**2. Context of the global groundwater crisis**

Problems of the twenty-first century must be seen as different facets of one single crisis, which is largely a crisis of perception [5]. In Ref. [6], the World Economic Forum reported the identified risks for 2020. They are classified into five categories: economic, environmental, geopolitical, technological, and social but, above all, it is fundamental to underscore the interrelation that exists between them. Certainly, given the systemic nature of Earth, there are expectations that environmental risks are interrelated. However, the relationship between these and those of the other categories is not obvious and, as suggested in Capra and Luisi [5], the incapacity to identify and understand these relationships has not allowed us to manage these risks. In this framework, the water crisis emerges.

In this context, water management can no longer be postponed. The modern approach of water management is characterized by two fundamental concepts: water security and integrated water resources management (IWRM), where the former is the strategic objective, and the latter is the method for reaching it [7]. It is important to underscore that IWRM requires a multidisciplinary perspective to be conducted; it must consider biophysical aspects provided by science and engineering but in addition, got to be enriched with the perspective of social and economic sciences given the wide range of stakeholders involved in water issues. This last premise, along with the increasing computation power and the increase in the complexity of water problems, constitutes the paradigm of complexity of water management [8].

*The Usefulness of System Dynamics for Groundwater Management DOI: http://dx.doi.org/10.5772/intechopen.105162*

**Figure 1.** *Water stress in the world. Adapted from Hofste et al. [9].*

The water crisis has a global dimension. In **Figure 1**, the water stress in the base scenario, which considers data for 1960–2014. It is evident that in the subtropical region, especially in the northern hemisphere, the water stress is predominantly high and very high. The cases of Mexico and the United States in North America in the west and India and Saudi Arabia in the east are worth highlighting. Analogously, in the subtropical region of the southern hemisphere, the outlook is not favorable in northern Chile and some regions of Argentina, in South America and, in the region of the Sahel, South Africa, and Australia, as well. Likewise, in **Figure 2**, the projection of change in water stress concerning base scenario towards 2040 under a businessas-usual scenario (combination of socioeconomic scenario SSP2 and climate change scenario RCP8.5) is shown. In previously mentioned regions, there will be an increase of water stress in a higher proportion.

In this global context, groundwater performs an essential role. In principle, it is important in sustaining streams, lakes, wetlands, and aquatic communities [10], therefore it is relevant for sustaining biodiversity. On the other hand, groundwater represents almost half of freshwater supply worldwide, around 40% of irrigation water, and a third of water required for industry [11]. Nevertheless, despite its importance, groundwater remains a minor player in water resources management [1] and

**Figure 3.** *Groundwater stress projection for 2041–2070. Adapted from Herbert and Döll [12].*

the evidence is that, although the impact of groundwater extraction is most acute and obvious at local scales, right now, groundwater depletion is a global problem [2].

In that respect, in Herbert and Döll [12] the scenario shown in **Figure 3** is suggested. In the latter, the projection represents the mean of 10 scenarios, which considers five General Circulation Models (GCMs), forced by a climate change scenario RCP8.5 and socioeconomic SSP2, and two irrigation scenarios. It is noted that subtropical regions of the northern hemisphere are currently the most affected and, and if that was not enough, affectations may increase in the future. The case of Mexico, the United States, the Middle East, South Africa, and the Sahel region are worth highlighting [12].
