Watershed and Stream Delineation Tool for

ArcGIS 8.1

Watershed and Stream Delineation Tool for

ArcGIS 8.1By Milver A. Valenzuela

TEXAS A&M UNIVERSITY

IntroductionIntroduction

What is ArcGIS 8.1?

What is new on ArcGIS 8.1?

ArcGIS 8.1ArcGIS 8.1

The three desktop GIS components of ArcGIS are:

ArcView :composed by ArcMap, ArcCatalog and ArcToolbox.

ArcEditor: same as ArcView but with capacities for editing coverages and geodatabases.

ArcInfo: same as ArcEditor plus capacities for geoprocessing and with a full version of ArcInfo Workstation.

ArcView 8.1ArcView 8.1

Arc View 8.1

ArcCatalog ArcMap ArcToolbox

EditShapefilesGeodatabases

Extensions

ArcGIS 8.1ArcGIS 8.1

Top ten features shared by ArcInfo, ArcView, and ArcEditor

Advanced editing tools High-quality cartography Internet-enabled On-the-fly projection Geocoding Wizard-driven tools Support for metadata standards using XML COM-based customization Extensible architecture Direct read of more than 40 data formats COM-based customization

What is COM?What is COM?

Component Object Model It’s a technology developed by Microsoft Corporation.

COM establishes a common way of building software components.

Because of these, it can be written macros in VBA(GIS) or extensions in VB, Delphi and C++.

What is COM?What is COM?

Component Object Model

Client ServerInterfaces

Interfaces

Interfaces

Interfaces

What is COM?What is COM?

Component Object Model

Interfaces

Properties Methods

The ToolThe Tool

Developed in VBA(GIS).

Follows a simple linear procedure.

From a simple input it can be delineated watersheds.

The ProcedureThe Procedure

INPUT

Procedure

Output

The InputThe Input

Digital Elevation Model

Threshold number

Output directory

The ProcedureThe Procedure

Fill sinks Flow Direction Flow Accumulation Threshold condition Grid Streams Grid Watersheds Vectorization of Streams Vectorization of Watersheds

The OutputThe Output

The following layers:

Filled DEM (fdem) Flow Direction Grid (fdr) Flow Accumulation Grid (fac) Streams Grid (str) Links Grid (lnk) Watersheds Grid (wsh) Vectorized streams (strl) Vectorized watersheds (wshp)

An Example: An Example:

Delineating watersheds and streams for the Guadalupe River Basin. (Similar exercise done with CRWR-PrePro in class)

DEM: Guadalupe River Basin derived from USGS 15” of the United States (500m cell size), UTM projection.

Threshold: 500 cells: 500x500mx500m as minimum drainage area

The DEM The DEM

The InterfaceThe Interface

The Output: Filled DEMThe Output: Filled DEM

The Output: Flow Direction GridThe Output: Flow Direction Grid

The Output: Flow Accumulation GridThe Output: Flow Accumulation Grid

The Output: Streams GridThe Output: Streams Grid

The Output: Links GridThe Output: Links Grid

The Output: Watershed GridThe Output: Watershed Grid

The Output. Vectorized streams and watershedsThe Output. Vectorized streams and watersheds

File system output File system output

Limitations Limitations

The process is irreversible. We can’t save other output in the same

workspace because the names of the files are fixed. It gives an automation error.

The program doesn’t have an specific error handler.

The next step… The next step…

Add an “advance” button as well as more features.

Convert the program to dll.

Questions & CommentsQuestions & Comments