Sinkholes in Urban Environments: Mechanisms, Analysis, and Mitigation1. IntroductionUrban sinkholes stem from natural karst dissolution (limesto...
Published on by Hossein Ataei Far, Deputy Manager of the Research, Technology Development, and Industry Relations Center at NWWEC
1. Introduction
Urban sinkholes stem from natural karst dissolution (limestone, dolomite, gypsum, halite) and human factors such as leaking pipes, pumping, tunneling, poor drainage, and loading/backfilling. Urbanization conceals karst while increasing risk by altering runoff, focusing infiltration, and sustaining leaks.
2. Mechanisms
Dissolution and epikarst: Cavities form and collapse when sediments fail.
Types: Cover-collapse (sudden) and subsidence/solution dolines (gradual).
Triggers: Aging pipes, groundwater use, excavation, and land-use changes.
Climate: Heavy rain and storms increase infiltration and collapse risk.
3. Analysis
Remote sensing: LiDAR and DEM for depression mapping.
Geophysics: GPR, ERT, seismic, and gravity surveys for void detection.
GIS and models: Integrate geology, hydrology, land-use, rainfall, and utilities.
Laboratory models: Simulate leakage, suffosion, and collapse.
4. Mitigation
Inspect and rehabilitate buried utilities.
Grouting and void filling for structural stability.
Zoning: Limit loads and define buffer zones.
Monitoring: InSAR, levelling, repeat geophysical surveys, and leak-detection networks.
5. Recommendations
Inventory karst areas and underground utilities, prioritize inspections, use multi-method surveys, develop GIS-based risk maps, and integrate findings into policy and planning.
6. Gaps
Develop early-warning indicators, incorporate aging infrastructure data into models, and assess climate change impacts on sinkhole frequency and severity.
7. Summary and Results
Urban sinkholes result from the interplay of natural karst processes and human activities. Sudden cover-collapse events dominate urban failures, often triggered by leaking utilities, excavation, or extreme rainfall. Analytical approaches, including remote sensing, geophysics, GIS modeling, and laboratory simulations, effectively identify vulnerable areas and precursors to collapse. Mitigation through utility management, grouting, zoning, and integrated monitoring reduces risk. Key results indicate that prioritizing inspections in karst-prone zones, employing multi-method surveys, and integrating climate and infrastructure data into susceptibility models significantly improve urban sinkhole risk management and resilience.
8. Key References
Beck (1988); Waltham et al. (2005); Martinez et al. (1998–2005); Brinkmann (2008); Kwak (2020); Yumba (2024); De Waele (2011); Gutiérrez (2014, 2019); Parise (2015); Wood and USGS (2023); Sajedi (2018).