geographia - Studia

AHMAD KHORSANDI, SEYED HOSSEIN GHOREISHI, MANIJE ABDALI, CACOVEAN HORIA
Sinkholes are karstic forms that geological aspect are cylindrical and conical shaped
holes with dimensions ranging from one to tens of meters. The sinkholes are formed in one
of the two following manners (B. Markoo, 1998):
a) Movement and discharge of surface materials from top layers along solution
channels developed in basal carbonated rocks;
b) The collapse of upper rocky layers on large caves formed in the carbonated
bedrock.
At least 140 sinkholes were formed from 1961 to 1986 in Orlando in USA
(L. William, 1992).
Fig. 1. The map of Iran and situation of Hamadan Plain in northwest (A) and
the Lar region in north (B) (Khorsandi 2007).
During a series of research, parameters such as depletion of ground waters, oil and
gas explorations, and the movement of rocks during mine operations and the drainage of
marshes are the main causes for sinkhole formation (L. Pewe, 1990 and A. Waltham, 1989).
The model proposed by Waltham (1989) described the different types of sinkholes
and their specifications in karstic and non-karstic soils.
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