Selecting and Assessing Distinct Scenarios for Sustainable Water Governance Strategies

Sustainable water governance strategies and policy need to be guided by a comprehensive vision of a sustainable water system and account for uncertainty through robust performance against a spectrum of distinct future scenarios. Climate and water science in general have made significant progress over the last years in understanding the complexity of regional climate-water systems, progress well exemplified by the work of the Decision Center for a Desert City (DCDC) at Arizona State University.  This success has been demonstrated through the development of sophisticated system dynamics models elaborated further by including energy and econometric models, such as the WaterSim model from DCDC. However, dynamic models in general, and WaterSim in particular, have been limited in their application and not fully utilized for policy-making and governance. Reasons for this limited applicability include: dynamic water-climate models are not generally used to construct distinct, recognizable futures scenarios (such as the IPCC stress scenarios); water-climate models are still evaluated on their ability to forecast the future which limits their scope and potential to guide planning; results of the model are often not evaluated against a comprehensive set of criteria; and finally, dynamic models are often not used to their full potential in a constructive way, to develop future pathways and strategies. To address these deficits in water-climate models and enhance the usability of the WaterSim model, plausible future scenarios were constructed based on stakeholder and decision maker input and output from WaterSim that includes external social and natural factors of uncertainty (e.g., long-term drought, growth, and climate change). Results include a set of 5 distinct, recognizable future scenarios that identify critical key factors and policies that serve to guide decision-making related to water and conceptualize the systemic consequences of water management and mismanagement beyond groundwater overdraft. The scenarios explicate the possible impacts of climate change as well as resource management and economic development decisions at the municipality and metropolitan scales in Central Arizona. In this way, the scenarios contribute to further scientific and political dialogue regarding water management in the face of climate change and close the gap between scientific knowledge about climate change impacts and the adaptive capacity of decision makers.