An introduction to the karst geomorphology of the Bisetun–Taqe Bostan historical region (northeast Kermanshah, Iran) with special emphasis on karst development as a serious threat for the UNESCO World Heritage Site

The Bisetun–Taqe Bostan crushed carbonate massif (northeast of Kermanshah City) is a historical region that includes several famous monuments. Several types of karst features, the surface kind especially, have been developed in the area because of high rainfall in the area, tectonic crushing and high purity of the rocks. The field survey showed that the major karst features are karren, including rillenkarren, trittkarren, and solution runnels. Some of the monument stones by it have been deteriorating. Cavities and caves, solution dolines, and karstic springs are other observed karstic features in the area. Cavities and caves present mostly at intersections of shear faults or joint sets, which are considered the main location of water seepage throughout the limestone mass. Dolines in the region can be divided into two groups including solution and collapse dolines. The first group involves deep and large dolines without surface deposit cover, whereas the second group includes shallow dolines with smaller sizes covered by soil layers. Dolines are not problematic for the monuments because of their relatively high distance from them. There are a number of karstic springs in the study area; the Bisetun and Taq-e Bostan springs are the most important among them. Both springs discharge at a fault surface in vicinity of the monuments. As a part of the present study, deterioration occurring in the monuments due to the karst development was investigated. Moreover, some physical and chemical preservation methods were proposed to protect the monuments.