Building a stream network for the 12 th Hydrologic region using ArcInfo CVEN 689 Prepared by: Héctor Olmos

Objectives Build a stream network for the 12 th hydrologic region, based on NHD datasets. Create a step by step guide.

ArcInfo 8x Same components ArcMap ArcCatalog ArcTools More powerful than ArcView

Geodatabase Relational databases that contain geographic information Organize the data Create the geometric network Personal Geodatabase Feature dataset Feature Class Table

Network Set of edges and junctions that are topologically connected to each other. Edges Junctions

Geometric Network One dimensional nonplanar graph Network connectivity is based on geometric coincidence name Logical network = virtual representation Defines rules of behavior

Study Region Hydrologic Regions

Region 12 Texas-Gulf 11 subregions 22 accounting units 122 Cataloging Units

NHD National Hydrography Dataset Contains information about surface water features Medium resolution (1:100,000) High resolution (1:24,000)

Center line Shore lines NHD (1:24,000) Digital raster graphics (DRG) 1:24,000 Rf1 Rf1 (1:500,000) Center line Shore lines NHD (1:100,000) Data quality comparison

Procedure

Download NHD Download & extract NHD datasets

Append NHD Create a single dataset Append_NHD tool

Select the streams Streams, pipelines, channels, shorelines “Clean” the streams

Create Sinks Flow direction Stream network (only sinks) Sink

Snap gauging stations Not connected to streams

Create the Geometric Network Select features Define sinks Snapping options Errors table

Invalid geometries Invalid features were deleted Before After Isolated feature

Loop Longest path Loops Flow direction not defined Delete the longest path

Tracing Tracing downstream Tracing Upstream

Conclusions Preparing the data takes a lot of time (this was a huge area) Some of the deleted features were really streams. Building a stream network is not very difficult once the data has been filtered. A stream network has a lot of applications.

Future work Create a tool that automatically finds loops and corrects them. Create a new network with high resolution NHD datasets.

Questions?