Many regions around the world are facing water shortage, low water quality, unsustainable overuse or other problems that may even cause conflict among different actors. These water resources are typical examples of common-pool resources. Leaders seem to play a crucial role in the emergence of community-based management of resources and overcoming the collective action problem. The main purpose of this study is to find the mechanism behind the emergence of leaders in the process of starting collective action.
I synthesized leadership studies from different domains and created Leadership for Community Development (LCD) theory. Based on LCD, leadership emerges from influencing interactions that are done to share a vision and make other community members dedicated to it. In this process, leaders gather the requirements of collective action, like support or political capital. Central to this idea is the innovation process, which has four phases of idea generation, idea elaboration, idea promotion, and idea adoption. The idea in the innovation process is the same as the vision.
According to this theory, first, there might be problematizing leaders who challenge the current state and give attention to a problem through influencing interactions. Dissatisfaction with the current state can lead to idea generation. In the idea elaboration phase, the idea creator will try to elaborate and gather support for the idea among his or her close connections. If this is successful and enough support is received, dedicated actors will start promoting the idea by influencing others. In the idea promotion phase, enabling leadership emerges when actors promote their own vision and echoing leadership emerges when convinced actors advocate the vision of their influencers. Enabling leadership and echoing leadership form up effective leadership, which is the indispensable influencing effort of actors for reaching the next phase. Idea adoption or implementation, which is in the domain of management, starts when requirements such as political and intellectual capitals are enough. This theory is further supported by a case study and interview.
I created an agent-based model based on the LCD theory. The model was a successful proof of concept for the LCD theory and how the identified types of leadership emerge through the process of initiating collective action. I used the model to identify the most significant factors on the role of leaders and the initiation of collective action. The social network proved to be the most important factor.
Based on these findings, I emphasized on the importance of focusing on networks and building connections in the communities. Moreover, I have suggested using these findings to diagnose the lack of collective action in communities and to use this diagnosis in the process of facilitating collective action in communities. I proposed many recommendations for future steps in this study. The top priority recommendations are a call for case studies to be done to further validate the LCD theory and to perform group experiments to increase understanding of the role of the social network in collective action problems.

Nature-based water management is rising as an alternative approach to engineered water management. Nature-based water management makes use of ecological, hydrological, and morphological processes of natural rivers in designing river management policies. Furthermore, it helps conserving or restoring these natural processes for environmental purposes. Next to changes in water management, changes in the earth’s climate are occurring, which decrease the water flow in summer and autumn and increase the flow in winter. These changes will affect river uses and might cause conflicts between them. The river uses studied in this research are environment, navigation, and flood protection and an integrated model is developed to answer the research question: What conflicts arise between environment, navigation, and flood protection when nature-based water management policies are implemented under different water flow scenarios and how can insights in these conflicts be used in the policy-making process?

The system dynamics (SD) modelling method has been used, because SD enables integration of physical, social and economic factors influencing water resources while addressing inter-sectoral, long-term problems. The scope of the model has been set to analysing a side channel as a nature-based water management example. The model has been built up of four sub-systems that are interrelated: the river system (including a main channel, side channel, and floodplain), the environmental system, the navigation system, and the flood protection system. The model results show that no conflicts arise during high water inflows. Furthermore, environment and flood protection or navigation and flood protection can find a solution that is beneficial (0r neutral) for both during low water inflows. However, the environment requires a side channel that is connected on both its ends – and therefore has a year-round water flow –, while navigation prefers a side channel that is only connected on its downstream end in order to prevent lowering of the water level in the main channel during low water inflows.

Insights for policy-makers are found in five ways. First, the conflicts between river uses do not necessarily arise regarding the side channel per se – but concern the configuration of the side channel. Secondly, the conflicts strongly depend on the changes in water inflow due to climate change. Third, attention should be paid to compromises that are made. The side channel connected on one side can be seen as a compromise between nature and navigation and it indeed eliminates the negative effects on navigation, but it strongly reduces the benefits for nature. Fourth, for nature-based water management to be truly effective for environmental purposes, integration of several measures is required. Finally, the model showed that system behaviour is strongly dependent on fixed standards (e.g. maximum amounts of vegetation and presence of summer dikes). The model that was developed in this research can also be used to study the effects of river channel widening, floodplain widening, summer dike removal, and changes in floodplain vegetation management.