1. Floodplain Mapping Using AV-RAS Esteban Azagra and Francisco Olivera, Ph.D. Center for Research in Water Resources University of Texas at Austin

2. Objective AV-RAS is a system of ArcView tools developed in Avenue -- the ArcView programming language -- that: extracts hydrologic data from digital terrain data, and maps the HEC-RAS results back on the digital spatial data

3. Floodplain Mapping Approach CRWR-PrePro AVRas Water surface profiles ArcView Geometric data Parameters Schematic Flow discharge HEC-HMSHEC-RAS

4. Digital Spatial Data ArcView HEC-RASHEC-HMS Digital spatial data required: Digital elevation model (DEM). Vector stream network. Land use / land cover Soils

5. Streams and Watersheds ArcView HEC-RASHEC-HMS CRWR-PrePro is used for: Stream and watershed delineation. Determination of stream and watershed hydrologic parameters.

6. HEC-HMS: Flow Determination ArcView HEC-RASHEC-HMS

7. HMS-RAS Connection HMS Junctions RAS Cross-sections ArcView HEC-RASHEC-HMS

8. HMS-RAS Connection ArcView HEC-RASHEC-HMS (0500, 3559.6) HMS Hydrograph RAS Flow Data

9. Digital Terrain Model: TIN ArcView HEC-RASHEC-HMS Observed points and breaklines for constructing a triangular irregular network (TIN).

10. TIN components: - nodes - edges - triangles Digital Terrain Model: TIN ArcView HEC-RASHEC-HMS

11. 3D display of a TIN. Digital Terrain Model: TIN ArcView HEC-RASHEC-HMS

12. Digital Terrain Model: TIN Embedding Buildings into the TIN. ArcView HEC-RASHEC-HMS

13. Cross Sections Stream centerline. Banks. Flow paths. Cross sections. ArcView HEC-RASHEC-HMS

14. Bridges are not captured by the TIN: cross sections should NOT be defined at the bridges. ArcView HEC-RASHEC-HMS Cross Sections

15. Hydraulic Modeling with RAS RAS stream geometry. Cross-sections extracted from the TIN. ArcView HEC-RASHEC-HMS

16. Hydraulic Modeling with RAS Water surface elevations. ArcView HEC-RASHEC-HMS

17. Floodplain Mapping ArcView HEC-RASHEC-HMS Floodplain for 500 cfs.

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

19. Floodplain Mapping 2-D representation of the Central Park detention pond.

20. Floodplain Mapping 3-D floodplain animation.

21. Limitations Bridge and culvert data has to be entered by hand.

22. Limitations The accuracy obtained from TIN data might not be good enough.

23. Solutions Source: digital representation of NYC generated by ASI and published by ESRI. New technologies (i.e. LADAR) are improving the quality of the digital terrain representations.

24. Source: digital representation of NYC generated by ASI and published by ESRI. Solutions New technologies (i.e. LADAR) are improving the quality of the digital terrain representations.

25. Conclusions Automation of floodplain delineation results in time and resource savings. The lack of subjectivity provides standardized results. Applications include: Design of control structures (detention ponds, culverts, bridges, …). Flood insurance rate determination. Real-time flood emergency mapping. The accuracy of the digital terrain model has to be improved. Some field data will be still required.