1. Trinity River Network Development
Kim Davis
6 MAY 1999

2. Outline
Data Needs
Methods
Results
Conclusions

3. Data Used Modified Trinity River RF3 SWQM Stations TMDL Segments
Jona Finndís
SWQM Stations
TNRCC
TMDL Segments
TNRCC

4. Methods Create Network Dynamic Segmentation
Connectivity Test (Arc/Info)
Topology (Dr. Olivera)
Orientation
Attach Points (Richard Gu)
Dynamic Segmentation
RIT-Reach Indexing Tool

5. Create Network Trial and Lots of Errors Connectivity Test
Nothing worked right until I re-performed this step!!!
Lowered the tolerance value for network simplification (to preserve detail)
Connectivity Test
Arc/Info traces paths that flow to outlet
Branches that are connected can be displayed

6. Create Network Topology Gives each stream a unique number
Gives each stream intersection a unique number
Allows streams to have an orientation (upstream v. downstream)

7. Create Network Orientation Based on Topology Too slow!
Memory Intensive

8. Create Network Orientation Based on Topology Based on DEM
Too many flat spots
Hard to error-check

9. Create Network Orientation Based on Topology Based on DEM
Back to Topology
Used a different way of ‘looking up’ streams
Easy to error-check

10. Create Network Attach Points
Small errors make points fall off the stream
Attach them without changing their position-- create “virtual points”

11. Dynamic Segmentation
Useful for properties that change with distance on a line

12. Dynamic Segmentation What on earth is it?
A way to display spatial information without having to store the spatial data
A flexible way to show the characteristics of spatial data

13. Dynamic Segmentation What that last bit meant
Every GIS map has a table of data with it
Dynamic Segmentation makes it possible to make the table smaller
You can display the data spatially without storing the shapes

14. Dynamic Segmentation
This column is what makes the map draw in GIS

15. Dynamic Segmentation
These columns allow the following spatial display of this non-spatial data

16. Dynamic Segmentation
A line shape in a GIS table can only have one value assigned along its length.
Example: a reach 5 miles long can only store a single velocity value
That line can be dynamically segmented to store values at various points along its length

17. Results
Topologically coherent dendritic river network with attached points and dynamic segmentation of (some) TMDL segments

18. Conclusions
We have the basis of a good set of network manipulation tools
Future work
Exploiting dynamic segmentation
Error-checking current work
Points
Orientation