Hydrochemistry and stable isotopes revealed focused and diffuse recharge processes in the Sonora River basin, Mexico

ABSTRACT

A hydro-geochemical characterization was conducted in the northern part of the Sonora River basin, covering an area of 9400 km². Equipotential lines indicated that groundwater circulation coincided with the surface water flow direction. Based on the groundwater temperature measured (on average ∼21 °C), only one spring exhibited thermalism (51 °C). Electrical conductivity (160–1750 μS/cm), chloride and nitrate concentrations (>10 and >45 mg/L) imply highly ionized water and anthropogenic pollution. In the river network, δ¹⁸O values revealed a clear modern meteoric origin. Focused recharge occurred mainly from the riverbeds during the rainy season. During the dry season, diffuse recharge was characterized by complex return flows from irrigation, urban, agricultural, mining, and livestock. Drilled wells (>50 m) exhibited a strong meteoric origin from higher elevations during the rainy season with minimal hydrochemical anomalies. Our results contribute to the knowledge of mountain-front and mountain-block recharge processes in a semi-arid and human-altered landscape in northern Mexico, historically characterized by limited hydrogeological data.

KEYWORDS:

• Diffuse recharge
• focused recharge
• groundwater
• hydrochemistry
• hydrogen-2
• isotope hydrology
• oxygen-18
• semi-arid environment
• Sonora River basin
• water management

Acknowledgments

We appreciate the technical and valuable comments provided by Alejandra Cortés Silva, Instituto de Geofísica, UNAM.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We thank the partial funding obtained from the Universidad Nacional Autónoma de México (UNAM) via the Support Program for Research and Technological Innovation Projects (Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica, known as PAPIIT) (project number TA100320).