I don't see a clear distinction between reductionist thinking and broader systems thinking; I see more of a continuum of simplistic to more complex and nuanced. But then let's go further into the complexity and conceptualize "water security" as sustainable enjoyment of the benefits that water makes possible. This approach expands the boundaries of the water "system" to help us capture even more potentially relevant dynamics about water and well-being. We are reluctant to cast such a wide net because it becomes impossible to model this greater complexity, but that's not a reason for limiting our definition of what constitutes "water security". Let's follow the linkages between water and well-being to wherever they take us, and then worry about analytical tools for dealing with the messy reality that we have discovered. The tool that I would suggest we give more attention to in this regard, is ethics, a philosophical approach developed in response to the messiness of actual decisions. By asking (or in philosophy-speak, "reflecting on") how to maximize the overall benefits of water management over the very long term, we orient our attention to embrace the interactions of water systems and subsystems. We can still make use of modeling but we will not be so tempted to ignore the many factors lying beyond the models, particularly in the realms of psychology and culture (identity, spirituality, dignity, sense of community, etc.). Another advantage of ethics is in tracking the value chains of the subsystems of water security, e.g., the security and sustainability of the food system, the energy system, and urban water systems. For more about this, see my 2013 book, Water Ethics: A Values Approach to Solving the Water Crisis.
I don't see a clear distinction between reductionist thinking and broader systems thinking; I see more of a continuum of simplistic to more complex and nuanced. But then let's go further into the complexity and conceptualize "water security" as sustainable enjoyment of the benefits that water makes possible. This approach expands the boundaries of the water "system" to help us capture even more potentially relevant dynamics about water and well-being. We are reluctant to cast such a wide net because it becomes impossible to model this greater complexity, but that's not a reason for limiting our definition of what constitutes "water security". Let's follow the linkages between water and well-being to wherever they take us, and then worry about analytical tools for dealing with the messy reality that we have discovered. The tool that I would suggest we give more attention to in this regard, is ethics, a philosophical approach developed in response to the messiness of actual decisions. By asking (or in philosophy-speak, "reflecting on") how to maximize the overall benefits of water management over the very long term, we orient our attention to embrace the interactions of water systems and subsystems. We can still make use of modeling but we will not be so tempted to ignore the many factors lying beyond the models, particularly in the realms of psychology and culture (identity, spirituality, dignity, sense of community, etc.). Another advantage of ethics is in tracking the value chains of the subsystems of water security, e.g., the security and sustainability of the food system, the energy system, and urban water systems. For more about this, see my 2013 book, Water Ethics: A Values Approach to Solving the Water Crisis.