Floodplain Mapping using TINs

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Floodplain Mapping using TINs

• Triangulated Irregular Networks (TINs)
• Representation of stream channels using TINs
• Floodplain delineation using HEC-HMS, HEC-RAS and
  ArcView

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TIN with Surface Features
Classroom
UT Football Stadium
Waller Creek
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A Portion of the TIN
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Input Data for this Portion
Mass Points
Soft Breaklines
Hard Breaklines
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TIN Vertices and Triangles
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TIN Surface Model
Waller Creek
Street and Bridge
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3-D Scene
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3-D Scene with Buildings
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Floodplain Mapping using TINs

• Triangulated Irregular Networks (TINs)
• Representation of stream channels using TINs
• Floodplain delineation using HEC-HMS, HEC-RAS and
  ArcView

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River Modeling

• River hydraulic modeling provides a tool to study
  and gain understanding of hydraulic flow
  phenomena
• Topographic data describe the geometry of the
  simulated river system and permit the
  establishment of model topology
• HEC-RAS, MIKE 11 all hydraulic models require
  channel information for model development

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River Morphology
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Flood Inundation
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Floodplain Delineation
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Floodplain Delineation
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Channel and Cross-Section
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ProfileLines
Types 1- Thalweg 2- LeftBank 3- RightBank 4-
LeftFloodLine 5- RightFloodLine
ProfileLines and CrossSections are linked through
Channel_ID
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TIN as a source of cross-sections
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CrossSections
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Elements of a Cross-Section

• Identifier
• Georeference

• Property
• Supplementary

• Geometry

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Floodplain Mapping using TINs

• Triangulated Irregular Networks (TINs)
• Representation of stream channels using TINs
• Floodplain delineation using HEC-HMS, HEC-RAS
  and ArcView

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Floodplain Mapping Approach
CRWR-PrePro
HEC-GeoRas
ArcView
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Purpose

• Integrate/Validate existing tools for floodplain
  determination and visualization.
• Reduce the dependence on field data.
• Improve the floodplain analyses capabilities
  (lower costs and more accuracy).

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Digital Spatial Data

• Digital elevation
• model (DEM).
• Stream definition.

HEC-RAS
HEC-HMS
ArcView
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CRWR-PrePro

• Watershed delineation.
• Reach/Watershed
• parameters determination.

HEC-RAS
HEC-HMS
ArcView
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HEC-HMS Flow Determination
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HMS-RAS Connection
HMS Junctions
RAS Cross-sections
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HMS-RAS Connection
HMS Hydrograph
RAS Flow Data
(0500, 3559.6)
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Digital Terrain Model TIN

• Observed points and
• breaklines for
• constructing a
• triangular irregular
• network (TIN).

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Digital Terrain Model TIN
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GIS-RAS Connection

• Stream centerline.
• Banks.
• Flow paths.
• Cross sections.

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GIS-RAS Connection

• Location of cross
• sections.

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Hydraulic Modeling with HEC-RAS

• Cross-section extracted
• from the TIN.

• RAS stream geometry.

HEC-RAS
HEC-HMS
ArcView
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Hydraulic Modeling with HEC-RAS

• Resulting water
• elevations.

HEC-RAS
HEC-HMS
ArcView
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Floodplain Mapping

• Floodplain for
• 500 cfs.

HEC-RAS
HEC-HMS
ArcView
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Floodplain Mapping

• 2-D floodplain
• animation
• (500 5,000 cfs).

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Floodplain Mapping

• 3-D floodplain
• animation.

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Limitations

• Bridges/culverts
• - depend on
• field data.
• - data input
• by hand.

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Limitations

• The accuracy
• obtained from
• our TIN is not
• good enough.

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Solutions

• New technologies
• (i.e. LADAR) are
• improving the
• quality of the
• digital terrain
• representations.

• New technologies
• (i.e. LADAR) are
• improving the
• quality of the
• digital terrain
• representations.

Source digital representation of NYC generated
by ASI and published by ESRI.