Is Guarani aquafier located in western chaco of the Paraguay m
Executive summary
The Guarani (Guaraní) Aquifer System is a vast transboundary groundwater body beneath Argentina, Brazil, Paraguay and Uruguay, but the bulk of its Paraguayan footprint lies in the country’s southeastern sector—not the western Gran Chaco—so it is not accurately described as “located in western Chaco of the Paraguay” [1] [2] [3]. Scientific and policy sources consistently place the Guarani within the Paraná/Paraná–Chaco basins and the lowland areas of southeastern Paraguay rather than the arid western Chaco plains [4] [5].
1. The official footprint: four countries, Paraná-dominated geology
Maps and basin descriptions used by hydrogeologists and international programs show the Guarani Aquifer System underlying Argentina, Brazil, Paraguay and Uruguay and emphasize its association with the Paraná basin and its geological units; most of the system’s extent lies under Brazil and the Paraná/Chaco–Paraná basins rather than the Gran Chaco plain in western Paraguay [1] [4] [5].
2. Paraguay’s share: concentrated in the southeast, not the western Chaco
Multiple programmatic and outreach sources put Paraguay’s share of the aquifer at a relatively small percentage of the whole and describe its Paraguayan presence in the country’s southeastern territory—references to “southeastern Paraguay” and regional maps appear repeatedly in accessible summaries and educational pieces, indicating that the Guarani’s Paraguayan outcrop and exploitation zones are in the east and southeast rather than the country’s western Chaco region [3] [6] [5].
3. Geological signals that exclude a large western-Chaco presence
Hydrogeological literature locates the Guarani within Triassic–Jurassic sandstones overlain by Cretaceous basalts in the Paraná and Chaco–Paraná basins and describes average thicknesses and confining units that correspond to eastern/southeastern parts of the region; those basin geometries and the mapping work cited in scientific modeling place the principal aquifer bodies away from the typical geology of western Gran Chaco, arguing against a major Guarani presence there [4] [7] [8].
4. What the international governance and project documents say
The Guarani Aquifer Initiative, Guarani Aquifer Agreement and related World Bank/GEF materials consistently frame the resource as shared among Brazil, Argentina, Paraguay and Uruguay with most area in Brazil and measurable but smaller shares in Paraguay and Uruguay; these governance-documents and project maps underpin the claim that Paraguay’s portion is limited and generally in the country’s east/southeast rather than its western Chaco plain [6] [5] [9].
5. Sources of confusion and legitimate exceptions
Some summaries and popular articles simplify the aquifer’s footprint to “under Paraguay” and may omit the important qualifier that the Paraguayan portion is mainly southeastern; geological complexity—outcrops, local aquifer connections, and smaller Mesozoic sandstone bodies—means localized groundwater features in western Paraguay might be mistaken for Guarani units, but the peer-reviewed and institutional mapping work treats the Guarani as primarily eastern/southeastern in Paraguay [3] [10] [11].
6. Limits of available reporting and final assessment
The sources reviewed do not present a detailed hydrogeological map explicitly labeling the Gran Chaco’s westernmost tracts as part of the Guarani, and authoritative literature and project maps place the Guarani largely within the Paraná/Chaco–Paraná framework and in Paraguay’s southeast; therefore the statement that the Guarani Aquifer is “located in western Chaco of the Paraguay” is not supported by the cited geologic and governance literature and is misleading without further local hydrogeologic evidence [4] [5] [12].