GIS Final Map

Final Project Map

Lab #10

Geoprocessing- Geoprocessing takes an input dataset, performs an operation on that dataset and returns the result of the operation as an output dataset. Common actions are to include a geographic feature overlay, feature selection and analysis, topology processing, raster processing, or data conversion.

Model- One process or a sequence of connected processes in ModelBuilder.

Multipart polygon- A digital representation of a place or thing that has more than one part but is defined as one feature because it references one set of attributes. This can be a point, line, or polygon.

Discrete Data- Data that represents phenomena with distinct boundaries. Example include property lines and land-use areas.

Continuous Data- Data that varies without discrete steps such as temperature and elevation data.

Esri Grids- This is a way that Esri stores raster data that defines geographic space as an array of equally sized square cells arranged in rows and columns. When the grid is on the map, cells are assigned colors according to their numeric values and each grid is references by its x,y coordinate location.

No Data- The absence of recorded data in raster data. This does not equate to a value being 0. The measurement just has not been taken for this cell.

Neighborhood- User-defined are used to establish new output values. Neighborhood functions establish new values for locations use the values of other locations within the given area.

Intermediate Data- Any data in a process that did not exist before the process existed and that will not be maintained after the process is executed.

Reclassification- Process of taking input cell values and replacing them with a new output cell values. This is used to simplify or change the interpretation of raster by changing a single value to a new value or grouping ranges of values into single values.

1.      Explain how dissolve works.

a.       Dissolve merges polygons together to create a larger polygon that incorporates all of the areas data through specific common characteristics. For example, if there are over lapping layers, they would be merged into one single polygon rather than have polygons overlapping one another.

2.      Give one example of when to use dissolve and when to use clip

a.       You would use dissolve rather than clip when trying to merge data together. With dissolving you are incorporating the data that is related together. When clipping, it is like cutting out the data that you are not trying to focus on.

3.      Give two different applications for the buffer tool

a.       One application of buffers is for magnitude of earthquakes. The circles around origin of an earthquake radiating out are buffers because they are a constant distance around the feature. Another application of buffers could be for strength around a cell tower. There would be a constant distance around the cell tower.

4.      What is the difference between union, intersect, and merge?

a.       Union is when the polygons are joined together and new polygons are made where the first polygon does not overlap anything, the second polygon does not overlap anything, and the area of overlap between the two polygons. An intersect only shows the area of polygons where they intersect or overlap. A merge just combines the two polygons to create a new shape.

5.      Give an example of when you would use union over merge

a.       An example of when I would use union over merge would be if I am comparing two different events that happened in the same area. For example, if there was a fire that occurred on a hillslope and I was showing the extent of that with the incident of a slope failure. It would be helpful to see a union of the two separate events in order to see the extent of each rather than merging them together.

6.      Is the clip tool used for only vector, only raster, or both?

a.       The clipping tool can only be used for vector data. Arc GIS specifies that the data can be points, lines, or polygons which are vector data only.

7.      What might you use a mask for?

a.       I might use a mask when I have a lot of data but I only need a certain amount. The mask will take that portion of data that is needed and match the extent to other data that I am used for a specified area.

8.      How are environment settings use in arc map?

a.       The environment setting is used to match the ArcMap session and all the tools that I am currently using in the model.

9.      What might be an advantage of using model builder?

a.       An advantage to using model builder could be that it allows you to organize the inputs, tools, and outputs that will be used to perform the analysis.

Final Project Preview

Zombie vs Vampires

The interpolation approach that is best suited for the extent of the data set would be Inverse Distance Weighted. I think that we have enough points and that they are close enough to that this method would work best with the specific data set. The points in the data set looked evenly spaced out and that is the type of data that should be used for that set of sample points. However, the drawback to using IDW would be that it does not look at all of the data trends when interpolating the data.

Based on last year's precipitation events, the Amador-Calaveras area could experience even more drought for the recently burned area. Although the areas that do receive decent rainfall could potentially have a variety of earth flows and slides because the soil is compacted to the ground and is riddled with burned dead material. The soil is no longer being held together by the roots of the vegetation that was once there. The areas that are not as burned and affected by the fire would still have some ability to hold the soil together and therefore would be more stable and be less susceptible to mass movements when precipitation does arrive. Granted in order for mass movements to occur there would have to be an intense amount of precipitation that would saturate the soil enough to cause instability. Although the soil is less stable due to the recent fires in the area.

Aftermath of the Butte Fire

I chose to utilize the before (August NDVI) and after (September NDVI) to portray the loss of vegetation in the most simplest way possible. My map is oriented in a way that frames the before and after data of Normalized Difference Vegetation Index because it shows how the fire burned through the vegetation and caused the NDVI to shift. It is easily identified that the shift was from high NDVI to low NDVI from the stark color change. The two maps show the change that the fire caused. There is a large difference between the NDVI as can be seen from the large color change within the fire perimeter. From the two images one can see that there is a huge loss of vegetation. I also added a little comment about what NDVI is and what the different values mean because it might be confusing the people who are no familiar with the index and the way the data was collected.

I also chose to make an extent map that displayed where the fire was in relation to California but also on the smaller extent to show where the fire within Amador- Calaveras county. I assumed that this map would be only viewed by Californians because it is one specific fire within California during this year. This helps the readers of the map locate exactly where the fire was in relation to where they are. It is obvious that the fire burned a very large area within Amador-Calaveras County, over 70 thousand acres burned. It will take many years until the area will be back to its state before the fire. The topography of the area did not help with containing the fire due to the terrain.