Sample GIS project
Growth or Shrinkage:
A Case Study of Seasonal Sinkhole Changes in Geneva, Florida, Using Aerial Photography from 1950 to 2002
Background:
While the bulk of a specific sinkhole pond rests on one property lot in the Seminole Woods subdivision, it occasionally spills over onto the neighboring lot. The question of access to the water is contentious. When the water is over the property line then both property owners have access. The purpose of this study is to discover how variable the seasonal growth or shrinkage of a specific sinkhole pond which straddles two property lines in Geneva, Florida. This study will resolve ownership of the pond based on Florida law stating that seasonal waterways are outside of riparian rights legislature.
Data & Material:
The aerial photographs were gathered from EarthExplorer.
Geographic methods/models applied to data:
To determine whether this pond was a seasonal body of water, I used ArcGIS. First, I curated a selection of aerial photographs based from Earth Explorer, based on availability. Selected earliest and most recent with one CIR for contrast.
I then georeferenced the two un-referenced aerial photographs using ArcGIS to best demonstrate location on map.
I then georeferenced the two un-referenced aerial photographs using ArcGIS to best demonstrate location on map.
Summary of Key Results:
A macro-overview demonstrates the extent of coverage of the 1995 CIR photo compared to the 2002 photo. It also gives a better sense of the overall topography & habitat surrounding the property. Again, with the intention of providing geographic context for the aerial photographs in use, this overlay of the georeferenced 1950 photograph and the CIR shows a more northerly extent of the overall environment, suggesting the prevalence of waterways, intermittent and permanent.
In 1950, the pond was connected with a larger pond to the east. The other ponds in the area appear to be relatively stable by comparison. By 1995, the sinkhole-pond has detached from the larger pond and clear evidence of seasonal shrinkage is visible around the edges creating what appear to be concentric circles, indicating the dried pond vegetation surrounding the areas that have been evaporated. In 2002 the pond is nearly completely dry, as is the neighboring larger pond. The surrounding ponds have also suffered similar shrinkage, suggesting that the whole complex of waterways are seasonally intermittent because of the underlying Karst topography & prevalence of sinkholes.
Conclusions:
The three case studies presented, from 1950, 1995, 2002, show a demonstrable shrinkage in the pond. In 1950, the pond was part of a large waterway system, connecting to a larger pond. However, by the mid-1990s, the pond has detached from the large pond. This pond has been groundproofed annually from 1999 to 2022, and although it is currently at a much higher volume than in 2002, the data from the three aerial photographs suggests that the overall trend is for shrinkage and that the 2002 nearly dried out state of the sinkhole indicates that it is not a permanently navigable waterway and therefore not under the riparian rights statutes of Florida.
Real World Application:
• Produced a report to present to the Home Owner's Association demonstrating that the pond lays outside of Florida riparian rights because of its protean seasonality.
• Demonstrates knowledge of Florida-specific environmental legislature; ability to assess historical physical geography & non-human changes to landscape; understanding of surveying maps; communication of technical detail to non-specialist audience; aerial photography analysis; ArcGIS Pro skillset.