Building a stream network for the 12th Hydrologic region using ArcInfo

CVEN 689

Prepared by:Héctor Olmos

Objectives Build a stream network for the 12th

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

Before

After

After

Isolatedfeature

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?