A simple method to evaluate groundwater vulnerability in urbanizing agricultural regions

Area of Science:

• Environmental Science
• Hydrogeology
• Water Resource Management

Background:

• Oaxaca, Mexico, faces groundwater challenges due to intensive agriculture and inadequate water policies.
• Assessing groundwater vulnerability is critical for sustainable water resource management, especially in developing regions.

Purpose of the Study:

• To develop and test a methodology for evaluating groundwater vulnerability.
• To analyze anthropogenic and natural stressors impacting groundwater resources in the Central Valleys of Oaxaca.

Main Methods:

• Utilized an analytical hierarchy process (AHP) and geographic information systems (GIS) for scenario evaluation.
• Employed Monte Carlo analysis to assess uncertainty in the groundwater vulnerability model.
• Selected five key indices: abstraction (A_bs), pollution (P_o), runoff (Ru), groundwater recharge (Re), and marginalization (Ma).

Main Results:

• Abstraction, pollution, and recharge rates were identified as the primary drivers of groundwater vulnerability, explaining 87% of the total vulnerability.
• The developed model demonstrated consistent results with low uncertainty.
• Over 50% of the region's groundwater exhibits moderate vulnerability, with increasing stress linked to abstraction, reduced recharge, and pollution.

Conclusions:

• Groundwater in Oaxaca's Central Valleys is under significant stress, with rising pollution and abstraction exacerbating water crises.
• The developed methodology provides a valuable baseline for water resource management in data-scarce developing countries.
• Effective groundwater management strategies are urgently needed to address increasing water stress and ensure access for rural communities.