Global groundwater sustainability, resources and systems in the Anthropocene

Abstract

Groundwater is a crucial resource for current and future generations but is not being sustainably used in many parts of the world. The objective of this review is to provide a clear portrait of global-scale groundwater sustainability, systems and resources in the Anthropocene, in order to inspire a pivot towards more sustainable pathways. We examine groundwater from three different but related perspectives of sustainability science, natural resource governance and management, and Earth Systems science. We propose that groundwater sustainability can be defined with a direct link with observable data, governance and management as well as the crucial functions and services of groundwater. An Earth System approach highlights the connections between groundwater and the rest of the hydrosphere, biosphere, atmosphere and lithosphere, and how these connections are impacting, or impacted by, groundwater pumping. Regional differences in priorities, hydrology, politics, culture and economic contexts mean that different governance and management tools are important. But a global perspective can support higher level international policies in an increasingly globalised world, that require broader analysis of interconnections between regions and knowledge transfer between regions. 1.Groundwater is depleted or contaminated in some regions and ubiquitously distributed which, importantly, makes it broadly accessible, but also slow and invisible and therefore challenging to govern and manage.2.Groundwater is the largest store of unfrozen freshwater on Earth and is heterogeneously connected to a number of Earth System processes on different timescales.3.A coherent overarching framework of groundwater sustainability is more important for groundwater governance and management than the concepts of safe yield, renewability, depletion or stress.

Asymmetric impact of groundwater use on groundwater droughts

“…In regions where the annual average groundwater use is smaller than the annual average recharge, the frequency of groundwater droughts increases, resulting in shorter events of a lower magnitude (second panel in Figure 4). This corresponds to the 'dynamic sustainable range' as presented in the conceptual model of Gleeson et al (2019). In regions where the annual average groundwater use approaches annual average recharge, the opposite is found with less, but prolonged droughts of higher magnitude and duration (third panel in Figure 4) corresponding to strategic aquifer depletion, when meeting the dynamic sustainable range over a long time scale (Gleeson et al, 2019).…”

“…This corresponds to the 'dynamic sustainable range' as presented in the conceptual model of Gleeson et al (2019). In regions where the annual average groundwater use approaches annual average recharge, the opposite is found with less, but prolonged droughts of higher magnitude and duration (third panel in Figure 4) corresponding to strategic aquifer depletion, when meeting the dynamic sustainable range over a long time scale (Gleeson et al, 2019). The last panel shows the extreme conditions of groundwater depletion, in which groundwater droughts are not recovering by the average annual recharge and groundwater levels tend to fall consistently.…”

“…The developed methodology shows how qualitative information on groundwater use and annual long-term averages aid to get a better understanding of asymmetric impact of groundwater use on groundwater droughts. Considering the large-scale modification of the hydrological cycle and the consequences for droughts (Van Loon et al, 2016a), it is important to further this approach and investigate the sustainable use of groundwater resources (Gleeson et al, 2019).…”

Recharge observations indicate strengthened groundwater connection to surface fluxes

“…In addition, upscaling recharge estimates derived from extensively studied sites to other locations is challenging because many landscape and surface properties can affect recharge (De Vries & Simmers, 2002;Crosbie et al, 2018;Moeck et al, 2020). These issues are problematic because accurate recharge estimates are needed to assess the sustainability of groundwater use and the role of groundwater in supporting ecosystems and surface waters (Gleeson et al, 2020).…”

Global Groundwater Sustainability

“…Some hydrogeologists reasonably question the appropriate scale to assess groundwater problems: are groundwater resources, governance and management a global problem (Konikow & Kendy, 2005), or are groundwater problems best examined and solved at local-to-regional scales? On one hand, groundwater resources and their sustainability will always depend on local hydrology, politics, law, and culture (Foster et al 2013), yet a number of arguments highlight why a global perspective on groundwater is useful (Gleeson et al 2020…”