Inventario, clasificación y génesis de los colapsos del terreno en la Masa de Agua Suberránea Macha Occidental I

Abstract

This paper presents one of the first detailed studies about the ground collapses that have taken place in recent years in the central area of the groundwater body of the Western Mancha I, in the province of Ciudad Real. The main source of the collapses is the breakdowns of the roof of the karst cavities, as a result of a rapid and unusual increase in the groundwater, due to the widespread and intense rainfall, such as those that took place in the wet period (2009-2013). This brought about a washing of the karstic system, the movement of water through sinks and preferential channels, which had been dry for decades, as well as dissolution of the chalky material itself. This ascent phase of the groundwater was preceded by a steady decrease in the piezometric levels, caused by prolonged drought and over-exploitation through pumping.To obtain an optimum knowledge of the area of study, important research has been done to localize, measure and classify each of the collapses. Along with this, we have compiled, expanded and updated the data of the piezometry, to a high level of detail. We have been able to distinguish four types of ground collapses: alluvial collapses, collapses in areas of dolines, lagoon collapses and of intermediate types of collapses. It is also evident that with the passage of years, the collapses that have been produced are of lesser dimensions. Finally, we have deduced the areas which have a greater susceptibility for new collapses, in places such as the river Guadiana, the lagoon areas, and some areas of dolines.