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.
Seyed Alireza Mousavi; Hossein Arzani; Gholamali Sharzei; Hossein Azarnivand; Mahdi Farahpour; Stephani Engel; Esmail Alizadeh; Aliakbar Nazari-Samani
Abstract
Soil conservation is one of the most important regulative functions of natural ecosystems. This function is of high importance in Taleghan Watershed due to high erosion quantity and sediment accumulation in Taleghan Dam reservoir. Soil loss reduction, sedimentation control and fertility conservation ...
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Soil conservation is one of the most important regulative functions of natural ecosystems. This function is of high importance in Taleghan Watershed due to high erosion quantity and sediment accumulation in Taleghan Dam reservoir. Soil loss reduction, sedimentation control and fertility conservation were considered as different aspects of soil conservation. Effect of land use and vegetation cover on soil conservation was studied by overlaying soil erosion map with other environmental data layers. Abandoned rainfed lands with low cover were considered as benchmark to evaluate the role of rangeland vegetation cover in soil conservation. Economic value of soil loss reduction function was estimated using opportunity cost approach and the benefits of rainfed agriculture. Economic value of sedimentation control also was calculated considering SDR ratio and avoided cost approach. Soil fertility conservation was quantified regarding the volume of soil conserved and nutrient content of soils of the study area. Economic value of this function was estimated using replacement cost approach. Results show that Mid-Taleghan rangelands conserve 60545 cubic meters of soil per annum. Annual economic value of soil loss reduction, sedimentation control and fertility conservation functions were estimated about 6262, 25287 and 8626 US dollars, respectively. These functions are just some limited aspects of rangeland functions and economic valuation of these functions could effectively be utilized for conservation of rangeland ecosystems.
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Fariba Alavizadeh; Kamalledin Naseri; Ali Golkarian; Ali Tavili
Abstract
Soil erosion is a main hazard in most area of the country specially in arid and semi-arid regions and itis very important because of sedimentation, pollution, increased flooding and its negative effects onsoil productivity. One of the features of arid and semi-arid areas is the presence of low cover ...
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Soil erosion is a main hazard in most area of the country specially in arid and semi-arid regions and itis very important because of sedimentation, pollution, increased flooding and its negative effects onsoil productivity. One of the features of arid and semi-arid areas is the presence of low cover ofvascular plants. These empty spaces are usually good niches for biological soil crusts or cryptogamslike mosses. These crusts contribute to a variety of ecological functions and have different effects onsoil features and vascular plants. The present study was carried out in the rangelands of Torogh dambasin of Khorasan- Razavi province in order to find the effects of such kind of plants (mosses) onwater erosion. For this purpose, artificial runoff streams in plots with two intensity (low and high) for30 minutes. In order to study the effects of different amount of mosses on sedimentation and specificerosion, four different density of mosses in the same experimental situation were studied: high (60-75% of plot), medium (35-50% of plot), low (10-20% of plot) and control (0%). The results ofanalysis of variance and tukey method by the use of Minitab software showed a significant differencein 95% level between the four considered density of mosses and the two intensity of water. As mossesdensity decrease, sedimentation and specific erosion increased consequently. But there were nosignificant differences in infiltration between the different treatments.
