Andrea CITRINI, Corrado CAMERA, Francesca ALBORGHETTI, & Giovanni Pietro BERETTA (2021)

This study assesses the intrinsic vulnerability of two key karst spring catchments in the Middle Valseriana Valley, Northern Italy—Nossana and Ponte del Costone. Both springs are critical for local drinking water supply. The goal was to develop a tailored vulnerability mapping approach for mountainous karst regions where traditional tracer tests and detailed datasets are often limited.

∇ – Methods

A three-step methodology was implemented:

1. Application of Classical Methods
   • Used EPIK and COP, two established index-based methods for karst vulnerability mapping.
   • Each method assesses vulnerability using a combination of factors such as epikarst development, soil cover, infiltration characteristics, and karst network complexity.
2. Development of COPA+K
   • A new integrative approach combining the COP method with:
     • A Factor: Considers proximity and density of geological discontinuities (e.g., faults) relative to spring locations.
     • K Factor: Represents karst network development, reused from the EPIK model due to data limitations.
   • This integrative model (COPA+K) provides a more refined, locally calibrated vulnerability map.
3. Validation with Isotope Data
   • Used δ¹⁸O isotopic signatures to estimate recharge elevations, validating the vulnerability maps.

∇ – Main Results

• Improved Vulnerability Mapping:
  • COPA+K produced a more nuanced map than COP or EPIK alone.
  • Identified 23.6% of the area as highly vulnerable (vs. 35.6% under COP), enabling better prioritization.
• Spring Behavior Differentiation:
  • Nossana: More responsive to rainfall events, highly karstified, and more vulnerable.
  • Ponte del Costone: Less karstified, more stable flows, and lower vulnerability.
• Validation Success:
  • Elevation estimates from δ¹⁸O data closely matched the high-vulnerability zones for Nossana.
  • Discrepancies for Ponte del Costone suggest mixing with Serio River water.

∇ – Conclusion

The COPA+K method offers a reliable, adaptable tool for groundwater vulnerability assessment in mountainous karst settings with limited data availability. It improves upon traditional models by integrating local structural and hydrological features. The method is suitable for broader application across the Pre-Alpine karst belt and aids strategic water resource protection.

∇ – Resources

Citrini, A., Camera, C. A., Alborghetti, F., & Beretta, G. P. (2021). Karst groundwater vulnerability assessment: application of an integrative index-based approach to main catchments of middle Valseriana springs (Northern Italy). Environmental Earth Sciences, 80(17), 610.

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