Floodplain Mapping using TINs Triangulated Irregular Networks TINs

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

TIN with Surface Features Classroom Waller Creek UT Football Stadium

A Portion of the TIN

Input Data for this Portion Mass Points Soft Breaklines Hard Breaklines

TIN Vertices and Triangles

TIN Surface Model Waller Creek Street and Bridge

3 -D Scene

3 -D Scene with Buildings

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

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

River Morphology

Flood Inundation

Floodplain Delineation

Floodplain Delineation

Channel and Cross-Section Direction of Flow Channel Cross-Section

Profile. Lines Types 1 - Thalweg 2 - Left. Bank 3 - Right. Bank 4 - Left. Flood. Line 5 - Right. Flood. Line Profile. Lines and Cross. Sections are linked through Channel_ID

TIN as a source of cross-sections

Cross. Sections

Elements of a Cross-Section w. Geometry w. Identifier w. Property w. Georeference w. Supplementary

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

Floodplain Mapping Approach HEC-HMS HEC-RAS Flow discharge CRWR-Pre. Pro Parameters Schematic Geometric data Arc. View HEC-Geo. Ras Water surface profiles

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).

Digital Spatial Data • Digital elevation model (DEM). • Stream definition. HEC-HMS HEC-RAS Arc. View

CRWR-Pre. Pro • Watershed delineation. • Reach/Watershed parameters determination. HEC-HMS HEC-RAS Arc. View

HEC-HMS: Flow Determination HEC-HMS HEC-RAS Arc. View

HMS-RAS Connection HMS Junctions RAS Cross-sections HEC-HMS HEC-RAS Arc. View

HMS-RAS Connection HMS Hydrograph (0500, 3559. 6) RAS Flow Data HEC-HMS HEC-RAS Arc. View

Digital Terrain Model: TIN • Observed points and breaklines for constructing a triangular irregular network (TIN). HEC-HMS HEC-RAS Arc. View

Digital Terrain Model: TIN • Embedding Buildings into the TIN. HEC-HMS HEC-RAS Arc. View

GIS-RAS Connection • Stream centerline. • Banks. • Flow paths. • Cross sections. HEC-HMS HEC-RAS Arc. View

GIS-RAS Connection • Location of cross sections. HEC-HMS HEC-RAS Arc. View

Hydraulic Modeling with HEC-RAS • Cross-section extracted from the TIN. • RAS stream geometry. HEC-HMS HEC-RAS Arc. View

Hydraulic Modeling with HEC-RAS • Resulting water elevations. HEC-HMS HEC-RAS Arc. View

Floodplain Mapping • Floodplain for 500 cfs. HEC-HMS HEC-RAS Arc. View

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

Floodplain Mapping • 3 -D floodplain animation.

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

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

Solutions • 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.