Causal loop diagram for Medina del Campo

Description

A causal loop diagram is a qualitative map of the factors acting in a system and of the directions in which they influence one another. Around each link the diagram records the polarity — whether an increase in one factor raises or lowers the next — and where the links close into loops, which of them reinforce change and which oppose it.

The diagram for Medina del Campo was produced through group model building: individual interviews with stakeholders were each turned into a small qualitative model, the individual models were merged into a group model, and the group model was then validated and completed in a workshop. The result is a representation of the catchment that the participants recognise as their own, built from the risks they identified, the impacts they expect and the social issues they consider relevant.

It is deliberately qualitative. The diagram is the step before quantification: it fixes which variables belong in the system and how they are connected, and it is the basis on which the stock-and-flow structure of the System Dynamics model is then built.

Applications to decision making in the insurance sector

Insurance-relevant decisions depend on causal chains that cross institutional boundaries — a land use change alters runoff, which alters flood peaks, which alters claims. The diagram makes such chains explicit and shows where a lever exists and where it does not, which is the first question to answer before considering any measure as a risk reduction.

Added value of this modelling approach

It captures feedback. Conventional appraisal treats an intervention as a one-way effect; the diagram shows the loops in which an intervention also changes the conditions that produced the risk — sometimes in the opposite direction to the intended one.

What decision can be improved with this modelling approach

Which factors a strategy must address to change the outcome; where an intervention elsewhere in the system would undermine it; and which variables need to be monitored to know whether the strategy is working.