**6. Conclusion: opportunities for the application of system dynamics in groundwater management**

The water crisis is already happening and one of its manifestations, although silent and lagging, is on groundwater. The paradigm shift of water management must manifest in practice urgently. This implies a radical change of thought where water management is not addressed from a unidimensional perspective, but rather from a multidisciplinary one. In this context, there is a requirement of simulation models that allow this multidisciplinary to be included, along with the role of stakeholders in water issues and effects of climate change in the hydrological cycle. These simulation models must inform public policy and projects aimed at achieving water security.

Several approaches are available in the literature, among which system dynamics is found. System dynamics models can be predictive, descriptive, or participatory and may have multiple goals, like supporting public policy and/or increasing the

understanding of the system among stakeholders; also, they possess valuable features that allow addressing water management complexity.

There are several opportunities for system dynamics application to water management. Firstly, to integrate several water subsystems. This is already happening in the context of groundwater management with aquifers, which are usually modeled in the broader context of a watershed. However, there are opportunities to include them in disaster mitigation (droughts, for instance), water quality, groundwater-dependent ecosystems, and water supply. Also, it is necessary to include the effects of climate change and variability in water systems and in aquifers particularly.

In addition, water systems must be included within broader human systems: food security, economic security, energy security, and environmental security. For example, an interesting opportunity is to model land-use policies to analyze their effects on aquifer recharge and surface runoff. Another one deals with the analysis of the water-energy nexus in the context of unconventional hydrocarbons exploitation. Finally, the inclusion of water pollution control infrastructure to include reuse or managed aquifer recharge (MAR) in water policy can be assessed.

Certainly, to materialize these applications system dynamics would have to be integrated with other methods, such as GIS, RS, hydrologic models, water quality models, or reliability methods. In addition, to incorporate social and political processes there is a need to add qualitative variables, as well as to increase the interaction with stakeholders, not only during the technology transfer and divulgation but during the modeling process itself. Moreover, we must continue developing tools to validate the models. This is especially important for groundwater models because usually aquifer data is scarce and therefore, models cannot be calibrated.

System dynamics represents not only a modeling approach but a radical change of thought that is appealing to the interconnected crises that the world lives in; in particular, to the water crisis. Countries where the water crisis is already evident, like Mexico, must embrace system dynamics to inform public policies and projects that improve water management. This chapter elaborated on why this is necessary and why system dynamics represent an interesting opportunity to address these issues.
