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Show The second major step in the development of a working mathematical computer model is between the conceptual model and the computer or working model itself. During this step an attempt is made to express in both mathematical and verbal forms the various processes and relationships identified by the conceptual model. Thus, the strategy involves a conversion of concepts concerning the real world into terms which can be programmed on a computer. This step usually requires further simplification, and the resulting working model may be a rather gross representation of real life. The loss of information, first between the real world and the conceptual model, and second, between the conceptual model and computer implementation, might be compared to a filtering process, as depicted by Figure 3 ( Riley, 1970). The real world is ' viewed' through various kinds of data about the system which are gathered. Additional data usually produce an improved conceptual model in terms of time and space resolutions. The improved conceptual model then provides a basis for improvements in the working model! Output from the working model can, of course, be compared with corresponding output functions from the real world, and if discrepancies exist between the two, adjustments are indicated in both the conceptual model and the working model. The important steps involved in the process of model development are depicted by the diagram of Figure 4 ( Riley, 1970), and these steps will be followed in the following development of a management strategy for the water resource system of Great Salt Lake. Identification of Objectives Clearly, the starting point in the formulation of a management model is a precise definition of the function or purpose of the model. As already indicated, an important objective of the investigation described by this report is to define the management problems and objectives involving the Great Salt Lake system. Without this essential first step, a meaningful and effective management strategy obviously could not be formulated and implemented. By definition, a problem is associated with a characteristic of a physical or social system which is in some way detrimental to, or perhaps not amenable to, a particular social use. The problem for the particular social use is solved by modification of the system so as to better accommodate the use. For example, a dam might be constructed to provide flood control and so reduce the risks associated with flood plain development. However, the construction of the dam m'ght well have adverse effects on other social uses, such as transportation and farming within the reservoir area. A modification at any point in a system initiates a whole series of adjustments throughout the entire system until a new equilibrium condition is reached. These adjustments produce both physical and social impacts, some of which are positive and others of which are negative, but all of which need to be anticipated and assessed by a program of efficient system management. The kind of " chain reaction" which is triggered by a change or modification at some point in a system is illustrated by the diagram of Figure 5. This figure illustrates some of the possible impacts of constructing a causeway in Great Salt Lake to facilitate transportation. In this example, the physical system is altered in order to better accommodate a transportation use. However, it is speculated that the causeway also produces effects which might adversely influence other social uses. Figure 5 suggests, for example, that the causeway alters prevailing lake circulation patterns and obstructs open water surface areas. Thus, some of the other social uses of the lake which might be adversely affected are water transportation, water recreation ( such as boating), brine shrimp harvesting, and mineral extraction industries. A system is managed in order to accommodate particular social uses which are identified with specific goals and objectives. For this reason, the first step in identifying possible problems associated with the management of a particular system is to delineate the various potential social uses for the system. In the case of the Great Salt Lake system the major social uses are identified as follows: 1. Recreation and tourism. 2. Mineral extraction. 3. Transportation. 4. Brine shrimp harvesting. 5. Oil drilling. 6. Fresh water supply. On the basis of the 6 major uses listed above, a chart was prepared ( Table 1) which lists desirable system characteristics for each use and some of the methods or system modifications by which these desirable characteristics might be achieved. For example, more stable water levels in Great Salt Lake to benefit recreation and tourism might be achieved by the construction of additional storage reservoirs on the major tributaries. Also suggested by Table 1 are some possible problem areas which might be influenced by the various system changes. These are possible areas of adverse impact on other social uses, and these also are indicated by the table. Continuing with the storage reservoir example, developed lands might be flooded which, of course, would have adverse effects 14 |
