amir moradinejad; Amir Hamzeh Haghabi; Mojtaba Saneie; Hojatola Yonesi
Abstract
Sediment entering lateral intakes depend on flow pattern in intake entrance. Using a structure in front of the intake entrance can change this pattern and as a result the entering sediment. One of the effective methods to change pattern and manage sediment entering lateral intake is using skimming wall. ...
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Sediment entering lateral intakes depend on flow pattern in intake entrance. Using a structure in front of the intake entrance can change this pattern and as a result the entering sediment. One of the effective methods to change pattern and manage sediment entering lateral intake is using skimming wall. By removing sediments from intake entrance, the skimming wall reduces the volume of sediments entering the intake. To direct the flow towards intake and increase skimming wall efficiency, a spur dike is used on the opposite side of the intake. The length and angle of the spur dike were 0.25B and 60° and was located at distances 2b from intake center. In this study, the effect of skimming walls angle with the bank, a combination of spur dike and skimming walls and discharge changes on controlling sediments entering the intake, intake ratio and bed topography were investigated experimentally. The effect of the skimming walls with three angles (β1=10, 14, and 18 degrees) and a combination of skimming walls and spur dike on opposite sides of the intake was investigated. Conducting dimensional analysis, non-dimensional ratios were extracted and test variables were specified. Results showed that in the case of having a skimming wall combined with spur dike, the amount of sediment entering the intake has decreased to 81%, 78.5% and 76% on average in walls with an angle of 10, 14 and 18 degrees respectively. The combination of using skimming wall and spur dike has a superior effect on reducing enterance sediments to intake than employing skimming wall alone, namely about 15% for three angles.
Hooshmand Safari; Aliashraf Jafari
Abstract
Most of Iranian rangelands are located in arid and semi arid areas, therefore, drought resistance is an important issue in this regions' plants. Drought resistance variation of forage yield for 11 genotypes of Elymus hispidus was examined in complete block design with three replications under normal ...
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Most of Iranian rangelands are located in arid and semi arid areas, therefore, drought resistance is an important issue in this regions' plants. Drought resistance variation of forage yield for 11 genotypes of Elymus hispidus was examined in complete block design with three replications under normal and dryland farming system, in Islam Abad Gharb, Kermanshah, Iran, during 2004-2006. Significant variation (p<0.01) for forage yield were observed between with and without tension environments and between genotypes. Drought resistance indices of genotypes were measured for dry matter forage yield (Yp) of irrigated and dryland (Ys) conditions, like sensitivity to stress index, Tolerance (Tol), Mean Productivity (MP), Drought Tolerant Index (DTI), Harmonic Mean (HM) and Geometrical Mean of Productivity (GMP). Variance analysis of drought resistance indices showed that genotypes had significant variation at 1% level for DTI, MP and Yp and at 5% level for HM and GMP. Significant variation for SSI, Tol and Ys were not observed among genotypes. The indices of MP, GMP, HM and DTI showed the significant positive correlation with Ys and Yp, therefore selection for drought resistance were performed based on this indices. Also, the results of mean productcomparision of Ys, Yp and drought resistance indices by Duncan method at 5% level showed that genotypes 890-5 and 890-6 has higher drought resistance value and can be introduced as a suitable genetic material for rangeland reclamation or breeding programs for drylands in Kermanshah province. This results were confirmed by claster and principle component analysis.
Majid Soufi; Hossein Esaei
Volume 2, Issue 2 , July 2010, , Pages 73-82
Abstract
Gully erosion is more important than both rain splash and sheet erosions due to both higher sediment productions. Estimation of the volume of gully erosion requires some indices that could be measured easily in the field. This research aims to present simple models to estimate the volume of gully erosion ...
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Gully erosion is more important than both rain splash and sheet erosions due to both higher sediment productions. Estimation of the volume of gully erosion requires some indices that could be measured easily in the field. This research aims to present simple models to estimate the volume of gully erosion with minimum cost. After determining influenced regions, using anecdotal, historical and field surveying, two regions in each modified Dumartin climate zone and region, three representative gullies were selected. Then, morphometric and edaphic characteristics such as length, depth, top and bottom width, clay, silt, sand, Ca, Na and Mg percentages of the gullies were measured both in their heads and cross sections in 25, 50 and 75% of their length from the headcut. The volume of gully erosion was calculated by the sum of partial volumes in each gully. The results revealed that gullies were initiated and developed in two arid and semi-arid climates on the loess sediment with little cohesion. Gully widening is higher than deepening and silt has an important role in it. Statistical analysis indicated that linear relationship with R2 of 0.86 is more suitable than power relationship with R2 of 0.54 for estimation of the volume of gully erosion. Results indicated that the volume of the gullies had a significant linear relationship with gully length, depth and top width in 0.01 level. Results also, revealed that gully length with 86% interpretation of changes in gullies volume and had the most impact among the variables. These results prove that suggested comments in literature using gully length to sediment yield estimation in EGEM is applicable in the northeast of Iran.
Majid Khazaei; Mohammad Reza Mirzaei
Abstract
Prediction in hydrology is as estimation of hydrological and meteorological conditions in a specific interval time. In this regard, understanding the relationship between precipitation and runoff is necessary for water resources optimal management. The purpose of this study was to compare different models ...
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Prediction in hydrology is as estimation of hydrological and meteorological conditions in a specific interval time. In this regard, understanding the relationship between precipitation and runoff is necessary for water resources optimal management. The purpose of this study was to compare different models of artificial neural networks (two type of ANNs: RBF and MLP) and time series models (ARMA) to discharge estimation in a part of the Taleghan watershed, using monthly flow discharge data for a period of 30 years between 1977 and 2007. Among the different ARMA models, a model with a lowest error and akaike (AIC) criterion was selected as an optimal model. Using trial and error method, ANNs were designed by specifying the number of hidden layers and neurons in each layer, sigmoidal transfer function, training function, weight/bias learning function and performance function. Using trend analysis, Halt-Winters and Box-Jenkins (ARMA) methods, time series analysis showed that ARMA (2, 2) (R= 0.77) and Halt-Winters (R=0.72) presented more accurate results. In general, it could be concluded that ANNs models produced more accurate predictions of flow discharge than time series approaches. Also, the results revealed that the MLP model (average R=0.83) produced more accurate predictions of flow discharge than RBF model (average R=0.81). Assessment of accuracy of all models based on RMSE and R showed that the model 1 (with RMSE= 6.45 and R= 0.86) obtained with a network architecture of 4-20-1 configuration. Model 1 used the input vector consisting of antecedent monthly discharge with one to four time lag.
Seyed Hamid Reza Sadeghi; Seyedeh Laleh Razavi; Mohammad Mahdavi
Volume 1, Issue 2 , July 2009, , Pages 78-86
Abstract
Many different runoff prediction methods are being used among which SCS model has been applied throughout the globe. It is therefore very important to evaluate the circumstances and input specifications under which such models could be applied. The present study was conducted to investigate the role ...
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Many different runoff prediction methods are being used among which SCS model has been applied throughout the globe. It is therefore very important to evaluate the circumstances and input specifications under which such models could be applied. The present study was conducted to investigate the role of rainfall main characteristics on accuracy of SCS model in runoff prediction for Kasilian and Darjazin watersheds. For this purpose, the simultaneous rainfall-runoff data were selected and the storm runoff was estimated using determining rainfall characteristic, providing Curve Number map and calibrating the model. In order to determine the effects of rainfall characteristics on model output, the standardized values of regression coefficient (β) of the best fitted multiple regression, developed between rainfall circumstances and maximum storage index coefficient, were determined. The results of the study showed the depth, maximum rainfall in concentration time, maximum 30 minutes intensity, 2nd quartile and 1st quartile have the highest rate of effectiveness on model output respectively.
Amir Samadi Tabrizi; Hamid Reza Peyrowan; Ahmad Motamed
Abstract
This study is about the relation between erodibility rate and plasticity features ofNeogene Marl deposits of Gatchab and Gitcha in southeast of Garmsar. The erosions alfeature of Neogene sediments are rill, gully and waterway shapes. The depth of soilsampling for rill and waterway types is from surface ...
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This study is about the relation between erodibility rate and plasticity features ofNeogene Marl deposits of Gatchab and Gitcha in southeast of Garmsar. The erosions alfeature of Neogene sediments are rill, gully and waterway shapes. The depth of soilsampling for rill and waterway types is from surface to 30-centimeter thickness and forgully one is from head cut and all outcrop of gully bank. The engineering analyses forsediments include liquid limit, plastic limit and plastic index and engineeringgranulometry. On the basis of engineering classification of soil, the sediment ofGatchab and Siahkoh mountains are fine grained soils with low to very low degreecohesive, consequently low plastic limit and low internal consistency. The comparisonof the results between marl units of Gatchab and Gitcha area have shown the M2 unithas low plasticity and high sensitive to erosion to other units M1 and M2. By the way,the M1 unit is high resistance to water erosion in comparison to M3 unit. From allaspect, Abundance of the lime and clay particle amounts is positive effects ondecreasing of sensitivity rate to erosion of Neogene deposits. The above mentionedresults base on plasticity features of Neogene deposits confirmed by field witness.
Mohsen Shariatjafari; Mohammad Hadi davoudi; Mehrdad Safaee; Afshin Partovi
Abstract
The establishment and development of fast-growing trees with effective root systems and avoidance of deforestation are effective ways for slope stability and to reduce landslides. Soil reinforcement and reduction of erosion by tree root systems are influenced by physiological and ecological characteristics ...
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The establishment and development of fast-growing trees with effective root systems and avoidance of deforestation are effective ways for slope stability and to reduce landslides. Soil reinforcement and reduction of erosion by tree root systems are influenced by physiological and ecological characteristics of roots. In this research, root reinforcement of Diospyros lotus, one of dominant species in the forests of northern Iran, was investigated by reinforced soil sampling and laboratory testing. Based on the results, shear strength of reinforced soil is related to two factors of root density and diameter. Evaluating test results by RDR and RDDI indexes showed that soil cohesion and shear strength of reinforced soil by Diospyros lotus roots increased by 207 and 350 percent respectively compared to unreinforced soil and this process has an effective role in Soil reinforcement and massive erosion control, especially in shallow landslides.
Shabanali Gholami; Masoumeh Nasiri
Abstract
Human life is affected by different hydrological events such as floods, water storage, droughts, water pollutions, avalanche and etc. that the risk range of these events depends on the behavior of hydrological variables and watersheds characteristics. Lack of correct data and information or inadequate ...
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Human life is affected by different hydrological events such as floods, water storage, droughts, water pollutions, avalanche and etc. that the risk range of these events depends on the behavior of hydrological variables and watersheds characteristics. Lack of correct data and information or inadequate correct data is the important factor affects on regognition of the behavior of hydrological variables and watershed charactristics. In this regard, there are different models which could follow watershed characteristics and estimate or simulate runoff and sediment load and other water balance factors in watershed. SWAT model is one of the important hydrological models. In this research, Atrak River monthly runoff was simulated using this model based on collected data in Maraveh Tappeh watershed, Gholestan province, Iran. Required information such as topography, land use, pedologyand also, hydrological and meteorological data such as daily rainfall, temperature, relative humidity and runoff have been collected. To determine important and sensitive parameters, sensitivity analysis has been performed using one parameter at a time (OAT) method. The results indicated that curve number, channel hydraulic conductivity, surface runoff lag coefficient, base flow alpha factor and soil evaporation compensation factor have the most influence on different parts of water balance. Calibration and validation of the model were performed using the SUFI2 algorithm for the periods of 1994 to 1999 and 2000 to 2008, respectively The simulation accuracy using Nash-Sutcliffe and coefficient of determination were 0.54 and 0.54 for the calibration period and 0.46 and 0.46 during the validation period, respectively. So, it can be concluded that the performance of the SWAT model for estimating monthly flow is quite good.
Mansour Mehdizadeh Youshanloei
Abstract
Computation and estimation of flood discharge is necessary in hydraulic structure planning and flood control projects. The precise estimation of runoff and flood discharge needs comprehensive data of the amount and condition of rainfall and design precipitation. Rainfall Depth-Area-Duration curves (DAD) ...
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Computation and estimation of flood discharge is necessary in hydraulic structure planning and flood control projects. The precise estimation of runoff and flood discharge needs comprehensive data of the amount and condition of rainfall and design precipitation. Rainfall Depth-Area-Duration curves (DAD) of each region, are used to estimate the optimal precipitation. In this research, these curves were provided for 1, 3, 6, 9, 12, 18 and 24 hours intervals and their relations were studied for Northern parts of Western Azerbaijan province. Eleven maximum and pervasive storms were selected to draw the cumulative rainfall graph. There are adequate recorded and non-recorded rain gauges in the region. Mass curves were prepared for non-recorded stations using relations between rainfall gradient and altitude in the isohyets maps. Results showed that the maximum rainfall for 1 km2 is related to 18 h rainfall with 42 mm and its minimum is related to 1 h rainfall with 4.29 mm. Also, 9 and 12 h curves indicated no difference in different areas. Comparing 18 and 24 h curves indicated that the amount of precipitations are equal in small areas and 18 h curve is above 24 h curve in wast areas that could be related to the shortage of rainfalls with 24 h duration.
Jafar Dastoorani; Ali Fazlollahi; Ali Salajeghe; Ghasem Dastoorani
Volume 2, Issue 3 , October 2010, , Pages 133-142
Abstract
Effective discharge (Qeff) that transports the most of suspended sediment in rivers and controls the bed conditions is an important criterion for evaluating the quality of water. Qeff usually has 1.5 years recurrence interval on the yearly maximum flood data series. For examining similarity between Qeff ...
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Effective discharge (Qeff) that transports the most of suspended sediment in rivers and controls the bed conditions is an important criterion for evaluating the quality of water. Qeff usually has 1.5 years recurrence interval on the yearly maximum flood data series. For examining similarity between Qeff and Q1.5 in ten stations of Daryacheh Namak Drainage Basin, at first the probability density function (pdf) of daily flows and sediment rating curves was plotted, after that probability density function of suspended sediment was constructed by multiplying the coefficient of sediment rating curves with pdf of daily flows. Then its recurrence interval was estimated by Vibul's method. The results showed that there are not any similarities between Qeff and Q1.5, and the ratio of Qeff to Q1.5 ranged from 1.03 to 16.8. Therefore more research is required to reach more certain result.
Hossein Kheirfam; Seyed Hamidreza Sadeghi
Abstract
Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was ...
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Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was carried out in order to design a bed load sampler based on the conditions prevailing in the mountainous rivers flumes. The sampler with dimensions of 120 cm length, 60 cm height and 60 cm width was designed and subsequently fabricated. The accuracy of sampler was evaluated through comparing the bed loads estimations made by the designed equipment and those measured by collecting the whole discharged runoff to a 300 liters water tank installed at the outlet flume and with the help of statistical criteria. The t-test, relative erorr (RE) and relative bias (RBIAS) criteria were then used for statistical analyses. The results showed that the mean mesured bed load by water tank and designed sampler were 0.00635 and 0.0064 gl-1, respectively with no siqnificant differece (p<0.0763). In overall, the designed sampler had a high accuracy and efficiency in river bed load measurement with relative erorr and relative bias of about 8.5% and 0.107, respectively.
Mojtaba Saneie
Abstract
Spur dikes are used widely to prevent outer bank river bends and path-modification river projects. Local scouring in spur dile nose is due to contraction and strong eddy is among the important problems occurring in designing Super dikes. Experimental study has been done on effect of length and alignment ...
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Spur dikes are used widely to prevent outer bank river bends and path-modification river projects. Local scouring in spur dile nose is due to contraction and strong eddy is among the important problems occurring in designing Super dikes. Experimental study has been done on effect of length and alignment of minor spur dike to reduction of main spur dike scouring. In order to do this study a shorter spur dike was used in two stages, one perpendicular and one angled to flow channel direction. By non dimensional parameters, contraction ratio L/B=0.3, 0.35, 0.4, 0.45, (L=length of spur dike, B=width of channel), Length ratio L’/L=0.5, 0.6, 0.7, (L’= length of minor spur dike) and distance ratio x/L=0.5, 1, 1.5, 2, 2.5 have been studied. Scour depths at nose of minor and main spur dike have been measured. Data collection were fitted by regression analysis and a relation for reducing scour depth at nose of first spur dike is provided, with and without minor spur dike.
Mahshid Souri; Khadijeh Tork; Omolbanin Bazrafshan
Abstract
Site selection is the most significant and fundamental process in dam construction. Site selection of dam is one of the most important and effective steps of project implementation. Optimal site selection impacts on reducing the costs of dams establishing. Today, this matter is considered by managers ...
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Site selection is the most significant and fundamental process in dam construction. Site selection of dam is one of the most important and effective steps of project implementation. Optimal site selection impacts on reducing the costs of dams establishing. Today, this matter is considered by managers and decision makers. So, different methods apply to site selection. Different parameters are important in text of site selection such as the sub-basins characteristics and hydraulic characteristics. This research determined the optimal location of stone–mortar dams implementation based on nine effective criteria in ten sub-watersheds in Yakhlaqan Makoo region. In this research, criteria weighting was done by AHP method. Then in order to implement stone-mortar dams, Priority of sub-watershed is identified by TOPSIS and VIKOR methods. According to the results, efficient criteria of stone-mortar dams site selection were the catchment area and channel length with 0.191, 0.204 weights. While, the road distance and villages distance were the inefficient criteria with 0.033 weights. The results of both methods identified sub-basins D1, D and H as suitable sub-basins to site selection. The purpose of this research was introduction of the decision support system techniques in identifying and ranking suitable sub-basins in the feild of stone-mortar dams' site selection.
Marzieh Hajimohammadi; Abolfazl Azizian; Bagher Ghermezcheshmeh
Abstract
Knowledge of climate variabilities and their behavior in future periods and their effects in various fields has great importance especially in strategic and macro planning in water resources. This study aims to evaluate the effect of climate change on hydrological condition of the Kan Watershed. For ...
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Knowledge of climate variabilities and their behavior in future periods and their effects in various fields has great importance especially in strategic and macro planning in water resources. This study aims to evaluate the effect of climate change on hydrological condition of the Kan Watershed. For this purpose the HadCM3model under the A2 emission scenario and also statistical downscaling model (SDSM) were applied for temperature and rain variables simulation. Then, SWAT model was used for monthly runoff simulation and SUFI-2 algorithm was used in SWAT-CUP software pack for calibrating and uncertainly analyzing. The performance of SDSM model was evaluated base on MBE and NRMSE parameters, the result indicated that temperature variable was simulated more accurate than of precipitation. The result of the predicting temperature in period (2011-2040) compare with the base period (1961-2001) showed the maximum and minimum temperature will increase by 1.3 and 0.8 °C, respectively. Also, the rainfall will decrease by 3-4 percent for all of selected stations. The most rainfall reduction will be for spring. While in some months of winter an increase of precipitation was predicted. The result of calibration and validation of SWAT model agreed well with the observed data, so that Nash-Sutcliff efficiency coefficient, as objective function, was 0.82 and 0.71, in calibration period (1983-1991) and validation period (1992-1996) respectively. Finally, results of runoff prediction showed an increase in winter and a decrease in other seasons based on climate scenarios. Overall, according to obtained results runoff will decrease by seven percent for future period.
Ali Shojaeian; Sara Amouzegar; Sajjad Jokar
Abstract
The morphological and geomorphological characteristics of rivers are constantly changing due to their continuous nature. In this research, the geomorphology of a part of Karun River in relation to the changes leading to meandering has been studied using satellite data and with a "descriptive-analytical" ...
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The morphological and geomorphological characteristics of rivers are constantly changing due to their continuous nature. In this research, the geomorphology of a part of Karun River in relation to the changes leading to meandering has been studied using satellite data and with a "descriptive-analytical" methodology. For this purpose, first the cell values of different bands of TM images (related to 1991) and ETM (related to 2002 and 2010) were weighted using fuzzy hierarchical analysis method to detect the bands showing the most changes compared to other bands. Then, from the weighted bands, the main components of the corresponding bands TM 1991 and ETM 2010 (as the beginning and end years of the studied period) were extracted and finally, by defining the fuzzy membership of the changes, the regions with the highest amount and intensity of changes in five The floor is provided. The results show that bands 7 and 5 show the most weight changes (river area) among the other bands for the images of 1991, 2002 and 2010, respectively. On the other hand, the fuzzy membership function of the changes showed that the maximum changes with intensity of zero to 20%, with values of 149 square kilometers including 48.3% and also the minimum changes with intensity of 80 to 100% with values of 8.2 square kilometers including 2.6% of the total study area. Therefore, from the study area of Karun, an area of eight square kilometers (about 3% of the total area evaluated) has experienced the intensity of changes above eighty percent and about 20% of the area with an intensity factor of fifty percent or more, prone to meandering or about to.
Sattar Chavoshi; Mohammad Reza Yazdani; Abdorasoul Telvari
Volume 1, Issue 3 , October 2009, , Pages 153-159
Abstract
Flood risk estimation is one of the most important subjects for Hydrologists. The main objective of flood risk estimation is study on past events in order to determine the following flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations are the most ...
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Flood risk estimation is one of the most important subjects for Hydrologists. The main objective of flood risk estimation is study on past events in order to determine the following flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations are the most recently used methods. In these methods, rainfall is the main parameter influencing flood mechanism. In this research, spatial distribution of rainfall pattern in Esfahan province is studied. Esfahan province with 10.5 million ha area is located in central part of Iran with different topography, climate and ecological condition. A number of 203 rainguages, located in the study area and nearby, were studied. Recorded data of 32 years, from 1968-2000 and a total number of 1654 storm events with less than 1 hour to 72 hours duration were investigated and three index events, i.e. widespread and maximum events, were used. The common methods of geostatistics like kriging, Co-kriging, IDW and TPSS were applied to interpolate the recorded points to non-observed ones. Results showed a low correlation between rainfall and elevation in the study area. Among the studied interpolation methods, kriging showed the best results, from which the Gussian and Spherical models best fitted to the observed points. In order to gain best results, it is recommended to add the number of rainfall gauge sites according to the World Meteorological Organization (WMO) standards. Also, grouping the study area into homogeneous regions and studying DAD in each homogeneous region is advised.
Ali Jafari; Davood Nikkami; Esmail Abbasi; Fateme Tavakoli Rad
Abstract
Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. ...
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Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. The main objective of this research was determining the optimal level of land use to increase the income of residents and reducing the effect of erosion in the Sana Dam Watershed. To apply an optimal pattern of land used for minimizing soil erosion and maximizing land income by a multi-objective programming model, optimal scenarios were chosen proportion to the shape of objective functions and constraints. For this purpose a linear programming model was used for three different scenarios of a) present land use conditions b) present land use condition with some applied land use management and c) standard land use conditions according to principles and scientific criteria. The results showed that present land use is not in optimal level and should be changed. Also, results demonstrated that the amount of soil erosion could be decreased by 5.3, 31.7 and 43.4 percent and the amount of net income could be increased by 47.73, 242.57 and 242.57 percent by land use optimization in present land use conditions, present land use condition with some applied land use management and standard land use conditions, respectively.
Ahmad Mokhtari; kourosh shirani; Navid Moslemzadeh
Abstract
Extended abstractIntroductionSegzai plain, 40 kilometers from Isfahan city, with an area of about 40,000 ha, is considered a serious threat to this historical city. This plain, which until a few decades ago was a relatively prosperous reed and meadow, has now become a huge danger in terms of nature destruction ...
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Extended abstractIntroductionSegzai plain, 40 kilometers from Isfahan city, with an area of about 40,000 ha, is considered a serious threat to this historical city. This plain, which until a few decades ago was a relatively prosperous reed and meadow, has now become a huge danger in terms of nature destruction and environmental pollution. Two natural and human factors play a role in the desertification of this region. Among the natural factors are low rainfall, high evaporation, the presence of limiting layers in the soil and strong winds and from human factors, excessive grazing and overgrazing of livestock as well as bush-cutting, rapid population growth and excessive exploitation of existing resources decline Underground water and most importantly, exploitation of surface mines, especially gypsum mines, can be mentioned. The main goal of this research was to evaluate the effectiveness of the SEBAL model for estimating the actual evaporation and transpiration of the Segazi Plain, considering the arid and semi-arid location of the region using the landsat 8 image. Materials and methodsTo do this research, first, landsat 8 images were processed. Extraction of required information from satellite images in this research was done during three main stages, i.e. pre-processing, processing and post-processing. In other words, in the pre-processing stage, after performing atmospheric, geometric and other necessary corrections, the image was referred to the ground. In the area of data processing, different highlighting methods and statistical analyzes and remote sensing were done in order to achieve the information layers of the plan. In order to evaluate the results in the image processing stage, the post-processing of the data based on various analyzes was used to evaluate the reliable layers in terms of accuracy and precision. After that, the SEBAL algorithm was implemented. first the amount of net radiation (Rn) was calculated according to the temperature of the earth's surface and vegetation and the amount of energy reaching the earth, then the heat flux of the soil (G) was obtained to determine the amount of transfer capability The heat into the soil was determined, then it was determined to calculate the amount of sensible heat flux (H), which determines the loss of energy from the soil to space. Finally, after determining the sensible heat flux, evaporation and transpiration were calculated. The SEBAL algorithm calculates the energy balance equation in order to calculate the actual evaporation and transpiration of the plant. Results and discussionSurface albedo parameters (the highest and lowest weighted values are around 0.85 and 0.16), soil surface temperature (the highest and lowest weighted values are around 326 and 299 degrees Kelvin), NDVI vegetation index (the highest and lowest weight values related to areas with good vegetation close to +1 and related to water and water bodies close to -1), the amount of net energy reaching the surface of the earth (the highest and lowest weight values are about 703 and 210 Wm-2, soil heat flux (the highest and lowest weight values are about 130 and 35 Wm-2), sensible heat flux (the highest and lowest weight values are about 323 and 23 Wm-2 , momentary evaporation and transpiration (the highest and lowest weight values are about 0.842 and 0.225 mm) and daily transpiration evaporation (the highest and lowest weight values are about 20.2 and 5.4 mm) are among the most important effective parameters in this Sabal algorithm which were investigated in this research. Changes in actual transpiration evaporation (the highest weight values about 0.85 mm and the lowest weight values about 0.16 mm). The obtained results showed that the SEBAL model has well predicted evaporation and transpiration in areas that have vegetation, mostly agriculture and gardens, so that the amount of water loss through evaporation has been predicted close to the values found in the eastern synoptic station of Isfahan (airport Shahid Beheshti) is registered. ConclusionThe amount of error obtained in SEBAL calculation was 0.1%. The amount of real momentary evaporation and transpiration has been calculated in the range between 0.22 and 0.84 mm, according to the weather conditions of the region and the temperature of the air near the surface (27 to 50 degrees) and the amount of evaporation and transpiration recorded by the Penman-Monteith equation (30.0 mm in the east of Isfahan synoptic station), this value is in a reasonable range. Comparing the outputs of Sabal model with the amount of evaporation and transpiration obtained in the same station, which shows the root mean square error (RMSE) value of 0.1, indicates the suitability of this algorithm in calculating evaporation and transpiration in Segazi region. Considering the growing need of the country to prevent the wastage or excess consumption of water in the agricultural sector, either through changing the cultivation pattern or changing the irrigation methods, the application of the developed tool of the Sabal algorithm in this research can provide valuable information to the experts and managers of the water sector put agriculture. The results obtained from this implementation of this research showed that remote sensing has a good potential for estimating actual evapotranspiration (ETA) by having different algorithms such as SEBAL algorithm and minimum ground information.
Mohammad Shabani
Abstract
Estimating instantaneous peak flow in watershed is one of the most important problems that cause hydrologists and experts to work seriously on it. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human ...
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Estimating instantaneous peak flow in watershed is one of the most important problems that cause hydrologists and experts to work seriously on it. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human brain to find the internal relation between data based on the training process. The objective of this study is to compare the efficiency of artificial neural network method and experimental methods for estimating instantaneous peak flow in Fars province watershed. For this purpose, 24 years of daily peak and instantaneous peak flow of seven hydrometric stations were considered and tested for outlier data. Then the estimation was done based on experimental methods including Fuller, Sangal and Fill-Steiner and artificial neural network method and were compared based on RMSE, MAE and R2. Results showed that estimation of artificial neural networks is more accurate than experimental methods in all stations which indicated the lower errors of artificial neural network method compared with experimental methods.
Mohammad Shabani
Abstract
Selection and accuracy of the appropriate methods for zonation and preparing the map of groundwater quality parameters depend on regional condition and availability of data which is an important stage for groundwater management of the region. The purpose of this research is determining the most suitable ...
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Selection and accuracy of the appropriate methods for zonation and preparing the map of groundwater quality parameters depend on regional condition and availability of data which is an important stage for groundwater management of the region. The purpose of this research is determining the most suitable interpolation method for determining salinity (EC), nitrate (NO3), pH and total dissolved salts (TDS) parameters of groundwater and mapping of them by using of geographic information systems in Neyriz plain located in southeast of Fars province. For this aim, different methods of geostatistics including ordinary kriging (OK) and simple kriging (SK) as well as deterministic methods such as inverse distance weights (IDW), radial basis function (RBF), local polynomial interpolation (LPI) and global polynomial interpolation(GPI) were used. The result based on the lowest root mean squared error (RMSe) and mean absolute error (MAE) showed that simple kriging (SK) method is the most appropriate method for salinity (EC) mapping (RMSe=3907.53 and MAE=2911.05), TDS mapping (RMSe=2587.19 and MAE=1936.48), pH mapping (RMSe=0.196 and MAE=0.143) and NO3 mapping (RMSe=4.868 and MAE=3.839) among all the methods in the study area. Finally, the results of this research indicated that geostatistical methods have higher priority than deterministic methods and thus are selected as suitable methods in Neyriz plain.
Seyed Mahmoud Reza Tabatabaei; Mohammad Roghani
Volume 2, Issue 4 , January 2011, , Pages 197-205
Abstract
In calculation of catchments time of concentration, TC, lump equations are often used. Therefore, TC is not accessible for different parts of the catchments. In this research, using object oriented programming in the GIS environment a fully distributed model has been designed and developed. The model ...
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In calculation of catchments time of concentration, TC, lump equations are often used. Therefore, TC is not accessible for different parts of the catchments. In this research, using object oriented programming in the GIS environment a fully distributed model has been designed and developed. The model is able to calculate the time of concentration for any parts of the catchment to its outlet in a raster map. Model input layers are DEM, rainfall intensity, Manning’s roughness coefficient and catchment stream network. The most important outputs of the model are slope, flow direction and flow accumulation layers and isochronal surfaces. In the presented model, catchment cells are divided into two basic classes including channel cells and overland flow cells. Kirpitch and Kinematic wave equations have been used to calculate the time of concentration for the channel and overland flow cells respectively. In addition, rainfall-runoff hydrologic software, RAFTS-XP, has been used to evaluate the accuracy of TC model results. The result of TC model shows that calculated travel time had suitable synchronization to real time, which has been estimated using observed events and the calibration of RAFTS-XP. Considering the point that catchment response for all events which used by RAFTS-XP is based on different rainfall intensities with identical time of concentration, so observing different behaviors in flood hydrographs seems reasonable.
Hamed Nozari; Sahar Alsadat Razavian; Seyed Moezeddin Nabavi Hamedani
Abstract
In order to reduce the losses caused by floods and economize flood control projects in an area, construction of appropriate structures and operating watershed practices in areas with high risk of flooding is essential. One of the approaches to identify high risk flooding regions is watershed simulation ...
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In order to reduce the losses caused by floods and economize flood control projects in an area, construction of appropriate structures and operating watershed practices in areas with high risk of flooding is essential. One of the approaches to identify high risk flooding regions is watershed simulation and evaluation of sub-watersheds participation in outlet discharge. In this research, hydrological units of Hamedan-Bahar basins were simulated using ArcGIS and HEC-HMS hydrological model. Then, flooding indexes were calculated and their changes in all sub-basins were mapped.Effective hydrological units on peak discharge were identified and prioritized for watershed management, by reviewing and comparing these indexes. Site selection of flooding indexes showed that Bahador Beyg and Qareh Aghaj sub-basins had the highest and the lowest effect on flood peak, respectively. Analyzing results demonstrated that sub-basins with large areas or with huge amount of runoff not necessarily cause more effect on flood peak. Performance of management practices and construction of suitable hydraulic structures in studied hydrological units efficiently reduce flood damages in Hamedan-Bahar basin.
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.
Farhad Shiva; Jalal Attari; Mojtaba Saneie
Abstract
Scour phenomena can impair infrastructures and result in non-reparable damages. Few researches conducted so far show that application of non-cohesive criteria for situations where the bed is formed of cohesive materials, overestimates dimensions of the scour hole and will impose large costs to the project. ...
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Scour phenomena can impair infrastructures and result in non-reparable damages. Few researches conducted so far show that application of non-cohesive criteria for situations where the bed is formed of cohesive materials, overestimates dimensions of the scour hole and will impose large costs to the project. According to the previous researches, type and content of clay also significantly affects scour in the cohesive materials. In this paper, the local scour in the cohesive bed due to a horizontal submerged jet issued from a vertical sluice gate is experimentally studied. Initially, the effective factors were identified and Bentonite clay was selected as cohesive material. A total of 48 tests, considering four different clay contents, three amounts of gate openings and four different tailwater depths, were conducted in a rectangular flume of Soil Conservation and Watershed Management Research Institute laboratory. The results show that by adding Bentonite clay to the erodible bed, effect of cohesion appears in the 10% ratio and with further increase of the clay content the scour depth decreases considerably. So that in a bed containing 20% Bentonite clay the maximum scour depth reduces by 76% on average in relation with a non-cohesive bed. Based on the experimental results, a general equation for predicting the maximum scour depth valid in both conditions of presence and absence of the cohesive materials is presented. A sensitivity analysis on the existing parameters that effect on scour depth was conducted and compared with the results of previous researches. Finally, two types of scour hole profiles were defined which showed a relatively good agreement with previous empirical relationships.
Ali Bagherian Kalat; Gholamreza Lashkaripour; Mohammad Ghafoori; Naser Hafezi Moghadas; Gholamali Ghazanchian; Reza Ghafoorian
Abstract
In recent years, activities on trout fish farming is developed significantly in Ortakand River. Fish production may have huge impact on the river ecosystem if an environmental rule is neglected. This research was carried out in Ortakand River in Kalat city in Khorasan Razavi with the aim of investigation ...
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In recent years, activities on trout fish farming is developed significantly in Ortakand River. Fish production may have huge impact on the river ecosystem if an environmental rule is neglected. This research was carried out in Ortakand River in Kalat city in Khorasan Razavi with the aim of investigation of fish production projects effluent effect on the river water quality. Two fish farms and seven stations were selected and during one year in each season, water samples were collected. The samples were analyzed in the laboratory for determining some physic-chemical and biological parameters of water samples. The results showed that the average of these parameters were within a range between 13.3-15 °C of temperature, 7.9-8.1 of pH, 354-732 mmhos/cm of EC, 8.4-9.6 mg/L of DO, 1-3.7 and 2.5-13.9 mg/L of BOD5 and COD, respectively. The results showed that BOD5 and COD concentration had a significant increasing toward upstream (p<0.01), spatially. Meanwhile, amount of DO showed a significant decrease (p<0.01), temporaly. This research revealed that changes in concentration of BOD5, COD and DO were dominantly due to fluctuations of environmental conditions and activity rates of the farms. Although, the amount of COD and BOD5 in fish farms effluent in current situation are less than the standard environmental amount, but environmental impacts could be increased by activities of new fish farms,.
