JWSS - Journal of Water and Soil Science

Changes in Climate parameters have been accelerated in the coming age, which can affect agricultural activities directly and indirectly. Temperature and precipitation are the most complex climatic factors. Spectral analysis is a scientific and efficient technique used to recognize and detect the hidden behaviors of these variables. In this research, in order to study and analyze the temperature and precipitation return periods using spectral analysis, the statistics of climate parameters (precipitation, mean, maximum and minimum temperature) for a period of 27 years (1989-2015) were used for the sustainable land management. For this purpose, the climatic data of temperature and precipitation entered the MATLAB software environment and Periodogram of each of the climatic parameters was drawn in a separate way. The results of each Periodogram study showed that the absolute minimum of temperature had significant cycles with the return periods of 3.8 and 2.4 years; the absolute maximum of temperature had a significant cycle with a return period of 2.1 years and the mean temperature was significant with a return period of 2.7 years. Also, the review of the Periodogram related to precipitation showed a significant cycle with a return period of 3.4 years. The Results from studying cycles indicated the existence of short-term return periods for climate variables in the region. Given this issue and the need to protect agricultural products, especially garden products, it should be done by applying water and soil resources management methods, including creating terraces and increasing soil roughness; Also, cultivation of appropriate plant species for the suitable regional climatic conditions, Drought resistant and low water requirement, the most optimal conditions could be created for the cultivation of horticultural and agricultural products.

The soil engineering evaluation can be useful for construction and soil use. Aljarafe model has been used to evaluate the soil engineering properties by multiple regression techniques. In this research, Aljarafe model was used to predict the optimum moisture and plasticity index based on 184 series soils data of the Miandoab region. Based on all correlations between clay percentage and plasticity index, the optimum moisture proved to be highly significant (0.88 & 0.72). Also, Cation Exchange Capacity was significantly correlated (0.84 & 0.70) with the engineering properties. However, the correlation coefficients for the organic matter with optimum moisture and plasticity index were very low in the absolute amount. Application of the aljarafe model revealed that 50.3, 5.7, 0 and 44 % of the total extension could be classified as low, moderate and very high, respectively; on the other hand, based on the experiment data, 46, 13, 6 and 35 % could be classified as low, moderate, high and very high plasticity index classes, respectively. So, there was an overall agreement between the aljarafe model and Analytical Plasticity index maps, which was 80.4. Also, the coefficient of Determination, Root Mean Square Error (RMSE), Nash-Sutcliffe index (NES) and Geometric Mean Error Ratio (GMER) between calculated and experiment engendering properties was calculated to be 0.767, 9.3, 0.671 and 0.86 for the plasticity index and 0.739, 14.5, 0.543 and 0.73 for optimum moisture, respectively, were significant (P>5%). Finally, the aljarafe model provided a reliable estimate of engineering properties. 

 

To study the soil-landscape change in the Chaldoran region, 9 representative soil profiles were studied in 5 dominant geomorphic units of the study area including piedmont plain, mantled pediment, alluvial fan, plain, and flood plain. The results showed that the accumulation of pedogenic carbonate in some soils was concretion and light in color. In control soils in the piedmont plain (profile 5 and 7), mantled pediment (profile 6), and flood plain (profile 8) clay transferred from the surface horizons and accumulated in the lower horizon, due to relatively good rainfall in the region and distinct dry and wet seasons has led to the formation of argillic horizons along with the formation of crust on the surfaces of aggregates and building units and has formed the Alfisoils order. Mineralogical results showed the presence of chlorite, illite, kaolinite, and smectite minerals. According to the evidence, illite, chlorite, and kaolinite minerals were inherited and smectite minerals were formed due to weathering and evolution of illite, chlorite, or palygorskite minerals. Also, the results of the CIA index in the region indicated that the soils of the region are in the stage of weak to moderate weathering. In general, the results indicated the critical role of drainage, land use, and parent materials in the soils of the study area.