Evaluating shallow flow-system response to climate change through analysis of spring deposits in southwestern Wisconsin, USAEvaluation de la réponse d’un système aquifère superficiel au changement climatique par l’analyse des dépôts d’une source dans le sud-ouest du Wisconsin, Etats-UnisEvaluación de la respuesta de un sistema de flujo somero al cambio climático a través del análisis de depósitos de manantiales en el sudoeste de Wisconsin, EEUUAvaliação da resposta do sistema de fluxo subsuperficial às alterações climáticas através da análise de depósitos de nascente no sudoeste de Wisconsin, EUA

Tufa-depositing springs in the southern Driftless Area of Wisconsin, USA, are used to inform the response of shallow and local groundwater flow systems to changes in climate over the last 3,000 years. The springs emanate from a shallow, unconfined, sedimentary bedrock aquifer and at stratigraphic positions similar to a shallow, perched aquifer that was identified in the eastern Driftless Area. The perched aquifer was shown to be stable under current climate conditions and over decadal time scales. This study provides further evidence of the significance of the stratigraphic interval in controlling shallow groundwater flow patterns in the region and in the stability of shallow and local groundwater flow systems over thousands of years. The tufa carbonates in three cores collected from the mounds adjacent to the springs show variations in stable isotope (δ13C, δ18O) and elemental (Mg/Ca) values that agree with well-established paleoclimate records for the region, suggesting that the springs were active and depositing tufa in the past, during climate conditions that were similar to the present and during conditions that were drier than the present.