Thinking about the effects of remedial actions
Principles of making scenarios
Dynamic systems are always changing. With a conceptual model it is possible to collect data about the present state of the system. With a time-based data set, it is possible to hypothesize how the system has changed up to the present moment. To predict how the system will develop in the future, the time based data-sets could be extrapolated. However, because of the many variables in dynamic systems and the impossibility of knowing all these variables it is only possible to make extrapolations built on a set of presumptions. The creation of a set of presumptions is a choice. And because you need a lot of understanding of the system to make a choice that is relevant, this is an expert choice.
Since the actual choices about the management of megasites are made by the stakeholder, most of them not being experts, communication between experts and stakeholders is needed to make relevant and adequate choices. Scenarios are the communication domain of the experts. Their function is to translate expert knowledge of the system into understandable representations for laymen that make it possible to make the right choices.
Making of the scenarios
Experts can make any scenario out of a dynamic system with an endless list of data. To limit the number of scenarios, they need some kind of guidance. This guidance comes from the stakeholders. The stakeholders have to decide upon what kind of states they are adverse to and what kind of states they desire. This information doesn’t come from the data itself but from the stories of the stakeholders with their representations, goals and interests. It is the task of the stakeholders to help focus the scenarios and the more they do, the better the transparency of the scenarios will be.
Once the scenarios are made they are tested by the expert on their accuracy and robustness. Though it would be ideal to use another set of data to validate the scenarios with the models, often the data come from the same origin as the data that were used to make the scenarios.
Evaluating the scenarios
Stakeholders will evaluate the scenarios with a set of criteria. In many cases these criteria are related and will represent a dilemma. The most common dilemma is that of three sets of criteria: i) the remediation goals from the environmental point of view, ii) the financial goals from the economic point of view, and other criteria and goals related to “practical aspects”, such as obtaining permits, liability, existing contract obligations, etc. It is the essence of balanced decision-making that all aspects are taken into account and that the optimal scenario is chosen.
For the first two subjects (environmental effect and costs), the optimisation of the evaluation criteria can be done by trial and error if the list of variables is not too long. For complex optimisation processes, cost-effectiveness models can be used. In the Welcome case studies, (examples) different approaches were followed.
Cost-effectiveness
Balancing environmental benefits and economic factors is an important step in the IMS. On the one hand is the improved environmental quality and economic viability of the region, on the other hand there are the costs of remediation and management action. It is a reality that only remediation actions and plans that fit within the budget of the local economy and have a positive effect on environmental and economic viability are accepted by decision makers. Within Welcome, different approaches were used for the various case studies.
