mehdi bashiri; Seyede Maedeh Kavousi Davoudi
Abstract
The soil erosion affects watershed health and lead to different negative consequences.Marl is an erosion sensitive rock that due to its special physicochemical characteristics,establishment of vegetation on it is difficult,so,it needs to management.One of the soil improvement methods is dynamic compaction,which ...
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The soil erosion affects watershed health and lead to different negative consequences.Marl is an erosion sensitive rock that due to its special physicochemical characteristics,establishment of vegetation on it is difficult,so,it needs to management.One of the soil improvement methods is dynamic compaction,which applies using devices such as rollers.Also,adding pozzolan is another method for soil improvement to modify its physical and mechanical properties.Because the pozzolan in the presence of water,show adhesive properties in a stable and non-solvent form.Therefore,this study tried to evaluate the roles of soil compaction(using rollers having weights of 0,20,25,30and35Kgs)and adding natural pozzolan(in values of 0,50,100,150and200g/m2)in the taftan-pumice type on marl stabilization in Islam-Qaleh region of Razavi-Khorasan.A factorial experimental design done with3replications and totally75field plots with an area equal to30*30centimeters exposed to a rainfall with a10minutes duration and0/8Mm per minute intensity with a slope of15/5°.The results of statistical analysis in the95%confidence level showed that considering runoff,sediment load and sediment concentration variables together,the main effects of soil compaction and pozzolan treatments are significant(sig.=0/000)but their interaction effect isn’t significant(sig.=0/780).Soil compaction treatment has an increasing and significant effect(sig.=0/000)on runoff and sediment production. But the pozzolan treatment showed decreasing and significant effect (sig.=0/000) on sediment and no significant effect (sig.=0/709) on runoff. Also, the interaction effect of 2 treatments on runoff and sediment was not significant. Therefore, the soil compaction due to degradation of surface sealing and marls structure is not suitable, but according to low price and availability of natural pozzolan, for marls stabilization operations, is suggested as an economic and appropriate option.
Mohammad Nohtani; Sadat Feiznia; Hasan Ahmadi; Hamidreza Peirovan
Abstract
Loess Deposit is one of the most important Quaternary Deposits of northeastern parts of Iran which have high erosion rate. This study was performed with field- Rainfall- Simulator which has a plot area of 1 m2 in Gorganrood Drainage Basin to determine the effective factors on sediment yield. Landuse, ...
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Loess Deposit is one of the most important Quaternary Deposits of northeastern parts of Iran which have high erosion rate. This study was performed with field- Rainfall- Simulator which has a plot area of 1 m2 in Gorganrood Drainage Basin to determine the effective factors on sediment yield. Landuse, slope and erosion feature maps were overlaid in GIS to obtain land unit map. Then on work units, rainfall simulator analyses were performed. The produced runoff and sediment in 69 points on work units were collected and were measured. Adjacent to each rainfall simulator plot, samples of surface material were collected in the field to analyze for physical and chemical characteristics. In the field, descriptive tables were prepared for different work units in which locality, slope percentage, elevation, depth of A horizon of the soil and other necessary informations were recorded. In order to determine logical relationship between different variables, regression and correlation analyses were performed. In statistical analyses, it was found that slope percentage has the highest correlation coefficient and has the highest direct relationship with sediment yield and sediment production and silt amount is the second factor. The investigation of multiple regression analyses generated a model which shows %80 of sediment production variations. In this model slope percentage, cation exchange capacity and silt have possitive relationship and Calcium cation has negetive relationship with sediment yield.
