FINAL PROJECT – GEOGRAPHIC INFORMATION SYSTEM (GIS 6100)

FALL SEMESTER 2010

HOW POPULATION SETTLEMENT IMPACTED THE CALOOSAHATCHEE RIVER

CHLOE DELHOMME

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1. Introduction

My thesis is related to the restoration of oxbows of the Caloosahatchee River. Over the past decades the Caloosahatchee River has been greatly impacted from human settlement. Indeed, after being channelized, the Caloosahatchee River gave opportunities for commercial (navigation), agricultural and population growth. As the population growths, pollution and waste contamination increases. I was interested in using GIS to learn more about the Caloosahatchee watershed and study the changes over time.

2. Study Area and Data

The Caloosahatchee River watershed is located in the west part of South Florida, USA (Figure 1). The Caloosahatchee River flows from Lake Okeechobee to San Carlos Bay (Gulf of Mexico) and is approximately 75 miles long. The River passes through cities such as Moore Haven, LaBelle, Fort Myers and Cape Coral. The watershed encompasses an area of 1,400 square miles and is spread among five counties: Lee, Glades, Hendry, Charlotte and a tiny portion of collier counties. The actual population is 800,000 inhabitants.

Figure 1. Caloosahatchee River watershed.

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I acquired my data from four different sources:

-USGS website: http://viewer.nationalmap.gov/viewer/ for the watershed boundaries. I had to export the Caloosahatchee River watershed before analyzing it because it was assembled with neighbor watersheds.

-SFWMD website: http://my.sfwmd.gov/gisapps/sfwmdxwebdc/dataview.asp for landuse from 1988 and 1995.

-ESRI website: http://arcdata.esri.com/data/tiger2000/tiger_final.cfm?RequestTimeout=500 for census tract boundaries 1990 and 2000 and population in 2000. In addition, I got urban areas in 1990 and 2000.

- Census bureau website: http://www.census.gov/ for census population 1990. As I could not find any dataset or table with the demographic census tract in 1990 and I used a pdf file from the Census Bureau and updated myself the table.

3. Methods

3.1. Density population in 1990 and 2000

For 2000, I used the union tool in ArcGIS to make appear the tracts within my watershed boundaries. Then, I used the clip tool in Arc GIS to keep only the tracts within my watershed. Then, as in the table I already had the population density I just had to make it appear via symbology-quantities-graduated colors. I first used natural break classification as a guide and used a manual classification in order to be able to compare with 1990.

For 1990, I had to first change coordinate system to the layer census tract for each county in order to be able to calculate the area. I chose Albers conical equal area. Then, for each county I calculated the area in square miles by adding a field in the table and using the ‘calculate geometry’ tool. Then, I entered my data from my pdf file in a new field ‘population’ for each census tract. I merged with the ‘merge tool’ the tables of all the counties (Charlotte, Lee, Hendry, Collier and Glades) in one table. I clipped with the ‘clip tool’ to get only the census tract within my watershed. Finally, I made appear the population density in a similar way than for 2000, except that I normalized the population field with the area and used the same manual classification.

3.2. Urban areas in 1990 and 2000

I merged with the ‘merge tool’ from Arc tool all the five counties urban areas in one table. Then I used the ‘union tool’ from Arc tool to make them appear in the watershed. Then, I used the ‘clip tool’ from Arc tool box to make appear only urban areas within the Caloosahatchee River Watershed. Via properties – symbology - categories I chose the colors and updated the labels. I did the same process for 2000.

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3.3. Landuse in 1988 and 1995

For 1988, I used the ‘clip tool’ from the toolbox to get only the land cover within the watershed and then via properties – symbology - categories I chose the color for each category of landuse, change labels…For 1995, I did the same process.

Concerning the table, after the clip, I updated the fields and recalculate area (square miles) and perimeter (miles) with the ‘calculate geometry’ tool. I turned off the unnecessary fields. Then I used the summarize tool to get the sum of areas and perimeters per category of landuse. Then, I edited the table by adding the sum with the help of statistics button, changing labels, and adding field such as percentage. Then with the ‘field calculator’, I got my percentage per landuse. I did the same process for both table (88 and 95). Then I merged and edited both table to obtain my final table.

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4. Results

4.1. Density population in 1990 and 2000

Figure 2 shows my results. As we can see, the major change in the population density between 1990 and 2000 is in the South and Southwest part of the watershed. In addition, it seems that population increased in the Fort Myers - Cape Coral area. The major density within the watershed is between 0 and 150 inhabitants per square miles, which is low.

Figure 2. Map showing the population density in the Caloosahatchee River watershed in 1990 and 2000.

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4.2. Urban areas in 1990 and 2000

Figure 3 shows my results. As we can see, only one area was considered as urban in 1990 which is the Fort Myers – Cape Coral metropolitan area. However, in 2000, four new areas were considered as urban: Clewiston, Moore Haven, LaBelle and Lehigh Acres. In addition, Fort Myers – Cape Coral metropolitan area spread North-East.

Figure 3. Map showing the urban areas within the Caloosahatchee River watershed in 1990 and 2000.

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4.3. Landuse in 1988 and 1995

Figure 4. Map showing the landuse within the Caloosahatchee River Watershed in 1988 and 1995.

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Figure 4 shows my results. At first sight, we can say that the major land uses are agriculture, urban areas, forest and wetlands. The main difference between 1988 and 1995 appears to be a loss of wetlands. Table 1 shows the percentage of landuse for each year which makes the comparison easier. Indeed, the table confirms that the major land uses are first agriculture, then forest, wetlands and urban areas with similar percentage. According the table, there is not a significant difference between 1988 and 1995 for wetlands and urban areas. Agriculture coverage seems to have decreased of 6 % and while forest coverage seems to have increased of 5 %. Range land and barren land remain the same.

Table 1. Comparison between the areas of each landuse between 1988 and 1995.

5. Discussions and conclusions

Concerning the urban areas (figure 3), it was surprising that in 1990, only Fort Myers and Cape Coral metropolitan area was present. Clewiston, LaBelle, Moore Haven and Lehigh Acres probably existed at that time but were not considered as urban areas yet. It is probably a matter of semantics.

Then, for the final part of my project, it seems that there is a difference between my results from my maps and table. For instance, it seems that wetlands considerably disappeared in 1995 comparing to 88 but according the table, it lost only one percent of its coverage. The reason is that maybe in 1995 there is more parcels divided (15091) comparing to 1988 (3466). So at that resolution we cannot see the colors of the smaller parcels. In addition, between 1988 and 1995, the area of the watershed is different. I think I can explain it by the fact that in 1988, the San Carlos Bay was not counted as part of the watershed. Indeed there is a great difference (7 versus 37 square miles) for water coverage. That would explain also the 26 square miles differences in the total area of the watershed.

Overall, I was expecting a bigger difference between 1988 and 1995. I suggest that in further work more recent land use data need to be used to have a more holistic view. Overall, the last maps show that the main landuse in the Caloosahatchee River Watershed is agriculture. Indeed, the latter has great impact on the water quality of the river. With runoff, fertilizers contaminate the river and lead to an excess in nutrient impacting the water quality and the ecosystems functions of the river. Even though agricultural best management practices are being implemented, excess in nutrient is a major concern for the Caloosahatchee River.