Overview of the Hillsborough County Model 



In research situations, each energetics model must be tailored to the 

 particular application at hand; each energetics model incorporates its unique 

 features into the design. Although it is beyond the scope of this report to 

 examine in detail all facets of the Hillsborough County model, some of the 

 more salient features are summarized in the following paragraphs. 



One such feature is the "Power Maximizing Land Exchange," shown as the 

 four-cornered logic module in the approximate center of the diagram. It re- 

 distributes land between the three subsystems. Hillsborough County, like many 

 Florida coastal counties, has a rapidly increasing population. This increase 

 has brought about a conversion of some of the natural and agricultural lands 

 to urban lands, as the City of Tampa and its surrounding communities have 

 grown. The model exchanges land between the three sectors according to the 

 relative value of the change in gross county energy flow, just as in actual 

 land changes between sectors as land becomes economically feasible to develop 

 (or preserve) within a subsystem. Land exchange is important because the nat- 

 ural energy flows into each subsystem are proportional to the total land area. 



In addition to monitoring changes in land areas, the Hillsborough County 

 model also simulates changes in the marine environment and in phosphate 

 reserves. Both are important to the local economy and were included in the 

 model to show county administrators the effect of different scenarios on these 

 resources. 



Another feature of this particular model is the fuel price monitor in the 

 upper right-hand corner of the diagram. (It is represented by the small cir- 

 cle and diamond.) As the price of fuel increases, the rate of fuel imported 

 per unit of exported goods and services declines. This allows the effects of 

 fuel increases to be simulated. "What if" scenarios, such as "What if the 

 price of fuel doubles?" can be examined using this feature and can be compared 

 with the results of alternative scenarios. 



A summary of the synthesis of socioeconomic and natural system data 

 (Tables 3 and 4) was made by evaluating the energy flows and storages in the 

 Hillsborough County model (Figure 9). 



Results of Energetics Simulations 



The results of the Hillsborough County energetics simulation are shown in 

 Figure 10. Using 1943 data, the model simulated historical changes in the 

 land area of each subsystem and of population for the county. The values 

 obtained by the simulation closely paralleled the actual data available for 

 1978. (Although the oil embargo of 1972 did affect energy flows in each sub- 

 system of the county, the effects on land area and population were small in 

 comparison to changes in 1948.) Although the rate of conversion slowed when 

 the simulation was continued into the future, the historical trend of land in 

 the natural subsystem being converted into urban and agricultural land con- 

 tinued (Figure 10). This simulation was predicated on the assumption that 

 fossil fuel, such as oil, coal, and natural gas would continue to be available 

 through the end of the century, but it included a sudden price jump in 1973 

 for these fuels to reflect world events as they occurred. 



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