Every nation has a different set of resources, which can nurture its economic development, affecting its patterns and rates of growth. Figure IV-17a is a generic model of any developing country in aggregated overview. The diagram shows environmental, renewable resources inflowing on the left (I0), non-renewable resource reserves (F), price (P3) indicating availability of goods and services, availability of population for immigration (NE), availability of investment capital inflow (IV), and availability of markets indicated by prices for finished products (P2) and raw environmental products (P1).

The state of the nation is indicated by four storages within the system assets, (A); population (N); money on hand (M); and debt to outsiders (D). When a typical simulation is run (Figure IV-17b), these variables are plotted. In the lower section of Figure IV-7b, assets (A) rise as reserves (F) are used up. Population (N) rises due to attracted immigration and reproduction. Indicated in the upper part of the graph, debt (D) increases, helping to reduce the money (M) available to purchase other inputs. D includes investments that purchase parts of the economy so that profit is transferred outside. Although not shown separately, information may be considered as aggregated with population, an essential part of development of a vital economy.

Examples

The hundreds of states and nations of the world are examples. Some like near east countries have large non-renewable reserves (F) and less renewable inputs (I0). Some countries received massive investments and have large debts. Some countries had slow immigration of people and their information. Some sell more cash crops; some develop their resources more for home use. The effects of differences in resources can be studied in the model, which may help understand the much more complex real systems.

"What If" Experimental Problems

To study the effects each type of resource may have, make changes in the program and rerun. After making one change, be sure to return that quantity to its original condition before doing the next "what if" change.

1. What is the effect on the simulation shown in Figure IV-17b if there were no nonrenewable resources? Set F = 0.
   


2. What is the effect on the growth if there were no investments from outside and thus no outside debt or exported profit? Set M = 0.
   


3. What is the effect of rising prices of outside imports relative to prices of exports? Double P3.
   


4. What is the effect of isolation from trade with all resources used at home, with no money to buy outside goods and services? Set PI and P2 to 0 and redirect exports into assets by adding the terms N3*R and N4*R*A*N to the change equation for assets (DA).

COMPUTER MINIMODELS AND SIMULATION EXERCISES FOR SCIENCE AND SOCIAL STUDIES

Howard T. Odum* and Elisabeth C. Odum+
* Dept. of Environmental Engineering Sciences, UF
+ Santa Fe Community College, Gainesville

Center for Environmental Policy, 424 Black Hall
University of Florida, Gainesville, FL, 32611
Copyright 1994

Autorização concedida gentilmente pelos autores para publicação na Internet
Laboratório de Engenharia Ecológica e Informática Aplicada - LEIA - Unicamp
Enrique Ortega
Mileine Furlanetti de Lima Zanghetin
Campinas, SP, 20 de julho de 2007