Geological and hydrogeological effective factors in the high permeability zones of several dam sites of the Zagros Region, Iran

Abstract

Stratigraphical, discontinuity and hydraulic characteristics of a karstic region are crucial factors in solution development, producing areas with strong contrasts in permeability with probable water seepage from dam foundations and abutments. The aim of this study is to explore the effect of these elements on karstic dam sites of the Zagros region in Iran. Although the Asmari Formation is inherently fractured, according to the distribution of boreholes and dams, and there is no case that is merely controlled by one of these elements; therefore, all factors are unequally responsible for creating a high-permeable zone. The river and adjacent karst connect in three possible ways: water flows from the river to the adjacent rock mass, the river gets water from the adjacent rock mass, and there is no hydraulic connection between the river and adjacent karst areas. The settlement of impermeable layers, such as marly limestone and marl inside carbonate bodies, may create suitable places for water collection and initiation of dissolution. Finally, at the borehole scale, it is possible to find some high-permeable zones controlled only by one of the three mentioned elements, but there is no borehole or no dam site in which all high permeable zones are controlled by only one of these elements.