It provides topography modification options using 2d_zsh, 2d_zln and 2d_ztin for TUFLOW with respect to the DTM. It also discusses about various conditions while modifying topography.

1. Topography Modifications in
TUFLOW
Mayuresh Padalkar
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2. 1. 2d_zln
• To represent levees, flood defences, roads, railways and embankments
that obstruct flow. Gullies can also be represented
• Command: Read GIS Z Line (thin line)
• THIN line modifies ZH, ZU, ZV elevations only if MAX/RIDGE is used but if
you use GULLY/MIN, then ZC are connected to give a continuous flow path
• Mention GULLY in command line if modelling a creek/watercourse/thalweg
• THICK line modifies the whole cell
• ADD option adds/lowers the DEM
• GULLY option cannot be used along with THICK
• Attribute: Elevation
• Check: 2d_zln_zpt
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3. 2. 2d_zsh
• Useful for any modelling with point, polyline and polygon feature
• Command: Read GIS Z Shape
• 2d_zsh has all the functionality of 2d_zln and a lot more options/attributes
• MAX/RIDGE/RAISE – Only changes a Zpt elevation if Z Shape elevation at Zpt is higher for a
polygon/polyline
• MIN/GULLY/LOWER – Only changes a Zpt elevation if Z Shape elevation at Zpt is lower for a
polygon/polyline
• MERGE ALL – ignores elevations from points snapped to the perimeter and merges all perimeter
vertices
• NO MERGE – Doesn’t merge the perimeter elevations
• Attributes: Z (elevations), dZ (change in elevation), Shape Width/dMax (THICK) and Shape
Options
• Check: 2d_zsh_zpt
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4. 3. 2d_ztin
• Triangulation of elevation points and lines (converted to points
ultimately) within a polygon (mandatory)
• Command: Create TIN Zpts Write TIN
• Attributes: Z and dMax (optional and applied only for line and
polygon)
• Check: 2d_sh_obj
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5. Condition 1: Elevations in txt/csv/xyz
• Option 1: 2d_ztin (preferred)
1. Create Points and add it to Map
window from *.csv
2. Modify the table structure using
Table Structure
3. Polygon shouldn’t be snapped to
points
• Option 2: 2d_zsh
1. Repeat steps 1 and 3
2. Elevations should be in “Z”
attribute
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6. Condition 2: Removal of raised structure
• Option1: 2d_zsh (preferred)
1. Draw a polygon along the
periphery
2. Leave all the attributes blank
• Option 2: 2d_ztin
1. Repeat above steps with
proper attribute table
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7. Condition 3: Ponds/Lakes/Reservoir
• 2d_zsh
1. Draw a polygon along the periphery with NO MERGE
in Shape Options
2. Lines should have an elevation in “Z” with TIN in
Shape Options
3. Leave other attributes blank
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8. Condition 4: Raising a polygon with fixed value
• 2d_zsh
1. Draw a polygon along the periphery of a building having
an elevation in “Z” (0.15m) with ADD in Shape Options
2. Leave other attributes blank
• 2d_za
1. Use an empty layer 2d_z__
2. Draw a polygon giving an elevation
3. Use Read GIS Zpts ADD in command line
ADD means it adds to DTM i.e. 100 (DTM elevation in mAOD)
+ 0.15 (m) = 100.15 (mAOD)
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9. Condition 5: Raising an
embankment/pond/area
• 2d_zsh (Polygon with points)
1. Draw a polygon with NO MERGE in Shape Options
2. Snap the points to polygon giving an elevation in “Z”
3. Leave other attributes blank
• 2d_zsh (Polygon only)
1. Draw a polygon with an elevation in “Z” and NO MERGE in Shape Options
2. Leave other attributes blank
• 2d_zsh (Polyline with points)
1. Draw a polyline with no attributes
2. Snap the points to polyline giving an elevation in “Z”
3. Optional: Use dMax to specify the width (similar to THICK) eg. Bridge
• 2d_zln
1. Draw a polyline giving an elevation
2. Use Read GIS Z Line THICK in command line to modify ZC, ZU, ZV and ZH
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10. Condition 6: Raising/Lowering
• 2d_zsh (Polyline with points)
1. Draw a polyline with no attributes
2. Snap the points to polyline giving an elevation in “Z”
3. To the same points use “dZ” to raise (+) or lower (-)
4. Leave other attributes blank
• 2d_zsh (Polyline only)
1. Draw a polyline with Z=0.15/(-)0.15 with ADD in
Shape Options
Note: Mention 1 in Shape Width for THICK in polyline
feature
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11. Condition 7: Fill an empty area
• 2d_zsh
1. Draw a polygon without any attributes
2. It will use the neighbouring elevations
• Set Zpt (Not preferred)
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12. Condition 8: Smooth the topography
• Option 1: 2d_zsh with
elevations from DTM
1. Draw a polygon
without any attributes
2. Snap points to the
polygon with Z=-99999
leaving other
attributes blank
• Option 2: 2d_zsh with desired elevations
1. Draw a polygon NO MERGE in Shape Options
2. Snap the points to polygon giving an elevation in “Z”
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13. References
• TUFLOW User Manual Build 2016-03-AE
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14. Thank you!!!
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