Seyed Majid Reza Hosseini Mofrad; Hassan Ahmadi; Ali Akbar Mehrabi; Baharak Motamedvaziri
Abstract
For this purpose, according to Cochran's equation, from Hashtgerd-Taleghan asphalt road 26 km long and Hashtgerd-Taleghan dirt road 9 km long, road sedimentation was calculated with 17 and 11 samples, respectively, and finally, using statistical relationships, the erosion rate was calculated. And sedimentation ...
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For this purpose, according to Cochran's equation, from Hashtgerd-Taleghan asphalt road 26 km long and Hashtgerd-Taleghan dirt road 9 km long, road sedimentation was calculated with 17 and 11 samples, respectively, and finally, using statistical relationships, the erosion rate was calculated. And sedimentation was estimated in the entire route. By direct measurement of erosion, the total sediments remaining along the route were equal to 17259.32 tons per year, of which 6241.45 tons per year are related to the excavation wall and 11017.87 tons per year are related to the embankment wall. Using the WARSEM model, the total amount of sedimentation from asphalt and dirt roads was estimated as 15172.67 tons per year, equivalent to 52.14 tons per hectare per year, of which 9464.53 tons per year, equivalent to 48.03 tons. Per hectare per year, the contribution of the excavation wall and the embankment wall of the asphalt road is 14.5708 tons per year, which is equivalent to 22.63 tons per hectare per year, the contribution of the excavation wall and the embankment wall of the dirt road. The sensitivity of the WARSEM model for the standardized parameters for the asphalt road showed that the slope and geological factors are important factors in the sedimentation of the embankment wall and the height factor of the embankment wall is a very important parameter in the sedimentation of the embankment wall. The sensitivity of the model on the dirt road according to this score of the parameters was very close to each other.
Ali Rajaee; Baharak Motamedvaziri; Aliakbar Nazariye samani; Hasan Ahmadi
Abstract
In this study, 18 variables affecting avalanches have been studied. These variables are related to the conditions: geomorphological and topographic, climatic, snow and also Some activities are related to human factors. In this study, the avalanche risk map was prepared and analyzed using the risk model ...
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In this study, 18 variables affecting avalanches have been studied. These variables are related to the conditions: geomorphological and topographic, climatic, snow and also Some activities are related to human factors. In this study, the avalanche risk map was prepared and analyzed using the risk model (HEV) and the variables affecting the occurrence of avalanches. Avalanche hazard map was prepared using three models: AHP, Garp and MaxEent. Based on three risk factors for avalanches, obstacles in the avalanche route and also sensitivity to avalanches, a risk map was prepared. Comparison of the results with field visits and avalanche occurrence areas and past statistics and information indicate the accuracy of the hazard map with 93.85% accuracy by the AHP method. One of the most important variables in avalanche occurrence in this area is the slope. Then, using two maps of avalanche risk elements and avalanche susceptibility map and avalanche hazard map, snow avalanche risk map has been prepared. The results showed that the avalanche hazard map has a very inherent difference with the avalanche risk map. Areas in the low-hazard category on the avalanche risk map became more important in the avalanche risk map. The most important reason is the existence of endangered elements and the development of residential lands in this area over the past few decades
Saeed Pourheadari; Hassan Ahmadi; ِAbolfazl Moeini; Sadat Feiznia; Mohammad Jafari
Abstract
Due to physical and chemical composition and lack of vegetation cover and therefore less organic matter, Marlons formations are the most sensitive formations to erosion, so that by removing the particles of the soil and transporting their to the lower regions, cause different forms of erosions. Due to ...
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Due to physical and chemical composition and lack of vegetation cover and therefore less organic matter, Marlons formations are the most sensitive formations to erosion, so that by removing the particles of the soil and transporting their to the lower regions, cause different forms of erosions. Due to the physical and chemical properties of marls, the study area has caused various types of erosion in the basin and downstream urban areas has been affected followed by mudflows resulting from their erosion and sedimentation. In this research, 35 soil samples were taken from the different work units to determine the physical and chemical characteristics and also to study the soil losses using a rain simulator. Along to this, 5 samples from particular marl units of the area was taken and transferred to the laboratory for mineralogical experiments. The K method in the global erosion equation was used to evaluate the degradability of detached materials that according to this method, the highest value of k is related to forms with a coefficient of 70%, and the least of which is the surface and rainfall erosion form with a coefficient of 25%. Also, due to the fact that there were 4 units of work with attached materials, the stripy method was used to evaluate their erodibility.
Alireza Sepahvand; Hasan Ahmadi; Aliakbar Nazari Samani; Sebastiano Trevisani
Abstract
The geomorphometric indexes have been widely used for separation of surface landform features in the geomorphology science over the past decades. In this study, Multilayer Perceptron Neural Network (MPNN) was used to provide karstic landform classification. To that regard, initially, geomorphometric ...
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The geomorphometric indexes have been widely used for separation of surface landform features in the geomorphology science over the past decades. In this study, Multilayer Perceptron Neural Network (MPNN) was used to provide karstic landform classification. To that regard, initially, geomorphometric indicators were extracted from Digital Elevation Model (DEM), and then these indexes were used as neurons of input layer in artificial neural network. Furthermore, the box plots were applied to analyze the relationship between karstic landforms (such as dolines, hills, karstic plains, karstic valley and headland) and geomorphometric indexes. The results showed that 34, 6.9, 1.07, 48.5, 9.51 percent of the studying area are spatially covered by valleys, plains, dolines, highlands and hills respectively. It has also been found that the optimal structure of artificial neural networks for classification of landform is model No. 12-9-1 by having the learning rate 0.1 and 87.18 percent of determination coefficient. Also, it should be noted that the accuracy of the innovative method for classification of karstic landform is 90.58 percent. The analysis revealed that variations in geomorphometric indexes are very visible in the landform of hills, highlands and karstic valleys, whereas there are slightly overlapping in the plains and dolines.
Salman Zare; Mohammad Jafari; Hassan Ahmadi; Hasan Rouhipour; Reza Khalil Arjomandi
Abstract
In this regard, the present study aimed to evaluate the performance of some of the non-oil mulch to stabilize sand dunes in the Kashan's Rig-boland desert. monthly surveys are conducted in the desert areas. To evaluate the effect of mulch on stabilizing the sand dunes, the effect stabilization index ...
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In this regard, the present study aimed to evaluate the performance of some of the non-oil mulch to stabilize sand dunes in the Kashan's Rig-boland desert. monthly surveys are conducted in the desert areas. To evaluate the effect of mulch on stabilizing the sand dunes, the effect stabilization index was used. The results indicate there is a significant difference between different mulch. The comparison test showed that the highest coefficient effect of stabilization with significant effect done on the biological mulch. After that, however, three other mulches including resins, inorganic and polymer are, respectively had the most significant effectiveness. Although there was not significant difference between these three types of mulches. Biopolymer Mulch with the lowest coefficient of stabilization effect showed significantly different from other mulches. Mulching in the hills with biological mulch, due to tightly crust formation against erosion, removal of sand and dunes almost stopped and hill completely has been stabilized. In this study, used mulches were initially very resistant and feasting the sands dune surface such as resistance crusts which were loss against any tensile and compressive force before mulching practices. . Therefore, different mulches treatments according to their durability and nature of structural have different effectiveness in reducing wind erosion effect. Among the studied mulches, just biological mulch and has usability and is capable for executive pilots.
sedigeh mohamadi; Ali Salajegheh; Hassan Ahmadi; Jamal Ghoddousi; Ali Kianirad
Abstract
Suspended sediment load is the biggest non-point pollution source and a major factor of degradation of surface water quality. Because of hydraulic models of sediment transport can not predict the suspended sediment load, sediment rating curves as usual hydrological methods are utilized spread for this ...
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Suspended sediment load is the biggest non-point pollution source and a major factor of degradation of surface water quality. Because of hydraulic models of sediment transport can not predict the suspended sediment load, sediment rating curves as usual hydrological methods are utilized spread for this goal. Cause of regression equations of rating curve have a lot of bias due to logarithmic convert, correction factors in optimization of sediment rating curve were used for eliminating of logarithmic conversion effect and bias of extrapolation in 20 hydrometric stations in up streams and major rivers of Sefidrood watershed. Comparing of 9 rating curve methods as one-linear, one-linear with correction factors as CF1, CF2, FAO, two-linear, mean loads within discharge classes, mean loads within discharge classes with correction factors as CF1, CF2 and FAO was conducted by RMSE and NASH criteria. Results showed that mean loads within discharge classes, mean loads within discharge classes with CF1 and CF2 correction factors have the most fitting to Sefidrood watershed stations. Our findings illustrated that CF1 and CF2 correction factors in majority of stations have compensated underestimation of rating curves and increased efficiency of models. Power of equation between sediment load and area was more than of one. According to results 30 million ton suspended sediment load enter to reservior of Sefidrood dam annually. Key words: sediment rating curve, Sefidrood, model efficiency, logarithmic conversion, NASH criteria.
Hesam Ahmady-Birgani; Sadat Feiznia; Hasan Mirnejad; Hassan Ahmadi; Ken Mc Queen; Mohammad Ghorban Pour
Abstract
This study investigates the mineralogy and physico-chemical properties of atmospheric particulates collected at Abadan (southwestern Iran) near the Persian Gulf coast and Urmia (northwestern Iran) during ambient and dust events over 6 months (winter 2011; spring 2012). Particle sizes collected were: ...
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This study investigates the mineralogy and physico-chemical properties of atmospheric particulates collected at Abadan (southwestern Iran) near the Persian Gulf coast and Urmia (northwestern Iran) during ambient and dust events over 6 months (winter 2011; spring 2012). Particle sizes collected were: TSP (total suspended particulates); PM10 (particulates <10µm); and PM2.5 (particulates <2.5µm). Minerals were identified using X-ray diffraction (XRD); particle morphology and composition were examined by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX). Major minerals detected are calcite, quartz, clay minerals and gypsum, with relative abundance related to sampling site, collection period, wind direction, sampling head, and total sample amount. The anomalously high calcite content appears a characteristic feature originated from calcareous soils of the region. SEM observations indicated a wide range of particle morphologies over the 1-50 µm size range, with spherical, platy, cubic, elongate and prismatic shapes and rounding from angular to rounded. Energy dispersive X-ray analysis of TSP samples from both sites for non-dusty periods indicated that the sampled mineral suite contained Al, Mg, Na, Cl, P, S, Ca, K, Fe, Ti, and Si, mostly reflecting calcite, quartz, aluminosilicates, clays, gypsum and halite. Additionally, As, Pb, Zn, Mn, Sc, Nd, W, Ce, La, Ba and Ni were detected in TSP, PM10 and PM2.5 samples collected during dust events.
Mozafar Ansari; Sadat Feiznia; Hassan Ahmadi; MohammadAli Fattahi Ardekani
Abstract
Soil is one of the most vital natural resources in any country. Nowadays, lands are rarely found worldwide without having severe erosion problem. Landslide is one of the soil erosion processes in which a huge volume of soil is washed away. SHETRAN Model was used in this study to assess the landslides ...
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Soil is one of the most vital natural resources in any country. Nowadays, lands are rarely found worldwide without having severe erosion problem. Landslide is one of the soil erosion processes in which a huge volume of soil is washed away. SHETRAN Model was used in this study to assess the landslides being occurred in Zidasht catchment, Taleghan. At the first stage, sediment-water mixed samples were gathered at the outlet of the Catchment for calibration purpose in 2011. To run the model, regions undergoing landslide were identified using GISLIP sub-model. Secondly, after hydrological and sediment production simulations in a sub-model of SHETRAN for the region, calibration was made for spring season. After the calibration process, the model was run again, this time for the regions having landslide (for 418 spots), and in regions where landslide sediments do not pour into water courses, these regions were omitted, the final amount of sediment was calculated using SHETRAN sub-model and the results were compared with the previous studies. The results show that 19.75% of the total sediment belongs to landslides. With regard to the current sediment quantity of about 111248 kg, total sediment in landslides was estimated to be around 120668kg.
hamid hosseyni marandi; mohammad mahdavi; hasan ahmadi; baharak motamed vaziri; abdolali adelpour
Abstract
Abstract Common causes for groundwater quantity and quality changes are infiltration through the seasonal floodwater, effects of the artificial recharge projects and adjacent aquifers, and groundwater extraction for deferent uses. However, recognizing the impact of their contributions to these changes ...
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Abstract Common causes for groundwater quantity and quality changes are infiltration through the seasonal floodwater, effects of the artificial recharge projects and adjacent aquifers, and groundwater extraction for deferent uses. However, recognizing the impact of their contributions to these changes can be often challenging. Still, to understand the changes, monitoring groundwater level and several chemical factors are taken into consideration. Certain problems of course can complicate the analysis of the observations; for instance, insufficient data and manually prepared and measurement intervals can degrade the accuracy of such observations. In this paper, device-measured daily time series of Electrical Conductivity (EC), Temperature (T) and Groundwater Head (GH) are analyzed. The main purpose is to evaluate the groundwater changes and its relation to the processes on the aquifer surface in an arid region. Two wells (PZ2 and W20) with 1,200m distance from each other selected and installed a sensitive device for recording the groundwater level, temperature and salinity fluctuations. Time series of changes from December 2012 to July 2013, were analyzed. Groundwater head in PZ2 showed a decline but in W20 showed a minor rise. Salinity variations were different and were 15.3mS/cm in PZ2 and 1.7mS/cm in W20. The backdrop of increased salinity in the surface layers of groundwater in PZ2 identified and showing a correlation between groundwater head and salinity fluctuation with 83.5% R squire.
Gholamreza Zehtabian; Hassan Ahmadi; Aliakbar Nazari Samani; amir houshang ehsani; Mahdi Tazeh
Abstract
Plains are one of the most important geomorphological units and different parameters have been considered for classification of plain areas. One of most common classifications in natural resources studies in Iran entailing different qualitative and quantitative factors is: bare plains, apandazh plain ...
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Plains are one of the most important geomorphological units and different parameters have been considered for classification of plain areas. One of most common classifications in natural resources studies in Iran entailing different qualitative and quantitative factors is: bare plains, apandazh plain and covered plain. Such classifications are used to make plains distinguishable from one another. In this study, the geomorphometrical parameters were considered for plain classification by using artificial neural networks and sensitivity analysis. These parameters were extracted by using mathematical equations and applying the corresponding relations on digital elevation models and they are not widely used in Iran. Geomorphometric parameters that were used in this study included Percent of slope, Plan Curvature, Profile Curvature, Minimum Curvature, the Maximum Curvature, Cross sectional Curvature, Longitudinal Curvature and Gaussian Curvature. These parameters were calculated in an area of 125000 hectare and at 1500 points, and the result was compared and calibrated with ground truth map. Sampling method in this study was Latin Hyper cube that is a kind of stratified random sampling. Results of this study show that the most important geomorphometric parameters to classify desert plains include Plan Curvature and Profile Curvature that have the highest sensitivity among different plain types. The more the topography of the area reduced the more the contribution and importance of these factors for separating plain types decreased so that these parameters were most prominent in bare plains but had the lowest efficiency in covered plains.
Khosro Shahbazi; ali salajagheh; mohammad jafari; hassan ahmadi; ali akbar nazari samani; mohammad khosro shahi
Abstract
Negative impacts of gully erosion in marl areas are severe due to improper landuse practices such as irrigation, tillage, overgrazing and degradation of vegetation cover. The objective of this research was to evaluate hydraulic flow thresholds of gully erosion in the agriculture (AG), fair rangeland ...
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Negative impacts of gully erosion in marl areas are severe due to improper landuse practices such as irrigation, tillage, overgrazing and degradation of vegetation cover. The objective of this research was to evaluate hydraulic flow thresholds of gully erosion in the agriculture (AG), fair rangeland (FR) and poor rangeland (PR) areas in the Qasre-shirin, Kermanshah, Iran. Nine flumes were performed in the field to determine the critical values of hydraulic parameters including flow discharge, velocity, Froude and Reynolds numbers, Darsi resistance coefficient, shear tension, head-cut dimensions as well as vegetation cover. Results showed that respective critical value of discharge as the gulling thresholds for AG,FR and PR was 1.53, 12.0 and 4.49 li/s indicating significantly higher (p<0.05%) in the FR due to higher vegetation cover. In addition, there were no significant differences for flow disturbance based on Froude number, while the respective value of Rinuldze number in the AG, FR and WR were obtained 3113, 26092 and 9525 significantly higher in the FR. Furthermore, the critical level of shear tension for gully formation in the AG, FR and WR were found 12.12, 14.01 and 9.28 Nm-2, respectively showing significant differences among them. Finally, it is concluded that hydraulic flow parameters as the gully triggering are strongly affected by vegetation cover through landue practices so that higher plant cover in the FR was the key factor resulting in significant enhancement of gully.
Ali Fazlollahi; Ali Salajegheh; Sadat Feiznia; Hassan Ahmadi
Abstract
Sediment fingerprinting is a method for identifying sediment sources and determining the rate of contribution of each source. In this method, the natural tracer technology is used, that combined from samples collection, laboratory analyzing and statistical modeling. The natural tracers are measured in ...
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Sediment fingerprinting is a method for identifying sediment sources and determining the rate of contribution of each source. In this method, the natural tracer technology is used, that combined from samples collection, laboratory analyzing and statistical modeling. The natural tracers are measured in both the sources and suspended sediment to determine the rate of contribution each sources. The suspended sediment traps were constructed and used for the first time in country. In this research sediment fingerprinting was used in the loess area. 27 tracers were measured in all samples. Data were evaluated about outlier. The capability of each tracer in separating the sources was evaluated with kruskal-wallis test. All tracers were accepted. Then the best combination of tracers was determined with discriminate analysis. This combination is total carbon, Na, organic carbon, Pb, Co, Sr, Al, C/N and Rb. Then, the rate of contribution of each source was determined with normal method and optimized method. Among all the sediment sources, Gully and forest have the highest and lowest rates, respectively. The field observations were confirmed the results. The use of genetic algorithm increased the accuracy of determination of contribution of each source in comparison to normal method
nasim arman; Ali Salajegheh; Sadat Feiznia; Hassan Ahmadi; Jamal Ghoddousi; ali kiani rad
Abstract
Identification of homogenous watershed sub basins allows generalization of environmental study results. For this purpose, first available data for 27 selected watersheds in North Alborz regarding 21 variables including physiographic and climatic characteristics was gathered. The most important factors ...
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Identification of homogenous watershed sub basins allows generalization of environmental study results. For this purpose, first available data for 27 selected watersheds in North Alborz regarding 21 variables including physiographic and climatic characteristics was gathered. The most important factors impacting upon soil erosion and sediment yield were equivalent rectangular length, mean annual precipitation, rock susceptibility, aspect and drainage density which were identified using factor analysis (Principle Component Analysis : PCA) and a 80.72 percent variation of data was observed (KMO =0.516). For determination of homogenous region, different methods of cluster analysis (hierarchical, K-means and two step clustering) were used and three homogeneous regions were specified. Discriminant function analysis was employed and confirmed the results of cluster analysis in homogenous region. On the other hand, based on these five factors, a discriminant function was defined and canonical correlation, chi-square, wilks’ lambda values revealed that three homogenous regions were quite separate.
Mohsen Armin; hasan rouhipour; Hassan Ahmadi; Ali Salajegheh; mohammad Hossein Mahdian; vajihe ghorban nia kheybari
Abstract
Knowledge of soil components controlling aggregate stability is very important to soil structure conservation. Also, identification of the critical soil properties affecting aggregate stability is central to understanding where erosion might be located within a catchment as a result of natural patterns ...
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Knowledge of soil components controlling aggregate stability is very important to soil structure conservation. Also, identification of the critical soil properties affecting aggregate stability is central to understanding where erosion might be located within a catchment as a result of natural patterns in aggregate stability. The objective of this study, which was carried out in surface soils from Taleghan, was to relate aggregate stability to selected soil properties. In this study, based on homogeneity in slope, aspect and lithology work units were prepared, and then by relying on results of geostatistical studies in homogeneous work units in soils of Taleghan watershed, with 3260 hectares in area, 84 points as the soil sampling points were selected. The indices of stability used are the mean weight diameter (MWD) and wet aggregate stability (WAS). Correlation between mean weight diameter and measured properties were extracted using Pearson correlation coefficient and evaluated in terms of their statistical significance. Then based on the results of correlation and using stepwise regression, models of aggregate stability prediction were developed. The unexpected results have been obtained from correlation between soil properties and aggregate stability so that the correlation between aggregate stability and the percentage of Caco3, clay and saturation are negative while that with fine sand and very fine sand are positive. Thus the improvement of aggregate stability and soil erosion control in Taleghan watershed depends on management of these soil properties and soil conservation projects in order to adjust and optimize them
hossein mohammad asgari; shahram khalighi sigarodi; Parviz Irannejad; Hassan Ahmadi; Arash Malekian
Abstract
Aerosol impact on people health, social and economic activities, land and water ecosystems and meteorological parameter. The GOCART scheme was evaluated for simulating PM10 in this study. GOCART was run into WRF model as a host model. Reanalysis data from FNL for every 6 hour was used for initial conditions. ...
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Aerosol impact on people health, social and economic activities, land and water ecosystems and meteorological parameter. The GOCART scheme was evaluated for simulating PM10 in this study. GOCART was run into WRF model as a host model. Reanalysis data from FNL for every 6 hour was used for initial conditions. One domain and two nests were used to cover region from West Africa till East Asia, Iran and Khuzestan Province. Primary results shown that the model overestimate surface moisture and the results was weak for simulating PM10 ,so we modified surface moisture using welting point of soil texture in desert region for summer. In addition, erodibility index was defined using surface moisture and threshold wind velocity and coefficient of this index modified using Tir and Day PM10 data at 1387. Results of modified model were compared with observed data in environmental station in Ahwaz for one week from 25, 3,1388 till 31,3,1388. Statistical analyses shown that, GOCART has a good capability for simulating PM10.
Elham Meshkati; Hassan Ahmadi; Aliakbar Nazari Samani; M.H Davoodi
Abstract
Landslide occurs inevitably and naturally in many slopes due to sensitive formations, moisture, andother factors. Taleghan watershed is prone to landslide due to the presence of huge Miocene marlmasses. After construction of Taleghan reservoir dam, moisture and ecological condition of theregion changed. ...
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Landslide occurs inevitably and naturally in many slopes due to sensitive formations, moisture, andother factors. Taleghan watershed is prone to landslide due to the presence of huge Miocene marlmasses. After construction of Taleghan reservoir dam, moisture and ecological condition of theregion changed. In this paper, factors impacting upon landslide hazard (slope, aspect, hypsometry,geology, land use, distance to road, distance to lake) were studied and their role and importance onthis phenomenon were verified in a large (maximum distance of 1500 meter from lake) and a small(maximum distance of 450 meter from lake) spatial scale. Thus, GIS maps of the above mentionedparameters were provided using satellite and aerial images and field activities. All maps werecrossed with a resolution of 100m*100m. It was found out that the distance to the lake didn’tinfluence upon landslide in a large spatial scale but it falls effective as the distance to the lakereduces. In fact lake has a local effect and mostly influences at maximum 200 meter distance.
Mohsen Armin; Hassan Ahmadi; hasan Rouhipour; Ali Salajegheh; mohammad Hossein Mahdian; Vajihe Ghorban nia kheybari
Abstract
Due to the constraints in determining of soil susceptibility to water erosion or soil erodibility through field tests, use of laboratory methods on small soil samples, are easy to implement and far less expensive and time-consuming. among different laboratory methods based on the soil properties, those ...
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Due to the constraints in determining of soil susceptibility to water erosion or soil erodibility through field tests, use of laboratory methods on small soil samples, are easy to implement and far less expensive and time-consuming. among different laboratory methods based on the soil properties, those relating to aggregate stability have received much attention. In this study, by relying on observations and changes in the macroscopic scale of homogeneous work units in marly soils of taleghan watershed, with 3260 hectares in area, 84 points as the soil sampling points were selected.In order to distinction between aggregate breakdown mechanisms and assessing of soil structural behavior in different environmental conditions, aggregate stability is measured with respect to three treatments fast wetting, slow wetting and stirring after pre-wetting using Le Bissonnais method. Results showed that aggregate breakdown mechanisms have a significant influence on aggregate stability. The instability main mechanism of marly soils in Taleghan watershed is slaking that caused by the compression of entrapped air during fast wetting and this situation can occur during rain storms on dry soils and irrigation flooding. So it seems that the method of agricultural land irrigation can be one of the most important soil erosion factors in the study area.
Reyhaneh Masoudi; Gholamreza Zehtabian; Hassan Ahmadi; Shahram Khalighi sigarudi
Abstract
Desertification is a major problem in many countries. International efforts have been considered to combat and prevent this phenomenon. The most important cases of these measures are the United Nations Convention to Combat Desertification. In this study, IMDPA model and GIS were used to assess desertification ...
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Desertification is a major problem in many countries. International efforts have been considered to combat and prevent this phenomenon. The most important cases of these measures are the United Nations Convention to Combat Desertification. In this study, IMDPA model and GIS were used to assess desertification phenomena in Kashan Plain. Some indices of Climate and water criteria were selected to consider for each condition of the region. Final desertification intensity was calculated based on geometric average of the selected criteria and their indices. The numerical value was classified in 5 classes including non-significant, low, medium, severe and very severe and desertification intensity map was drawn using GIS in the studied period. According to the results, among the studied indices, the groundwater level depletion, EC and Transu aridity index with 3/82, 3/04 and 3/01 numerical values are the most effective factors. The threshold of ground water level, EC and Transu aridity index were determined respectively: more than50 cm/year, 2250-5000((μmohs)⁄(cm)) and 0/05-0/2. Also, the case study has classified in medium class of desertification with DS=2/4. Regarding the determined thresholds were specified the sensitive areas, and the required equipment are proposed to install on these areas for observing the thresholds.
Nayereh Ghazanfarpour; Sadat Feiznia; Hassan Ahmadi; Mohammad Jafari; Masoud Nasri
Abstract
Estimation of the amount of soil loss measurement of field indicators is a low-cost method, is easy to learn and can be simply applied. In order to measure and make assessment of soil loss amount by field indicators method in Shahrak Watershed, first map of the work units was prepared and then, measurements ...
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Estimation of the amount of soil loss measurement of field indicators is a low-cost method, is easy to learn and can be simply applied. In order to measure and make assessment of soil loss amount by field indicators method in Shahrak Watershed, first map of the work units was prepared and then, measurements of the relevant field indicators were carried out within these units. Then, EPM model was calibrated and verified. Then the measured data for the amount of the soil loss obtained by using field indicators were analysed and assessed using EPM experimental model. Mean of relative error and correlation coefficient between values from filed indicators method and EPM model were around 7.6 and 0.9, respectively which these results verify field indicators method for estimation of soil loss intensity. Estimation of the average of soil loss amounts relevant to each of the field indicators shows the following soil losses: Rock exposure indicator: 47.61 (ton/ha), Pedestal indicator: 22.61 (ton/ha), Rill indicator: 5.67 (ton/ha), Sediment in drains indicator: 2.21 (ton/ha), Gully indicator: 2.17 (ton/ha) and Build up against barriers indicator: 34.78 (ton/ha).
golaleh ghaffari; Hassan Ahmadi; Omid Bahmani; Ali akbar Nazari samani
Abstract
In Iran due to the lack of long experience in the implementation of Soil Conservation and Watershed Management Plans, these measures have not been evaluated quantitatively and specific methods for this purpose have not been provided. In this research effort is to investigate the effect of watershed management ...
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In Iran due to the lack of long experience in the implementation of Soil Conservation and Watershed Management Plans, these measures have not been evaluated quantitatively and specific methods for this purpose have not been provided. In this research effort is to investigate the effect of watershed management operations performed in Can Basin in 1379, on the amount of erosion and sedimentation and rate of project success or failure and its causes. So after providing the required information and statistics and being sure about the authenticity and accuracy of statistics and statistical reconstruction of defects with conventional methods, to investigate the effect of implemented projects on erosion and sedimentation rates, average of suspended sediments in the period before project implementation (1986-2000) and in the period after project implementation (2001-2008) was calculated using sediment rating curves through intermediate technique class, and using daily water discharge, watershed erosion and deposition were also calculated using MPSIAC model. Specific erosion and deposition map was provided in the period after project implementation using Arc GIS software and finally the amount of efficiency and effect of this operation on the amount of erosion and deposition rates was judged. The results of studies showed that due to operating this plan, the average amount of suspended sediment has changed from 47892 tons per year during the statistical period before the plan to 22365 tons per year during the eight-year statistical period after it. The amount of erosion and sedimentation has shifted from 66758 tons to 50549 tons, which shows the positive effect of plan on reducing the amount of suspended sediment and the lack of effective role in reducing the rate of erosion. The main reasons for the low efficiency of Watershed Management Plan implemented in relation to decreasing the amount of erosion are: lack of suitable biological operations in the basin (less than 25 percent of the volume of the proposed action), focusing on mechanical operations, weaknesses in project monitoring and evaluation During all stages of its implementation, failure to observe the standards and technical points such as non-conforming structures built between locations and proposed locations, lack of standards in building the necessary structures and inappropriate dimensions of structures, destruction of floor section in mortar stone structures and etc.
Ali Golkarian
Abstract
Erosion is one of the important factors in soil degradation and decrease fertility and slope length is one of the most effective factors in land form and amount of erosion. The objective of this study was investigation of spatially variation of sediment concentration in slope length until to receive ...
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Erosion is one of the important factors in soil degradation and decrease fertility and slope length is one of the most effective factors in land form and amount of erosion. The objective of this study was investigation of spatially variation of sediment concentration in slope length until to receive transport capacity. To obtain this goal a hill slope simulator system designed and manufactured. This system include 10 flumes, each has five meter length which after series them become fifty meters. This system can produce cumulative flow via fifty watering can tube which are install on flumes with one meter interval and each flume discharging is 100 cc. Other variables include two type of soil and slope in three level 15, 22.5, 30 percent. Three replications were used for each treatment and totally 18 experiment was done. In each experiment four samples were gathered from end of each flume and concentration was determined. Complete randomized design with factorial arrangement was used for data analyzing. Richard’s function was used for fitting a suitable curve on observed data. Result was shown that effect of soil type on sediment concentration was not significant while slope and slope length effects was significant. Otherwise sediment concentration in the two last flumes was located in same class which is shown that sediment concentration achieved to transport capacity in this slope length. Also results were shown that Richard’s function can simulate trend of concentration variety in slope length.
shima nikoo; Hossein Azarnivand; Gholam Reza Zehtabiyan; Hasan Ahmadi; Mohammad Ali Zare Chahouki
Abstract
Combating desertification which is a serious threat for the environment and human welfare requires understanding complex issues of this phenomenon using evaluation, awareness of severity of it's processes and determination of it's factors. So here, after recognizing the characteristics of the region ...
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Combating desertification which is a serious threat for the environment and human welfare requires understanding complex issues of this phenomenon using evaluation, awareness of severity of it's processes and determination of it's factors. So here, after recognizing the characteristics of the region showing existence desertification, we assess its current status with emphasis on climate, water, geology-geomorphology, soil and wind erosion as the most criteria of desertification. According to more consensus on regional model or flexible model to modify, Iranian Model for Desertification Potential Assessment (IMDPA) ,which is calibrated to use in arid area of Iran, was chosen. At first the rainfall seasonality indicator was added to the model as a special climate character. Then primary assessment of desertification was done. At last according to the result of primary assessment, the area environmental conditions and revealed issues during assessment the model was modified, final assessment and mapping of desertification were done. At last according to the result of primary assessment, the area environmental conditions and revealed issues during assessment the model was modified, final assessment and mapping of desertification were done. Based on the results desertification intensity in 33/94% and 66/06% of the area are severe and moderate respectively. Also the major factors affecting desertification across Damghan region are climate, salinization of water and soil resources, improper land use, over exploitation of underground water, over grazing and improper irrigation method.
Hossein Eslami; Ali Salajagheh; Shahram Khalighi sigaroudi; hasan Ahmadi; Shamsollah Ayoubi
Abstract
Rainfall erosivity is the ability of rainfall to detach the soil particles. This study was conducted to evaluate spatial variability of rainfall erosivity indices in Khouzestan Province. The point data of indices (EI30, AIm, KE>1 and Onchev indices) in 74 stations were used to generate spatial erosivity ...
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Rainfall erosivity is the ability of rainfall to detach the soil particles. This study was conducted to evaluate spatial variability of rainfall erosivity indices in Khouzestan Province. The point data of indices (EI30, AIm, KE>1 and Onchev indices) in 74 stations were used to generate spatial erosivity maps through deterministic and geostatistical interpolation methods (Radial Basis Functions, Inverse Distance Weighted, Kriging and Cokriging). Results indicate that cokriging have least error and most correlation with determining coefficient of 0.89, 0.89, 0.48 and 0.49 for EI30, AIm, KE>1 and Onchev indices. Based on the correlation relationships between the basins specific sediment yield (in basins dominating the sedimentation stations) and mean indices of EI30, AIm, KE>1 and Onchev, EI30 index with correlation coefficient of 0.98 (P<0.01) is selected as the appropriate rainfall erosivity index. Based on the prepared map on the basis of Cokriging method with secondary variable of maximum mean monthly rainfall, the east and northeastern regions presented the highest values of EI30 index, while the southern and western regions showed the lowest values of EI30 index. The annual rainfall erosivity (EI30) ranged from 404 to 3064 Mj.mm.ha-1.h-1.y-1.
Abazar Esmali; Hasan Ahmadi; Mohammad Tahmoures
Abstract
The aim of this research is to describe the development of a methodology based on present knowledge and available data for evaluation of water erosion behavior and risk as well as modeling and estimation of soil erosion, which is compatible for other similar areas of Iran. Accordingly, the conducted ...
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The aim of this research is to describe the development of a methodology based on present knowledge and available data for evaluation of water erosion behavior and risk as well as modeling and estimation of soil erosion, which is compatible for other similar areas of Iran. Accordingly, the conducted research was based on four major types of water erosions including: sheet, rill, channel and riverbank which have considerable role on sediment yields of Baleghli Chay Watershed, Ardebil Province, were separately and spatially studied. In order to determine the inter-effects of effective factors, the study was conducted using stepwise multivariate statistical tests. For each erosion type, an individual model was then presented. In the next step, after determining of relations between sediment yield and environmental factors (fixed & variable) through statistical analyses and selecting of effective factors on erosion and sediment yields, was created an empirical structure for modeling erosion and sediment yields based on MPSIAC erosion model. In formulation of the new model, were used of eight effective factors on erosion in the area. These factors are susceptibility of geological formation, soil erodibility, rainfall erosivity, runoff erosivity, topography, hydrographic drainage, Normalized Difference of Vegetation Index (NDVI) and field conditions of erosion features. In the presented model, with summation of the scores of mentioned eight factors, obtains the M value, which can estimate the amount of erosion and sediment yields of the area, using exponential formula between sediment yield and M values. In addition, in order to obtain the confidence of presented model, it was used in "Nir" catchment for evaluation the precision. The results showed 11 percent difference. With accepting of this error value, the water erosion hazard map of the area was provided and presented using new model.
Mohsen Padyab; Sadat Feiznia; Hassan Ahmadi; Ardeshir Shafei
Abstract
Small precipitation with temporal and spatial variation of rainfall is the main responsible factors on flood occurrence in arid and semi arid regions. Floods in their regions usually contain high concentration of sediments which when they are deposited on the surface of lands, they change the properties ...
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Small precipitation with temporal and spatial variation of rainfall is the main responsible factors on flood occurrence in arid and semi arid regions. Floods in their regions usually contain high concentration of sediments which when they are deposited on the surface of lands, they change the properties of soils of the area. In this research, the effect of floodwater spreading on physic-chemical characteristics of soil in Gachsaran floodwater spreading station, after 12 years of floodwater spreading, is investigated. For this purpose, soils and sediments were sampled from 0-15, 15-30, 30-45 and 45-60 centimeter depths, from the flood spreading and representative (without floodwater spreading) fields. Samples were analyzed for following proportion: percentages of clay, silt, sand and gravel, pH, EC, percentage of lime, anions and cations. The result have show that the amounts of clay, silt and sand have increased, chemical properties have changed slightly and among the chemical properties, pH and percentage of lime have higher change so that pH decreased and lime increased in floodwater spreading field respect to the representative field. It is concluded that due to floodwater spreading, physical properties of the field underwent considerable amount of changes and gravelly texture has changed to less gravelly texture. The surface soil has undergone more changes and from the surface to the depth, change of physical and chemical properties becomes negligible.
