GIS I Lab 5: Atrazine Restriction Areas in Columbia County

Fig. A: Top Left, Fig. B: Top Right, Fig. C: Bottom Left, Fig. D: Bottom Right

Introduction:  Atrazine is one of the most widely used herbicides in the United States.  Every year over 76 million pounds of it are applied on crops in the US.  However, atrazine is a major threat to groundwater as it remains in soil for months and degrades in groundwater at a very low level.  Atrazine also has been linked to several health issues.  It has been shown to be an endocrine disrupter, have possible carinogenic effects, and it even has been linked to low sperm levels in men.  Due to these possible health risks, atrazine prohibitions and restrictions have been placed on around 1.2 million acres of Wisconsin land.

My objective of this project was to look into where more potential atrazine restriction areas could be placed in Columba County in the future.  I wanted to look at the current areas and research the different criteria that were used to choose the original restriction areas in Columbia County.  I then wanted to use the found criteria to help me query appropriate locations for potential atrazine restriction areas.

Through research, I found that areas with dolomite as bedrock are more in danger of groundwater infiltration by pesticides than other areas such as ones which contain sandstone bedrock.

Data Sources:  In order to answer my question of where additional atrazine restriction areas should be placed, I needed: data regarding the geological features of Wisconsin, areas in Wisconsin specifically set aside for farming, current atrazine restriction and prohibition areas, and water features.  

I was able to find farming preservation areas (which are areas specifically set aside for build up or development over the next fifteen years) and current atrazine restriction areas from the Wisconsin Department of Agriculture, Trade and Consumer Protection.  This data, along with the metadata can be found at ftp://ftp.datcp.state.wi.us/GIS/.  One concern I have about this data is how updated it is.  I'm not sure how recently they updated the data or if there are additional atrazine prohibition or restriction areas already in place in Columbia County.

I found geological attributes of Wisconsin from the United States Geological Survey.  This allowed me to locate the bedrock features throughout Columbia County.  However, this data is rather incomplete and doesn't include very much information about each bedrock type.  I'd prefer a more complete data set in the future.  The metadata can be found at http://mrdata.usgs.gov/geology/state/metadata/wi.html.

I found urban areas from the US Census Bureau and water features from the WI Department of Natural Resources.  Both of these data sets were already installed on the campus drives at the University of Wisconsin-Eau Claire.

Methods:  

In order to find the best locations to place new atrazine restriction areas in Columbia County, I decided on several factors.  I wanted to put the new zones in areas which were designated as farm preservation areas, were outside of urban areas, weren't already atrazine restriction areas, and were on dolomite bedrock.  Also, I didn't want to include areas that were part of a large body of water, as it is unnecessary to place the restriction zone over a large body of water.

I began by projecting all of my data to the NAD83 HARN Wisconsin CRS Columbia projection.  I then took all of the data and clipped it to only keep what was inside of the Columbia County border to prepare all of the data for querying.

The next step involved creating a dolomite feature class from the geology feature class.  I then buffered the dolomite feature by one kilometer.  After the buffer was completed, I intersected it with the dolomite itself and the farm preservation areas to create a potential restriction area.

After this I created the area I wanted to erase from the potential restriction area I'd created previously.  I did this by making a feature class from only the largest 25 percentage of water features, and creating a union with this, urban areas, and current atrazine restriction areas.  Then after performing the erase with the potential areas I'd created previously I came up with my new atrazine restriction zones which can be seen in Fig. C as the orange area.

Figure C

Results:  The final product is the orange area as shown in Figure C above and in the complete map at the top.  This area is within the farm preservation area set aside by Columbia County, is within one kilometer of dolomite bedrock, isn't within an urban area, and doesn't intersect a current atrazine restriction area.

Figure D, below and in the original map, shows the total atrazine restriction area (in yellow) which includes the current area and the proposed area I created by querying my data.  It also includes the urban areas (in red) for spatial reference.

Figure D

  Evaluation:  For this project I was forced to design my own project.  In order to do this, I learned how to develop a valid question, search for the data online, download the data and prepare it for presentation in ArcMap, and query the data in order to answer my question.  I was able to do this all independently with only minor consulting regarding my querying process.  Going through this process gave me confidence that I'd be able to go through a process similar to this but more complicated in the future.  If I was asked to repeat the project I would try to explore for more specific criteria in placing future atrazine restriction areas.  I'd look further into the criteria they precisely used to choose the existing restriction and prohibition areas such as wells in the areas.  One of the most difficult parts of the process was finding the the GIS data to help me answer my question.  Also, once I found this data, I had to download it and some of it wasn't in a form readily available for me to place into ArcMap.  An example of this is when I downloaded the geographic attributes of Wisconsin it came in an e00 format which I had to convert into a usable form using a tool in ArcGIS.  Due to this, in the future I will know how to make sure all of my data is usable for me in ArcMap, even if I have to convert it.  The independent nature of this project allowed me to explore something I find interesting and learn on my own.  By being able to do these two things, I feel that I've learned much more than I otherwise would've with normal coursework.