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U.S. protected areas and U.S. counties

XiaoouHan

Hi,

I am doing research in endangered species and land management. I am very new to ArcGIS.

I have this U.S. protected areas geodatabase which has the information of each U.S. protected area, including state (but not county), type, acreage, etc. I also the U.S. county map. Now I would like to figure out in which county each of the protected areas is located so that I can do some analysis on the county-level data. Could anybody kindly teach me how to do this? I'd appreciate the help!

Jane

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LangdonSanders2

What you are describing is the a common GIS procedure. For the the analysis, there are a variety of methods available at your disposal that depending on your research question and the data available.

Do the protected areas have a shape component?

Do they draw in ArcMap or are they just a table?

Are you summarizing the (dissolving) the protected areas by county?

You would do well to review Overlay Analysis with tools such as intersect, selection and union. A Spatial Join would also work well to transfer attributes (county name) to your protected areas. You can search youtube for special tutorials as well.

Here is a link for summarizing points in other features

More adventures in overlay: point in polygon | ArcGIS Blog

XiaoouHan

Hi Langdon,

Thank you very much for your reply. The protected areas database is in gdb

format. So I guess the answer to your first question is that it has a shape

component. And it was drawn in ArcMap.

The protected areas database has two attributes that are mostly useful to

us: the land management type of each area and the acreage of each area. So

what we would like to do eventually is to aggregate the acreage in

different management types to county level.

I just tried union and seems like it worked. However, there are something I

do not quite understand in the new attribute table that I opened from the

post-union file.

First, a new OBJECTID and two new FID fields are generated. This I figured

out. The two new FID fields are duplication from the OBJECTID fields of the

two original databases. However, in the post-union file there are some -1s

in the new FID filed for the protected areas data. I wonder if it means

some counties just don't have any protected areas. So -1 here represent

"null"?

Second, many of the protected areas appear multiple times with different

county names in the post-onion file. Does it mean that each of the areas

covers more than one county? If so, is there a way to calculate the acreage

of a certain protected in each county?

Xiaoou

2014-12-11 16:46 GMT-08:00 Langdon Sanders <geonet@esri.com>:

U.S. protected areas and U.S. counties
reply from Langdon Sanders
<http://jiveon.jivesoftware.com/wf/click?upn=Dg1s4x8le7Lmxv8KWGaqo7A4BXwO9PY1WvQ5cXCtK49SE6CgBhkqdCl5jXWeF6BfisCUhelAv9sZBQC2Ct6Hp1rbv20hnthJI38OrE7fL7U-3D_xvy4qIJyhUdGfVHy7TMOxkcWnYc-2F-2FBtsZLAnBLW9qzrGpunfcw5r-2Fy4tn4jZV8kma8CcmJvxtXmJxFaKbzoUu87m75BFJB3mBPyiVgbw-2BYBP9FfR3pIyVoI36OlVDfTKUljhTaRdz8BZlkoaf3SOpvaSpLIAZBFrdCLKeXj4j1s7-2FHS7aKT-2BvkOdp8mT8xILS1J5k1rWNuUAME7VHQ3dPwxurYW9ecKQX8vJgKlp15YDzJ54sB-2BQKQ8Jgy-2BQGP97pmeT8nO004J1P-2F1Ey-2BbqtxrmEYIg-2BtaGF0EAQ9pcO4mM3smEnH8QTtgLS-2BYOoMnz>
in Xiaoou Han - View the full discussion
<http://jiveon.jivesoftware.com/wf/click?upn=Dg1s4x8le7Lmxv8KWGaqo0VQjeJBYpG9HGC8QZBT-2FEwbSgEjcAxJsWXJ-2FUD6AT5hr-2FnWp7tEtB-2BgrzbWsuKLQxtKkjOLpm9xiTz7BYf0MsE-3D_xvy4qIJyhUdGfVHy7TMOxkcWnYc-2F-2FBtsZLAnBLW9qzrGpunfcw5r-2Fy4tn4jZV8kma8CcmJvxtXmJxFaKbzoUu87m75BFJB3mBPyiVgbw-2BYBP9FfR3pIyVoI36OlVDfTKfI3mt6jLiuzUxzP-2BWt7A1amsCmB3iE-2BKRzGKI5sJ53gwRA-2BnTVLwdMjcvPRKIT4JEBNtOclRSNkqcjqLd3SCwBflteEVK4AkDnFJlbqEWraMZC-2BxfWO-2BWFyAbB7z6IJr8HITNnhCmyiqTxCUtrIXBSsRm2tC7SsXx-2F8-2Bf0s1bGrozCWCrfxb0ymumfvriDPs>

LangdonSanders2

Hello Xiaoou,

SUMMARIZE

The protected areas database has two attributes that are mostly useful to
us: the land management type of each area and the acreage of each area. So
what we would like to do eventually is to aggregate the acreage in
different management types to county level.

To aggregate or summarize features based on a common category, such as land management type, county, region, etc, you will typically use the Dissolve function or to export just with stats use summarize. You will typically dissolve as the last step of the analysis at which point you can export the table to a csv or excel file for reports and graphing.

For the Union tool, you are correct in you understanding. The -1's will be non-matches where there was no corresponding intersection between the features and therefore no FID to attributes to bring over. This is in the tool documentation for Union under "Usage". Note that any tool in ArcMap you can click "tool help" as well for more details.

UNION

Second, many of the protected areas appear multiple times with different
county names in the post-onion file. Does it mean that each of the areas
covers more than one county?

If you take a look at the image it shows that features will be sliced on their crossing boundaries. You should inspect some examples of repeated land areas, but it is likely that one part of the land area is in County A and the other part(s) are in County B, C, etc.

CALULATE AREA

If so, is there a way to calculate the acreage
of a certain protected in each county?

First create a new field in your attribute table to hold acreage (type double will be fine). In the attribute table, you can right click a field and calculate values all records or selected records in that field. You can select Calculate Geometry and select US Acres from the drop down menu. The Field Calculator calculate algebraic equations and programming expressions based on other fields. Become very familiar with using the field calculator as it is a primary tool in GIS and data manipulation.

To summarize acreage by county, union the features, dissolve by county, state name (to avoid false positives), and land type, then calculate field in acres for resulting table.

XiaoouHan

Hi Langdon,

Thanks so much for your answer. This saves my life! Will follow your

suggestions and try to figure it out in ArcGIS.

Best,

Xiaoou

2014-12-12 6:13 GMT-08:00 Langdon Sanders <geonet@esri.com>:

U.S. protected areas and U.S. counties
reply from Langdon Sanders
<http://jiveon.jivesoftware.com/wf/click?upn=Dg1s4x8le7Lmxv8KWGaqo7A4BXwO9PY1WvQ5cXCtK49SE6CgBhkqdCl5jXWeF6BfisCUhelAv9sZBQC2Ct6Hp1rbv20hnthJI38OrE7fL7U-3D_xvy4qIJyhUdGfVHy7TMOxkcWnYc-2F-2FBtsZLAnBLW9qzrGpunfcw5r-2Fy4tn4jZV8kma8CcmJvxtXmJxFaKbzoUu87m75BFJB3mBPyiVgbw-2BYAzCsB9jCJsDCA0pCzJuyusrxUSP1XY1lfjr6Wz7V2aaAIBFHq2uoj8-2FoFwuRHW2PyHI-2FWZWQ6hSC1u1oe8r-2FyZ1L8YrdUTPWtdOyRogFq1DtJ4PuYBkPV7bgFSis8WLiIxtGZnbDrh3O9BB1ac-2Fq-2B-2Bg6-2Bxjv-2BLePxKdyUk1mUVqrSG-2FbocrCeesL9NfMRauc6MSbSpwMhhJO5sHwP3jM1q>
in Xiaoou Han - View the full discussion
<http://jiveon.jivesoftware.com/wf/click?upn=Dg1s4x8le7Lmxv8KWGaqo0VQjeJBYpG9HGC8QZBT-2FEw5-2FR-2BRqfVf4U5Gc-2FD-2FURVExo5Qkd51Zyank3F1FpEXqtsDvPgysmQH-2FExQuYs0B2g-3D_xvy4qIJyhUdGfVHy7TMOxkcWnYc-2F-2FBtsZLAnBLW9qzrGpunfcw5r-2Fy4tn4jZV8kma8CcmJvxtXmJxFaKbzoUu87m75BFJB3mBPyiVgbw-2BYAzCsB9jCJsDCA0pCzJuyusjV57s-2F2D9zWEwZboOd3pzeS18wy6YbA9ELZVMCt7VEJB-2BLBh1aM0FJDo-2B4QJTQchMY30l-2F-2BjM-2BArZ6tAL831B6jrfRKC-2BoRAJiT0vzBjZOw-2FRLAaff7d-2F8okX0AKIxzey73jbeYt8UjxHDG61Kp-2FM2Tr1vGSWO1qFc9qwAhYY7WWXQg9Tgd7zrzuaKWiNW-2BQ>

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