To deal with large uncertainties about future climate and socio-economic developments, planners in deltas are adopting an integrative and adaptive planning approach referred to as Adaptive Delta Management (ADM). Bangladesh has used the ADM approach for the development of its adaptive plan; Bangladesh Delta Plan 2100 (BDP 2100). The success of policy strategies in an adaptive delta plan critically depends on a specific adaptation of livelihoods of local communities (Community Livelihood Adaptation; CLA), especially in an agriculture-oriented society like Bangladesh. For example, while triple rice cropping might be evaluated as a robust strategy in all futures considered, its success eventually depends on whether farmers’ will actually make that choice, which is deeply uncertain. In this paper, we use literature review, insights from interviews and field observations to examine how the uncertainty in CLA impacts (adaptive) delta management. We study two historical cases of livelihood adaptation of farmer communities confronted with salinization and waterlogging in the polders of southwest Bangladesh since the 1960s. We conclude that historically the uncertainty about CLA in polders has been ignored in the development of policy plans, leading to the failure of anticipated policy outcomes. We recommend planners in Bangladesh and other deltas worldwide to take account of CLA as uncertainty when developing long-term adaptive plans.

Delta communities worldwide are facing a multitude of challenges in their life and livelihood. In many developing countries, improving the quality of life and livelihood is a key challenge. While development is a central goal of delta planning in such countries, the effectiveness of planning is challenged by uncertain changes in climate and socio-economy. Bangladesh (one of the countries) is moving towards the adaptive delta management approach to deal with such uncertainties. Historical examples illustrate that Community Livelihood Adaptation (CLA) can critically influence the effectiveness of a policy strategy. Therefore, there is a clear need to explore CLA under uncertainty. For that purpose, this paper develops and applies a conceptual model-based approach combining the mental model and scenarios techniques. Our approach starts by using a participatory process to elicit mental models a farmers’ community uses when considering adaptation decisions; we capture these in the form of a cognitive map, and this map can serve as a conceptual model for analyzing livelihood adaptation decision-making in a future-oriented scenario analysis. To illustrate the approach, a case study of cropping decision-making of farmers community at a polder location under the saline condition in the southwest of Bangladesh has been elaborated. Results show that the approach is useful in structuring the cognitive and qualitative nature of complex decision-making process, and helps in understanding the dynamic interactions of farmers’ adaptation decisions with other actors, their environmental attributes, and market traits. It can help policymakers anticipate the adaptation direction of policy strategies.