Aquifers, known as “free groundwater” in Turkish, are permeable rock formations containing water. Their porous nature renders aquifers abundant in water resources. However, changes in land use and cover affect the characteristics of aquifer’s streams, rivers, and recharge zones, influencing both the availability and quality of water resources. Presently, freshwater resources, crucial for human survival, face threats due to human activities and climate change induced by these activities. As engineering and technical capabilities continue to advance, humanity’s options for transforming water systems and supply are expanding. Among these options, strategically significant aquifer resources emerge as a key alternative for accessing clean water resources. Consequently, regions experiencing water scarcity may become potential areas of conflict in the future, thereby heightening the strategic importance and necessity of aquifers in water policy. In response, policymakers in water-scarce regions prioritize increasing technical capacity to utilize aquifer resources for clean water provision. This underscores the sufficiency of aquifers as underground water reserves to fulfill both current and future agricultural and drinking water needs in many regions. Furthermore, the storage of soil moisture and surface water in shallow depressions contributes significantly to meeting current demands, thus reducing reliance on surface water resources.

Aquifers, shared by many countries akin to transboundary rivers and lakes, are sources of contemporary international conflicts and issues, reminiscent of historical occurrences. While not as widely recognized the public as conflicts stemming from other transboundary water resources, conflicts related to aquifers have roots tracing back to ancient times. In fact, conflicts over aquifers in various regions of America and Asia have persisted for many years. Notably, conflicts have arisen from aquifer systems linked to rivers such as the Indus, Brahmaputra, and Ganges in Asia and the Parana (Guarani), Rio Grande, and Colorado in America. Presently, similar to the past, the potential for conflict remains high in river basins and associated aquifers in South Asia and South America. Particularly, the regions with the greatest conflict potential in these geographies are those housing the Brahmaputra and Guarani river basins and their respective aquifer systems. Consequently, an analysis was conducted to understand the role of the Brahmaputra and Guarani basins and aquifer systems in international conflicts.

Water, being a limited natural resource, holds immense importance for ensuring food security and promoting sustainable development. This significance is particularly evidence for countries like India, China, and others. For instance, India, despite having over 18% of the global population and 2.4% of the world’s land area, possesses only 4% of renewable water resources. Moreover, the foreseeable increase in water-related conflicts among nations is attributed to factors such as climate change induced floods, drought, population growth, and the necessity to cater to the escalating demands of rapidly developing nations. Similarly, China faces similar challenges regarding water security, with internal pressures to effectively manage water resources to meet national requirements. The geopolitical dynamics of regions like Arunachal Pradesh, situated within the Brahmaputra/Yarlung Tsangpo River basin, holds critical importance for both India and China. Issues surrounding water sharing, extending to include aquifer security, have contributed to border disputes in the region. India vehemently rejects all of China’s claims over Arunachal Pradesh, while China continues to assert its claims, causing persistent tensions with India over the area.

The Guarani Aquifer System stretches across central–western Brazil, Paraguay, and southeastern and southern regions of Brazil, northeastern Argentina, as well as central and western Uruguay. Covering an area of approximately 1.2 million km2 , this aquifer system is home to an estimated 15 million people, with nearly 70% residing in Brazil. With a total recharge area of 150,000 km2 and an average thickness of 250 m, it reaches a maximum thickness of 800 m, with depth ranging from near zero at the surface areas along the Guarani border (Brazil, Paraguay, and Uruguay) to over 1,000 m below the surface at its center. The Guarani Aquifer System receives an average annual recharge of 160 km3 and is estimated to contain around 40,000 km3 of fresh water based on hydrogeological studies. Approximately 90% of this freshwater volume is deemed potable. Notably, the water reserves of the Guarani Aquifer System are equivalent to more than 125 years’ worth of total water flow in the Paraná River. It is projected that the aquifer system can sustainably provide water for 360 million people at a rate of 300 L/day per person over a span of 100 years.