Geographic Information Systems

What is GIS

How is it used

What are some sample applications

GIS… a definition:

Think of this as a map – database combination.Designed to ask questions that are answered with spatial informationAsk the map and the answer lights-up in the database.Ask the database and the answer lights-up on the map.

You have already used a GIS

If you have used MapQuest or similar sites for an address or driving instructions.

If you have searched online for an ATM banking machine location.

How is it used?

Creation of maps (visualizing spatial relationships)

Beyond maps- shows dynamic relationships

Front-end to databaseAnswers questions like “where is” and “what is nearest…”

Front-end to interactive modelsNow we see “what-if” answered in a spatial way

This web page asks “where is the nearest ATM from a specified point, and how do I get from here to there…

How is it used? Example 1

This website allows access to a county GIS department

Example 2

Example 3

This website displays traffic problems in the context of the street network.

Example 4 Arcview 3 D

A common product is a simple map like this.

Many GIS programs can go from flat map to 3D.

ArcView can easily make a 3D version of the map on the previous slide.

This shows use zone (commercial versus residential) in color and buildings extruded

Answer to query lights-up on map

See a short video of thishttp://pasture.ecn.purdue.edu/~tgis/images/howgiswrk.avi

Example query

GIS is used for maps–but offers more power than mapping software.

A common product is a simple map like this.

ArcMap for display and analysis

ArcToolbox for data preparation

ArcCatalog for data browsing

GIS – visualizing beyond maps

Another typical GIS application – a model output created from many layers.

Animation of air quality change over 7 days time – from a GIS

GIS - Visualizing beyond maps

GIS – analysis and visualizing

CAAGIS is distributing digital aerial photos for all of Indiana

Interactive (and on-line) databases

User-friendly database query (through maps)

Many tools to get online fairly easily

Distribution by INTRA-NET is possible

This site is a local government ( county with 100,000 people) GIS effort. The citizens need to get GIS data for permits to build homes or dig wells and septic tanks. Photos and map layers are available, tied to street address.

Interactive front-end to models

Greatly speeds use

Much wider clientele

You won’t lose the documentation

This is a new and growing use of GIS. It saves the model user much time formerly spent making data layers fit the format required by the model.

Interactive (and on-line) models-

LTHIA (Long Term Hydrologic Impact Analysis)

This model needs many inputs: soils, zoning, weather.

The mapserver-based website allows the user to select a location and have the GIS fetch all the pertinent layers, parameterizing them for the LTHIA model.

http://pasture.ecn.purdue.edu/~watergen/

Watershed Management Decision Support Using Web-Based Hydrological Tools and GIS

Bernard A. EngelJin-Yong ChoiLarry Theller

Agricultural and Biological DepartmentPurdue University

Processes for Hydrologic Impact Analysis Using Web-GIS Tools

Outlet Point Selection Using Web-GIS

Run Watershed Delineation

Watershed Delineation Result

Reflect Land Use Change Using Online Digitizing

Run L-THIA

Runoff and NPS Output/Impact Evaluation

Starting Page

Select Outlet Point Main Menu

Layer ControlOn/Off

Map Display

Display ControlZoom in/outPan, Full extent

Auxiliary functions

Reference Map

WD Submit Button

Watershed Delineation and Result Page

Results Display

Print and Download Page

L-THIA Input Data Preparation about Present Land Use and Hydrologic Soil Group

Buttons for Online Tool

Change Land Use in the Watershed Delineated Using Online Digitizing Tool

Add Low Density Residential, Commercial, and High Density Residential Areas

Results Page after Merging the Land Use Change

Present Land Use Data

Proposed Land Use Data

Application Buttons forHydrological Model Operation

L-THIA Input Page After Changing Land Use

Input is created for the second scenario

L-THIA Result Runoff Tables

Comparison Chart to evaluate the impact on hydrology of the proposed landusechange.

Runoff Landuse

NPS Pollutant Loading Chart

LTHIA and WD training

We created an 8 minute video which steps you through the WD and LTHIA process.

You will see this in lab, and you can view it here: http://

pasture.ecn.purdue.edu/~theller/abe325/wd_lthia_new.avi