Assess the potential of land subsidence and its related factors(Case study: Plain Saidan Farouk MARVDASHT(
Abstract
In recent years due to excess exploitation of ground water in fertile plains, land subsidence has become one of the main natural disasters. Neglecting such a phenomenon can cause severe irreparable damages. Accordingly, it is indispensible to assess the potential of fertile lands for subsidence. This study evaluates the potential of land subsidence and effective factors in Farough - Seydan fertile land in Marvdasht. First, the 11 piezometers of 14 available piezometers in statistical period of 1374 – 1378 are evaluated. And the empirical relationship of Lamb- Whitman is used to have the map of land subsidence risk. Hence, after Thiessen networking some parameters are prepared such as primary osteoporosis, the coefficient of compression capacity, the initial thickness of intended layers,
effective stress the primary and secondary, Raster layers of thickness of saturated area between raw water table and hypothetical layer, initial pore water pressure, changes in effective stress, probable subsidence and its risk .The data show that there are two zones with extra high risk ( 5.57 percent of the plain) and high risk ( 19.76 percent of the plain) in which two factors are the most effective ones; the density of the clay layers and excessive water withdrawals.During the period of 1375 – 1388 there were 1700 agricultural wells in the plain that caused the drop of 17.96 meter of underground water. This, in turn paves the way for the high density of clay layers and land subsidence.
effective stress the primary and secondary, Raster layers of thickness of saturated area between raw water table and hypothetical layer, initial pore water pressure, changes in effective stress, probable subsidence and its risk .The data show that there are two zones with extra high risk ( 5.57 percent of the plain) and high risk ( 19.76 percent of the plain) in which two factors are the most effective ones; the density of the clay layers and excessive water withdrawals.During the period of 1375 – 1388 there were 1700 agricultural wells in the plain that caused the drop of 17.96 meter of underground water. This, in turn paves the way for the high density of clay layers and land subsidence.
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