Study of effective factors in the formation of sinkholes in south of Poldokhtar, Iran


Department of Geology, Sciences Faculty, Bu Ali-Sina University, Hamedan, Iran


Sinkholes are more abundant, in the quaternary-covered basins with soluble bedrock. In the folded Zagros in Iran, the Most of plains are karstic. This research was carried out in an area of 155 km2 in location of old the Jaydar and the Gori Balmak lakes, in south of Poldokhtar city, SW Iran. The purpose of this study was to evaluate the factors affecting the formation of sinkhole. In this area are expanding lake sediments of the Seymareh landslide dams. The thickness of lake sediments have been estimated using geophysical studies include GPR with 10 MHz antenna and ERT, respectively an average 70 m and less than 10 m in the Jaydar and Gori Balmak plains. The bedrock of study area is the Gachsaran Formation (Middle Miocene) includes gypsum massive and marl. Uniaxial compressive strength (UCS) and tensile strength of gypsum section of bedrock is respectively 16.39 and 1.5 MPa. At least 4 joint sets are expanded in the bedrock. The source of the filling materials of the joints is eroded marl units of Gachsaran Formation and lake sediments. The dispersion of joints filling material is approved by Crumb, dual hydrometer and chemical tests. The dual consolidation test showed that the covering sediments of bed rock are collapsible. Pezometric data show that the average depth of groundwater in the past 10 years has loss about 3 m and lies at a depth of 20 m at ground level now. Field observations show less than 32 sinkholes in the study area


Bell, F.G., Maud, R.R., 1994. Dispersive Soils: A Review from a South African Perspective. Quaternary Journal of Engineering Geology 11, 195 -210.
Deer, D.U., Miller, R.P., 1966. Engineering classification and index properties for intact rock. Technical Report No. AFWL-TR-65-116, Air Force Weapons Laboratory, Kirland Air Force Base, New Mexico.
Ezersky, M., Frumkin, A., 2013. Fault-Dissolution fronts relations and the Dead Sea sinkhole problem. Journal of Geomorphology 201, 35-44.
Galloway, D., Jones, D.R., Ingebritsen, S.E.,1999. Land subsidence in the United States US geological Survey Circular, pp. 182.
Gutierrez, F., Galve, J.P., Lucha, P., Bonachea, J., Pardo, G., Sanchez, J.A., Gutierrez, M., Gimeno, M. J, Remondo, J., Cendrero, A., 2009. Sinkholes in the salt-bearing evaporate karst of the Ebro River valley upstream of Zaragoza city (NE Spain) Geomorphological mapping and analysis as a basis for risk management. Journal of Geomorphology 108, 145-158.
Gutierrez, F., Guerrero, J., Bonachea, J., Lucha, P., 2008. A sinkhole susceptibility zonation based on paleokarst analysis along a stretch of the Madrid-Barcelona high-speed railway built over gypsum and salt- bearing. Jornal of Engineering Geology 102, 62-73.
Heidari, M., Khanlari, G.R., Taleb Beydokhti, A.R., Momeni, A.A., 2011. The formation of cover collapse sinkholes in North of Hamedan, Iran. Journal of Geomorphology 132, 76-86.
Jennings, J.E., Knight, K., 1975. A guide to construction on or with materials exhibiting additional settlement due to collapse of grain structure. Proceedings of the sixth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, pp. 99-105.
Sherard, J.L., Dunnigan, L.P., Deker, R.S, 1976. Identification and nature of dispersive soils ASCE. Journal of Geotechnical Division 102, 69-85.
Sourinezhad, A., 2002. The estimation of runoff in the watershed basin of Kashkan River using GIS. Journal of Geoghraphic Researches 43, 57-80. (In Persian).
Taheri, K., Gutierrez, F., Mohseni, H., Raeisi, E., Taheri, M., 2015. Sinkholesusceptibility mapping using the analytical hierarchy process (AHP) and magnitude-frequency relationships: case study in Hamadan province, Iran. Geomorphology 234, 64-79.
Waltham, T., Bell, F., Culshaw, M., 2005. Sinkhols and subsidence, karst and cavernous rock in engineering and construction, Springer, Chichester, pp. 373.