An Isotope‐Based Snapshot Reveals the Combined Influence of High‐Elevation Recharge and Local Return Flows on Groundwater Across Guatemala City

ABSTRACT

Guatemala City is the most populous urban center in Central America. In this urban center, groundwater extraction within the last 40 years has substantially declined water table levels and accelerated land subsidence. In this study, stable water isotopes information was used to infer groundwater recharge areas and mechanisms within an urbanised and high‐elevation graben. In total, 261 samples were collected from precipitation ( N  = 43; elevation range: 1241–1879 m asl), wells ( N  = 195; depths between 70–676 m; elevation range: 1022–2110 m asl) and springs ( N  = 23; elevation range: 1212–2260 m asl) during 2023–2024. New isotope data were contextualised using GNIP and other available isotope records. Our results indicate that: (a) isotopic compositions are consistent with the regional spectrum previously reported for the Central American intermontane region; (b) isotopic evidence suggests three main recharge components: (i) local‐urban recharge without isotopic alteration (33.0%), (ii) recharge occurring at elevations higher than extraction points (24.3%) and (iii) a locally derived component that is isotopically altered (43%), likely influenced by wastewater, irrigation return flows, or surface water bodies; (c) the methodological approach was effective in 89% of the sampled wells and 70% of the sampled springs; (d) potential recharge elevations range from approximately 1100 to 2350 m asl; and (e) identified recharge zones predominantly correspond to urban, forested, crop and pasture land uses. Future water management plans should consider the implementation of water use and quality regulations and conservation practices in highly relevant groundwater areas within the urban and peri‐urban domains.