Data Downloading and Geodatabase Design

Disclaimer

The following post is out of order. Creating a geodatabase and acquiring data would be the first logical step. Due to a federal government shutdown shortly after our class began this exercise, we were forced to put this important step on hold as most of our data was to be accessed from federal government websites. Please keep in mind that, under normal circumstances, this post would precede my geocoding post.

Goals

The goal of this exercise was to become familiar with acquiring geospatial data from various sources on the Internet, then importing this data into ArcGIS for use and interpretation. During this process, we were required to design and set up a geodatabase for storing all this data, as well as make sure everything was projected in the same coordinate system.

Methods

The first data set I downloaded was the railroad data from the National Atlas website. This data, like the others, was compressed in a zip file and had to be unzipped before use. Next, I visited the National Map Viewer website at http://nationalmap.gov/viewers.html. Here, using the interactive web map, I selected Trempealeau County. There were several data sets available, but I downloaded only landcover and DEM (Digital Elevation Model) data. From the USDA Geospatial Data Gateway (http://datagateway.nrcs.usda.gov/), I downloaded cropland data for Wisconsin. Lastly, I downloaded soil survey data from the USDA soil survey website (http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm).

Other than just unzipping it, some of the data had to be manipulated somewhat before it could be used. The elevation data was sent in two separate raster files so that a singe image wasn't too large of a file. In order to make one DEM raster image, I ran the mosaic to new raster tool. This created a single, uniform image that covered Trempealeau County.

I decided to use NAD 1983 Wisconsin Transverse Mercator for my projection, as this one would work best to display the whole state of Wisconsin. After I had that decided, I created a geodatabase and imported all of the data I had acquired. I also created a feature data set for the natural resource feature classes.

Results




Figure 1 - Data obtained from government websites

Figure 1 shows a very basic image of the different data we downloaded with the railroad layer on all of them. I used the spatial analyst tool to show only data within Trepeleau County, however this tool did not work on the map of crop land. The tool negatively affected the colormap of the image, and the data was not portrayed as well. I left it as is for now.





Geocoding

Goals and Objectives

The goal of this exercise was to learn the process of obtaining data in the form of a spreadsheet and geocoding that data in ArcMap. We were to download an excel file that contained the locations of frac sand mines in Wisconsin from wisconsinwatch.org and display the addresses on our map.

The data was not able to be geocoded right away. The addresses were in different forms; some were street addresses, some PLSS locations, and some just had directions like "west of Augusta." Our objective was to map these locations as accuratly as we could.

Methods


Figure 1- Data table prior to being normalized.

Because of the inconsistancy of the data, I first needed to normalize the table so that each location had a street address, city, county, and state in seperate fields. Figure 1 shows how the data appeared before I worked on normalizing it. When running the geocoding tool using this table, almost no locations were matched. The ones that did match were mostly wrong.

Figure 2 shows a sample of my data after normalization. By using a combination of aerial photo interpretation, websites referencing specific mines, Google Earth, and mapquest.com, I was able to come up with a street address for each location.

Figure 2 - Normalized addresses.

When I ran the geocoding tool using this new normalized table, I had much greater success. All 14 of my mines were "matched," however some of them were in the wrong locations. For those, I simply used the "pick address from map" option and moved the point.



Figure 3 - Map showing my geocoded mines and those done by classmates

Results


Each mine had its own "unique ID" so that we could keep track of them. Classmates of mine had geocoded some of the same mines that I had. By merging all of the classes geocoded mine shapefiles together, then running a query and selecting those mines that had the same unique IDs that I had used, I created a layer that was made up of mines that should have been the same addresses as the ones I had geocoded. Just by glancing at figure 3, it's easy to see that simple errors can cause drastically different outcomes.

Figure 4 - Distance (in meters) between points.

Figure 4 is a table that shows the distance between my mines and the closest mine to it. The problem with this is that there is no way to get the tool to calculate the distance between my mine and the ones that have the same unique ID. We have to assume that the distance shown in the table to the closest mine is the same mine. Usually, this is probably the case. In some situations, however, a mine could have been geocoded to as far away as a different county.

Discussion

Some of these errors could be inherent, such as issues when changing the projection of a shapefile, but most of the discrepancies are operational errors. Operational errors occur when managing and processing the data. Inputting the wrong address, misinterpreting data, or selecting the wrong location from aerial photography are all situations that could lead to the sizable distance between some of these mines (Lo and Yeung, 2006). The only way in which we can know for sure what points are correct would be to contact the owner or manager of the mine, or visit the facility personally.

Conclusion

During this lab, I have learned the different ways to geocode, as well as the importance of normalization. I also realized how big of a difference seemingly small mistakes can make. Calculating point-distance is an interesting tool that will come in useful in the future, which I did not even know existed before doing this lab.

References

Lo, C.P., Yeung, A.K.W., (2003), Concepts and Techniques in Geographic Information Systems. (pp. 107-108). Pearson Prentice Hall.

Brief Introduction to Frac Sand Mining in Wisconsin

Intorduction

Locations of major shale gas resources

Wisconsin has an abundance of sand deposits, mostly concentrated in the west-central part of the state. This sand has been mined for hundreds of years for production of various products including glassware, mortar, and cement. Sand mining in Wisconsin has dramatically increased in recent years for use in hydraulic fracturing (fracing), a technique used for obtaining oil and natural gas from the earth. The frac sand is mined and processed in state, and shipped out to areas of the country where drilling operations are taking place. Texas, Oklahoma, and North Dakota are just a few of the places utilizing this technique.

Over the course of the semester, our GIS II class will be focusing our projects on studying the various facets of this booming industry, which I will be documenting in this blog. Our studies will be concentrated on Trempealeau county, as this area features some of the most frac sand operations.

Hydraulic Fracturing

Diagram of hydraulic fracturing operation

Fracing is the process of drilling a standard oil well, and using explosives to crack the bedrock. After the rock is cracked, water, chemicals, and sand are pumped into the well under high pressure to pry open the cracks, and the sand is left in the wound to hold it open. This creates a permeable area to extract oil or gas. 

Though fracing is in Wisconsin news more and more these days, it is not a new technique. Fracing has been used since the mid 20th century. The reason for the recent surge in demand for frac sand is that new horizontal drilling technology has been introduced, allowing for access to many deposits of resources that have long been out of our reach. This technology, combined with our ever-growing need for fuels, has made frac sand a huge industry in Wisconsin in just a few short years.

Sandstone locations and frac sand facilities in Wisconsin

Frac Sand

Fracing uses a very specific type of silica sand, popularly known as quartz. Sand used for fracing operations must be almost entirely quartz, rounded, and of a very specific size. Wisconsin has some of the best frac sand deposits in the country, which is why the excavation of this sand is such a huge (and controversial) topic in the state. Sandstone deposits suitable for frac sand are mostly concentrated in the western part of the state. As you can see in this map, Trempealeau county contains a large number of these mines and processing facilities, which is why we are focusing our studies here.

Impacts of Frac Sand Mining in Wisconsin

As was mentioned earlier, frac sand mining is a controversial topic. As with any industry, there can be impacts (good and bad) on the people, wildlife, and environment of the area. These impacts can vary from one mine to another depending on size of the operation, surrounding geography, and local population. 

Air pollution is always a large concern. As with any industrial setting, there will be some emissions. All the heavy equipment used to excavate, process, and eventually transport the product means a large increase in gasoline use and the emissions that come with it. There is also the issue of dust. With the amount of heavy equipment moving around, blasting of rock, and bare sandstone exposed, dust can get into the air. On a windy day, this dust may travel far away from the mining facility.

Overburden removal is the process of removing topsoil and biological matter such as plants and forests. This must be done before any mining can begin and is one of the main reasons that many Wisconsinites oppose frac sand mining. Removal of of overburden not only removes forests, but also the ecosystems that depend on it.

Water pollution is another reason Wisconsin residents are leery of sand mining near their communities. Sediment and chemical contaminated run off may make its way into the water system, either by overland runoff or seepage into ground water systems. Obviously, frac sand mines are held to the same water protection standards as any mining facility, but accidents can and do happen.

Just like other industrial settings, frac sand mines are loud. There is a great deal of heavy machinery in use, as well as occasional blasting. Because these mines are typically in rural areas, local residents who established their homes in the area specifically for a quiet country life are not usually happy about being near one of these operations. 

There are several other ways mining has, and will continue to, affect Wisconsin, but the last one I will mention is job creation. This is a huge industry with many more mines and processing facilites currently in production. Proponents of sand mining point to this as a great boom to the state economy. Those opposed to mining claim that they are only temporary jobs, unable to outweigh the possible harm the industry could do to the environment.

Using GIS to Explore these Issues

Throughout this course, we will delve further into these issues. Although this class is designed to help students learn and master the uses of ArcGIS and similar products, our labs and exercises will focus on assessing the risks and benefits of frac sand mining in Wisconsin. This strategy will not only help us master geospatial skills, but also help us learn a great deal about a topic so close to home. Each lab will be posted here on my blog, with explanations and results, allowing you to follow my progress. We have began working on lab 1, which involves learning how and where to obtain geospatial data. Unfortunately, many of the websites that are crucial for obtaining this data are currently closed thanks to a government shutdown. I will post more as soon as possible.

Thank you for reading.

http://dnr.wi.gov/topic/Mines/documents/SilicaSandMiningFinal.pdf

http://wisconsingeologicalsurvey.org/pdfs/frac-sand-factsheet.pdf

http://dnr.wi.gov/topic/mines/silica.html