Heidar Ghafari; Mahmood Arabkhedri; Manouchehr Gorji
Abstract
Tolerable soil erosion is the boundary between natural and accelerated erosion and is one of the most fundamental yet complex issues in soil erosion research. The tolerable erosion threshold is an essential criterion for awareness and judgment about the state of soil erosion and the extent of its potential ...
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Tolerable soil erosion is the boundary between natural and accelerated erosion and is one of the most fundamental yet complex issues in soil erosion research. The tolerable erosion threshold is an essential criterion for awareness and judgment about the state of soil erosion and the extent of its potential economic, social and environmental risks and damages. Therefore, it is very important to determine it accurately and correctly using appropriate methods. For this purpose, various methods have been developed, which can be divided into three general groups including methods based on soil formation rate, methods based on agricultural soil productivity and methods based on off-site effects of erosion. First, the details of the various methodologies along with their disadvantages and advantages were examined, and finally, research challenges and opportunities in this field were presented. Various scientists in recent years have emphasized the need for comprehensiveness in determining tolerable thresholds, but existing methodologies have so far failed to achieve this, and are still at the beginning of the road. Thus, the main challenges and opportunities are mainly related to methodology and the presentation of new integrated and applied approaches to determine tolerable erosion.
Aliakbar Noroozi; Ziaoddin Shoaei
Abstract
Wind erosion is one of the important processes of desertification in arid and semi-arid regions. This process causes destruction in the land, soil and water resources and etc. Dust phenomenon is one of the major consequences of wind erosion in the world and Iran, particularly in the west and south west ...
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Wind erosion is one of the important processes of desertification in arid and semi-arid regions. This process causes destruction in the land, soil and water resources and etc. Dust phenomenon is one of the major consequences of wind erosion in the world and Iran, particularly in the west and south west of the country. Therefore, the present study aimed to identify areas of dust generation potential in the Khozestan, Iran using the combination of statistical methods, remote sensing and modeling. The statistical results showed that the most frequent occurrence of this phenomenon happened between 2008 and 2009. Most dust events happened in the seasonal scale, late spring and early summer and in the monthly scale, happened in May, June and July. Dust detection on satellite images and study their concentration using indicators AOD and BTD represents the greatest concentration of dust in the west and south west regions of the Khuzestan province, since 80 percent of these dust occurred in these zones. Tracking of dust showed that during the warm period, most dust happened from north west-south east and west-east and during the cold period, especially at the end of period, the northern-southern dust affected the province. The assessment of land use change showed the reduction in the irrigated areas, vegetation and arid lands increased in 2015, especially for the half of area of western Khuzestan. These features and physiographic features such as erodible formations, saline soils and marshy, low soil moisture and high changes in land use, indicates the presence of dust prone areas and potential for west and southern province.
Farzad Heidari; Razieh Saboohi
Abstract
Marl formations have problems in watersheds due to high sediment yield. The purpose of this research is the marls classification of Isfahan province according to erodibility indices and their physical and chemical properties. In this regard, region marl units were identified and their sediment yield ...
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Marl formations have problems in watersheds due to high sediment yield. The purpose of this research is the marls classification of Isfahan province according to erodibility indices and their physical and chemical properties. In this regard, region marl units were identified and their sediment yield was measured using rainfall simulator. Then, based on erosion type, they were sampled and soil physical and chemical properties were analyzed. Cluster analysis statistical method was used to classify marl units. Statistical analysis was performed by three sets of data including chemical, physical and both chemical and physical accompanied by slope and measured sediment from six mmh-1 rainfall in each step of the analysis. Results showed that the most important similarity factors in marls are chemical properties and the effect of climate. According to information obtained from investigations, climate is the most effective factor of differences among marl units in this province. In addition to its direct impact on creation and evolution of marls, it affects on other parameters directly and indirectly and choosing either of these parameters is related to climate.
Kamal Nabiollahi; Ahmad Haidari
Abstract
Arsenic has been recognized as a toxin element for human. Minerals frequency can affect on arsenic content and Sufficient mineralogical characterization of contaminated sites should assist geochemical models that assess the potential of natural attenuation remediation of a subsurface contaminated with ...
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Arsenic has been recognized as a toxin element for human. Minerals frequency can affect on arsenic content and Sufficient mineralogical characterization of contaminated sites should assist geochemical models that assess the potential of natural attenuation remediation of a subsurface contaminated with arsenic. In order to mineralogy investigation in the arsenic soil in Bijar area, 83 profiles were selected based on the prepared geopedology map and 229 soil and 15 parent material samples were collected. Routine physical and chemical characteristics and soil arsenic contents were measured in all samples. Relative quantity and types of clay and powder minerals were determined for 35 soil and 15 parent material samples by XRD analysis. Smectite, illite, kaolinite, chlorite and vermiculite were the most important clay minerals in the region. enargite, arsenoilte, sphalerite, nicoolite, conichalcite, arsenosulvanite and cobaltite based on the powdery mineralogy results were the most important arsenic bearing minerals in the region. The type and content of minerals were different and their content were higher in the profiles with very high arsenic. In the mudston and Fe-rich rock arsenic concentration are higher compared to the other parent materials. Also the minerals content were higher in the mudston and Fe-rich rock compared to the other parent materials.
Atefeh Davari Dolatabadi; Akbar Ghazifard; Kourosh Shirani; Farzad Heidari Morche khorti
Abstract
East of Isfahan City, especially around Segzi Plain is one of the desert areas of the country that due to the flatness and soils sensitivity to wind erosion, there is high susceptibility to wind erosion. The aim of this study is to evaluate the possibility of using saline water of Segzi Plain and its ...
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East of Isfahan City, especially around Segzi Plain is one of the desert areas of the country that due to the flatness and soils sensitivity to wind erosion, there is high susceptibility to wind erosion. The aim of this study is to evaluate the possibility of using saline water of Segzi Plain and its effect on the soil strength properties, crust formation and its stability against wind erosion. In order to conduct this research, five soil samples with different textures were collected from top soil surface and were transferred to the laboratory along obtained saline water sample from surface aquifer. After determining some of the physical and chemical properties of samples, they were examined in wind tunnel with specified velocity for soil erosion tests. The first soil sample was flooded with saline water and the rest were treated with either spraying of undiluted saline water or spraying of diluted saline water with 2 to 1, 1 to 1 and 1 to 2 ratios of saline water to water. In this regard, parameters such as salinity of saline water, erosion threshold velocity of dried treated soil samples, maximum dry density, thickness, strength and sieve analysis of the crusts were determined. The results indicated that, as the salinity of saline water increases, the strength, thickness and maximum dry density of forming crust and wind erosion threshold velocity also increases in the model. Analysis of variance used to investigate the effects of soil texture, salinity of saline water, crust thickness and threshold velocity to control wind erosion showed significant difference in 1% level. Sample C1 with the highest percentage of fine grains had threshold velocity of 11 m.s-1, but sampleE1 with the lowest percentage of fine grains had threshold velocity 6.23 m.s-1. The presence of a high amount of sodium makes restrictions on the possibility of using saline water as mulch scientifically and practically but the results showed that the use of saline water can increase the density of dirt roads.
Mohammad Hossein Jahangir; Keyvan Soltani; Ahmad Nohegar; Seyed Javad Sadatinejad
Abstract
Evaporation as a natural parameter due to the release of water from the upper part of mankind has always been of interest to scholars and researchers. In this study, we try to apply the artificial neural network model to estimate evaporation from the Amir Kabir dam and to evaluate the model accuracy. ...
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Evaporation as a natural parameter due to the release of water from the upper part of mankind has always been of interest to scholars and researchers. In this study, we try to apply the artificial neural network model to estimate evaporation from the Amir Kabir dam and to evaluate the model accuracy. In this context, 18 years data from 1997 to 2014 were used and after consecutive try and error, the best structure for computing the amount of evaporation from the surface of the dam was selected. This structure has five neurons in the first, fourth and second layers that showed the best result in 1000 replications. Also, statistical coefficients obtained from the analysis using artificial neural network was considered in choosing the best structure with the amount of 0.9365 which was the highest amount among other tests and the amount of test and training data error were 0.0321 and 0.0311, respectively. In addition, general trend of effective data on evaporation was determined, using Mann-Kendall test on 15 years daily data. In Mann-Kendall method, temperature changes, wind speed and precipitation graphs had no significand trend and showed -1.69< U
Amin Salehpour Jam; amir sar reshtedari
Abstract
Investigation of desertification trend needs an understanding of phenomena creating changes alone or action and reaction together in the manner that these changes end up in land degradation and desertification. In investigating pedological criterion affecting on land degradation in alluvial fans, first, ...
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Investigation of desertification trend needs an understanding of phenomena creating changes alone or action and reaction together in the manner that these changes end up in land degradation and desertification. In investigating pedological criterion affecting on land degradation in alluvial fans, first, maps of slope classes, land use and geology were created, then a map of units was founded by overlaying and crossing these maps and grid layer created by extension of ET GeoWizards in ArcGIS 10.3 software. In this research, three indices of erodibility, salinity and permeability of soil were considered, finally each was shown in the shape of classified map. Then, weights of criteria and consistency ratio were calculated by AHP method. In this research, VIKOR method was used to prioritize the options. Results showed that the VIKOR index obtained from AHP-VIKOR technique alters from 0.002 to 1.000. Units of V1 and V10 with VIKOR indices of 1.000 and 0.002 have a maximum and minimum of desertification potential, respectively. The alluvial fans in research area were classified in two classes of I and IV from the view point of pedological criterion affecting on desertification using AHP-VIKOR technique, in the manner that 74.18 % of the area is in the low desertification potential, and 25.82 % is in the very high desertification potential, respectively.
Mahmoudreza Tabatabaei; Amin Salehpour Jam; Jamal Mosaffaie
Abstract
The proper estimation of the amount of suspended sediment in rivers has an important role in erosion and sediment studies, hydrology and management of watersheds. The simulation of suspended sediment in hydrological systems that has a lot of complexity and at the same time our understanding of the components ...
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The proper estimation of the amount of suspended sediment in rivers has an important role in erosion and sediment studies, hydrology and management of watersheds. The simulation of suspended sediment in hydrological systems that has a lot of complexity and at the same time our understanding of the components and processes within them is always uncertain led to the use of many intelligent models, including artificial neural networks (ANNs). However, the use of these smart models also faces challenges. Determining the proper structure of the network requires optimization of the parameters used (such as the optimal number of neurons and layers, weight and bias, and the type of activation functions), which their proper calibration, using test and error, leads to a lot of time spent in low efficiency. In this study, a multilayer perceptron (MLP) was used to simulate the daily sediment load of the Nirchai River at the site of the Nair hydrometric station in Ardebil province. In order to train the models, in addition to the error back propagation (BP) algorithm, Particle Swarm Optimization (PSO) algorithm was used to optimize the weight and bias of ANNs. The fuzzy clustering method was also used to increase the power of generalization of the models. The results showed that training of ANN models with PSO algorithm with decreasing estimation error (decreasing the PBIAS of estimation and root mean square error up to 0.3% and 10.4 tons per day respectively) is more effective than ANN models that use only error BP techniques. Due to insufficient recorded sediment data in most hydrometric stations of the country on the one hand and the need to train ANNs with sufficient data on the other hand, the use of evolutionary algorithms (e.g. PSO algorithm) can be a good solution for improving the efficiency of intelligent models.
Raziyeh Motamedi; Mahmood Azari; Reza Monsefi
Abstract
Landscape is one of the main factors influencing hydrological processes of the watershed. Changes in structure and spatial pattern of land use play important role in surface runoff and sediment yield. Determining the relationship between landscape patterns and hydrological processes can be used as an ...
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Landscape is one of the main factors influencing hydrological processes of the watershed. Changes in structure and spatial pattern of land use play important role in surface runoff and sediment yield. Determining the relationship between landscape patterns and hydrological processes can be used as an indicator of watershed soil erosion and sediment yield. Therefore, due to the problems in field measurement of sediment yield, its estimation using landscape properties and land use pattern is an appropriate alternative for current estimation methods. The purpose of this research is to determine the relationship between watershed sediment yield and landscape metrics in the selected sub-watersheds of Golestan Province. To this end, suspended sediment concentration data for all hydrometric stations of the studied province were obtained from the relevant resources and appropriate sub-watersheds were selected. Then, using the land use map of Golestan Province, 15 landscape metrics related to sediment yield were determined for different land uses by Fragstats 4.2 software. In order to determine the relationship between watershed sediment yield and landscape metrics, a partial least squares regression was used which combines the methods of principal component analysis and multiple linear regression. The relative importance of landscape metrics was determined through examining the values of Variable Importance for the Projection (VIP) and Regression Coefficients (RCs). The results of this study indicated that the watershed sediment yield is densely associated with land use patterns. The main indices in reducing sediment yield were the Largest Patch Index (LPI), the average of the nearest neighbor distance (ENN-MN) and the average of perimeter-area ratio (PARA –MN) with values of VIPs of 1.296, 1.184 and 1.747, and regression coefficients of -0.014, -0.039, and -0.002, respectively. The main indices in incrising sediment yield were Landscape Shape Index (LSI) and mean patch size (AREA-MN) with regression coefficients of 0.020 and 0.017, respectively. The landscape characteristics in watersheds could account for as much as 71% of the variation in sediment yield of watershed. The results of study showed that the landscape characteristics can be used for watershed sediment yield modeling.
Jalal Yarahmadi; Seyed Majid Mirlatifi; Ali Shamsoddini; Majid Delavar
Abstract
Evapotranspiration has a key role on spatial and temporal distribution of available water, as vital component of water balance. ET ground measurements at large scale has limitation, so, different methods have been developed to estimate actual ET based on remote sensing data. The purpose of this study ...
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Evapotranspiration has a key role on spatial and temporal distribution of available water, as vital component of water balance. ET ground measurements at large scale has limitation, so, different methods have been developed to estimate actual ET based on remote sensing data. The purpose of this study was to evaluate accuracy of actual ET estimation for MOD16, MYD16 and SSEBOP global database models in monthly and seasonal time scales for different land use and wet, dry and normal climate conditions at Karkheh Dam Basin. First, SWAT model was calibrated and verified based on data of hydrometric stations included: river discharge, base flow and aquifer storage. After ensuring the accuracy of SWAT model performance in estimating water balance components at the studied basin, simulated actual evapotranspiration values were used to evaluate the temporal-spatial accuracy of actual evapotranspiration data of global database models. Results showed that all three models underestimate actual evapotranspiration values with a significant difference from the SWAT model results. The RMSE and MBE values varied from 15 to 21.74 and -15.93 to -8.19 mm on a monthly scale and from 40.17 to 59.32 and -47.74 to -19.36 mm on a seasonal scale, respectively. The concordance between the actual evapotranspiration results of the global database models and the simulated SWAT model values in the dry year is lower than wet and normal years. Although the results of the SSEBOP model had less error than SWAT model, the actual evapotranspiration time variations of the MOD16 and MYD16 models were more consistent with the time series data of the SWAT model. The results also showed that in the dominant agricultural basins, the SSEBOP model and in the forest and pasture basins, the MYD16 and MOD16 models have less error.
Elham Mahmodzadeh; Sedigheh Anvari
Abstract
The accurate estimation of daily Evapotranspiration (ET) improves the efficiency of water resources management especially in areas where suffers from water scarcity. In the present study, ET was estimated using surface energy balance algorithm for land (SEBAL) and the experimental model of FAO-Penman-Monteith ...
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The accurate estimation of daily Evapotranspiration (ET) improves the efficiency of water resources management especially in areas where suffers from water scarcity. In the present study, ET was estimated using surface energy balance algorithm for land (SEBAL) and the experimental model of FAO-Penman-Monteith (FPM) and finally compared and verified with those calculated from pan evaporation method. Since many climatic factors affect the ET values, the sensitivity analysis of SEBAL inputs variables was finally cerried out to determine the key affecting parameters. In this regard, by SEBAL model and emplying the satellite data of Landsat 8 (OLI and TIRS sensors), the ET values were estimated on a daily scale for the time period 2018/07/25 to 2018/09/11. Results of SEBAL model showed that the values of SEE, RMSE and R2 indices were equal to 1.27, 0.76 and 0.77 mm /day and 0.91, 0.6 and 0.92 mm /day, while compared with those of FPM and pan evaporation methods, respectively.
Kiyoumars Roushangar; Saman Shahnazi
Abstract
In most water resources studies, the bed load transport rate is considered as a constant proportion of total load due to the difficulty and costs associated with measuring of it, which is not reasonable due to the high variability of this ratio. In this study, data collected from 19 coarse-grained rivers ...
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In most water resources studies, the bed load transport rate is considered as a constant proportion of total load due to the difficulty and costs associated with measuring of it, which is not reasonable due to the high variability of this ratio. In this study, data collected from 19 coarse-grained rivers in the United States were employed to predict bed load, total load transport rates and the ratio of bed to total sediment load using Support Vector Machine which is a branch of intelligent methods. Next, the results were compared and evaluated with classical methods. Results showed that this method has a very high performance compared to the classical methods and performance criteria in predicting the bed to total sediment load ratio has acceptable results. In addition, the modeling showed that the ratio of average velocity to shear flow velocity and the Froude number is the most effective parameters in predicting bed load, total load and the ratio of these.
Abstract
Homogeneous sub watershed Are useful for comparison and better understanding of the complex structure of watershed and thereby facilitating the development and management approaches specific to each class to deal with the destructive phenomena such as soil erosion, drought and flood. In this study, the ...
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Homogeneous sub watershed Are useful for comparison and better understanding of the complex structure of watershed and thereby facilitating the development and management approaches specific to each class to deal with the destructive phenomena such as soil erosion, drought and flood. In this study, the database contains 6 groups of information such as climatic and socio-economic, topography, soil, water, remote sensing were studied.These Factors converted to raster and then the pixel data converted to text data (ASCII). So matrix was produced with dimensions of 27 * 147 506. Eigenvalues and the variance associated with each factor showed that 6 first component includes a total of 83.27% of the changes. In order to select the optimal number of clusters and clustering evaluation and validation of the method, hierarchical clustering and discriminant analysis and clustering using k- mean cluster of the data was performed. Karoon Sub watersheds were classified into 16 groups.
Mohsen Farzin
Abstract
The aim of this study was to investigate the ability of different supervised and unsupervised classification algorithms of remote sensing data for detecting and separating of land cover on Beshar River Basin using Landsat 8 data. For this purpose, after checking the geometric accuracy and radiometric-atmospheric ...
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The aim of this study was to investigate the ability of different supervised and unsupervised classification algorithms of remote sensing data for detecting and separating of land cover on Beshar River Basin using Landsat 8 data. For this purpose, after checking the geometric accuracy and radiometric-atmospheric corrections on satellite data, the data set was created to the combination of spectral bands (bands 2, 3, 4, 5, 6, 7 and 8) and thermal (band 10). Next, pixel-based classification using supervised algorithms including maximum likelihood, support vector machine, mahalanobis distance, minimum distance, neural network, parallelepiped, spectral angle mapping, spectral information divergence, binary coding, and unsupervised algorithms including K-Means and IsoData was done. The accuracy of the algorithms for identifying each land use /land cover based on the error matrix analysis was evaluated using the producer's accuracy, user accuracy and overall accuracy based on the omission and commission errors, and the kappa coefficient. The results showed that the most appropriate algorithm for separation and identification of land use/land cover including agriculture, construction, cliff, forest, orchard, rangeland, water body and fallow is maximum likelihood, mahalanobis distance, maximum likelihood, mahalanobis distance, neural network, support vector machine, support vector machine, and maximum likelihood, respectively. The percentage of overall accuracy and Kappa coefficient shows that the four algorithms including maximum likelihood, support vector machine, mahalanobis distance and neural network with overall accuracy 77.25, 75.9, 69.59, 68.26 and the Kappa coefficient 0.72, 0.69, 0.63, 0.58, respectively, is better than other algorithms. Generally, the integration of appropriate classification algorithms in mountainous areas increases classification accuracy and will have better results.
Hossein Kheirfam; Behzad Kheirfam; Yaaghoub Azhdan; Saleh Hossein
Abstract
Variability analysis of river sediment transport in different temporal and hydrological conditions is important in hydraulics and hydrological science and engineering. Otherwise, behavior analyzing of the riverian systems at the different temporal conditions is necessary in managerial decisions to control ...
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Variability analysis of river sediment transport in different temporal and hydrological conditions is important in hydraulics and hydrological science and engineering. Otherwise, behavior analyzing of the riverian systems at the different temporal conditions is necessary in managerial decisions to control and reduce sediment transport. However, knowledge about the type and amount of sediment in watersheds in various temporal and hydrological conditions is limited. Therefore, this study aimed to investigate the variability of bed and suspended load and bed to suspended load ratio. The 6-years period (1998-2003) data of bed and suspended load (g l-1) and discharge (m3 s-1) were collected from Yazdekan station of Qotour Chay River. The analyses also were carried out in Excel 2007 software. The results indicate that discharge increasing caused that the suspended load was increased and the bed to suspended load ratio was decreased at all seasons. As well, the lowest and highest bed and suspended load transport were occurred at the winter and spring, respectively. Amounts of minimum, maximum and median bed to suspended load ratio at spring, summer, autumn and winter were 5.02, 563.99 and 27.34%; and 0.075, 2034.91 and 135.80%; and 28.31, 659.15 and 184.94%; and 28.96, 457.61 and 169%, respectively. Also, during the study period the bed to suspended load ratio was varied about 0.7 up to 2034%. Therefore, using indirect methods to estimate sediment is not accurate because of complex behavior of sediment particularly bed load and bed to suspended load ratio with discharge. By and large, it is necessary that daily bed load measuring in sediment gauges.
Sedigheh Mohamadi
Abstract
With regard to financial and technical problems normally measured sediment data are limited in developing countries; therefore a model that uses water discharge data as input can be a reliable option for estimates of sediment. Due to widely application of the variety of models to predict the suspended ...
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With regard to financial and technical problems normally measured sediment data are limited in developing countries; therefore a model that uses water discharge data as input can be a reliable option for estimates of sediment. Due to widely application of the variety of models to predict the suspended sediment, this study aims to determine optimal prediction model based on the amount of discharge flow gauging stations of Halilrood River including, Soltani, Henjan, Cheshmeh Aroos, Meydan and Konaruiyeh. In this regard, efficiency of some rating curves models including one-linear, two-linear and the intermediate categories ones (by and without coefficients as CF1, CF2 and FAO) and black box models including artificial neural networks and neural-fuzzy in modeling sediment were evaluated. The results of the evaluation of the model using the parameters of MAE and RMSE showed that neuro-fuzzy models in major hydrometric stations studied, including Pole Baft, Henjan and Konaruiyeh with an equivalent amounts of 35.07, 11958.74 and 34235.27 ton/day for MAE and 42.07, 28672.78 and 52735.92 ton/day for RMSE, respectively are the best models to simulate the suspended sediment. The artificial neural network model of radial basis function in Meydan with 384.83 ton/day MAE and 669 ton/day RMSE amounts is the optimal model. Also two-linear sediment rating curve resulted the best simulation in Cheshmeh Aroos Station with MAE and RMSE as 1.7 and 4.1 ton/day and one-linear sediment rating curve with CF1 correction in Soltani Station with MAE and RMSE 9723.2 and 41235.6 ton/day, respectively are the best. According to changes of efficiency of models with varying location of gauging stations, it can be concluded that ecological conditions and statistical community determine the optimal model of the suspended sediment simulation.
Anvar Sanaei; Mohammadali Zare Chahouki; Esmaeil Alizadeh; Omid Asadi Nalivan
Abstract
The aim of this study was to evaluate the effects of grazing intensity around water resources on vegetation characteristics. For arrive this goal, three water points selected in the Silve watershed of Piranshahr rangelands. Around of each water point two regions with 0-150 and 150-300 meter intervals ...
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The aim of this study was to evaluate the effects of grazing intensity around water resources on vegetation characteristics. For arrive this goal, three water points selected in the Silve watershed of Piranshahr rangelands. Around of each water point two regions with 0-150 and 150-300 meter intervals separated. In the four geographical direction and in each distance, a 150 m transect established (total 12 transects), and along of each transect with 15 m intervals a 1 m 2 plot was placed (total 240 plots). Sampling was done with random-systematically method, the list of exist species, canopy coverage, percent of species composition class I, II, III and number of individuals per species were recorded for each plot. Analysis of the data in factorial on the base of complete randomized block design and to calculate diversity, richness and evenness with past software was done. The results showed that there is significant difference (p<0.01) in percentage composition of class I, II, III, annual, perennial plants and total canopy cover. The highest composition percentage and density of the species Br. tomentelus (1.48 and 4.35 respectively) and Fe. ovina (1.12 and 3.44 respectively) was observed. Between water points except annual species composition percentage in the other studied properties there are significant difference (p<0.01). Maximum amount of Shannon wiener and Margalef index there are in second distance of third water point and were 2.18 and 4.10 respectively. The Pielou evenness index was non-uniformly in both distance and three water points.
Hamzeh Noor; Ali Bagherian Kalat; Aliakbar Abbasi
Abstract
Rangeland exclusion is one of the watershed management methods that is applied for range rehabilitation. However, most rangeland hydrology studies have been focused on exclusion effects on soil loss at plot scale, whereas their effects on sediment yield at micro-watershed in seasonal and annual scales ...
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Rangeland exclusion is one of the watershed management methods that is applied for range rehabilitation. However, most rangeland hydrology studies have been focused on exclusion effects on soil loss at plot scale, whereas their effects on sediment yield at micro-watershed in seasonal and annual scales have rarely been considered. The present study was conducted in two sub-watersheds under exclosure and open grazing treatments, with area of 1.0 and 1.1 ha, respectively, in Sanganeh Watershed, Khorasan Razavi Province, Iran. Runoff and sediment associated with 56 storm events occurred during 2006 to 2016 were estimated at the main outlet of the watershed. The results showed the significant decreasing effect of exclosure treatment on sediment yield at micro-watershed scale (p≤0.05). So that, 582% decrease in sediment yield was obtained in exclosure treatment compared to open grazing. Results also showed seasonal and annual variations of exclosure on hydrological processes so that, maximum and minimum differences in sediment yield among study treatments were founded. The results of this study suggest that livestock grazing management during sensitive seasons as well as rangeland exclosure, if its social problems are resolved, is a practical solution to reduce watershed sedimentation.
Rahim Kazemi; Forood Sharifi
Abstract
Watershed planning and management of water resources requires various data including base flow and its index. This parameter is influenced by Morphometric, geologic, hydrologic and climatologically factors and has always been one of the most important issues in hydrology. In this research, the Domarton ...
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Watershed planning and management of water resources requires various data including base flow and its index. This parameter is influenced by Morphometric, geologic, hydrologic and climatologically factors and has always been one of the most important issues in hydrology. In this research, the Domarton method was used to map the climate of Iran with the use of temperature and precipitation data. Then, using daily stream flow data and after controlling for time series, base flow and related index, using two parameter the recursive digital filter were extracted in selected catchments of six climatic zones including; arid, semi-arid, humid and semi-humid and very wet and Mediterranean. Hydrological and climatically parameters of the basins measured and physiographic factors were extracted in the digital environment. To identify independent factors affecting base flow, factor analysis were down using 14 parameters in each climate zone and then effective factors were analyses. The results showed that more than 80 percent of the variance of parameters was explained by selected parameters. The intrinsic factors related to the penetration and retention of water in all climate zones are in the first importance order with the weight more than 45 percent. Flow duration curve indices in very humid, humid, semi-humid and semi-dry climatic zones respectively with 45, 53, 52, and 53 percent and in the dry and Mediterranean climate zones parameter of storage capacity, Respectively with 49 and 58 percent have the greatest influence over the base flow. The results showed that the weight of the factors affecting base flow, vary depending on the type of climate.
Mahdis Amiri; Hamid Reza Pourghasemi
Abstract
The current study aims to investigate the relationship between hydrological and meteorological droughts in the Maharloo Watershed, Fars Province. In order to assess the hydrological drought, Standardized Water-Level Index (SWI) was used, calculated from piezometric groundwater level data from 60 observation ...
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The current study aims to investigate the relationship between hydrological and meteorological droughts in the Maharloo Watershed, Fars Province. In order to assess the hydrological drought, Standardized Water-Level Index (SWI) was used, calculated from piezometric groundwater level data from 60 observation wells within 15 years (2000-2014). The Standardized Precipitation Index (SPI), calculated from the 15 years of rainfall data from 18 stations was used to assess meteorological drought in the study area. Two geostatistical techniques were employed to create drought zonation maps namely Inverse Distance Weighting (IDW) and simple kriging. Correspondingly, three criteria were chosen to evaluate the results including Mean Absolute Error (MAE), Mean Bias Error (MBE), and Root-Mean-Square error (RMSE). Furthermore, the Mann-Kendall test was used to assess the temporal trends of hydrological and meteorological droughts. As a result, trends in hydrological drought were increasing in a significant manner, while meteorological drought trend was decreasing at first and increasing afterwards so that it did not follow any particular trend. With regard to the results of hydrological drought assessment, the driest period has been occurred in 2000 with the SWI value of about 2.25, while 2003 had the highest SWI value equals -2.66 as the most significant wet period. Moreover, the most intense drought and wet periods have been occurred respectively in northwestern and southwestern to central parts of the study area. The results of meteorological drought assessment indicated that the Komehr station has had the most intense wet period in 2000, however; it turned to have the most intense drought periods later on. As regards the evaluation of interpolation techniques, the IDW method with the lowest MAE value of 0.2688 and the lowest RMSE value of 0.0629was chosen as the best interpolation method compared to simple kriging. Also, the drought map obtained from the SPI method with the lowest values of MAE (0.2688) and MBE (-0.000051) found to be the most desirable method to assess the drought behavior in the study area.
asrin hosseini; mohammad reza golabi; safar marofi; nasim khalediyan; mohammad solatani
Abstract
Simulation of the rainfall-runoff process is the most important step in water engineering and water resource management studies. Exploitation of surface water and underground water resources, river management and flood warning requires prediction of river and runoff discharges of the watershed. In this ...
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Simulation of the rainfall-runoff process is the most important step in water engineering and water resource management studies. Exploitation of surface water and underground water resources, river management and flood warning requires prediction of river and runoff discharges of the watershed. In this study, Extended Kalman Filter-based Neural Network (EKFNN) method was used for rainfall-runoff modelling. Then, the results were compared with the Gene Expression Planning method, which showed good performance in rainfall-runoff modelling in most recent studies. The data used in this study is related to daily runoff and rainfall of the rain gauge and hydrometric stations of Malayer plain which includes Peyhan, Marvil and Namyleh stations, during the period of 2001 to 2013. The results indicated that the EKFNN model was superior to GEP model in daily river flow modelling in Malayer plain. In addition, the speed of implementation of the Gene Expression Planning model was greater and was able to present results in a short time. Finally, EKFNN model was selected as the superior model for Malayer plain.
Morteza Miri; Mojtaba Rahimi; Aliakbar Noroozi
Abstract
Todays, satellite precipitation data with high spatial and temporal resolution is an appropriate alternative source for conducting various studies of meteorology and hydrology in areas with inappropriate distribution of stations. These data are very important for a country like Iran which is always faced ...
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Todays, satellite precipitation data with high spatial and temporal resolution is an appropriate alternative source for conducting various studies of meteorology and hydrology in areas with inappropriate distribution of stations. These data are very important for a country like Iran which is always faced with problems of water shortage and precipitation. Therefore, the main purpose of this study is to evaluate the accuracy of GPM and TRMM daily precipitation against the recorded daily precipitation data of selected stations in Iran. Statistical methods were used to achieve this purpose. The data used include daily precipitation data from meteorological stations and daily rainfall from latest GPM and TRMM products in the period 2015-2000 in Iran. Statistical analysis showed that the daily precipitation values of these sensors are not accurate in Iran, and the estimated precipitation error is significant for most stations. Comparison of rainfall estimates from TRMM and GPM showed that although there is a great similarity between the estimates of precipitation values of GPM and TRMM, however, GPM data are more accurate than TRMM data in Iran. In terms of location, the best accuracy of the GPM and TRMM databases were observed in west of Iran, especially along the Zagros mountains, and like many other databases, the lowest accuracy was observed in coastal areas, especially along the Caspian Sea. Comparison of total annual precipitation of the stations and the remote sensing databases showed that not only there is a difference between the estimates of precipitation, there is also a spatial difference between high and low precipitation cores.
Mohammad Sadegh Porhemmat; Jahangir Porhemmat; Mehdi Mirzaee
Abstract
Karstic springs, as the main resources of rivers such as Karkheh, have encountered scarcity in the western of Iran during past years. It is necessary to consider the effects of climatic and human co-factors to prepar a rehabilitation plan in watershed scale. The present study was carried out to evaluate ...
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Karstic springs, as the main resources of rivers such as Karkheh, have encountered scarcity in the western of Iran during past years. It is necessary to consider the effects of climatic and human co-factors to prepar a rehabilitation plan in watershed scale. The present study was carried out to evaluate this phenomenon in the case of Sarab-e Niloufar, in Kermanshah Province. Two methods including Standard Precipitation Index (SPI) and Moving Average (MA) are used in this study. Four wet and dry periods were occured, including wet periods from 1980-1981 to 1997-1998 and from 2003-2004 to 2005-2006, dry periods from 1998-1999 to 2002-2003, and from 2006-2007 to 2014-2015 water years. The SPI results showed two main periods from 1989 to 2015, include 1989 to 1999 and 2000 to 2015. The first period is wet or normal, but the second period is very dry to normal and is characterized by persistence and severity of dryness. Also, the results showed that spring discharge has been stable in a-29 years period from 1969 to 1988 with fluctuations by seasonal rainfall, but a sharp decrease over the second period. The average spring discharge was 1100 ls-1 during the first period, but 337 ls-1 in the next 19 years. Other results showed a harmony period between decreasing of the spring discharge with drought cycles resulted from MA and SPI, except for the wet period of 2003-2004 to 2005-2006. Nevertheless, the spring discharge had decreasing rate in the wet period of 2003-2004 to 2005-2006. In addition, spring decreasing discharge rate was greater than rainfall. Therefore, despite the fact that the effects of drought are recognized as a major factor of spring deficit, other factors such as decreasing in water table of adjacent aquifers are also important to consider for rehabilitation of the spring.
hossin mosavi; mohamad kamangar; alireza karbalayy
Abstract
Understanding the behavior of phenomena requires attention to all its dimensions, and one way to understand their complexities is modeling. Soil surface moisture is a key variable for describing drought, water, and energy exchanges between Korea and the air, as well as assessing crop conditions. Soil ...
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Understanding the behavior of phenomena requires attention to all its dimensions, and one way to understand their complexities is modeling. Soil surface moisture is a key variable for describing drought, water, and energy exchanges between Korea and the air, as well as assessing crop conditions. Soil moisture is affected by both environmental variables and many environmental variables such as runoff, soil erosion, and crop production, but is highly variable due to unstable spatial and temporal conditions. The purpose of this paper is to investigate, extract and evaluate the spatial model of soil moisture dispersal after more than normal rainfall in 1979-98 in Kurdistan province. In this regard, after analyzing soil moisture dispersion as dependent variable and precipitation variables, snow water equivalent, topographic moisture index and vegetation index were selected as independent variables. Then, using a general regression model (OLS) and geographically weighted regression (GWR), spatial modeling was performed. Based on the evaluation criteria, the results showed that the GWR model with R2 = 0.74 has better explanatory power and better estimation than the general regression model with R2 = 0.68. According to the results of the GWR model, snow water equivalent variable in the northern mountainous regions had the highest effect on evapotranspiration and the least effect on soil moisture. The obtained spatial model can identify low or moist soil areas in order to identify environmental potentials and improve decision making, allocation and spatial distribution of agricultural services.
Malihe Sadat Zarif Moazem; Rasool Mahdavi; Soheila Javanmard; Marzieh Rezaei
Abstract
The rain process is affected by numerous environmental factors such as dust events and the interaction of these two events can influence the hydrological cycle. According to various reports on increasing of dust occurrences in different regions, this study aimed to investigate the potential impact of ...
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The rain process is affected by numerous environmental factors such as dust events and the interaction of these two events can influence the hydrological cycle. According to various reports on increasing of dust occurrences in different regions, this study aimed to investigate the potential impact of dust storms on rainfall in Khorasan Razavi during 2000-2013. The statistical method of "historical regression" was used to investigate dust effect on rainfall, which is based on comparison of observed rainfall with its prediction. Nine synoptic stations were selected as target stations. Regression equations were used to predict precipitation of target stations using the daily rainfall data of the hydrometric stations using the Least Squares Method. Then, the statistical ratio index for historical regression was calculated for each target station based on the observed and predicted rainfall values. The statistical ratio of each station was evaluated by Monte Carlo of permutation test using R-software. Since relative humidity variations play important role in the precipitation process, the correlation coefficient was calculated between the relative humidity and the statistical ratio index of each target station. The statistical test of correlation between relative humidity variables and the statistical ratio of historical regression were significant for all stations. The permutation tests for each station statistical ratio index showed a variable effect of dust on rainfall. The lowest statistical ratio index of 0.8 belonged to the Neyshabur Station with a relative humidity of 38%, whereas the highest statistical ratio index of 1.5 was found for Torbat Heydarieh Station with a relative humidity of 59.45%. In the present study, precipitation response to dust events was affected by relative humidity conditions. In a general conclusion, components of hydrological cycle does not have constant response to environmental variables and therefore, obtained comprehensive conclusions in atmospheric processes need more extensive studies.
