Mapping of sinkholes in highly urbanized areas: Queretaro, Mexico.

In recent years, there have appeared sinkholes of various dimensions in urban areas in different parts of the world. This phenomenon represents a serious social, economic and environmental danger, since it causes alarm among the population, and considerable damage in the infrastructure. The sinkholes are generated mainly by two causes: karstic geology (common in calcic sedimentary rocks) or by the presence of excess water generated by cracks in the pipe water and sewage systems.

The excess of water is the most frequent case in highly urban centres, where the lack of maintenance or the age of the drainage systems, generate internal erosion and dissolution of the finest particles, producing the abrupt vertical collapse of the soil, which develops an hole in the ground. From experimental studies, the mechanism of soils that generate internal erosion; soil stratification, soil types and their hydrodynamic properties, is well known.

In Mexico, sinkholes are a very common problem in the center of the country, mainly in states like Aguascalientes, Mexico City, San Luis Potosi, State of Mexico and Queretaro. In particular, in the city of Queretaro, there have been sinkholes, which have affected the traffic and movility of this city.

Documentary analysis and mapping indicate that this type of sinkholes show a tendency to be generated in the periphery of the capital of Queretaro, because these are areas of potential urban growth, as well as exceeding the service capacity of the sewage and potable water systems, regardless of the construction process of this type of work. The results show that in 2018, at least seven significant sinkholes were generated in the urban area, while in 2019, more than 15 sinkholes, most of which have been ruled to be caused by a rupture in potable water and sewage pipes, were reported.  In this first evaluation we can observe a double increase in the appeareance of sinkholes, therefore, it is necessary to carry out constant field and experimental studies, to understand the mechanism of these phenomena that occur in highly urbanized areas.