Konya-Karapinar Sinkholes (Obruks) of Turkey

Abstract

The karstic features in the Konya-Karapınar plain located in the Central Anatolia region of Turkey are very interesting and very important. The number of watery and dry sinkholes (obruks) formed in the lacustrine Neogene limestone in the Karapınar plain is close to thousands. Groundwater with unconfined aquifer characteristics appears close to the surface and form sinkhole lakes by taking part in some of the sinkholes. The basement formation underlying the Neogene limestone is Mesozoic crystalline limestone and hydraulically related to the Neogene limestone. While the groundwater level in the sinkholes here is close to the surface, in recent years, the unplanned groundwater discharge has dropped to 90–100 m and many watery and dry sinkholes have started to form in the plain. Neogene limestone has a porous structure and contains solution cavities. One of the main factors in the formation of sinkholes in this plain is the presence of limestone with pores and solution cavities, the presence of clayey, sand materials, and solution cavities formed by the carbon dioxide (carbonic acid) groundwater formed by the effect of nearby Hasandağı old volcano.