘n’ values– Ineffective flow areas– Bridges– Steady flow data

• Run water surface profile computations

• Model verification

Model Verification

Profile Output Table - Standard Table 1HEC-RAS Plan: trial1 River:Big Darby Reach: Big Dar by

# Rivers 1# Hydraulic Reaches = 1# River Stations = 152# Plans 1# Profiles 4

Reach River Sta Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Big Darby 128466.2 8500 883 894.52 894.75 0.000541 4.27 2939.11 574.15 0.23Big Darby 128466.2 14100 883 897.24 897.5 0.000513 4.85 4546.13 606.28 0.24Big Darby 128466.2 16900 883 898.35 898.63 0.00051 5.1 5225.02 617.56 0.24Big Darby 128466.2 25300 883 901.11 901.45 0.000515 5.76 7020.72 678.71 0.25

Big Darby 127136.7 8500 882 893.65 893.97 0.000611 4.8 2350.87 823.1 0.25Big Darby 127136.7 14100 882 896.61 896.86 0.000441 4.76 4821.87 845.11 0.22Big Darby 127136.7 16900 882 897.78 898.01 0.0004 4.77 5810.92 853.76 0.21Big Darby 127136.7 25300 882 900.61 900.85 0.000351 5 8276.34 897.03 0.21

Big Darby 125026.9 9500 881 893.21 893.27 0.00018 2.74 4964.09 695.99 0.14Big Darby 125026.9 15800 881 896.15 896.24 0.00019 3.26 7078.01 743.25 0.15Big Darby 125026.9 19000 881 897.3 897.4 0.000199 3.5 7939.82 755.52 0.15Big Darby 125026.9 28400 881 900.1 900.24 0.000224 4.13 10103.78 875.96 0.17

Big Darby 124952.8 9500 880 892.99 887.24 893.23 0.000664 5.18 2675.37 293.83 0.26Big Darby 124952.8 15800 880 895.81 888.54 896.19 0.000783 6.47 3539.84 345.34 0.3Big Darby 124952.8 19000 880 896.89 889.6 897.34 0.000853 7.09 3936.01 384.84 0.31Big Darby 124952.8 28400 880 899.52 891.2 900.16 0.001023 8.59 5071.84 480.4 0.35

Big Darby 124940 Bridge

Big Darby 124863.5 9500 880 892.91 893.15 0.000615 4.85 2652.29 293.82 0.25Big Darby 124863.5 15800 880 895.7 896.09 0.000731 6.11 3484.59 327.95 0.29Big Darby 124863.5 19000 880 896.77 897.24 0.000801 6.71 3864.74 382.05 0.3Big Darby 124863.5 28400 880 899.37 900.04 0.000971 8.2 5078.62 646.05 0.34

Profile Output Table - Standar d Table 1HEC-RAS Plan: Imported Pla River: RIVER-1Reach: Rea ch-1

# Rivers 1# Hydraulic Reaches = 1# River Stations 153# Plans 1# Profiles 4

Reach River Sta Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach-1 84 8500 882.5 894.19 894.43 0.000511 4.33 2848.65 570.49 0.23Reach-1 84 14100 882.5 896.84 897.12 0.000513 5 4400.28 601.59 0.24Reach-1 84 16900 882.5 897.94 898.25 0.000514 5.27 5072.79 614.58 0.24Reach-1 84 25300 882.5 900.73 901.09 0.000518 5.94 6864.65 671.91 0.25

Reach-1 83 8500 882 893.32 893.66 0.000656 4.76 2075.33 820.41 0.26Reach-1 83 14100 882 896.17 896.45 0.000497 4.86 4446.62 841.64 0.23Reach-1 83 16900 882 897.34 897.61 0.000443 4.85 5438.96 850.36 0.22Reach-1 83 25300 882 900.23 900.48 0.000373 5.02 7932.5 893.31 0.21

Reach-1 82.5 9500 881 892.75 892.84 0.000216 2.54 4662.96 690.22 0.14Reach-1 82.5 15800 881 895.59 895.71 0.000226 3.03 6683.21 734.42 0.15Reach-1 82.5 19000 881 896.76 896.89 0.000233 3.25 7549.42 749.77 0.15Reach-1 82.5 28400 881 899.63 899.8 0.000252 3.8 9743.03 780.35 0.16

Reach-1 82.4 9500 879.7 892.6 886.5 892.81 0.000636 3.62 2623.22 293.79 0.21Reach-1 82.4 15800 879.7 895.34 887.99 895.67 0.000749 4.61 3427.63 294.18 0.24Reach-1 82.4 19000 879.7 896.45 888.7 896.85 0.000813 5.06 3753.28 294.34 0.25Reach-1 82.4 28400 879.7 899.13 890.25 899.74 0.000996 6.25 4543.27 294.72 0.28

Reach-1 82.3 Bridge

Reach-1 82.2 9500 879.7 892.58 886.51 892.79 0.000745 3.63 2616.09 293.79 0.21Reach-1 82.2 15800 879.7 895.31 888.01 895.64 0.000875 4.62 3417.4 294.17 0.24Reach-1 82.2 19000 879.7 896.41 888.7 896.81 0.000948 5.08 3741.33 294.33 0.25Reach-1 82.2 28400 879.7 899.13 890.25 899.74 0.001147 6.25 4542.43 643.19 0.28

Original HEC-2 New HEC-RAS

Post-processing

• HEC-RAS export file

• AVRas post-processing

• Flood plain for 4 profiles– 17,800 cfs

– 30,800 cfs

– 38,000 cfs

– 58,000 cfs

Big Darby Flood Delineation

17,800 cfs - green

30,800 cfs - red

38,000 cfs - blue

58,000 cfs - purple

Adding AdditionalGeographic Information

17,800 cfs

Adding AdditionalGeographic Information

30,800 cfs

Adding AdditionalGeographic Information

38,000 cfs

Adding AdditionalGeographic Information

58,000 cfs