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Step1: Generation of Base Population Surface: |
The first step in developing a population distribution surface was the calculation of the base population (1995) for the public land survey system (PLSS) sections.
The property appraisal records for 1995 were summarized by section for each of the residential land uses, providing the total number of households per section, based on property data.
From the Census Bureau's data, the number of households per blockgroup was used to normalize the number of households per section, since in the section level, households was calculated as a function of number of residential properties per section and average number of households according to its type.
For example, a single family housing unit was considered equivalent to one household, while multi-family with less than 10 units was considered to be equivalent to 3 households.
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Base Population by PLSS - 1995 |
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General Population Distribution Methodology: |
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The Bureau of Business Research at the University of Florida, population projections for each County were used, enabling population distribution up to 2020 in the following general methodology:
1. Calculate the additional population to each county using the difference between the base population and the projected population.
2. Using the additional population and the projected average household size for the county, calculate the number of additional households to be added.
3. Select the section that fall into the areas of highest growth pressure
4. Until there is population to be added and there are sections with areas available for growth, assign households to the sections and update the number of households left.
5. If no more areas available can be found in the sections of a certain growth potential, and not all projected population has been distributed, move to the next highest growth pressure and return to 3.
6. Stop is there is no more population left to be distributed.
Using this basic method, two different scenarios were developed.
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Scenario 1: |
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The first scenario was based on the assumptions that existing vacant residential parcels were the first areas of each section that would have a housing unit built to hold the population increase.
For population increase exceeding the number of existing vacant residential parcels, the agriculture parcel with less than 10 acres were the ones most likely to become new residential parcels and consequently, have new housing units built.
Since the property appraisals data contained the number of existing vacant residential properties, those were summarized by section, as well as the agriculture parcels with less than 10 (ten) acres.
So, in step 4 of the method, scenario 1 details the distribution as follows:
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a. Each vacant residential parcel is assigned 1 household |
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b. The population for the section is then re-calculated, using the number of new hoseholds assigned and the average household size. |
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c. After all growth pressure areas have been analysed and no more vacant residential parcels can be found, return to step 3 in the model, and: |
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a.1. Each agriculture parcel with less then 10 acres is assigned 2 households per acre. |
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b.1. The population for the section is then re-calculated, using the number of new hoseholds assigned and the average household size. |
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Scenario 2: |
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In the second scenario, the same assumption made in scenario 1 for vacant residential parcels was used.
For population increase exceeding the number of existing vacant residential parcels, the agriculture parcel with more than 50 acres and less than 100 acres were the ones most likely to become new residential parcels and consequently, have new housing units built.
Since the property appraisals data contained the number of agriculture parcels in that criteria, those were summarized by section.
So, in step 4 of the method, scenario 2 details the distribution as follows:
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a. Each vacant residential parcel is assigned 1 household |
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b. The population for the section is then re-calculated, using the number of new hoseholds assigned and the average household size. |
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c. After all growth pressure areas have been analysed and no more vacant residential parcels can be found, return to step 3 in the model, and: |
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a.1. Each agriculture parcel with more than 50 acres and less then 100 acres is assigned 2 households per acre, if it falls into a hight growth pressure area (9 - 7 in the growth surface), and 1 household per acre if it falls into lower growth pressure areas. (7 - 1 in the growth surface) |
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b.1. The population for the section is then re-calculated, using the number of new hoseholds assigned and the average household size. |
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2020 Population Distribution Resulting Maps: |
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