Text B GIS

1.What Is GIS

GIS is a collection of computer hardware, software, and geographic data for capturing, managing,analyzing, and displaying all forms of geographically referenced information.

2.Why Geography

Geography is a serious discipline with multibillion dollars implications for businesses and governments. Choosing sites, targeting market segments, planning distribution networks, responding to emergencies, or redrawing country boundaries — all of these problems involve questions of geography.

Here’s an example of how Bank of America used GIS to show the geographic distribution of the bank’s network in relation to deposit potential in the New York City market area. From this analysis, Bank of America can determine where their coverage is strong and where it is weak. Red dots symbolize strong coverage; no dots means coverage is nonexistent.

3.How Does GIS Use Geography

With a geographic information system (GIS), you can link information (attributes) to location data,such as people to addresses, buildings to parcels, or streets within a network. You can then layer that information to give you a better understanding of how it all works together. You choose what layers to combine based on what questions you need to answer.

In this example, emergency medical service (EMS) call information,including call type, elapsed travel time, and which rescue unit was dispatched to the call’s location, has been linked to addresses. With this GIS-linked database, questions such as“What percent of dispatched calls did each EMS unit respond to within its assigned zone?”can be answered.

A GIS is most often associated with a map. A map, however, is only one way you can work with geographic data in a GIS, and only one type of product generated by a GIS. This is important, because it means that a GIS can provide a great deal more problem-solving capabilities than using a simple mapping program or adding data to an online mapping tool (creating a“mash-up”).

A GIS can be viewed in three ways:

·The Database View: A GIS is a unique kind of database of the world — a geographic database (geodatabase).It is an“Information System for Geography”. Fundamentally,a GIS is based on a structured database that describes the world in geographic terms.

·The Map View: A GIS is a set of intelligent maps and other views that show features and feature relationships on the earth’s surface. Maps of the underlying geographic information can be constructed and used as“windows into the database” to support queries, analysis, and editing of the information. This is called geovisualization.

·The Model View: A GIS is a set of information transformation tools that derive new geographic datasets from existing datasets. These geoprocessing functions take information from existing datasets,apply analytic functions, and write results into new derived datasets.

In other words, by combining data and applying some analytic rules, you can create a model that helps answer the question you have posed.

Together, these three views are critical parts of an intelligent GIS and are used at varying levels in all GIS applications.

4.What Can You Do with GIS

4.1 Map Where Things Are

Mapping where things are let you find places that have the features you’re looking for, and to see where to take action.

Find a feature—people use maps to see where or what an individual feature is.

Finding patterns—looking at the distribution of features on the map instead of just an individual feature,you can see patterns emerge.

Maps of the locations of earthquake shaking hazards are essential for creating and updating building codes used in the United States. Online, interactive earthquake maps,as well as seismicity and fault data, are available at earthquake.usgs.gov.

4.2 Map Quantities

People map quantities, like where the most and least are, to find places that meet their criteria and take action, or to see the relationships between places. This gives an additional level of information beyond simply mapping the locations of features.

This map shows the number of children under　18　per clinically active pediatrician for a particular study area. It was created by the Center for the Evaluative Clinical Sciences at Dartmouth Medical School as part of an effort to develop a national U.S. database of primary care resources and health services.

For example, a catalog company selling children’s clothes would want to find ZIP Codes not only around its store, but those ZIP Codes with many young families with relatively high income. Or, public health officials might not only want to map physicians, but also map the numbers of physicians per 1,000 people in each census tract to see which areas are adequately served,and which are not.

4.3 Map Densities

While you can see concentrations by simply mapping the locations of features, in areas with many features it may be difficult to see which areas have a higher concentration than others. A density map lets you measure the number of features using a uniform areal unit, such as acres or square miles, so you can clearly see the distribution.

Mapping density is especially useful when mapping areas, such as census tracts or counties, which vary greatly in size. On maps showing the number of people per census tract, the larger tracts might have more people than smaller ones. But some smaller tracts might have more people per square mile—a higher density.

4.4 Find What’s Inside

Use GIS to monitor what’s happening and to take specific action by mapping what’s inside a specific area. For example, a district attorney would monitor drug-related arrests to find out if an arrest is within 1,000 feet of a school—if so, stiffer penalties apply.

This image from the Sanborn Map Company, Inc., shows a geoprocessed sample explosion radius around an area in California. Each separate zone represents 1/4 mile, the outermost perimeter being　1　mile away from the source.

4.5 Find What’s Nearby

Find out what’s occurring within a set distance of a feature by mapping what’s nearby.

The Pacific Disaster Center has developed and applied a Vulnerability-Exposure-SensitivityResilience model to map people and facilities (what’s nearby) exposed to flood risk in the Lower Mekong River Basin (the feature).

4.6 Map Change

Map the change in an area to anticipate future conditions, decide on a course of action, or to evaluate the results of an action or policy.

By mapping where and how things move over a period of time, you can gain insight into how they behave. For example, a meteorologist might study the paths of hurricanes to predict where and when they might occur in the future.

Map change to anticipate future needs. For example, a police chief might study how crime patterns change from month to month to help decide where officers should be assigned.

Map conditions before and after an action or event to see the impact. A retail analyst might map the change in store sales before and after a regional ad campaign to see where the ads were most effective.

These images are from a poster titled“Losing Cape Cod”, which is distributed by the Woods Hole Research Center in Woods Hole, Massachusetts. The poster shows the severe change in land use on Cape Cod since 1951. The image on the left shows the town of Barnstable in　1951　and the image on the right shows Barnstable in 1999.

New Words

Phrases

a collection of　　　　有关……的收集

country boundaries　　　　国境线，国界线

base on　　　　基于

associate with　　　　和……来往，和……共事，同……联合

a set of　　　　一组，一套

earth’s surface　　　　地面

instead of　　　　代替，而不是

ZIP Code　　　　邮政代码

decide on…　　　　对……做出决定

Abbreviations

GIS (Geographic Information System)　　　　地理信息系统

EMS (Emergency Medical Service)　　　　急救医疗服务

ZIP (Zone Improvement Plan)　　　　区域改进方案

Exercises

【Ex.5】根据文章所提供的信息填空。

1.GIS is a collection of computer hardware,________, and________for capturing, managing, analyzing, and displaying all forms of________ .

2.Geography is________with multibillion dollars implications for________.

3.With________ , you can link information (attributes) to location data, such as people to addresses, buildings to parcels, or streets within a network.

4.A GIS is most often associated with________ .

5.A GIS can be viewed in three ways. They are________ ,________ and________ .

6.You can use GIS to map where things are, that is, it lets you________ , and________ .

7.Mapping quantities gives an additional level of information beyond________ .

8.A density map lets you________ , such as acres or square miles, so you can clearly see________ .

9.The Pacific Disaster Center has developed and applied________ to map people and facilities (what’s nearby)________ in the Lower Mekong River Basin (the feature).

10.The last thing GIS can do mentioned in the passage is________ .