We cannot manage what we do not measure.”

Pavan Sukhdev, environmental economist

The power of GIS is its ability to answer certain types of questions, such as (Maguire 1991):

Geographic Information Systems are sometimes categorized based on the questions they are used to address. Some of these application-specific classifications include the following (Maguire 1991):

One of the first major areas of GIS application was in natural resource management, which may include the management of some of the following (Foote and Lynch 1995):

Other applications are also investigated below.


Natural Disasters and Emergency Management

Emergency management is the organization and management of resources and responsibilities for dealing with all aspects of emergencies (National Research Council 2007). The four phases of emergency management include the following:

All disasters have a temporal and geographic footprint that identifies the duration of impact and its extent on the Earth’s surface. The term geospatial is used to refer to the interdependent resources—imagery, maps, data sets, tools, and procedures—that tie every event, feature, or entity to a location on the Earth’s surface and use this information for some purpose. Although location is an essential part of any item of geospatial data, it is the ability to link a location to the properties of events, features, or entities at that location that gives geospatial data their value.


Watershed Delineation

DEM
Digital Elevation Map
Outlet
any point along a river, stream or creek; defines a unique watershed
Watershed
an area of land that drains all the streams and rainfall to a common outlet (also known as a drainage basin or catchment)

A watershed is the area of land where all of the water that falls in it and drains off of it goes to a common outlet. Watersheds are important because the amount and the quality of water of a river are affected by things (e.g., human activity, pollution runoff, heavy rainfall), which are happening in the land area “above” the river-outflow point (U. S. Geological Survey 2016).

Delineating a Watershed in GIS

There are several ways to delineate a watershed; however, using standard GIS tools, the following are the basic steps for delineation.

Required spatial data:

Geoprocessing tools:


Habitat Suitability

Habitat suitability rank
identification of potential living areas based on various grades of suitability criteria
Habitat suitability
identification of optimal living areas based on a set of suitability criteria

Geostatistics

As a discipline, geostatistics was firmly established in the 1960s by the French engineer Georges Matheron, who was interested in the appraisal of ore reserves in mining.

Geostatistics did not develop overnight. Like other disciplines, it has built on previous results, many of which were formulated with different objectives in various fields.

Seminal ideas conceptually related to what today we call geostatistics or spatial statistics are found in the work of several pioneers, including:

Most geological phenomena are extraordinarily complex in their interrelationships and vast in their geographical extension. Ordinarily, engineers and geoscientists are faced with corporate or scientific requirements to properly prepare geological models with measurements involving a significantly small fraction of the entire area or volume of interest. Exact descriptions of such systems are neither feasible nor economically possible and therefore the results are necessarily uncertain. It should be noted, however, that uncertainty is not an intrinsic property of the systems, rather it is the result of the incomplete knowledge of the observer.(Olea 2009)

The main objective of geostatistics is the characterization of spatial systems that are incompletely known.

Geostatistics makes use of a collection of numerical techniques for the characterization of spatial attributes using primarily two tools:

The probabilistic models are used as a way to handle uncertainty in results away from sampling locations, making a radical departure from alternative approaches like inverse distance estimation methods.

References

Foote, Kenneth E., and Margaret Lynch. 1995. “Geographic Information Systems as an Integrating Technology: Context, Concepts, and Definitions.” In The Geographer’s Craft Project. Boulder, CO: Department of Geography, The University of Colorado at Boulder.

Maguire, D. J. 1991. “An Overview and Definition of Gis.” In Geographic Information Systems, 1st ed., 9–20. Hoboken, NJ: John Wiley & Sons Ltd.

National Research Council. 2007. Successful Response Starts with a Map: Improving Geospatial Support for Disaster Management. Washington, DC: The National Academies Press. https://doi.org/10.17226/11793.

Olea, Richard A. 2009. “A Practical Primer on Geostatistics.” Open-File Report 2009-1103. United States Geological Survey.

U. S. Geological Survey. 2016. “What Is a Watershed?” https://water.usgs.gov/edu/watershed.html.