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Shrinkage-swelling behavior and plasticity indices of paddy-soils of the Guilan province, Iran, their spatial variability and influential parameters were evaluated. Coefficient of linear extensibility (COLE), shrinkage index (SI), shrinkage (SL), plastic (PL), and liquid (LL) limits, plasticity index (PI), and the dimensionless geometry factor (rs) of deformation, cation exchange capacity (CEC), organic carbon (OC), saturated water content (θs), bulk density (BD), particle density (PD) and soil texture were determined. SI and COLE had extremely strong and LL and PI had strong positive correlations with θs. The significant effect of clay, CEC, OC and θs on Atterberg limits, COLE, and SI indicated their great impacts on soil strength in tillage and engineering applications of soils. Multiple-regression models could explain 97%, 92%, 76%, 61%, 55%, and 32% of the variations in COLE, SI, LL, PL, PI, and SL, respectively. Isotropic spherical and exponential models were the best-fitted models for the variograms. CEC and OC showed strong spatial structure, while PL and the remaining traits showed weak and moderate structure, respectively. All the soils with rs < 3 showed moisture-dependent anisotropy of vertical and horizontal deformation. Generally, the paddy soils had medium to high shrinkage capacity and vertical deformation was dominant during the shrinkage process. [ABSTRACT FROM AUTHOR]

This study deals with the distribution of the population in Khuzestan province and its impact on the political strength and the causes of variation in the distribution between administrative units that make up the province, leading to the results serve regional development which is reflected on the power of the population, it has been chosen study area of importance for Iran and geographical neighbors of Iraq, and the lack of Arabic Library for this kind of studies. This study includes numerical and proportional distribution of the population, and then the distribution study dense and the extent of concentration of population, and then the environmental distribution, and the study of the actual distribution and patterns of distribution of the population, down to the specific results reveal the importance of population distribution and its impact on building political power for the province. [ABSTRACT FROM AUTHOR]