Trinity River Network Development Kim Davis 6 MAY 1999

Outline Data Needs Methods Results Conclusions

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

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

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

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)

Create Network Orientation Based on Topology Too slow! Memory Intensive

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

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

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

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

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

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

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

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

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

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

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