Site Report - Valley of Oaxaca

For my final project, I chose to revisit the Valley of Oaxaca dataset from a previous module assignment. I used the soil and site data from the grids N6E4, N6E5, and N6E6 to test a hypothesis concerning the rise of the Zapotec state. If population pressure was exceeding the regional carrying capacity, we would expect to see phases where the population is much greater than could be supported by agricultural yield estimates in their catchment circles. I completed this analysis with the help of ArcGIS products. Here is a basic outline of steps I created for myself to help with the         analysis process.

Methods:

1) Determine time periods to use and make into separate layers.

     - 4 time periods total

2) Buffer the sites with a 2 kilometer radius with the Buffer tool.

     - Make sure buffers are set to dissolve all.

     - 4 buffer outputs total

3) Convert the site polygons into point features using the Feature to Point tool.

     - 4 site point feature outputs total

4) Use the site points to create Thiessan Polygons for each time period.

     - 3 Thiessan Polygons total

5) Combine the site buffers with the Thiessan Polygon outputs using the Intersect tool.

     - 3 intersects total

6) Edit the intersect outputs, snapping the edges of the Thiessan polygon to the buffer and grid boundaries.

     - 3 edits total

7) Clip the soil type to the newly edited intersect outputs with the Clip tool.

     - 9 clips total

8) Calculate area in hectares of soil clips using the Calculate Geometries function.

9) Perform a spatial join between the clip layers and point file data.

     - This combines the population data with the land area data.

Based on these results, I was able to determine if the population of each site could subsist on the amount of hectares available within their 2 km catchment radius. One adult human can subsist on a minimum of .5 ha of arable land. For ease of results, 1 ha will equate to feeding 1 human

The Rosario phase settlement had an estimated population of 10, and had 192 ha of Type I land and 451 ha of Type III all arable land. With only 10-20 hectares of land required for subsistence, the Rosario phase settlement would be able to support their population on Type I land and Type III land.

The Early I phase settlement had an estimated population of 185, with 220 ha of Type I land and 1507 ha of Type III all arable land at their disposal. They would require 185 to 370 ha at most in order to sustain their population. Based on the amount of each land type available to them, they should have been able to support their population on Type I and Type III all arable land.

The Late I phase has an estimated population of 941, with only 220 ha of Type I land available, 415 ha of Type III 10% arable, and 1834 ha of Type III all arable land. They would require 941 to 1882 hectares of land at most in order to sustain their population. In terms of yield productivity, they would not have enough Type I or Type III 10% arable land to sustain their population. There would be enough Type III all arable land, but productivity and yields would not be as reliable as Type I land. 

The Monte Alban II phase had an estimated population of 774, with only 220 ha of Type I land and 1579 ha of Type III all arable land available to them. They would require 774 to 1548 hectares at most in order to sustain their population. They would not have been able to produce enough yields with Type I land. They barely meet the requirements for subsistence on Type III all arable land, which was established as not having reliable yields.