GIS technology has the sophistication to go beyond
mapping and serve a larger purpose of a data management and analysis tool. GIS
technology aggregates the spatial data you need to make good decisions for
your organization. GIS can integrate georeferenced imagery as data layers or
themes and link them to other data sets to produce geospatial representations
of data. These geographical pictures not only depict geographic boundaries but
also offer special insight to researchers across disciplines such as health,
economics, agriculture, and transportation. By using GIS, our researchers are
able to establish the patterns and interactions between health, environmental,
and socio-economic variables with real world geographic locations. GIS
technology has greatly advanced in the last 30 years, and is capable of
performing sophisticated analysis of data. GIS analysis can answer questions
Good GIS applications use data analysis to benefit municipal, county and state
governments as well as commercial industry. Some examples are:
Municipal authorities, Central and state governments can use GIS to answer
important questions such as:
Real estate developers can use GIS to make informed decisions about where to
build a development, office complex or mall using analysis on:
Retail can use GIS analysis to find an optimal new store location. Analysis
of GIS data can yield a desirable demographic with respect to:
Commercially available GIS application packages offer a wide
range of analytical approaches. These include:
1. Neighborhood Analysis evaluates the
characteristics of an area surrounding a specific location. The analysis of
topographic features, e.g. the relief of the landscape, is normally
categorized as being a neighbourhood operation. This involves a variety of
point interpolation techniques including slope and aspect
calculations, contour generation, etc.
Elevation data usually takes the form of irregular or regular spaced
points. Irregularly space points are stored in a Triangular Irregular
An alternative in storing elevation data is the regular point Digital
Elevation Model (DEM). The term DEM usually refers to a grid of
regularly space elevation points. These points are usually stored with a
raster data model. Most GIS software offerings provide three dimensional
analysis capabilities in a separate module of the software.
Without doubt the most common neighborhood
function is buffering. Buffering
involves the ability to create distance buffers around selected features, be
it points, lines, or areas. Buffers are created as polygons because they
represent an area around a feature. Buffering is also referred to as
corridor or zone generation with the raster data model.
2. Connectivity Analysis
The distinguishing feature of
connectivity operations is that they use functions that accumulate values
over an area being traversed. Most often these include the analysis of
surfaces and networks. Connectivity functions include proximity analysis,
network analysis, spread functions, and three dimensional surface
analysis such as visibility and perspective viewing.
3. Proximity analysis
3. Proximity analysis
techniques are primarily concerned with the proximity of one feature to
another. Usually proximity is defined as the ability to identify any
feature that is near any other feature based on location, attribute value,
or a specific distance. A simple example is identifying all the forest lands
that are within 100 metres of a gravel road, but not necessarily adjacent to
4. Network analysis
is a widely used analysis technique used for
route optimization. Two example network analysis techniques are the
allocation of values to selected features within the network to
determine capacity zones, and the determination of shortest path
between connected points or nodes within the network based on attribute
values. Attribute values may be as simple as minimal distance, or more
complex involving a model using several attributes defining rate of flow,
impedance, and cost.
5. Three dimensional analysis
involves a range of different capabilities. The most utilized is the
generation of perspective surfaces. Perspective surfaces are usually
represented by a wire frame diagram reflecting profiles of the landscape,
e.g. every 100 metres. These profiles viewed together, with the removal of
hidden lines, provide a three dimensional view. Most GIS software packages
offer 3-D capabilities in a separate module. Several other functions are
normally available. These include the following functions:
User definable vertical exaggeration,
viewing azimuth, and elevation angle;
Identification of viewsheds, e.g. seen
versus unseen areas;
draping of features, e.g. point, lines, and shaded polygons onto the
of shaded relief models simulating illumination;
of cross section profiles;
of symbology on the 3-D surface; and
of sight perspective views from user defined viewpoints.
Practical Steps to Performing
1. Frame the Question:
Where are endangered ecosystems in Delaware
Where are potential recreational trail corridors
in Delaware County?
How can we understand the tangible state of
environmental justice in Delaware County OH?
Who is your audience? what is your final goal?
What is your final product?
2. Understand your Data
What is the context of your question? who are the experts?
What do you have to know about the context of
the question to answer it?
What is an endangered ecosystem? what are
What are the goals of recreational trails? what
do they connect?
What is Environmental Justice and what kind of
data helps us understand it?
What or who can help you to understand the
issue: literature, people
3. Choose a Method
What data is available to help answer your
question? cost? compatibility?
What data do you have to generate yourself? easy
vs. difficult vs impossible
4. Process the Data: specific
Example: Generate endangered areas by comparing
areas defined as important ecosystems to their closeness to recent development
Example: Generate potential trails by generating
important points and areas to connect; and determining feasible paths between
those points; relate potential trails to property ownership and other factors
5. Look at the Results
Generate a map (with a database) and use it to
Map of endangered ecosystems in Uttarakhand:
Map of potential trails in Corbett National
Park: planners, bike clubs, etc.