Mahin Kalehhouei; Raoof Mostafazadeh; Abazar Esmali Ouri; Rahmani Naneh Karan, Fardin; Fazeli, Alireza; Nazila Alaei; Zeinab Hazbavi
Abstract
Introduction
The rainfall system of a major part of Iran is mediterranean, where the precipitation amount during the vegetation period is low. In addition, the occurrence of precipitation in the non-vegetation period or beginning of the vegetation period, which does not cover the surface of the earth ...
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Introduction
The rainfall system of a major part of Iran is mediterranean, where the precipitation amount during the vegetation period is low. In addition, the occurrence of precipitation in the non-vegetation period or beginning of the vegetation period, which does not cover the surface of the earth well, is one of the important reasons for water erosion in Iran. Since vegetation has a special role in soil erosion control and runoff retention, any change in the vegetation structure and pattern, which expresses the landscape pattern and function, can have a significant effect on changing hydrological processes. Therefore, the assessment of soil and water loss and the quantification of its relationship with landscape metrics provide key information for the development of water and soil quality management strategies.
Materials and methods
The current research was conducted to investigate the hydrological component changes with landscape metrics on 2 m2 plots using simulated rainfall at an intensity of 32 mm.h-1 in a part of rangelands of Ardabil County. At first, considering the type and percentage of vegetation as the main variable, eight groups of vegetation composition along with one group without vegetation (control) were considered with three replications. The composition (and percentage) of the vegetation from the first to the eighth groups, respectively, include low-height graminea predominance (45), the composition of dense bushes with graminea (43), bushes with low-height and medium-distribution (37), sparse bushes mostly with low and medium height (31), the composition of sparse bushes with graminea (56), dense bushes in upper parts (54), low-height bushes with very low distribution (15), and dense bushes with almost uniform distribution (56). After measuring the runoff and sediment at the plot outlets, different hydrological components were calculated. Then, plots with nine different vegetation combinations were imaged in three replicates before and after rainfall simulation. After transferring the images prepared from the plots to the Arc/Map10.8 environment, nine important landscape metrics were calculated.
Results and discussion
Changes in the mean patch density (4.43-26.90), largest patch index (54.16-86.75), edge density (17.12-107.38), landscape shape index (1.50-4.47), mean shape area (4.16-37.46), mean Euclidean nearest neighbor distance (0.00-1.65), landscape division index (0.19-2.31), mean patch shape index (1.24-22.85), and the effective mesh size (15.80-43.96) indicate their different influence from different percentage and composition of vegetation cover. Spearman's correlation matrix analysis showed a nonsignificant relationship between the mean soil loss, runoff volume, runoff coefficient, and sediment concentration with landscape metrics (r<0.26 and p-value>0.10). The small scale of the studied plots, the lack of diversity in the vegetation composition, and the uniformity in terms of vegetation height can be cited as the reasons for the lack of correlation. In general, groups with vegetation values above 50% had a better condition in terms of LPI, AREA_MN, and MESH, which indicates more connectivity and less degradation. The increase in vegetation cover and spatial heterogeneity above the landscape surface can change the path of sediment transport, reduce sediment connectivity, and lead to a decrease in sedimentation.
Conclusion
The obtained results are applicable in explaining the appropriate reference to optimize water and soil protection measures on the watershed scale. However, It is suggested that similar and more comprehensive research be done in different scales of erosion plots and even in the landscape (slope) scale so that by considering a wide range of vegetation, topography, climatic conditions, as well as successive rains, it is possible to compare the results, optimum selection of study scale, and finally planning to manage and protect vegetation and water and soil resources.
Ariyan Matboo; Vahedberdi Sheikh; Ali Mohammadian Behbahani; Arash Zare Garizi
Abstract
Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological ...
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Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological Soil Crusts (BSC), has been destroyed due to lack of awareness of their values, sensitivity and ecological functions. Improving soil properties, preventing direct contact of raindrops with the soil surface, all indicate the important role of BSC in hydrological processes and soil loss control.
Materials and methods
In this study, the role of BSC in the hydrological processes of dry areas was investigated using a rain simulator. After a field survey and evaluation of the area, different treatments including biological crust with a dominant lichen cover, biological crust with a dominant moss cover, an area covered with vascular plants, an area without cover and areas covered with a combination of moss and lichen were selected to perform rain simulation and compare their effects on the hydrological processes of the selected region. Rain simulation was done in 2×1 meter plots for 30 minutes and intensity of 82 mm per hour. The start time of runoff and the volume of produced runoff at the outlet of the plot were measured and recorded. Also, at five-minute intervals from the beginning of the simulation process, 500 ml runoff samples were collected and transferred to the laboratory for testing in order to estimate the sediment concentration and mass. In addition, the depth of the wetting front caused by the infiltration of rain was measured at the beginning, middle and end sections of the plots.
Results and discussion
The results of rainfall-runoff simulations at a 2×1 m2 plot scale with a rainfall intensity of 82 mm.h-1 and a duration of 30 minutes plots, showed that the average mass of sediments from plots with the dominant cover of moss (104 g), lichen (91 g), lichen-moss combination (176 g) and bush (99 g) was significantly higher than bare soil (1133 grams). Therefore, in case of destruction of the existing BSC and the formation of bare lands, the sedimentation rate will increase by more than 5 times. A significant decrease in water infiltration into BSC causes a significant increase of 30-40% in runoff generation compared to the treatment covered with bushes and a significant increase of 8-18% compared to the bare soil treatment.
Conclusions
by reducing soil loss and sediment concentration, BSC cause the production and transfer of high-quality runoff to the wetlands and as a result maintain the ecological function and health of the region’s wetlands. The results of this research show the positive influence of BSC on the hydrological and ecological performance of arid areas in the north of Gorgan Plain and protection of Ramsar-listed wetlands in the region.
yasin salehi; Alireza vaezi
Abstract
IntroductionSoil erosion is the most important aspect of land degradation and one of the most important environmental, agricultural and food production problems in the world. More than half of the agricultural lands in semi-arid regions are under rainfed cultivation, and the tensions caused by erosion ...
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IntroductionSoil erosion is the most important aspect of land degradation and one of the most important environmental, agricultural and food production problems in the world. More than half of the agricultural lands in semi-arid regions are under rainfed cultivation, and the tensions caused by erosion and destruction of land are important in terms of the effects within the field of erosion, such as soil fertility, and the effects outside the field, such as soil pollution. Information about the size distribution of eroded particles is a substantial step for managing the loss of nutrients and the transfer of pollutants from the soil. For this purpose, this study was conducted to investigate the particle size distribution of sediments resulting from interrill erosion under the influences of slope gradient and soil texture in some soils of the semi-arid region of Zanjan Province. Materials and methodsToward this, four hillslopes having different soil textures (sandy loam, silty loam, sandy clay loam and clay loam) in four north-south slope percent (five, 10, 15 and 20%) were investigated using a simulated rainfall with an intensity of 60 mmh-1 for 60 minutes. In order to monitor the runoff and sediment samples from the beginning of the runoff until reaching a stable state, were taken at 5-min intervals from the initiation of runoff. The particles size distribution of sediment was determined by the method of particle separation using a series of sieves with diameters of 75, two, one, 0.5, 0.25, 0.1 and 0.05 mm. Also, the percentage of finer particles (silt and clay) was calculated by hydrometer method. Then the sediment particles are divided into eight categories: gravel (1-75 mm), very coarse sand (1-2 mm), coarse sand (0.5-1 mm), medium sand (0.25-0.5 mm), fine sand (0.1-0.25 mm), very fine sand (0.05-0.1 mm), silt (0.002-0.05 mm) and clay (<0.002 mm) were categorized. Results and discussionThe results showed that, with the increase in the slope of the land surface, the size distribution of sediment particles changed in all soils. So that, the transport of particles larger than 0.1 mm (including very coarse sand, coarse sand, medium sand and fine sand) increased with increasing slope. While the percentage of silt particles (0.002-0.05 mm) decreased in all textures. Also, particles with the size class of medium sand and fine sand formed between 40 and 50% of the sediment particles for each texture and did not change significantly with the increase of the slope. The highest ratio of particles in the sediment to the main soil was related to silt particles and in silty loam texture (4.33 times) and the lowest was related to clay particles and in silty loam texture (0.26 times). Sand and silt particles in different textures, had high transmission ratios. Silt particles in three textures of sandy loam, clay loam and silty loam had a ratio of more than one and clay particles less than one. Except in clay loam soil, sand particles changed in the range of 0.83 to 1.24 times compared to the main soil and the overall average ratio of its availability in sediment to original soil was 0.98 times. ConclusionIn general, this research showed that with increasing slope, the selectivity of fine particles decreases and the share of coarse particles increases. The effects of these changes are more visible in fine-textured soils. Due to the increase in the destruction of aggregates and flow rate with the increase of the surface slope, it is very important to prevent the removal of vegetation and observe the principles of tillage in order to reduce the direct impact of raindrops on the soil surface and reduce the transportability of particles by the flow. Also, the results show that the ratio of particles in the soil texture and the characteristics of soil structure (abundance and stability of aggregates) are the determining factors of particle transport and it is necessary to consider these characteristics in choosing soil conservation methods.
Jalal Heidari; Alireza Vaezi; Mohammad amir Delavar
Abstract
The variety of factors affecting soil properties leads to temporal changes in the soil erosion process. This research was conducted to assess short-term changes in runoff and soil loss in rainfed wheat furrows under fallow conditions. To this end, three rainfed lands with 15% slope gradient were selected ...
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The variety of factors affecting soil properties leads to temporal changes in the soil erosion process. This research was conducted to assess short-term changes in runoff and soil loss in rainfed wheat furrows under fallow conditions. To this end, three rainfed lands with 15% slope gradient were selected in south west of Kermanshah Province. In each land, furrows with five m in length and 30 cm in width were created using sowing set. Runoff and soil loss were measured using simulated flows with a discharge of 0.5, 1, 1.5 and 2 L.min-1 at intervals of five minutes to 60 minutes 60 minutes in three replications. Results showed that the lowest soil loss was recorded in flow discharge of 0.5 L.min-1 (2.66 g.m-2) and the highest of soil loss was produced in flow discharge of 2 5 L.min-1 (85.33 g.m-2). Also, the lowest runoff was recorded in flow discharge of 0.5 L.min-1 (0.47 L) and the highest of soil loss was produced in flow discharge of 2 5 L.min-1 (7.65 L). The effect of time on runoff and sediment variables was significant in all flow discharge (p<0.01). Runoff production was low at the beginning of the experiment and increased over time. The pattern of temporal changes in soil loss was different from runoff production, amount of soil loss at the beginning of the experiment was higher values than the final test times, which associated with to supply of erodible soil particles in the rills in the beginning of the experiment. With starting the experiment to 25 minutes, the rate of soil loss changes drastically and then until the end of the experiment, it followed a uniform reduction pattern and in the final stages, it is almost constant. The results showed that rill erosion is strongly influenced by flow intensity and its value changes over time and these changes are independent of flow production and depended on the transmittance of soil particles transferable in the rill.
Behnam Farid Gigloo; Ebrahim Omidvar
Abstract
Ephemeral Gully (EG) erosion is one of the most destructive types of water erosion, which contributes significantly to land degradation. EG erosion prediction is necessary to assess the magnitude of soil loss and to implement the appropriate conservation measures. The aim of current study was to ...
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Ephemeral Gully (EG) erosion is one of the most destructive types of water erosion, which contributes significantly to land degradation. EG erosion prediction is necessary to assess the magnitude of soil loss and to implement the appropriate conservation measures. The aim of current study was to evaluate the efficiency of EGEM model for EG erosion prediction in Ghoorichay Watershed, Ardabil Province, Iran. For this purpose, a number of 17 EG erosion was identified and monitored between the years 2014 to 2016. The morphological characteristics and erosion rate of EGs were measured and recorded after seven effective rainfall events. In order to calculate the EG erosion, EGEM model requires four major categories of input data, including identification information, watershed data, soil data, and rainfall data. The model has two major components: hydrology and erosion. The runoff induced by a rainfall event in each gully catchment was determined by the Natural Recourses Conservation service (NRCS) Curve Number (CN). The result of EGEM model performance evaluation showed that the eroded soil volume and cross-section were predicted with a determination coefficient of 0.96 and 0.89, respectively. Sensitivity analysis revealed that the curve number was the most sensitive parameter, so that, with a 10% increasing and decreasing in CN, the volume of soil loss varied 22.98 and -18.92%, respectively. It can be concluded that EGEM model was suitable for event-based EG erosion prediction in Ghoorichay Watershed and it can be recommended for studying and planning on EGs in similar watersheds.
Ali Bagherian Kalat; Gholamreza Lashkaripour; Mohammad Ghafoori; Aliakbar Abbasi
Abstract
On areas with highly eroded soils, where vegetation is absent or negligible, runoff generation and erosion processes can greatly be affected by the nature of parent material. This research was carried out to investigate the effects of lithology and soil parent material on erosion and soil loss, using ...
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On areas with highly eroded soils, where vegetation is absent or negligible, runoff generation and erosion processes can greatly be affected by the nature of parent material. This research was carried out to investigate the effects of lithology and soil parent material on erosion and soil loss, using rainfall simulator in Sangerd Drainage Basin which is located in Khorasan Razavi Province. To do this research, 11 homogeneous soil units (map units) with the same slope (20%), land use (rangeland), different lithology (marls and conglomerate) and erosion facies (sheet-rill, rill and rill-gully) were selected. A rainfall simulator producing 36 mm h-1 rainfall intensity and 30 minute duration was used at 33 locations over soil erosion plots. The amount of sediments was measured. In order to investigate factors affecting on soil erosion and sediment yield, soil was sampled from 0-15 cm depth of plot adjacent areas. For statistical analysis, SPSS 22 was used. Results showed that soil erosion and sediment yield have meaningful differences in different lithologies. Eem-RG and Plc-SR soil units with 260.9 and 45.1 gr m-2 have the most and the least sediment yield, respectively. It was found that the sediment yield had positive correlation with some soil properties such as silt, Ec, pH, SAR and antecedent soil moisture and negative correlation with sand, OC, NPV, vegetation and rock fragment cover.
Kianush Behrahi; Gholamabbas Sayyad; Ahmad Landi; Hamidreza Peyrowan
Abstract
Study of effective factors on runoff quantity to achieve optimum measures for runoff controlling is an essential subject in watershed management. This study aimed to investigate the effects of land use type and land slope degree on runoff quantity using an artificial rainfall simulator in Kakasharaf ...
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Study of effective factors on runoff quantity to achieve optimum measures for runoff controlling is an essential subject in watershed management. This study aimed to investigate the effects of land use type and land slope degree on runoff quantity using an artificial rainfall simulator in Kakasharaf watershed from branches karkhe watershed (Lorestan Province). Based on the land use map, at 6 work units (sub basins), three land use types of pasture, forest and agriculture; and three land slope degrees of 10, 20 and 30 percent was chosen. In total 93 tests were run using an artificial rainfall simulator and the runoff quantities were collected and measured. Artificial rainfall simulator was a plexiglass non-pressure rainfall simulator with a plot size of 83.5 × 119 cm2 and height 160 cm. Statistical analysis was done using SAS software. Results showed that the average, minimum and maximum runoff quantity were 1499, 0, and 9100 cm3, respectively. Analysis of variance showed a significant difference (p<0.01) between sub basins and runoff quantity. Also, the interaction of sub-basins and land use showed a significant difference (p<0.01) on runoff quantity. There was a significant difference (at 1% level) between runoff quantity and the land slope so that by increasing the slope from 10 to 30 percent, the produced runoff volume increased. Besides, there was a significant difference (1% level) among runoff quantity of pasture, forest and agriculture. The volume of runoff in the forest regions was more than pasture and agriculture land use types.
Seyed Hamidreza Sadeghi; Zeinab Karimi; Zahra Hashemiarian
Abstract
Annually, high amount of soil is washed out by erosion from the watershed. Implementation of appropriate management methods to control soil erosion is therefore essential. Application of economically-effective and environmentally friendly amendments to soil is one of the solutions and new technologies ...
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Annually, high amount of soil is washed out by erosion from the watershed. Implementation of appropriate management methods to control soil erosion is therefore essential. Application of economically-effective and environmentally friendly amendments to soil is one of the solutions and new technologies to control soil erosion. However, the comprehensive assessment of the impact of commonly used soil amendments on soil erosion has not been conducted. The present study therefore aimed to assess the performance of combined application of polyacrylamide powder (6 gm-2) and vermicompost (24 gm-2) in comparison with individual application of the polyacrylamide and vermicompost as well as control (without amendments) condition to control runoff and soil erosion under laboratory condition and on a clay-loamy soil. The study variables of runoff, soil loss and sediment concentrations were measured under a simulation rainfall intensity of 80 mm.h-1 and duration of 8 minutes. The results indicated a statistically significant effect (p=0.00) of all study treatments on the reduction of runoff, soil loss and sediment concentration from the study small plots. The combined effect of polyacrylamide and vermicompost on runoff and sediment concentration was also found greater than that recorded for soil loss.
Farzad Bayat Movahhed; Davood Nikkami; Mohammad Tokasi; Parviz Moradi; Hamideh Daghigh
Abstract
In arid and semi-arid regions the precipitation occurs erratically, and often, with high intensity which causes sediment production and soil loss especially in the areas ploughed parallel to the hill slope direction. In such areas, we can reduce those undesirable effects through employing proper management ...
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In arid and semi-arid regions the precipitation occurs erratically, and often, with high intensity which causes sediment production and soil loss especially in the areas ploughed parallel to the hill slope direction. In such areas, we can reduce those undesirable effects through employing proper management method. In this survey the effect of two treatments of applying straw mulch in standard plots and over three slope classes of 0-12, 12-20, and 20-40 % with three replicates in the split plot format on the base of RCB design were compared. In all plots, the parallel plough to slope direction was done. After wheat cultivation, on the half of plots, straw mulch was applied uniformly by hand on the soil surface. After any rainfall events, the amount of sediment was measured. Results showed that application of straw mulch caused a reduction of about 36.9, 10.8, and 55.4 % soil loss in three slope classes compared to the plots without mulch application respectively. These amounts for organic carbon loss were 33.2, 7.1, and 29.43 %. Statistical analysis by SAS software showed that difference between two treatments for sediment and Organic Carbon was significant at 5% probability. These results show that straw mulch application can highly increase the infiltration and water absorption and reduce soil and O.C. loss. Also, it can prevent the reduction of soil fertility through reducing organic material loss.
Ravanbakhsh Raisian; Amir Hossein Charkhabi; Mohammad Nekoueimehr
Abstract
One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes ...
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One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes on soil loss in Gorgak sub-watershed. The statistical design was split plot design with pasture and rain fed agriculture as main factors. A drop maker rainfall simulator with 40 mm/hr intensity and 30-minute rainfall period was used on five field locationsunder two soil moisture conditions of air-dry and field capacity and three slope classes of 10-20, 20-30, and 30-40%. A total of 180 sediment and runoff measurements were made using the above rainfall simulator under field conditions for two land use systems of rain fed cereal and overgrazed pastures. All the measurements were done in triplicates (5 fields x 2 land uses×2 moisture content×3 slope classes×3 replicates = 180 plots). The results showed the soil loss under overgrazed and air-dry soil condition was 45.6 times more than the rain fed agricultureunder the similar soil moisture condition. However, the results showed the soil loss under overgrazed and field capacity soil moisture condition was 2.33 times more than the rain fed agriculture under similar soil moisture condition. Once the soil loss was compared for different slope classes of 10-20, 20-30, and 30-40 slope percent, the results indicated the soil loss under overgrazed and air-dry soil condition were 4.77, 5.19, and 2.34 times more than the rain fed agriculture under similar soil moisture condition. Overall, soil loss under overgrazed conditionwas 3.38 times more than rain fed agriculture. Therefore, although most soil conservationists generally believe that the rain fed agriculture in Iran is very improper managed and it has high soil erosion rates but the results of this study showed the overgrazed pastures in the north Karoon watershed need much more priority for any soil loss measures and controls.
Abolghasem Dadrasi; Shahrokh Hakimkhani; Abdolsaleh Ranghavar
Volume 1, Issue 4 , February 2010, , Pages 227-239
Abstract
The fact that there are so many erosion models makes it necessary to critically select one of them as all have some limitations. Models are formulations of processes and logics as represented by the modeler. The formulations may be representations of either simple processes or complicated ones as the ...
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The fact that there are so many erosion models makes it necessary to critically select one of them as all have some limitations. Models are formulations of processes and logics as represented by the modeler. The formulations may be representations of either simple processes or complicated ones as the modeler deems necessary to solve a specific problem. These variables must be derived by a procedure of calibration for a specific case. The Soil erosion model of Morgan, Morgan and Finny (1982) from a large list of soil erosion models, have been applied to test the validity of the model in Sanganeh research station, Mashhad, Iran. After a field survey, plots with sheet erosion, were selected and their data was collected. Rainfall, slope and soil data were derived from station archive, vegetation cover and root depths were determined from field observations and some other parameters were tested on site. Soil loss was calculated by using overland flow for each plot after each rainfall and the measured records were compared with model estimations. The results show that in most plots, predictions deviated from the observations and in 28.21% of plots the results seem acceptable. The final result of present research shows that the model performs reasonably well for plots with lower density of vegetation cover (less than 20%), steep area with more than 40 percent, and soil depths of less than 10 centimeter.
Farzad Bayat Movahed; Davood Nikkami; Hassan Shami
Volume 1, Issue 4 , February 2010, , Pages 275-279
Abstract
In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction ...
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In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction and application of straw mulch in 1.8 * 22.1 meter erosion plots on three slope classes of 0-12, 12-20, and 20-40 percent with 3 replicates and RCB design in two different years were tested in Sohrain floodwater spreading research station. In the half of plots in 2003, the perpendicular plough to slope direction and in the others, plough on slope direction were operated. In 2005 at first, the plough on slope direction was done in all of the plots and then, straw mulch were used after wheat cultivation in half of plots. During the study period, the amount of soil loss was monitored after any rain fall by the tanks that located at the end of each plot. The results showed that operating of perpendicular plough to slope direction reduced soil loss about 10.1, 11.5, and 10.4 time relate to parallel plough to slope direction. Also, application of straw mulch reduced 36.9, 10.8, and 55.4 time relate to mulch application in three slope classes respectively. These results show that both perpendicular plough to slope direction and straw mulch application can reduce soil loss and thus, increase the infiltration rate and soil fertility.
Manouchehr Amiri; Hadi Nazari pouya; Hamid Reza Peyrovan
Volume 1, Issue 3 , October 2009, , Pages 179-188
Abstract
The marl soil types are very sensitive to erosion and are deposited into reservoirs of dams and areas of flood spreading in form of considerable sediment annually. This process increases the expenses of filtration of drinkable water and pre-filtration of water of artificial recharge severely. So the ...
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The marl soil types are very sensitive to erosion and are deposited into reservoirs of dams and areas of flood spreading in form of considerable sediment annually. This process increases the expenses of filtration of drinkable water and pre-filtration of water of artificial recharge severely. So the investigation of marl soil types from different aspects is very important for experts and researchers. In this research, it was tried to recognize the effective variables on erosion rate of marls in Hamedan province. 49 samples of 41 spots in 3 marl areas were taken to determine the physical and chemical properties. The characteristics of place of sampling like; slope, geographical situation and privilege of 7 parameters for surface factor of soil were noted. Also, the test of simulated rain was done by the Kamphorst΄s rainfall simulator apparatus in the 41 above spots and 41 samples of runoff were taken and the amount of soil lost were measured and calculated by simple method in the laboratory. The amounts of 23 physical and 15 chemical variables were determined. Then, all data were evaluated by Kolmogorov-Smirnov test and the abnormal data were normalized by logarithm and were evaluated by correlation, bi-variate and multivariate regression tests. The results showed that only 9 variables have significant and linear relation with soil loss, where plastic index, clay percent and clay ratio are the most important variables for evaluation of marl soil loss at marls of investigated areas respectively.
