Comparison of particle size distribution of sediments in mountain and river sand and gravel mining in Urmia City

Sand mines are one of the most important active mines. One of the key properties of sediments is their particle size distribution, which affects many physical and chemical properties such as hydraulic and electrical properties and characteristics related to the transportability by erosive agents. Determining the size of sediment particles in different environments can be used in reclaiming sediments from washing river and mountain sand mines for physical and chemical remediation of soil. By determining the size of sediment particles in different environments, it is possible to measure the reuse of sediments from washing river and mountain sand mines for physical and chemical remediation of soil.

The main aim of this study was to compare the capability of some mathematical models in describing particle size distribution of sediments of 26 sand mines in Urmia. For this purpose, sampling was performed from mine sedimentation ponds. By examining each of the mines, in the field surveyes of sediment ponds, sediment sampling was done. In sampling of each mine, three samples were taken from three different points of stilling pond (entrance, middle and end of the pond) in depth (approximate depth of 20 cm) and composed of sediment accumulation profiles with approximately one kilogram weight. The particle size distribution was determined by hydrometric method. In order to describe the sediments, 4 mathematical models of sediment size distribution including Weibull, Fredlund, Van genuchten and Jacky models were used. Different aspects of models performance were evaluated by some efficiency criteria.

The samples taken from mountain and river mines were in the sandy loam and loamy texture class, respectively, so they have fine to medium grain texture. The results showed the difference between the amount of particles forming river and mountain sediments and there is small difference between river and mountain sediments in terms of the amount of component particles. In mountain sediments, the amount of clay, silt and sand is much more than river sediments and the amount of sand in river sediments is more than mountain sediments. Based on the results, most of the sediments are sand, silt and very fine sand and clay, respectively. Six efficiency coefficients were used to evaluate the accuracy of sediment particle grading models. The results showed that Fredlund model had better performance in describing sediment size distribution than other models.

Analysis of daily, monthly, seasonal and annual trends of precipitation and minimum and maximum temperatures in the period Fredlund model has the lowest error compared to other models and increasing the number of model parameters is not a reason to increase the accuracy of the model.It is suggested that the physical and chemical properties of sediments of mountain and river sand mines be studied separately so that according to different origins and different processes involved in their formation, the feasibility of using these sediments for soil optimization can be investigated.