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Abstract

In arid regions, due to limited chemical weathering, resalinization with salt redistribution in the soil is important. In the Rudasht alluvial plain of Isfahan, the pattern of salt reaccumulation in the soils were investigated by studying topography, ground water fluctuation, and water application and distrubution. Data collected from water levels during one year shows in regions of lower topography salts accumulate on the surface, if excess water is not drained. It is recommended to use low salt water for irrigation and pump the excess water to control ground water level and to reduce soil salinity. Earth canals (Muddies) are also contributing to soil salinization. Zayandehrud river terraces sometimes create lower regions and nonuniform natural drainage and hence are partly responsible for soil salinization. In the study area, because of macro—relief, the local hydraulic gradient is opposed to the general hydraulic gradient, thus, preventing drainage of salt water from the region. The critical depth of ground water to prevent salt accumulation is proposed to be 2.5 m. In summary, factors contributing to salt accumulation and redistribu- tion are: heavy soil texture, relief, earth canals, and the system of water application and distribution.