Conditional analysis for land subsidence hazard zoning: a case study in the Aguascalientes Valley.

Abstract

Land subsidence caused by groundwater drawdown is an increasing threat to cities overlying overexploited aquifers. This study analyzes the phenomenon in the Aguascalientes Valley through a comprehensive approach combining spatial, statistical, and probabilistic analysis. Based on data from piezometric drawdown and vertical ground deformation, a risk zoning scheme was developed using nine geotechnical classes resulting from the combination of three levels of drawdown and three levels of land subsidence.

In addition to mapping geotechnical regimes, Bayes' Theorem was applied to estimate the conditional probability of subsidence under different drawdown conditions. Results indicate that the minimum probability of moderate or severe subsidence is 66.7%, increasing to 91.9% in areas with high drawdown. Even in areas without recent drawdown, 75% of sites exhibit ground deformation, while only 1.57% of the territory remains completely stable, with neither drawdown nor subsidence.

These findings suggest that the relationship between drawdown and subsidence is not linear nor exclusive, and that cumulative consolidation, lithological properties, and subsurface heterogeneity also play a significant role. The proposed methodology is transferable to other regions facing subsidence hazards and provides a practical tool for supporting risk management, preventive monitoring, and sustainable urban planning.