seid omid aleyasin; bahman shamsesfandabad; Hamid Toranjzar; abas ahmadi; Shahro Mokhtari
Abstract
Abstract: Wetlands are one of the most productive ecosystems in the world. They provide a unique and rich habitat for creature .they also perform a wide range of economic and service functions such as water conservation, runoff regulation, water quality treatment and recreational services. The aim of ...
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Abstract: Wetlands are one of the most productive ecosystems in the world. They provide a unique and rich habitat for creature .they also perform a wide range of economic and service functions such as water conservation, runoff regulation, water quality treatment and recreational services. The aim of this study was to evaluate the ecosystem health of Meyghan Wetland of Arak based on different methods. To evaluate the Meyghan Wetland of Arak and also to evaluate the status of benthic organisms and other parameters, sampling of sediments of the wetland floor was performed. Sampling was performed at 10 points of the wetland and at 5 replications at each point. Several indicators were used to assess the health of Meyghan Wetland. Which included a biotic-index (BI) based on the work of Borja et al. (2000). In addition to the above, the main framework includes bio-indicators, heavy metal pollution index and water quality index, which have been considered in this study. The ecosystem health of Meyghan Wetland was evaluated based on the mentioned indicators and the map of ecosystem health of Meyghan Wetland was prepared. The results of this study showed that except for the nickel, zinc and lead as well as pH, for other elements (EC, Na, Cl, Mg, Ca, HCO3, SO4 and TDS), the lowest and highest values belong respectively To stations 3 and 6. The high amount of these elements in station 6 can be due to the activity of sodium sulfate factory in the northern part of the wetland, which causes changes in the wetland ecosystem by removing sediments from the wetland floor. In the case of copper, zinc and lead, the lowest concentration is seen in the northwestern part of the wetland and the highest concentration is seen in the western and southeastern parts of the wetland.
moslem dehdari far; Mohammad Faraji; Mohammad salehi veisi; Jahangir Ehsani
Abstract
Rock behavior varies with different erosions, which depends on the inherent and environmental characteristics of the rock. In other words, some petrological units are susceptible to erosion and have sediment production potential. This study is conducted to investigate the sensitivity to erosion and resistance ...
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Rock behavior varies with different erosions, which depends on the inherent and environmental characteristics of the rock. In other words, some petrological units are susceptible to erosion and have sediment production potential. This study is conducted to investigate the sensitivity to erosion and resistance of rock formations of Fars group (Mishan limestone, Aghajari sandstone and Gachsaran Anhydrite) and Asmari formation using Selby method in Behbahan, Gachsaran, Deylam and Dehdasht areas. Results of analysis of ANOVA variance based on the comparison of 81 samples from 4 types of rocks showed that there was a significant difference between the rocks (p= 0.05).In general, the Asmari limestone with scoring mean of 66.72-70.99 is the most rock resistant based on theSelby method. Mishan, Aghajari limestone, Gachsaran Anhydrite will be in the next ranks, respectively.
hassan torabipodeh; ahmad godarzi; reza dehghani
Abstract
Simulation and evaluation of river sediment is one of the important issues in water resources management. Measuring the amount of sediment in conventional methods generally involves a lot of time and cost and sometimes does not have sufficient accuracy. In this study, a wavelet neural network was used ...
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Simulation and evaluation of river sediment is one of the important issues in water resources management. Measuring the amount of sediment in conventional methods generally involves a lot of time and cost and sometimes does not have sufficient accuracy. In this study, a wavelet neural network was used to estimate the sediments of the Kashkan River in Lorestan Province, and its results were compared with conventional smart methods such as artificial neural network. Parameters of discharge, temperature, water soluble solids content and precipitation as input and sediment discharge were selected as output during the monthly statistical period (1984-2013). Correlation coefficient, root mean squared error, and Nash Sutcliff coefficient were used to evaluate and compare the performance of the models. Results showed that the combined structure has been able to provide acceptable results in estimating sediment yield using two intelligent methods. However, in terms of accuracy, the wavelet neural network model with the highest correlation coefficient (0.850), the lowest root mean square error (0.151 tonday-1), and the Nash-Sutcliff criterion (0.758) were prioritized in the validation stage. Results also showed that the wavelet neural network model has a high ability to estimate the minimum and maximum values.
Iman Saleh; Ataollah Kavian; Mahmoud Habibnejad Roshan; Zeynab Jafari
Abstract
Iran has an arid and semi-arid climate as well as a more unstable ecosystem than humid regions; so the importance of water and soil resources conservation becomes higher in this country. The use of vegetative buffer strips is an effective strategy to reduce pollutions in surface waters as well as soil ...
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Iran has an arid and semi-arid climate as well as a more unstable ecosystem than humid regions; so the importance of water and soil resources conservation becomes higher in this country. The use of vegetative buffer strips is an effective strategy to reduce pollutions in surface waters as well as soil erosion. The present research has been conducted with the aim of study the effect of runoff rate, plant age and plant species on the efficiency of vegetative buffer strips to control runoff quality and quantity in Sari, Mazandaran, Iran. 1×10 m experimental plots were used and artificial runoff with two rates equal to the runoff generated by a precipitation with 25 and 100 years return period. The results indicated that the efficiency of vegetative buffer strips containing vetiver grass and turf grass affected by the runoff with a rate equal to the runoff generated by a precipitation with 25 years return period was higher than the buffer strips affected by the runoff with a rate equal to the runoff generated by a precipitation with 100 years return period, during the study period. Also, it was found that the efficiency of vegetative buffer strips to control runoff quality and quantity is affected more by the flow properties than characteristics of buffer strips, their plant age and species, when runoff rate is high. Two studied plant species including vetiver grass and native turf grass also showed a different performance to reduce runoff volume and its pollutants. On the other hand, variation of the plants’ age caused different efficiency for the studied vegetative buffer strips.
Alireza Arabameri; Kalil Rezaei; Mohammadhossein Ramshet; Kourosh Shirani
Abstract
Landslide susceptibility and its risk assessment is the main part of landslide risk mapping. In this study, landslide susceptibility of Oliya's Padena in Semirom is mapped using artificial neural network. A total of 23 factors in relation to landslide in the region were initially characterized. The spatial ...
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Landslide susceptibility and its risk assessment is the main part of landslide risk mapping. In this study, landslide susceptibility of Oliya's Padena in Semirom is mapped using artificial neural network. A total of 23 factors in relation to landslide in the region were initially characterized. The spatial location of landslide events was then determined by field study as well as aerial photo analysis. AHP analysis tends to 14 out of 23 parameters as the important factors for further steps. A total of 72 (70%) and 31 (30%) out of 103 detected landslide events in the study area were selected as training and validation data for neural network analysis, respectively. A multilayer perceptron back propagation algorithm with sigmoid as activation function was developed. The best topology was determined by using conventional criteria including mean square error, root mean square error, maximum absolute error and correlation coefficient. Results show that a 14-4-1 array is the optimum topology for landslide susceptibility zoning in the region. The weight of each input layer was estimated by frequency ratio. In order to map landslide, ROC graph and area under curve indices were used and the accuracy of output map was computed. Results from validation shows that area under curve for the obtained model is about 0.938 (93.8%) that is considered as high resolution prediction group. According to this study, a total of 29.61 square kilometers (93.25%) of the landslide areas is categorized in very high and high susceptible groups.
Elnaz Azartaj; Ali rasoulzadeh; Ali Asghari
Abstract
Soil and water are the most valuable national resources. Unfortunately in recent decade, due to land use change and vegetation cover degradation, most of the rainfall changed into runoff and in addition to loss of this vital resource, causes abundant loss of life and property by creating enormous floods. ...
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Soil and water are the most valuable national resources. Unfortunately in recent decade, due to land use change and vegetation cover degradation, most of the rainfall changed into runoff and in addition to loss of this vital resource, causes abundant loss of life and property by creating enormous floods. The aim of this study is to assess the effect of land use change from range land to agriculture with different percent of vegetation cover on runoff and soil erosion. For this purpose, three types of land use included preserved range land with 100 percent of vegetation cover; range land with 50 percent of vegetation cover and agricultural land (range land changed to agriculture) were identified in the study area. Then, in each land use, three slopes were determined (10, 15 and 24%). This study was carried out split plot experiment based on completely randomized design. In each land use and slope, runoff and erosion were measured in plots randomly using rainfall simulator with 1.5 mm.min-1 intensity and 15 min duration with 3 replicates. Results showed that the maximum of runoff, sediment mass and sediment density were in the range land changed to agriculture with 24% slope and the minimum of them were in the preserved range land with 10% slope. Also the results showed that the change of range lands to agricultures increase runoff 5 times. In the other hand, with increasing slope from 10 percent to 24 percent, runoff increased 1.7 times. Runoff coefficient was determined for 3 land uses and 3 slopes level. The maximum and minimum runoff coefficient were found 0.72 and 0.06 for the range land changed to agriculture with 24% slope and preserved range land with 10% slope, respectively.
Zahra Faghfouri; Nasim Arman; Mohammad Faraji; Zohreh Khorsandi
Abstract
Whereas investigation of effective factors in soil erosion and sediment yield, we can`t introduce specific factors basically as a main factors in water erosion. In fact, erosion condition in an area is a result of contract effect of impressive factors collection in erosion. In order to identify the effective ...
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Whereas investigation of effective factors in soil erosion and sediment yield, we can`t introduce specific factors basically as a main factors in water erosion. In fact, erosion condition in an area is a result of contract effect of impressive factors collection in erosion. In order to identify the effective factors in soil erosion and sediment yield in Seied Abad Basin, interrill erosion was determined by average intensity (30 min, 10 year: 40 mmhr-1) using rain simulator in 33 plots. Also, factor analysis, multivariate regression, logistic and Scalogram model were used. Using factor analysis (principal component analysis), between 15 effective variables in sediment ratio, six factors were selected. They were runoff coefficient, sand, rocks susceptibility, soil texture and land use that illustrate %82.009 of variation of data (KMO=0.53). The results of multivariate regression model were almost the same with factor analysis and the results of the Scalogram model confirmed this. Finally, runoff volume (0.02), rock susceptibility (0.001) runoff coefficient (0.00005), and sand percentage (0.00002) were effective factors in soil erosion and sediment yield. In this regard, regarding to these factors, we can conduct policy and planning for decreasing soil erosion and sediment yield.
Reza Sokouti; Mohammadhossein Mahdian
Abstract
Floods water contain sediments that affect the fertility of coarse grain alluvial fan and flood plains after deposition, through increasing their nutrients. In this study, the effects of flood spreading were investigated on the recovery of soil nutrients at the Poldasht flood spreading station of west ...
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Floods water contain sediments that affect the fertility of coarse grain alluvial fan and flood plains after deposition, through increasing their nutrients. In this study, the effects of flood spreading were investigated on the recovery of soil nutrients at the Poldasht flood spreading station of west Azerbaijan during 10 years., The first three bands that have been flooded, were selected at the flood spreading channels. In each strip, six soil samples of of 0-20 cm depths, were taken and total nitrogen, phosphorus, potassium, and soil organic carbon were measured. For statistical analysis, t-test non-parametric tests were used where the data had normall distribution or not, respectively; . According to the results, the amount of soil organic carbon and total nitrogen increased from 0.23 to 0.33 and 0.027 to 0.039 percent, respectively during the implementation years. Exchangeable phosphorus and potassium were significantly increased from 2.69 to 5.32 and 145.93 to 206.52 parts per million, respectively. On the other hand, there was a significant difference for some factors of the spreading bands at 5% probability. Amounts of phosphorus, soil organic carbon and nitrogen in the upper strips were significantly more than lower bands. However, there was no significant change on the amount of potassium. The results showed that the flood spreading increased soil nutrients which reduce the fertilizers application.
Mahnaz Babaei; Seyed Zeynalabedin Hosseini; Aliakbar Nazari Samani; Seyed Ali Almodaresi
Abstract
Recently soil erosion and sediment yield has become one of the most important problems of the environment. Soil erosion risk assessment and sediment yield are first steps to confront with this problem. In this regard, various models and methods proposed. What is certain, first of all must be verified ...
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Recently soil erosion and sediment yield has become one of the most important problems of the environment. Soil erosion risk assessment and sediment yield are first steps to confront with this problem. In this regard, various models and methods proposed. What is certain, first of all must be verified the functionality of these models. The present study is carried out to KanSoleghan watershed in order to estimate the soil erosion risk and sediment yield. RUSLE 3D was used in geographical information system platform. Rainfall Erosivity (R), were obtained from monthly and annual data and IDW techniques, Soil Erodibility (K) were obtained from soil data and regin map, Land cover Management (C) using remote sensing techniques (with use of NDVI), LS using digital elevation model, Soil Conservation Practice with using slope percent map. Eventually based on RUSLE 3D model combining these factors together, annual average risk of soil erosion was obtained 22.20 t.ha-1.y to estimate the sediment delivery ratio was used several models, accordingly, the estimated annual sediment yield was overestimated in all models. Sedimentation basin was calculated using statistics gauging stations sooleghan (1.82 tons per hectare per year). Our study indicated that LS factors of the RUSLE 3D model (r2=0.68) were the most effective factors controlling soil erosion in the region. In general, it can be said that the reliability of the used data and used methods is too low and too many uncertainses exist for areliable calculation of soil loss amounts in kan soleghan watershed using the RUSLE 3D Model.
Masoud Sajedi Sabegh; Mojtaba Saneie; Hosseinali Abdul Hai; Shahram Behmanesh; Abbas Matinfar
Abstract
Aquaculture cylindrical tanks are growing in the world due to the less water consumption and more product efficiency. Study on Hydraulic of this tank is the first step for recognition of sedimentation and solid removal efficiency. This paper is a laboratory study based on flow velocity analysis in different ...
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Aquaculture cylindrical tanks are growing in the world due to the less water consumption and more product efficiency. Study on Hydraulic of this tank is the first step for recognition of sedimentation and solid removal efficiency. This paper is a laboratory study based on flow velocity analysis in different flow depth. The results show that the flow velocity gradient increased in the vector of inlet current toward tank inner bank and due to the incoherence of ISO-velocity layers in different depth, the secondary currents shaped particularly near the tank bank. Also, related to jet current forces, reflected current formed in different parts of the tank pyramid by incidence of jet current to bank of the tank. Local velocity in the middle and beneath depth increased and reflected current depreciate in longer distance on circular current. By increasing the outlet central discharge, the current velocity increased in deeper depth. Due to the local and secondary flows, there is not a match velocity pattern for different discharges in tank. Range of ratio of local velocity to average velocity with depth of 0.2 from tank bottom changes between 0.6 and 1.78 for inlet discharges. Also the results show that the calculated Froude number in each local point related to ratio of local radius to tank radius.
Reza Sokouti; Hamidreza Peyrowan; Davood Nikkami; Mohammadhossein Mahdian
Abstract
Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties ...
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Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties were recognized and soils were sampled. Soil erodibility indices were determined and analyzed by statistical methods considering the form and the rate of erosion. Also portable rain simulator were used to study of the runoff and sediment yield potential of such soils. Finally the factors affected the soil erodibility were determined by variance analysis. Results showed erosion rate could be classified as moderate. Gully erosion had highest number in Gara-agaj and Gara-tape areas whereas rill erosion had high number in all area of marlly lands. Surface runoff volume ranged between 255 to 577 cm3 in Shabanlu and surface runoff coefficient 0.23 to 0.53 in Gara-tapeh. Maximum yielded turbidity was 180 gr/lit in Gara-Agaj area. Clay ratio was the effective factor to gully form and Surface runoff volume also was the factor to form surface and rill erosion.
Ebrahim Borooshke; Mahmood Arabkhedri
Abstract
Soil erosion and sediment transport is an important issue in many Iranian watersheds. Watershed planning without accurate estimates of erosion and sediment yield with appropriate models is not possible. The objective of this study was evaluating of two common empirical models of MPSIAC and EPM. First, ...
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Soil erosion and sediment transport is an important issue in many Iranian watersheds. Watershed planning without accurate estimates of erosion and sediment yield with appropriate models is not possible. The objective of this study was evaluating of two common empirical models of MPSIAC and EPM. First, 10 small watersheds were selected in Western Azerbaijan Province, with several consecutive check dams on their streams implemented under watershed management projects. No flow over the last downstream check dam was considered as the main criterion in each selected basin. In addition to the direct measurement of sediment deposited behind the dams, sediment yield of watersheds were estimated using the models. Comparison of means using (Mann-Whithney) did not show any significant difference at 0.05 percent level between measured and estimated data. At final step, both models were tested by MAE and MBE statistics. The MPSIAC showed better performance than EPM with MAE=1.34 and MBE =-0.12.
Mojtaba Saneie; Mahdi Azhdarimoghadam; Amin Hajiahmadi
Abstract
One of the sediment controlling methods in the hydraulics structures is application of the vortex settling basin. Such basins represent the higher speed in sediment separation in comparison with other usual settling structures. One of the problems of such settling structure is the settlement of a portion ...
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One of the sediment controlling methods in the hydraulics structures is application of the vortex settling basin. Such basins represent the higher speed in sediment separation in comparison with other usual settling structures. One of the problems of such settling structure is the settlement of a portion of the sediments on the basin floor as a result of disruption on the structure operation caused by remaining loads. Therefore, the curvature submerged vane was introduced by this research in order to solve the problem. Several curvature vanes patterns was applied in an experimental model of the vortex settling basin to investigate the efficiency and sediment removal from the basin floor. Experiments were carried out in a basin with diameter of 96 cm and a height of 206 cm. In this model, curvature submerge vanes were used for modification and their different arrangement in 60 degree diameter section for increasing in vortexes power. Experiments were continued by 45 and 37 Ls-1 water discharge, flushing orifice diameters of 36, 46 and 59 mm and six different arrangement of vane (R2, R3, R4, R23, R34, R234). Results showed that application of submerged vane on the vortex basin floor with suitable arrangement resulted in sediment removal from basin floor and in replacement of sediments toward the orifice. Present research showed that the best efficiency was obtained from R3, R4 and R34 arrangements which were located in the farther distance from orifice. Furthermore, results showed that variation in water discharge and orifice diameter is an effective factor in the efficiency of curvature submerged vane. In the most optimum case of curvature submerged vane arrangement, 25.56 percent of the sediment was removed from the floor of vortex settling basin.
Mojtaba Saneie; Moen Asefi Asefi; Kazem Smaeeli
Abstract
The vortex settling basin is a sediment control structure in conveyance water system which can be more economical than other designs in specific conditions. Deposition of sediment in the basin is a major problem. Mechanism of separates solids and water in these basins, based on flow vortex and difference ...
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The vortex settling basin is a sediment control structure in conveyance water system which can be more economical than other designs in specific conditions. Deposition of sediment in the basin is a major problem. Mechanism of separates solids and water in these basins, based on flow vortex and difference of density between water and sediments. Therefore the sediment increases in the basin for long time. In this study the hydraulic characteristics of these basins are investigated and offered a method to increase the efficiency of it. In this offer the submerge vans were used on the bed of the basin. Experimental results were showing that increase in deposition with a decreasing vanes interval (r<R/2). But in further distances (r>R/2), vanes with guidance sediments toward orifice bottom, flashing from bottom occur more than another. Results also indicated that located vanes with constant total flashing efficiency and flow losses, and has been able to change bottom sediments in the basins. Experiments show that if the vanes are placed in less radial intervals, the discharge loss increases. As well as increase input flow because that total deposition efficiency, hydraulic efficiency and vanes efficiency in flashing have been increased.
Abdolrasoul Shafiey Dastjerdi; Mohammad Hossein Mahdian; Kourosh Kamali; Hamid Hoseyni Marandi
Abstract
Entrance of high volume of floodwater containing huge amount of suspended sediments into the floodwater spreading networks which deposits sediments, as well as infiltration of soluble materials and fine grained, gradually changes the infiltration rate of soils. The aims of this project is to study the ...
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Entrance of high volume of floodwater containing huge amount of suspended sediments into the floodwater spreading networks which deposits sediments, as well as infiltration of soluble materials and fine grained, gradually changes the infiltration rate of soils. The aims of this project is to study the quantity and the process of changes made in the soil of Saravan floodwater spreading station. This research has tried to use direct method of infiltration rate measurement, using double ring infiltrometer in two separate time periods of one year each, and to compare it to the experimental area. In order to specify overall situation of infiltration rates in terms of increase or decrease in second period of measurement in comparison to the first one, and as far as data were not distributed normally, Wilcoxon signed-rank test was used. The results showed no significant difference between two separate measurement periods due to few number of floodwater occurrences (three times) in addition to short time interval of one year between the two measurement periods. To determine changing rate of infiltration between strips and between the strips and the experimental field, as far as abnormal distribution of data in this arrangement were concerned, Kruskal-Wallis test was used. Results indicated that the three strips of flood spreading area have no significant difference (at five percent probability level) in two periods of measurement, but the strip related to experimental area has significant difference with other three strips and in both measurement periods. In other words, infiltration rates of all strips under floodwater spreading have been decreased in relation to the experimental area. Moreover, the results were explanatory that only one of the rectangular in both measurement periods had significant difference with experimental rectangular (at five percent probability level) and all the other rectangular have had no significant differences with each other and in comparison to the experimental one, in none of periods of measurement. Main reason of this difference is also related to the thicker sediments deposits in rectangular location, compared to other blocks. Also, infiltration rate decreased by 55.94 percent in flood spreading area compared to experimental area during one-year timeframe and 3.23 percent of reduction.
Reza Bayat; Amir Sarreshtedari; Ali Jafari Ardekani; Reza Sokuti Oskuee
Abstract
Due to vegetation cover importance in protecting soil and its important role in controlling erosion, this study was conducted to determine the effect of land use managementon the Orumiyehlake watershed erosion rate, using GIS and RS technologies and EPM model. Using ETM+ 2002 satellite imagery, field ...
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Due to vegetation cover importance in protecting soil and its important role in controlling erosion, this study was conducted to determine the effect of land use managementon the Orumiyehlake watershed erosion rate, using GIS and RS technologies and EPM model. Using ETM+ 2002 satellite imagery, field work and existing map, required layer of model prepared and soil erosion was estimated in the current situation. Management scenarios, with good and bad actions through changes hypothetically in land use rank (decreased and increased in steps of five to 50 percent), the rate of soil erosion and changes in estimates were calculated. Results showed that maximum of erosion rates is belong to 3015 and 3054 sub-watershed with values of 768 and 749, minimum is belong to 3072 and 3056 sub-watershed with values of and 287 respectively and the mean for the watershed 485.9 . Trend of erosion rate change due to land use change was linearly and positive, meanwhile ultimate condition with 50% addition or reduction to land use rank, respectively caused 83.7 and -64.6 percent change in soil erosion.
Majid Mahmoudabadi; Samira Zamani
Abstract
Wind erosion is one of the aspects of land degradation resulting in some problems especially for arid and semi-arid regions. Recognition of Sediment size Distribution (PSD) as well as transport mechanisms is important in modelling of wind erosion. In the present study, this topic was investigated on ...
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Wind erosion is one of the aspects of land degradation resulting in some problems especially for arid and semi-arid regions. Recognition of Sediment size Distribution (PSD) as well as transport mechanisms is important in modelling of wind erosion. In the present study, this topic was investigated on two soils taken from cropland and sand dune with different PSD, using wind tunnel. Results showed that compared to the original soil, the collected sediment had finer sizes, indicating a selective mechanism in transporting detachable particles. It was found that for cropland soil, increasing wind speed from 2 to 18 m/s at the height of 20 cm, the PSD of sediment approached to the original soil. This trend was reverse for sandy soil so that, for higher wind velocities, the frequency of fine particles was more than the original soil. The result of transport mechanisms indicated that compared to saltation as well as suspension, creeping was the least important mechanism. The contributing percentage of creeping for cropland and sandy soils was determined less than 10 and 1 %, respectively. For the cropland soil at wind speed of 2 m/s, suspension was the most important mechanism of transport and depends on soil's PSD, 61.1- 68.5 % of particles were transported. Increasing wind speed up to 18 m/s, saltation with 50.4- 53.8 % was found as the main transport mechanism. Reversely, in the sandy soil at low wind speed, most of sediment (59.3 %) was transported through saltation, whereas increasing the speed, suspension with 55.3 % became the dominant mechanism. The finding of this study brings up the important of soil PSD on the PSD of sediment as well as transport mechanisms.
Seyed Ahmad Hosseini; Nasrolah Javaheri; Mehdi Habibi
Abstract
This study investigated the status of sediment transport and deposition in Khar-rud River, Qazvin province, Iran. The aim was to determine the possibility of construction of sand and gravel mining workshops in the margin of Khar-rud Flood-plain. Here with calculating sediment transport rate and specifying ...
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This study investigated the status of sediment transport and deposition in Khar-rud River, Qazvin province, Iran. The aim was to determine the possibility of construction of sand and gravel mining workshops in the margin of Khar-rud Flood-plain. Here with calculating sediment transport rate and specifying the distribution of sediment deposits in various parts of the river, an applied program for sand harvesting from the river bed, is developed. In this project, after preparing the basic information, such as information about river geometrical shape, roughness coefficients of different sections, information related to size gradation of suspended sediments and bed material, river hydrology data and boundary conditions of downstream hydraulic system, using HEC-RAS model, sediment loads and its distribution along the river was simulated. Simulation was done based on classified data from daily flow discharges during a 37-year period. After calibrating the HEC-RAS model and selecting Yang sediment transport equation as the closest relationship to the sedimentary data measured by regional Hydrometric stations, the average volume of sediment yield from the river was estimated 1.75 million tons per year. Finally, considering the changes in the river bed elevation for each cross-section, the amount of sediment passing during simulated 37-year was calculated. Using the results of the model and sedimentation changes along the study reaches, the volume of sediment transport in each river cross section, the river width and its private region and considering the maximum permissible depth of bed-material removal equal to 1 m, the most suitable mining length and period in the different reaches of river was determined, discussed and showed in ARC-GIS environment. Based on simulation results, the average depth of sand which can be taken safely from the river-bed was estimated to be 40cm and the most suitable period of time for sand mining along the river was recommended from January to May. It was determined that HEC_RAS hydraulic model, covers about %63 of initial engineering judgments for the amount and location of sand mining.
Davood Nikkami; Peyman Razmjoo; Farzad Bayat Movahed
Volume 2, Issue 2 , July 2010, , Pages 65-72
Abstract
The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different ...
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The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different basic times are correlated to the amount of runoff and sediment outflow from erosion plots to investigate rainfall erosivity index. For this purpose two years of precipitations of Sohrain-Gharacharian flood spreading research station were monitored by recording raingauge. During 2003-2004 period, two plough treatments of parallel and perpendicular to slope direction on three slope classes of 0-12, 12-20, and 20-40 percent with three replicates and randomized complete block design were studied under regional wheat planting and fallow conditions in 1.8x22 sq. meter erosion plots. The correlation between the amounts of runoff and sediment, as dependent variables, resulted from 12 rainfall events and the amounts of rainfall, maximum 1, 5, 15, 30, 60 and 120 minutes of rainfall intensity, rainfall energy and rainfall erosion index, as independent variables, computed by different methods were analyzed with the SPSS V11. Two variables of the amount of rainfall and the maximum rainfall intensity in different base times had the maximum correlation with the amount of runoff and sediment at the levels of 99 to 95 percent.
Abbas Pourmeydani; Abolfazl Khalilpour; Hossein Tavakoli Neku; Mohammad Hassan Marefat
Volume 2, Issue 2 , July 2010, , Pages 95-101
Abstract
One of the important problems is erosion and soil degradation in watershed areas. Polymer usage is a way for both erosion control and soil and water conservation. In this research the effects of the BT53 polymer application for moisture storage in soil, reduction of runoff and erosion and prevention ...
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One of the important problems is erosion and soil degradation in watershed areas. Polymer usage is a way for both erosion control and soil and water conservation. In this research the effects of the BT53 polymer application for moisture storage in soil, reduction of runoff and erosion and prevention of loss soil are studied for 1998-2001. The research plan was CRBD and factorial method. First factor included polymer levels of 0, 2 and 4 gr/m2. Second factor included Secale montanum species planted and not-planted. After every rainfall event both runoff volume and sediment amount were measured. Analysis of variance showed there was significant difference between polymer levels and sediments amount (P<0.01). Compression of averages by Duncan's method in first factor showed all polymer levels fall in one group from runoff volume point of view, and in three groups based on sediment amounts. The most effect of polymer usage was on sediment amounts reduction rather than runoff. This means that polymer BT53 is suitable more for soil protection besides runoff reduction. Polymer level 1 had most amounts and polymer level 2 had least amounts of sediment. So application of polymer BT53 in level 2 (4 gr/m2) was suggested for sediment control. Polymer level 2 with non-planted treatment had least effects on runoff volume and sediment amounts among six treatments of polymer levels and planted or non-planted.
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.
