Interaction effect of slope aspect and rainfall intensity on soil permeability compared to acidic

The amount of soil permeability depends on the size of the holes, the concentration of liquid, and the surface tensile force. In fact, the factors affecting the initial porosity are also effective in permeability.The results of different researches show that soil permeability has been prioritized in different researches. In Iran, various researches have been conducted on soil physical and chemical properties and its relationship with permeability. This study was conducted based on infiltration field measurements under simulated rainfall conditions in order to determine the penetration rate and interaction effect between slope aspect and intensity of precipitation relative to acidic precipitation on Aghajari and Gachsaran formations.

In this study, in order to determine the interaction effect between slope aspect and rainfall intensity in soil permeability compared to acidic precipitation in the deposits of Gachsaran and Aghajari formations due to the existence of petroleum pollutants and air pollution, a part of Gypsum and Margha watersheds of Izeh city with an area of 1202 and 1609 hectares was selected. Then, soil permeability was sampled at 16 points and with three replicates in rangeland land use and in the northern, southern, eastern, and western aspects of Gachsaran and Aghajari formations at different rainfall intensities of 1 and 1.25 mm/min and in distilled water precipitation, the acidity of 4 and 5 was performed using kamphorst rain simulator.

The results showed that in Aghajari formation, the interaction effect of slope aspect and rain intensity, as well as rainfall intensity had the highest sensitivity and slope aspect had the lowest sensitivity to soil permeability compared to acid rains. However, the Gachsaran Formation showed uniformity changes compared to acidic precipitation and showed positive effects on slope aspect and rain intensity and interaction effect of slope aspect and rain intensity almost all three concentrations. In addition, by increasing the amount of soil impregnated with acid rains, the amount of soil porosity will increase, which is due to this type of contamination on the main ingredients of soil and washing soil bonds. Of course, the slope aspect is also due to the different amount of clays in both Aghajari and Gachsaran formations due to erosion and different washing rates that are created from the beginning of the slope to its bottom especially in the Aghajari Formation and the influence of soil permeability on more acidic precipitations, as well as the existence of different organic matter in the main aspects of the slopes, especially in the northern and eastern slope aspects, creates a more complex situation in electrical charge changes, which necessitates further research to understand this complex mechanism.

In general, by increasing the acidic degree and increasing the penetration time, soil properties have been changed, including these changes can be noted the resistance characteristics and bearing capacity of the soil, which in the meantime, due to the amount of clay and different organic matter, causes more influence of acidic precipitation on soil permeability.