Review: Andesitic aquifers—hydrogeological conceptual models and insights relevant to applied hydrogeology

• Published in: Hydrogeology journal 2024-08, Vol.32 (5), p.1259-1286
• Main Authors: Baud, B., Lachassagne, P., Dumont, M., Toulier, A., Hendrayana, Heru, Fadillah, Arif, Dorfliger, N.
• Format: Article
• Language: English
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-024-02784-0

Research on the hydrogeology of andesitic volcanic aquifers in subduction areas is reviewed. Andesitic aquifers are of high interest in volcanic arc islands and subduction zones, where they constitute a strategic water resource. This review gathers a compilation of worldwide results and case studies to propose a generic hydrogeological conceptual model (GHCM). It is based on the geological conceptual model splitting the volcanic edifice, from upstream to downstream, into central, proximal, medial and distal zones. In this geological structure, the GHCM identifies where the main aquifer types (fractured lava, pyroclastic flows, and the volcano-sedimentary basins downstream) and the typical aquitards (lahars, fine pyroclastic falls and surges, indurated pyroclastic flow, and weathered rocks) are structured and organized. To integrate the evolution of volcanoes and some specific volcanic activities, a specific GHCM for old andesitic volcanoes or andesitic shield volcanoes is detailed. The paper also describes how the GHCM results are of use to hydrogeologists in terms of scale (from the lithological units to the regional scale), to effectively site water wells, and to sustainably manage groundwater resources in such aquifers. Among these various scales, the volcanic “flank continuum” is presented as the most adapted to support groundwater resources management. Several ways to improve this GHCM are suggested, notably to better consider the geological complexity of these aquifers. Une revue bibliographique des recherches relatives à l’hydrogéologie des aquifères volcaniques andésitiques des zones de subduction est effectuée. Les aquifères andésitiques présentent un grand intérêt dans les arcs volcaniques insulaires et les zones de subduction, où ils constituent une ressource en eau stratégique. Cette revue rassemble une compilation de résultats et d’études de cas à l’échelle mondiale afin de proposer un modèle conceptuel hydrogéologique générique (MCHG). Il repose sur le modèle conceptuel géologique divisant l’édifice volcanique, d’amont en aval, en zones centrale, proximale, médiane et distale. Dans cette structure géologique, le MCHG identifie la structure et l’organisation es des principaux types d’aquifères (lave fracturée, coulées pyroclastiques et bassins volcano-sédimentaires en aval) et des aquitards typiques (lahars, retombées aériennes fines, coulées pyroclastiques indurées et roches altérées). Un MCHG spécifique pour les vieux volcans andésitiques ou