Ghasem Habibi Bibalani; Shahriar Sobhe Zahedi; Zia Bazhrang
Volume 1, Issue 3 , October 2009, , Pages 160-166
Abstract
A traction effect by lateral roots is one way in which roots contribute to lateral in-plane reinforcement of a shallow soil mass. In contrast to the effect of vertically-extending roots, whereby soil is reinforced by an increase in its shear strength, the traction effect reinforces the soil by enhancing ...
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A traction effect by lateral roots is one way in which roots contribute to lateral in-plane reinforcement of a shallow soil mass. In contrast to the effect of vertically-extending roots, whereby soil is reinforced by an increase in its shear strength, the traction effect reinforces the soil by enhancing the tensile strength of the rooted soil zone. To verify whether or not a traction effect exists in the root system of Mamraz vegetation، north of Iran, and to investigate the magnitude of this effect, a direct in situ test was conducted at a site in the Shanjan rangelands. The results from the site showed that, in the topmost soil (0-20cm), the lateral roots are able to provide a tractive force of up to 167.4 N (Newtons) over a vertical cross-section area of 20-50 cm2, or an increase in the pulling resistance of the rooted soil by 24.5%. The test results imply that, together with the Mamraz vertical roots, which anchor the shallow rooted soil zone to the deep and more stable soil mass, the lateral roots of the Mamraz, through their traction effect, are able to mitigate against shallow instability in the rangelands slopes, such as shallow slide and creep, to a certain degree.
Saeed Najafi; Seyed Hamid Reza Sadeghi
Abstract
Many on-site and off-site problems occurred due to irregular human use of natural resources leading to increasing sediment loads in watersheds. Understanding relative importance and source of erosion and sediment is essential for effective control of aforesaid problems. Today's, there are different techniques ...
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Many on-site and off-site problems occurred due to irregular human use of natural resources leading to increasing sediment loads in watersheds. Understanding relative importance and source of erosion and sediment is essential for effective control of aforesaid problems. Today's, there are different techniques for determining sediment sources. However, the evaluation of their relative agreement has been less considered. Towards his attempt, the present study aimed to compare the results of fingerprinting, soil erosion feature map and direct field measurements of soil erosion. According to the results of fingerprinting technique, the red gysiferouse marl geological unit with 85 percent contribution in sediment yield was most important sediment source. It was in the same line with that reported from soil erosion feature map with code of CS23R41G42. The results of field measurements also showed that the red gysiferouse marl geologicalunit with soil erosion rate of 34.4 t ha-1 and 14023 t annual erosion had the highest proportion in sediment yield. Other geologic units viz. young alluvial deposits and old alluvial clastic lied in second and third orders. These were also consistent with those of fingerprinting technique. Totally, the differences in the results of fingerprinting technique, soil erosion feature map and field measurement techniques referred to their quantitative or qualitative approaches and not considering sediment delivery ratio concept and other sediment transition processes. It clearly confirmed the necessity of simultaneous use of all aforesaid techniques to get access to reliable results.
Padidehossadat Sadeghi; Abdulvahed Khaledi Darvishan
Abstract
Extended abstractIntroductionFire, as one of the important and common occurrences in all forest and rangeland ecosystems, in addition to affecting the physical characteristics of the soil, generally causes the soil to become hydrophobic and thus reduce water permeability. The set of these changes can ...
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Extended abstractIntroductionFire, as one of the important and common occurrences in all forest and rangeland ecosystems, in addition to affecting the physical characteristics of the soil, generally causes the soil to become hydrophobic and thus reduce water permeability. The set of these changes can affect the stability of soil aggregates and splash erosion as the first stage of soil erosion. Therefore, investigating the effect of fire on soil erosion can lead to a better understanding of post-fire processes in ecosystems. Accordingly, the present study was planned with the aim of investigating the effect of fire on soil aggregates stability and splash erosion components in laboratory conditions on the rangeland soil in Kajur watershed located in the north of Iran. Materials and methodsThe corresponding experiments were done in three control plots and 12 plots covered with dry residues of rangeland species with four densities (250, 500, 750 and 1000 g m-2) based on the mass of plant residue per unit area and cpnsequently with four different fire intensities in three replications. Then, splash cups were placed on the soil surface and rainfall with an intensity of 60 mm h-1 and a duration of 30 minutes was simulated, and the splash erosion components including upward, downward, total and net splash were measured. The soil aggregate stability was also investigated by comparing the mean weighted diameter of the soil aggregates before and after the rainfall simulation in all plots. Results and discussionThe results showed that the effect of fire treatment on reducing total and net splash variables and increasing soil aggregate stability was significant at 95% and 99% confidence levels, respectively. With the increase in the intensity of the fire treatment, in general, the trend of changes in soil aggregate stability and splash components was increasing and decreasing, respectively. The fire treatment with an intensity of 250 g m-2 of the dry residues of the rangeland species reduced total and net splash by 35 and 44%, respectively, while the treatment of fire with the intensities of 500, 750 and 1000 g m-2 of the dry residues of the rangeland species reduced total and net splash more than 95%. Although the soil aggregate stability increased significantly with increasing the intensity of the fire treatment, the reduction of the total and net splash in the fire treatments with an amount of >500 g m-2 of the dry residues of the rangeland species was no longer significant. The significant participation of small particles of the soil surface without aggregation in the splash changed the intensity of the effect of fire treatment. The percentage of reduction of total and net splash due to the fire treatment with different intensities was not the same, which shows that the splash in the upstream and downstream directions did not decrease in the same proportion. The soil aggregate diameter from the control treatment to fire treatments with low to high intensities had a decreasing trend, generally. ConclusionsAccording to the results of the present research and the importance and recognition of the effect of fire on soil stability, the effect of fire treatment on soil stability should be done in soils with different textures and organic matter contents, especially considering the fire treatment with lower and higher intensities and shorter and longer dutations. It is suggested that the use of suitable tools to measure soil surface temperature during fire treatments should also be considered in future studies.
Mohammad Reza Mirzaei
Abstract
In this study, the mean monthly air temperature data from Shah-Mokhtar hydrometric station in Kohgiloyeh and Boyer Ahmad province for a period of 39 years between 1970 and 2009 was investigated. Using different graphical EDA techniques such as spectral, autocorrelation and partial autocorrelation plots, ...
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In this study, the mean monthly air temperature data from Shah-Mokhtar hydrometric station in Kohgiloyeh and Boyer Ahmad province for a period of 39 years between 1970 and 2009 was investigated. Using different graphical EDA techniques such as spectral, autocorrelation and partial autocorrelation plots, i) existence of seasonal part and ii) suitability of using time series analysis to model the residuals were determined. The lag plot and autocorrelation plot of the original data showed that a sinusoidal model was appropriate to model the seasonal effect. So using sinusoidal model and determining its parameters precisely, the seasonal effect was modeled properly. Time series analysis was also used to model the residuals using ARIMA models. Among different models, ARIMA(0,1,2) model was selected as the best model using Normalized Bayesian Information Criterion (NBIC). Finally, null hypotheses for Kolmogorov-Smirnov and Ljung-Box tests were not to be rejected at 5% level for the obtained model which confirms the adequacy of the model.
Ahmad Hosseini; Ebrahim Saberi; Mehdi Habibi
Abstract
This project is about evaluation of groins in Zanjanrood River, which located in Zanjan province with aim the investigation affected groins in control and recovery land use in the buffer river. Therefore, first we study of groin design standards, thus, we compare the executive groins with these standards. ...
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This project is about evaluation of groins in Zanjanrood River, which located in Zanjan province with aim the investigation affected groins in control and recovery land use in the buffer river. Therefore, first we study of groin design standards, thus, we compare the executive groins with these standards. The official and field studies show that the executive groins were designed in low risk and most of parameters like length, space and height of groins are over design. This means the costs are high and non economical. The problem was in operation, so that some components in build maps and plans are deferent from executed groins, especially in groin section and groin foundation. The problem is that hard groins in alluvial riverbed are more non-stable and score in head of them are more. Any way in regime condition space between groins and river width adjustment were suitable. In continue the report is about economical analysis. In this state, pure value for each groin and period time of investment and rate of social decreasing was calculated. Then by calculating for relative between benefit to cost the efficiency rate was taken.
Masoud Sajedi Sabegh; Mojtaba Saneie; Mehdi Habibi; Ali Akbar Abbasi; Mehdi Ghadimkhani
Volume 2, Issue 4 , January 2011, , Pages 206-210
Abstract
In this paper the effect of tree planting in a river bank on the shear velocity of flow was studied in a laboratory environment. At first a physical model was established in a 1.5m wide, 30m long experimental flume with a longitudinal slope of 0.01. Then a number of bars with 6.5mm in diameter, ...
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In this paper the effect of tree planting in a river bank on the shear velocity of flow was studied in a laboratory environment. At first a physical model was established in a 1.5m wide, 30m long experimental flume with a longitudinal slope of 0.01. Then a number of bars with 6.5mm in diameter, stimulated as trees, were located on the bank surface with a slope of 1:3 in two different orientations (square and triangular forms), three different heights (5, 6.5 and 8cm), and three different intensities (6*6/6*3, 8*8/8*4, 10*10/10*5). After that, the flow hydraulic parameters (such as discharge, water level and velocity) and their variation versus the change in experimentally planted trees were measured and analyzed. At least 19 series of laboratory tests with 5 different discharges were implemented. The results showed that, there is a relationship between planted tree and shear velocity. Also relationship between shear Reynolds () and the average velocity to shear velocity ratio () showed that vegetation could increase the roughness coefficient also by increasing the tree density, the ratio of and the roughness are increased. The roughness coefficient in all cases of not using vegetation, tree planted in square form and tree planted in triangular form, was increased respectively.
Reza Abdi; Mehdi Yasi; Reza Sokooti Oskoui; Ehsan Mohamadi
Abstract
Determination of environmental flow in river systems and other watery ecosystems is a new science in Iran and other developing countries. This paper evaluates the ecological requirement in a typical river by different hydrological and eco-hydrological methods. In this study, environmental requirement ...
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Determination of environmental flow in river systems and other watery ecosystems is a new science in Iran and other developing countries. This paper evaluates the ecological requirement in a typical river by different hydrological and eco-hydrological methods. In this study, environmental requirement of Zarrinehrood river (located in North West of Iran), from downstream of Bukan dam up to Urmia lake (near to 140 km), was estimated by four methods: Tennant, Tessman, Desktop Reserve Model (DRM) and FDC Shifting using the hydrometric data of Sariqamish station. According to results, the amounts generated from FDC Shifting method are more proper because of considering the ecological management qualification. Therefore, 16.7 CMS (equals to 33% of mean annually flow) was obtained as average environmental requirement of Zarrinehrood river in ecological management class C (maintains minimum ecological term in river). Also, monthly distribution of recommended environmental flow was compared with monthly flow of Sariqamish hydrometry station. The critical period for the river is during August to October. In this period, the monthly flow of 12.6, 11.6 and 6.3 m3s-1, are required to flow downstream in order to preserve the river life.
Mohammad Shabani
Volume 1, Issue 4 , February 2010, , Pages 240-247
Abstract
Estimation of soil erosion and sediment yield in a river is a difficult task and several methods have been suggested for its estimation. 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 ...
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Estimation of soil erosion and sediment yield in a river is a difficult task and several methods have been suggested for its estimation. 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 out the internal relation between data based on the training process. The objective of current study is to explore the capability of artificial neural networks method for estimation of daily suspended sediment in Kharestan watershed located in the northwest of Fars province, Iran. The study of efficiency is based on the comparison of neural network with regression models. For this purpose, 22 years of water and sediment discharge data of Shoor Kharestan River were considered and tested for outliers. Then the estimation was done based on neural networks and linear regression method (sediment rating curve) and were compared based on RMSE, MAE and R2. The results showed that estimation of neural network is more accurate than that of linear regression (sediment rating curve). The estimations of RMSE, MAE and R2 for neural networks method was 19.27, 12.14 and 0.98 respectively while these values for linear regression were 36.84, 20.75 and 0.74 which showed the lower errors of neural networks method compared with linear regression.
Hamidreza Gharechaei; Alireza Moghaddamnia; Arash Malekian; Azadeh Ahmadi
Abstract
Climate change and anthropogenic effects are two main drivers of stream flow changes. In this study, the trend and Fluctuations in hydro climatic data series of Kashkan River were evaluated during 1972-2011. Then, the climate elasticity method was used for quantitative assessment of stream flow response ...
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Climate change and anthropogenic effects are two main drivers of stream flow changes. In this study, the trend and Fluctuations in hydro climatic data series of Kashkan River were evaluated during 1972-2011. Then, the climate elasticity method was used for quantitative assessment of stream flow response to climate variability and human activity. Results revealed that if precipitation decreases by 10%, runoff will decrease by 25.7∼25.1 percent, and if potential evapotranspiration decreases by 10%, runoff will increasing by 15.7∼15.1 percent. In 1999-2011, human activity was the main factor that decreased the amount of runoff in Kashkan river basin. The contribution of human activities were 73.97∼74.22 percent, while the increasing percentage due to climate variability accounted for 25.77∼26.02 percent, showing that runoff in the Kashkan river basin is more sensitive to climate variability than human activities. The results of this study can provide a reference for the development, utilization and management of the regional water resources and ecological environment protection.
Foad Naserabadi; Abazar Esmali Ouri; Hossein Akbari; Rokhsareh Rostamian
Abstract
In hydrologic models, a sensitivity analysis could be performed to identify important parameters and reduce their numbers in an easier and faster calibration process. This study describes an application of a useful method for sensitivity analysis of Soil and Water Assessment Tool (SWAT) model. This method ...
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In hydrologic models, a sensitivity analysis could be performed to identify important parameters and reduce their numbers in an easier and faster calibration process. This study describes an application of a useful method for sensitivity analysis of Soil and Water Assessment Tool (SWAT) model. This method determines parameters with the greatest impact on model results and gives a sensitivity ratio and an input-output relationship graph for each parameter. In this study, the SWAT model is used for a monthly rainfall-runoff simulation in Ghareh Su watershed with an area of 4062 km2. Calibration of the model were performed manually, using the recorded weather data from 2003 to 2008 and the validation was performed, using the recorded data from 2009 and 2010. The sensitivity analysis has been performed using One Factor At a Time (OAT) method to evaluate and demonstrate the influences of the model parameters on four major components of water balance, including surface runoff, lateral flow, groundwater and evapotranspiration. The results showed that the parameters of initial SCS runoff curve number for moisture condition Π (CN2), soil available water capacity (SOL_AWC), soil bulk density (SOL_BD), saturated hydraulic conductivity (SOL_K), maximum canopy storage (CANMX), soil evaporation compensation factor (ESCO) and minimum melt rate for snow during the year (SMFMN) have the greatest influence on remarked parts of water balance.
Alireza Shokoohi; Asghar Azizian; Razieh Jemaat; Vijay Singh
Abstract
Flood forecasting in a sound way leading to correct results has been a challenge for all researchers and engineers for many decades, which is the basic reason for developing many different types of mathematical rainfall runoff models. Correct estimation of infiltration during a storm is essential to ...
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Flood forecasting in a sound way leading to correct results has been a challenge for all researchers and engineers for many decades, which is the basic reason for developing many different types of mathematical rainfall runoff models. Correct estimation of infiltration during a storm is essential to a justified and rational modeling of runoff at watershed scale. There are many experimental or mathematical models for simulating infiltration and deriving net rainfall with pros and cons. In the present research, instead of evaluating infiltration simulation methods solely, four more widely used methods; namely, ɸ index, Horton, Green-Ampt and SCS methods were selected to find out their effects on the performance of a kinematic wave based geomorphological model called KW-GIUH. Furthermore, a sensitivity analysis with respect to different infiltration methods and different overland and channel roughness coefficient were performed. Horton and ɸ method led to a better performance of the model in terms of observed and simulated hydrographs in the study watershed. In this regard, Nash-Sutcliffe efficiency indices for Horton and ɸ index methods were obtained as 94.9 and 90.3, respectively, while it was 77.7 for Green–Ampt and 76.3 for SCS infiltration method. According to results of sensitivity analysis, KW-GIUH performance has the most and least sensitivity when using Green–Ampt and ɸ index as the infiltration method, respectively. Although studying in a steep watershed with an overland slope of about 17% and a small area of about 38 km2, changing the overland roughness coefficient has more effect on the model performance comparing with the change of channel roughness coefficient. Simulated flood peaks changed about 64 % due to changing the overland roughness coefficient while this value amounted to 25% for channel one. Shortly, it is concluded that KW-GIUH is highly sensitive to infiltration simulation method and overland roughness coefficient.
Mohammadreza Fazel Pouraghdaei; Hossein Malekinezhad; Mohammadreza Ekhtesasi; Jalal Barkhordari
Abstract
The main objective of water spreading projects is recharging aquifers. In this study, changes of soil surface permeability in Yazd water spreading projects, including Sirizi in Bafgh, Herat and Miankouh in Mehriz were investigated. Using a double ring, 12 Permeability tests (in first and ...
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The main objective of water spreading projects is recharging aquifers. In this study, changes of soil surface permeability in Yazd water spreading projects, including Sirizi in Bafgh, Herat and Miankouh in Mehriz were investigated. Using a double ring, 12 Permeability tests (in first and fourth strips and three tests for each strip) were performed. Using measured data the performance of permeability equations such as Kostiakov, Kostiakov-Lewis, Horton, SCS, and Philip were compared in estimating cumulative infiltration and infiltration rate in the study areas. Results showed that average permeability for Bafgh, Herat and Mehriz water spreading projects were about 1.06, 1.52 and 2.94 cmhr-1, respectively. The best equation for estimating cumulative infiltration in Bafgh was the Horton equation with RMSE and Nash Sutcliffe coefficients of 0.097 and 0.992, respectively, while in Herat and Mehriz the best equation was the Kostiakov-Lewis equation with Nash-Sutcliffe coefficient and RMSE of 0.385, 0.994, 0.081 and 0.991 respectively.
Mohammad Jafar Soltani; Baharak Motamedvaziri; Ali Akbar, Noroozi; Hassan Ahmadi; Jamal, Mosaffaei
Abstract
One of the natural and common hazards in recent years is the phenomenon of dust, which causes damage, especially to urban and human environments, and is very difficult to control and manage. One of the main and effective factors in the occurrence of this phenomenon is the geographical location and climatic ...
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One of the natural and common hazards in recent years is the phenomenon of dust, which causes damage, especially to urban and human environments, and is very difficult to control and manage. One of the main and effective factors in the occurrence of this phenomenon is the geographical location and climatic conditions of the regions of origin and the areas affected by this phenomenon. In this research, which has been done in Hindijan City of Khuzestan Province, first, issues and problems have been identified based on library studies, questions from experts, referring to the research area. Then, the Driving force-Pressure-Status-Impact-Response (DPSIR) framework was used to analyze the most important factors that have caused the occurrence of dust in the city of Hindijan. The DPSIR framework is an analysis of the "cause-effect" relationship of factors for policy-making and management planning. In this study, the factors related to each of the components of the DPSIR framework were identified and prioritized using a questionnaire of experts with a Likert scale and based on nonparametric Friedman tests. Explain that, to complete the questionnaire of experts, experts from the Departments of Natural Resources, Environment, Regional Water and Agricultural Jihad of Khuzestan Province were surveyed. Results showed that population growth, agricultural development, livestock development, industrial development and climate change are important from maximum to minimum, respectively, the most important drivers affecting the occurrence of dust in the study area. Attention to both reactive and preventive responses has an important role in improving the situation and reducing the adverse effects of dust occurrence in the research area.
Ebrahim Karimi Sangchini; Majid Ownegh; Amir Sadoddin; Nasser Tahmasebipuor; Hossein Rezaee
Abstract
This article describes a research aiming to investigate factors affecting community participation and to predict community acceptance of vegetation-based management scenarios in the Hable-rud River Basin. The Hable-rud River Basin which is a transboundary basin is extended between Tehran and Semnan provinces ...
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This article describes a research aiming to investigate factors affecting community participation and to predict community acceptance of vegetation-based management scenarios in the Hable-rud River Basin. The Hable-rud River Basin which is a transboundary basin is extended between Tehran and Semnan provinces in Iran. In this research, vegetative management scenarios include: the current condition, terracing, saxaul plantation, riparian restoration, forage growing, bunch seeding, contour furrowing, tree plantation, grazing exclusion, seeding, drill seeding, orchard development, and agroforestry. Through an interview with the stakeholders of the basin, a predefined questionnaire was completed for each respondent separately. Validity and reliability of the questionnaire were tested. On the basis of Cochran formula, 379 respondents were chosen in a stratified sampling scheme among the local communities of the basin. The factors influencing people's participation in various districts of the basin were investigated. The community acceptance level of watershed management actions was quantified using binomial probability distribution. Financial support policies of the government were identified as the most effective factor in community participation for the study area that attained the highest value in the viewpoint of people living in Sorkhe and Ivanakey districts. Community participation was evaluated in four forms including support by heart, labor support, financial support, and labor and financial support. The analysis indicates that scenarios of agroforestry and orchard development have the highest level of labor and financial support. Central Firoozkooh and Central Damavand districts have maximum labor and financial support level. The results of the binomial distribution analysis show that scenarios of agroforestry and orchard development have highest preferences among the local communities of the Hable-rud river basin. The results of this research can be used by managers and decision makers to promote soil and water resources protection as well as to promote the adoption of management actions at the watershed scale.
Seyedeh Akram Jooybari; Hamidreza Peyrowan; Peyman Rezaee; Hamid Gholami
Abstract
Hendijan wind erosion center is located in Khuzestan Province and southwest of Iran. In the last decade, with the increase of erosion rate and concentration of important dust centers in this area, the study of heavy metal concentration and pollution in this area has become very important. For this purpose, ...
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Hendijan wind erosion center is located in Khuzestan Province and southwest of Iran. In the last decade, with the increase of erosion rate and concentration of important dust centers in this area, the study of heavy metal concentration and pollution in this area has become very important. For this purpose, 33 soil samples of this zone were collected based on land use change and with the aim of uniform distribution and analyzed by ICP-MSS. The obtained data show that the highest average concentrations of metals belong to Cd <As <Cu <Pb <Zn <Ni <Cr, respectively. Enrichment indices, geo-accumulation index and contaminant factor showed that the highest pollution in Hindijan area belongs to nickel, chromium, arsenic, cadmium and plumbum, respectively. On the other hand, ecological risk assessment in the mentioned area has shown that this region has a low ecological risk that among the studied metals, the highest ecological risk belongs to the two metals arsenic and cadmium. The results of PCA test showed that the metals nickel, zinc, copper and lead have both non-anthropogenic and anthropogenic sources and the source of arsenic and cadmium metals is human activities. According to the pattern of metal distribution, it can be stated that the activities related to Bahrkan fishing pier on the one hand and oil rigs off the coast of Hindijan oil field on the other hand have caused the concentration of nickel, lead, zinc and copper in the south of the study area. Agricultural activities have also controlled the concentration of cadmium and arsenic metals in this area, and the source of chromium concentration was determined as agricultural effluents, traffic pollution and residual pollution from the 8-year Iraq-Iran war.
Mohammad Ebrahim Banihabib; Marina Ezzati amini; Mohammadhadi Shabestari
Abstract
Changing in urban life, climate change and successive droughts and floods have caused the issue of restoration of rivers to become one of the most important environmental issues and water resources problems. In recent years, the lack of attention to environmental issues, improper exploitation of water ...
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Changing in urban life, climate change and successive droughts and floods have caused the issue of restoration of rivers to become one of the most important environmental issues and water resources problems. In recent years, the lack of attention to environmental issues, improper exploitation of water resources, ignoring sustainable development, changes in natural structure and channelization of urban river have created undesirable conditions for urban rivers. This study tries to develop and select the best strategy to achieve river restoration by considering six sustainable development criteria and using the hybrid model of Analytical Hierarchy Process and Modified Technique for Order of Preference by Similarity to Ideal Solution (M-TOPSIS-AHP) and taking into account two goals of quantitative and qualitative restoration of base flow and securing against flood. The required data was collected through survey forms that have been filled by 38 experts in the field of water resources management. The inconsistency rates of surveys forms were investigated and inconsistent forms were removed. Then the pairwise comparison of AHP method was used to obtain the relative weights and finally the strategies were ranked by TOPSIS method and the best strategy was introduced.
Leila Mehdizadeh; Farrokh Asadzadeh; Abbas Samadi
Abstract
Particle size distribution of sediment is one of the key factors which affects many other physical and chemical characteristics of the sediments. In this study, particle size distribution of the sediments trapped behind successive check dams was evaluated. Two waterways (G1 and G2) were selected in Noshan ...
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Particle size distribution of sediment is one of the key factors which affects many other physical and chemical characteristics of the sediments. In this study, particle size distribution of the sediments trapped behind successive check dams was evaluated. Two waterways (G1 and G2) were selected in Noshan region of Urmia which have three and four check dams respectively. In each waterway, particle size distribution of sediment samples was compared with the original soil of the adjacent hill slope. Results indicated that the sediments have loamy-sand to sandy texture and have coarser particles than the adjacent soil samples. Selective deposition of sediment particles was observed in half full successive check dams of G1 waterway and the sediments of the check dam located at the downstream have a similar particle size distribution with adjacent soil sample. In filled dams of G2 waterway, considerable amounts of particles coarser than 0.124 mm in diameter were passed through dams. Some mathematical models were used to describe the particle size distribution of sediment samples and performance of them was evaluated by several efficiency criteria. Hierarchical cluster analysis of models, based on selected efficiency criteria, indicated that the Fredlund, ORL and ONL models have good performance in describing the particle size distribution of sediment samples. Coefficient of determination for these models was 0.99 and the Akaike’s Information Criterion (AIC) for these models were -44.13, -43.92, and -41.46 respectively. It can be concluded that these models are applicable for quantifying the particle size distribution of sediment samples.
Tayeb Raziei
Abstract
Drought characteristics were investigated in arid and semi-arid regions of eastern and central Iran using monthly precipitation records of 69 synoptic and meteorological weather stations for the period 1975-2005. After quality control of the data records, the the ُStandardized Precipitation Index (SPI) ...
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Drought characteristics were investigated in arid and semi-arid regions of eastern and central Iran using monthly precipitation records of 69 synoptic and meteorological weather stations for the period 1975-2005. After quality control of the data records, the the ُStandardized Precipitation Index (SPI) was computed at 3, 6 and 12 month time scales for all considered stations. The target area was regionlized into a few distinctive homoginious sub-regions by applying principal component alalysis and Varimax rotation to the SPI time series computed for 3-, 6- and 12-months time scales, i.e., the target area is composed of two homeginous sub-regions based on SPI at 3- and 12-months time scales, while it classified into 3 sub-regions considerng 6-months time scale. Drought charcteristics (severity, duration and frequency) were also identified for all considered stations and time scales and their respective spatial variability were analysed. The results indicate that drought events with different types of severity are more frequent in northern part of the studied area, while south-eastern part of the region is prone to severe to extreme drought events. The results also suggest that the target area experienced wide spread droughts in 23.5% of the years alaysed. In such years, the ratio of stations hited by severe to exterme droughts are lesser than the number of stations affected by mild to moderate drought events, indicating that the more severe drought the lesser areal extent.
Mahmoud Habibnejad Roshan; Kaka Shahedi; Sayed Hussein Roshun
Abstract
Introduction
Floods are one of the most destructive natural disasters that cause severe injuries and loss of life, major infrastructure damage, significant economic losses, and social unrest worldwide. Due to the fact that flood is a dynamic and multidimensional phenomenon, Geographic Information System ...
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Introduction
Floods are one of the most destructive natural disasters that cause severe injuries and loss of life, major infrastructure damage, significant economic losses, and social unrest worldwide. Due to the fact that flood is a dynamic and multidimensional phenomenon, Geographic Information System (GIS) and Remote Sensing (RS) data are used to a large extent to discover the extent of flooded areas and play a special role in preparing flood risk and susceptibility maps. Flood susceptibility mapping is essential for characterizing flood risk areas and planning flood control schemes.
Materials and methods
In this research, the identification of flooded areas in the Karun Watershed based on the Analytical Hierarchy Process (AHP) in the GIS environment and its validation with the NDWI blue index extracted from Landsat 8 satellite images has been considered. For this purpose, first, 15 effective parameters in floods occurrence including slope, aspect, elevation, curvature, rainfall, distance from stream, stream density, distance from fault, fault density, distance from road, road density, lithology, Curve Number (CN), land use, Topographic Wetness Index (TWI) and Stream Power Index (SPI) were selected and the weighting of these parameters was done based on AHP method in the Expert Choice software environment. Finally, by using the command to combine the layers based on the weighting of the AHP method in GIS, the final flood risk zoning map was obtained. NDWI water index was used to validate the flood risk map obtained.
Results and discussion
The results of the AHP model showed that the most effective factors in the occurrence of flood risk in the Karun Watershed include rainfall, the amount of slope and the height classes, which should be considered in order to reduce flood damage and provide management solutions for these factors. Also, the results show that the downstream areas of the watershed have the highest risk of flooding and more than half of the watershed's surface (52.24%) has a medium flood potential.
Conclusion
Preparing a map of flood-prone areas is one of the most constructive methods that enable the reduction of flood risk damages and help planners, stakeholders and decision-makers to properly monitor flood-prone areas and ensure appropriate and sustainable socio-economic development.
hamid moslemi; alijan abkar; saeid choopani
Abstract
In general, the protection and utilization of surface water in arid regions, done by different methods such as Flood water spreading that undoubtedly will affect on sustainable development of groundwater resources. In order to provide, suitable, executive and manageable solution, Continuous monitoring ...
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In general, the protection and utilization of surface water in arid regions, done by different methods such as Flood water spreading that undoubtedly will affect on sustainable development of groundwater resources. In order to provide, suitable, executive and manageable solution, Continuous monitoring is essential for such projects. For this reason the effect of Dehender Flood spreading on downstream unconfined aquifer was evaluated. For this purpose, the location of flood spreading and hydrogeological conditions of downstream aquifer determined by data and information that are Gathered from Hormozgan regional water authority along with field observations. Then 7 Observation wells were chosen. Finally, the effect of flood water spreading on water table surface groundwater changes was investigated by using underground water balance equation and unit hydrograph befor and after the construction of flood spreading system. The results of this evaluation showed that the average level of the water from sea level at the central of the plain(are not affected by flood water spreading) and near flood spreading (are affected by flood water spreading respectively) befor and after the construction of flood spreading system are: 213.4 ,209.5 and 254 ,251 meter of the sea level. As a result we can state that flood water spreading play an important role in sustainable development of ground water resources.
Mosayeb Heshmati; Mohammad Ghaietury; Mahmood Arabkhedri; Yahya Parvizi
Abstract
Forest and land use change has many negative consequences including increased flooding, erosion, sedimentation and dust storms. The aim of the research was thus to investigate the effects of land use change in Zagros forests on erodibility and sedimentation via soil quality reduction in some forests ...
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Forest and land use change has many negative consequences including increased flooding, erosion, sedimentation and dust storms. The aim of the research was thus to investigate the effects of land use change in Zagros forests on erodibility and sedimentation via soil quality reduction in some forests of Kermanshah Province, Iran. In order to achieve this aim, in the first step, afforest area and its adjacent rain-fed farm (which is developed during recent 10 years a result of forest land change), were selected and 35 soil samples were collected from the surface layer (0-20 cm). Then, the physico-chemical analyses were done on the soil samples. In the next step, soil erodibility factor was calculated and sediment yield was assessed using portable rainfall simulator. The results showed that six key properties of soil including soil aggregate stability, bulk density, organic carbon, total nitrogen, total absorbable potassium and cation exchange capacity were significantly (p<0.05) influenced by land use type. Additionally, in all tested samples, the total clay and silt content was about 80%, which resulted in the formation of soil with heavy texture. Subsequently soil erodibility factor (K) and sediment yield intensity in rain-fed farm was found significantly (P<0.05) higher than those of forest. According to the results and the role of Zagros forest ecosystem on water harvesting, aquifer recharge, flood and dust control, the current trend of changing forest landuse to arable lands accompanying improper tillage practice, crops residue burning and heavy machinery traffic in nearby rain-fed farms, cause accelerating global warming, increasing runoff coefficient and evaporation as well as water scarcity in future.
Ahmad Nohegar; Mohammad Kazemi; Seyed Javad Ahmadi; Hamid Gholami; Rasool Mahdavi
Abstract
Efficiency of sediment fingerprinting by using tracers as a successful method to determine the sources of sediment has been proved. Selection of the suite subset of tracers, capable of discriminating sediment sources, is the first and the most important step in the sediment fingerprinting method. The ...
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Efficiency of sediment fingerprinting by using tracers as a successful method to determine the sources of sediment has been proved. Selection of the suite subset of tracers, capable of discriminating sediment sources, is the first and the most important step in the sediment fingerprinting method. The presence of outliers affects the selection of the suite subset and possibly prevents picking the important tracers and reducing the accuracy of classification. Therefore, the outliers must be detected in order to be corrected or omitted, if enough evidences were present. The present study aims to detect outliers in the subset of tracers, to identify the best combination. For detecting outliers, We used univariate methods such as Grubbs test, Gauss test, Dioxin test, box plot, the Median ± 3MAD, the mean ± 3standard deviation and also multivariate methods such as squared Mahalanobis distance, separate box plots of squared Mahalanobis distance for each of sediment sources, principal component analysis and plot of the squared Mahalanobis distances against the quantiles of the chi-square distribution. we consider an observation as the outlier that at least half of these methods have detected it as an outlier. The results showed that Median ± 3MAD method introduced a larger number of data as outliers Methods of multivariate outlier detection has low agreement with each other. Univariate methods to identify outliers show higher agreement with each other. To use univariate analysis techniques to detect outliers namely Median ± 3MAD, box plot, and Dioxin one can recommended to test their sensitivity. The results also showed that the maximum consensus for univariate analysis techniques is four samples (observations) and for multivariate methods is two samples (observations). In general, there is no observation that is identified as an outlier by half of the used methods.
Ali Reza Vaezi; Ouldouz Bakhshi Rad
Abstract
Runoff is one of the major components of the hydrological cycle, which leads to soil loss from steep slopes and sediment production in watersheds. Investigation of effective factors in runoff coefficient is important in watershed management. The aim of this study was to investigate the effect of soil ...
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Runoff is one of the major components of the hydrological cycle, which leads to soil loss from steep slopes and sediment production in watersheds. Investigation of effective factors in runoff coefficient is important in watershed management. The aim of this study was to investigate the effect of soil properties on runoff coefficient in Alanagh, Livar and Shekaralichay sub-basins in East Azarbaijan Province. After soil sampling, some physicochemical properties were measured and runoff data were obtained from the relevant stations. Based on the results, runoff coefficient in the studied sub-basins is affected by various soil properties such as particle size distribution, gravel, organic matter, lime, aggregate size and stability, and saturated hydraulic conductivity. As the percentage of sand and gravel increases and the percentage of clay and silt decreases, soil permeability increases and runoff coefficient decreases. Organic matter and lime are two important factors in the aggregate formation and stability, and improving the saturation hydraulic conductivity which plays a key role in reducing runoff production. The results of multiple linear regression analysis showed that runoff production in the Alangh sub-basin has a significant relationship with soil organic matter (r=-0.95, p<0.01) and bulk density (r=0.9, p<0.01). Organic matter content has the main role in runoff production in Livar sub-basin (r=-0.94, p<0.01) and Shekaralichay sun-basin (r=-0.95, p<0.01). Runoff coefficient in all sub-basins in the area is strongly related to organic matter content (r=-0.86, p<0.01), soil structure stability (r=-0.68, p<0.01) and stream density (r=0.49, p<0.01). This study showed that preserving and increasing soil organic matter can be an effective strategy in conserving rainwater and reducing runoff by improving soil structure and permeability.
Leila Gholami; Ataollah Kavian; Abdulvahed Khaledi Darvishan; Azame Alipour; Zahra Besarand
Abstract
Determination of time to runoff and runoff volume in watershed response management against rainfall are the key parameters in watershed system management. Among different factors of effect on time to runoff and runoff volume, the rainfall intensity is one of the most important factors. In this study, ...
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Determination of time to runoff and runoff volume in watershed response management against rainfall are the key parameters in watershed system management. Among different factors of effect on time to runoff and runoff volume, the rainfall intensity is one of the most important factors. In this study, the effect of rainfall pattern on variables of time to runoff, runoff volume and coefficient was studied under simulated rainfall in the southeastern Noshahr city, Mazandaran province. To achieve the study purposes, four rainfall patterns, each with three changes in rainfall intensity (I: Low-Medium-High, II: Low-High-Low, III: High-Medium-Low, IV; High-Low-High) were simulated. Then, the time to runoff, runoff volume and runoff coefficient were measured for each rainfall pattern. The measured data were analyzed in Excel and SPSS 23 softwares to determine the relationship between the rainfall pattern and variables of time to runoff, runoff volume and runoff coefficient. The results showed that there was a significant difference (P≤0.05) in variables time to runoff, runoff volume and runoff coefficient resulted rainfall patterns. Also the results showed that, in all of rainfall patterns between mean amounts were the significant differences on time to runoff, runoff volume and runoff coefficient in level of 99 percent. The results showed that the rainfall pattern I had the longest time to runoff and rainfall pattern III had the largest amounts of runoff volume and runoff coefficient. The average time to runoff in rainfall patterns of I, II, III was 5.90, 4.24, 0.71 and 1.25 min, respectively. Also, the average runoff coefficient in rainfall patterns of I, II, III and IV measured 30.03, 49.63, 88.82 and 75.16 percent, respectively.
Hamed Harriri; seyed abbas hosseini; Amir Khosrojerdi
Abstract
Introduction
Predicting changes due to climate change and its possible consequences on hydrological processes of the watershed helps to solve the challenges facing managers and water resources planners in the coming period. The effects of this phenomenon and gabion check dams simultaneously on the sedimentation ...
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Introduction
Predicting changes due to climate change and its possible consequences on hydrological processes of the watershed helps to solve the challenges facing managers and water resources planners in the coming period. The effects of this phenomenon and gabion check dams simultaneously on the sedimentation of Dehbar Basin have not been studied so far, so the aim of this study is to investigate this with the perspective of the next 30 years, using SWAT and LARS-WG models and the ability of these two models to simulate climate change and remove gabion check dams.
Materials and methods
In this research, the performance of gabion dams as a reservoir in the Dehbar Basin, 10 km west of Mashhad and south of the city of Torghabeh, which has a cold semi-arid climate, is compared to the amount of sediment output from the basin for the next 30 years with the LARS-WG statistical model and SWAT hydrological simulation model has been evaluated. There are five gabion dams in this area. To predict the meteorological variables of the upcoming period at the level of Dehbar Watershed, after recalibrating the LARS-WG model, the HadGEM2 model and three scenarios of RCP8.5, RCP4.5 and RCP2.6 were used for the microscaling of meteorological data in the period of 2050- 2020. Kolmogorov Smirnov (K-S), t and F statistical tests were used to check the performance of the simulation results in this model. To prepare and implement the SWAT model, the map and digital model information of elevation, soil, land use, hydrological and meteorological data were used. The tank was used to introduce gabion dams to the model. In order to analyze the sensitivity, calibration and validation of the SWAT model, SUFI-2 semi-automatic algorithm was used.
Results and discussion
The average values of the simulated precipitation are in good conformity with the observed values and the biggest difference is related to the months of February and April. Regarding the standard deviation values of monthly rainfall, the biggest difference belongs to the months of February and March. The average simulated minimum temperature is also in very good agreement with the observed values. Also, for the maximum temperature, a trend similar to the minimum temperature is seen. Also, the p-value obtained from the t-test for the aforementioned variables, there is no significant difference between the average temperature and precipitation data produced and the observed data, and the LARS-WG model has been able to calculate the average temperature and precipitation very well. To simulate monthly precipitation in all scenarios (RCP8.5, RCP4.5 and RCP2.6) in the horizon of 2050 in the first seven months of the year is lower than the monthly precipitation in the base period, but an increase in precipitation is observed for the second five months of the year. Also, in the horizon of 2050, the temperature will increase on average compared to the base period. To draw the curve of the sediment gauge, the method of batch average with modified FAO coefficient was used. The amount of observed sediment was calculated as 2.14 tha-1yr-1. For the calibration and validation of the SWAT model, at first, using CUP_SWAT software, the parameters that had a greater effect on the discharge and sediment output from the basin were identified. In order to analyze the sensitivity, calibration and validation of SWAT model, SUFI-2 semi-automated algorithm was used. After that, the effects of climate change on the amount of runoff and sediment in the basin were investigated using the validated SWAT model. The results show a decrease in rainfall, an increase in temperature and a decrease in runoff in the horizon of 2050. The precipitation changes for RCP4.5 and RCP2.6 scenarios are +9.3% and +3.1%, respectively, and -4.6% for RCP8.5 scenario. On average, gabion dams reduce 57.09% of sediment exit from the basin.
Conclusion
In this research, the effects of climate change on the sediment output from Dehbar Basin in the period from 2020 to 2050 and the effect of gabion dams in the existing conditions (presence of dams) and in the conditions of removal of these dams were investigated. In all scenarios, the minimum and maximum temperature increased in the 2020-2050 period compared to the base period. One of the negative effects of temperature increase is change in the amount and time-spatial pattern of precipitation. The results indicate that the SWAT model is capable of simulating hydrological processes and sedimentation in relatively small to medium watersheds with complex conditions such as Dehbar Basin, even with limited observational data, with acceptable accuracy. The increase in the amount of sediment at the outlet point of the watershed, despite the decrease in rainfall and runoff, indicates short-term rainfall with high intensity, which increases the occurrence of flooding conditions. From the changes in the amount of erosion and sedimentation in the horizon of 2050 and with different scenarios, it can be concluded that the climate change will affect the erosion of the basin in the future and the simulation model can be effective in predicting the erodibility. Therefore, the results obtained from the SWAT model provide the possibility of recommending its use in the region.
