M@IN - Accessing Spatial Data Tutorial
NCGDC - Example, Solving the Use Statement
- "I am concerned about hazardous waste sites in Henderson County, NC, especially ones near my
water supply. I have access to computer mapping software. Where do I find
information or data that I can use?"
As described, way back on page 1, the answer is the North Carolina Geographic Data Clearinghouse
(NCGDC). We will now use the NCGDC to find information for the two themes above
- hazardouse waste sites and water supplies. Remember, when researching information, you often find that
the information your searching for is under a name you may not expect. So keep this in mind when using
any Clearinghouse to search for data.
Please Note: Downloading and printing (or writing) a copy of the steps below will help
your perform the searches by preventing the need to jump back and forth between the NCGDC and this
Remember to use your "BACK" button to return to this page.
As we saw on page 10, the NCGDC can be searched four ways. These searches can be divided into two types:
point-and-click, and fill-in-forms.
Point-and-click searches consist of choosing from a static set of hypertext (or "hot")
links presented by the author of the site. By following one or many of these links, you go to where they
will take you.
Fill-in-forms searches consist of inputting search parameters into a form on a browser,
submitting the form with a mouse "click", and having the computer bring query matches back to the
screen. We will try both types of searches. One looking for hazardous waste; and, one looking for
Point-and-click Search for Hazardous Waste
- 1.) Connect to the NCGDC homepage.
- Here you will see the options for the searches. The 3 point-and-click search options are by
Subject Index, Data Themes and Participants (agency).
- 2.) Select the Data Themes option and view the 8 major themes.
- 3.) Select the Subject Index.
- Scroll through the list until you find a theme or subtheme which might have information on hazardous
- 4.) Select the theme or subtheme of interest.
- This will take you to one of the 8 theme pages, which contain data listings and descriptions by name. Note that the connection took you directly to the data subtheme. If you scroll to the top of the page, you will see this is the Environmental Qual
ity theme page.
- 5.) Scroll back down the page until you find a layer which might have data on hazardous waste.
- Remember, it might be called something different than you are expecting.
- 6.) Select on the agency name link to go to where more information about the data is available.
(In this case, select on "Available from North Carolina Center for Geographic Information and Analysis).
- All point-and-click searches link from the NCGDC to the source agency through the agency's name.
- 7.) Scroll down the page to the layer of interest.
- Note that this page is also an order form.
- 8.) Read over the description, then select on the metadata.
- Remember, you are looking for the agency and contact where you can get this data.
- 9.) Select "Distribution Information" from the top menu on the metadata file to find out how to order
- You now know where to find data on hazardous waste.
Fill-in-forms Search for Water Supplies
- 1.) Connect to the NCGDC homepage.
- The fill-in-forms option, called "Custom Queries", is available either in the left hand Virtual
Index, or in the right hand, main window.
- 2.) Select Custom Queries.
- This will take you to a page showing 2 choices: Search North Carolina's Corporate Geographic Database; or, Search US and Other using the National Geospatial Data Clearinghouse. Since the NC link is under construction, we will use the US and Other op
- 3.) Select on the National Geospatial Data Clearinghouse gateway.
- This may take a little time to make a connection.
- 4.) Select Connect to Service
- This starts a conversation between your computer and their's.
- 5.) We are now going to fill in the options we want to use to search for water supplies.
- Note the types of query parameters.
If you know the coordinates you want, decimal degrees of longitude and latitude can be entered.
If you want data in a particular time, input date parameters.
- 6.) Scroll down to the Keyword & Fielded Search and input in the blank the term "water supply".
- Note that there is a pull-down menu which allows you to search full text, just the title field, or
one of many other specific fields within the metadata. Set this to Title.
- 7.) Scroll down to the Databases box. We want to select the North Carolina Corporate Geographic Database only. Depending on which browser you are using, you will need to unselect the default setting in different ways. Select on the d
atabase below the highlighted one. If it becomes highlighted also, you will need to click both again to unselect them. If, however, you select the second one and the first one becomes unselected, just go to the next step in this list.
- Remember, we want to make sure that the NCCGDB is the only database selected.
- 8.) Scroll down the list of searchable databases and select the North Carolina
Corporate Geographic Database..
- You have now set all the options we will use for our search.
- 9.) Hit the "Submit Query" button.
- Response time varies based on type of query, number of databases searched, and network traffic. You
will get back a page with a listing of response "hits".
- 10.) Scroll down the list and select the data set which most closely matches water supplies. (If "Title" was searched, only one may appear).
- This brings you the metadata from the source agency's server.
- 11.) Select the "Distribution Information" to see how to get the data.
- Note: Since not all the data in the NCGDC is searchable yet using the custom query gateway, it is a good idea to supplement this type of search with a point-and-click search if you do not find the data of interest. These two types of searches will
give more like results when the North Carolina custom gateway
- 12.) Either use the "Back" button on the web browser to back up through all these pages, back to the
M@IN page, or use the brower to go to http://www.main.nc.us/GIS/guide/using/tutp11.html to
return to where we started.
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