Understanding flexibility for multifunctional flood defences: a conceptual framework

Flexibility is often proposed as a valuable capability to cope with uncertainty and change. However, there is no consensus about what constitutes flexibility across the literature. A review of publications on flood management, real options and manufacturing reveals remarkable commonalities along with substantial inconsistencies in the use of flexibility. These observations are used for structuring the discussion of flexibility in this paper. A framework is proposed in the form of four self-consistent and step-wise questions: (Q1) why is flexibility needed; (Q2) what is it that flexibility is required for; (Q3) what are the dimensions of flexibility; (Q4) what needs to change or be adapted? In order to answer the questions in the context of multifunctional flood defences (MFFDs), eight characteristic features of flexibility in connection with the four questions are distilled from the synthesized publications. Subsequently, a working definition of flexibility is developed. An illustrative case study examines the framework's potential for the development of a MFFD. It is shown that the iterative use of the framework can serve as a guideline for identifying and evaluating flexibility for MFFDs. The paper ends with some challenges for future research.