Abdolali Adelpour; Majid Soufi
Abstract
Erosion and sedimentation study and design of the distance between spreading channels are basic requirement in flood water spreading projects. Different environmental parameters including topography and slope, soil texture, vegetation cover and flow resistance affect the hydraulic characteristics of ...
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Erosion and sedimentation study and design of the distance between spreading channels are basic requirement in flood water spreading projects. Different environmental parameters including topography and slope, soil texture, vegetation cover and flow resistance affect the hydraulic characteristics of the flood water spreading area. So it isnecessary to investigate the effect of environmental parameters according to natural conditions and simulation of overland flow. This study was done in the Gareh Bygone plain, in the south of Fasa city. An open hydraulic flume with 120 m length, 0.4 m width and 0.25 depth was used to simulate concentrated overland flow with 0.1 mdepth. Three experiments were examined and for each experiment, discharge flow and mean flow depth were measured directly and other parameters such as mean velocity and shear stress were calculated. Erosion or sedimentation depths were calculated by comparing flume bed elevations in the cross sections with one meter intervals. Results of this study show that erosion and sedimentation phenomena were changed with theincrease or the decrease in trends of shear stress along the flume and shear stress parameter were also changed with bed slope and roughness coefficient and became maximum at 75 m from the top end of the flume. On the other hand, according to the bed elevations of cross sections in two steps maximum erosion depth occurred at 75 mfrom the start of the flume which was confirmed with maximum shear stress. So, we can conclude that channel erosion threshold was established in 75 m from the top end of the flume and it can be considered as channel spreading distance.
Hossein Saadati; Shaban Ali Gholami; Foroud Sharifi
Volume 1, Issue 2 , July 2009, , Pages 87-98
Abstract
Lack of hydrometric data is the main issue for research and executive plans. In the present study in order to solve this issue, the capability of SWAT model has been studied in terms of daily discharge simulation in un-gauged watersheds. This model can simulate six hydrological and biological processes ...
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Lack of hydrometric data is the main issue for research and executive plans. In the present study in order to solve this issue, the capability of SWAT model has been studied in terms of daily discharge simulation in un-gauged watersheds. This model can simulate six hydrological and biological processes such as daily discharge, daily sediment, yearly and monthly water balance, water quality, agricultural products and estimation of vegetative cover for different animal grazing management systems. Simulation has been done for both gauged and un-gauged basins in Kasilian catchment for two time periods as calibration and validation of model. Calibration has been done using data derived from 4 years recording data (1987-1981) while validation has been done using 6 years data (1981-1986). Results show that, ABF, CN2 and REVAPC parameters are most sensitive and also Z and T-Laps parameters are low sensitive among other parameters. The model simulated runoff reasonable with r2=0.69, PBIAS=-2.5, and NS=0.72, whereas, the validation of model for the same data showed that r2=0.57, PBIAS=4.3, and NS=-0.54, which indicates that the performance this model is not quite valid for low stream flows because of sensitivity of hydrological parameters. The new version of SWAT model, modified during 2000 to 2005, has a capability in using GIS, thus it can be used in the same study area.
Seyed Aliasghar Hashemi; Sargis Ghazariyan
Abstract
In this research, two small sub-basins were selected in Darjazin Watershed of Semnan to evaluate the effect of ruck check dams on peak and volume of flood in small watersheds. Two watersheds were chosen as study area in a part of southern Alborz Mountain with arid and semi-arid climate. These watersheds ...
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In this research, two small sub-basins were selected in Darjazin Watershed of Semnan to evaluate the effect of ruck check dams on peak and volume of flood in small watersheds. Two watersheds were chosen as study area in a part of southern Alborz Mountain with arid and semi-arid climate. These watersheds are located in upland of Mahdishahr city and many check dams are constructed for flood control in past few years. All check dams were examined during field operation and their sedimentation were assessed. Results showed that all check dam reservoirs were filled by sediment. In this research, the peak and volume of floods were assessed in three scenarios of 1) watersheds with no check dams 2) watersheds with empty of sediment check dam reservoirs and 3) watersheds with full of sediment check dam reservoirs. HEC-HMS model was used for rainfall-runoff simulation. . Mean comparison test by paired method for all three scenarios showed that flood peak and volume have significant difference at α=1% level. But, flood peak and volume in scenario 2 are computed less than that of scenario 1 and in scenario 3 are computed more than that of scenario 2. On the other hand, flood peak and volume in the scenario 3 slightly decreased by 4.8 and 5.7 percent respectively compared to scenario 1 where is not significant based on the objectives of project.
Mehdi Bashari; Seyed Hamid Reza Sadeghi; Abdolsaleh Rangavar
Abstract
Investigation of effective factors on soil erosion and their variability analysis is essential for soil and water conservation projects. The present research was carried out to survey the role of two north and south facing slope plots on soil erosion on storm basis at Sanganeh watershed located in Khorasan ...
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Investigation of effective factors on soil erosion and their variability analysis is essential for soil and water conservation projects. The present research was carried out to survey the role of two north and south facing slope plots on soil erosion on storm basis at Sanganeh watershed located in Khorasan Razavi province, Iran. The study was conducted using a pair of small plots with dimensions of 2×2 meters. The plots were be designed using metal sheets and their outlet was directed towards collecting tanks. These plots were established close to each other at two different aspects. The generated runoff and sediment from plots caused by 12 storm events during October 2006 and May 2007 were collected and sediment concentration was ultimately calculated. The results of sediment concentration analysis verified a significant difference (p<0.01) between soil erosion study plots with very low quantities in plots installed in northern aspect. The difference was clearly associated with effect of slope aspects on vegetation cover.
Jalal Barkhordari; Davood Nikkami; Mohammadbagher Samadi; Monirosadat Tabatabaeizadeh
Abstract
Rainfall erosivity is one of the most important factors in determining soil erosion. This factor is usually expressed as erosion indices that are based on rainfall characteristics. In this study, after construction of 12 runoff-sediment plots in Nir Research Station in Yazd province, the amount of runoff ...
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Rainfall erosivity is one of the most important factors in determining soil erosion. This factor is usually expressed as erosion indices that are based on rainfall characteristics. In this study, after construction of 12 runoff-sediment plots in Nir Research Station in Yazd province, the amount of runoff and sediment from each plot were monitored and measured for 12 rainfall events. Then, based on a world wide literature review, 61 rainfall erosivity indices were identified. The rainfall erosivity indices were determined for each of the storms with extracting the required parameters. In order to determining suitable rainfall erosivity indices, the correlation between the rainfall erosivity indices and soil loss values were determined. The results showed that PI602, PI302, RPI602, RPI302, RI60 with 0.730, 0.713, 0.703, 0.694 and 0.664 percent had highest correlation with soil loss amount. Generally, in the climatic condition of study area, the indices based on rainfall intensity with total amount of rainfall multiply in the square of 60 and 30 minutes rainfall are better than other indices.
Seid Saeid Ghiasi; Faezeh Rajabzadeh; Somayye Najirda; Sadat Feiznia; Aliakbar Nazari Samani
Abstract
Shallow landslide susceptibility assessment by using appropriate methods and determine of effective factors in reduce of its hazards is so effective. The aim of this study is to determine the effective factors on shallow landslide occurrence and investigation of Statistical Index Method (SIM) efficiency ...
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Shallow landslide susceptibility assessment by using appropriate methods and determine of effective factors in reduce of its hazards is so effective. The aim of this study is to determine the effective factors on shallow landslide occurrence and investigation of Statistical Index Method (SIM) efficiency for landslide susceptibility mapping. So, determination of each class of factors’ weights was accomplished by using SIM. That was done by adoption of inventory landslide map and ten initial factors including: slope, aspect, rainfall, altitude, drainage density, plan curvature, land use, geology, geomorphological faces and rock unit sensitivity to erosion in ArcGIS 9.3. Then model efficiency was evaluated by using percentage of area under ROC curve and the results showed high accuracy (0.95) of SIM. Principal Component Analysis (PCA) was used for determination of primary causative factors of shallow landslide occurrence. Results showed that five variables of rainfall, slope, aspect, rock unit sensitivity to erosion and plain curvature are the most effective factors on landslide occurrence, respectively.
Seyed Hamid Reza Sadeghi; Gholam Reza Shojaee; Hamid Reza Moradi
Volume 2, Issue 3 , October 2010, , Pages 143-149
Abstract
The intensity and type of soil erosion are functions of climatic, topographic, soil and land use characteristics. The role of land use is more than others due to the human impacts. In order to study the relationship between land use change and soil erosion, the Manderijan watershed located upstream of ...
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The intensity and type of soil erosion are functions of climatic, topographic, soil and land use characteristics. The role of land use is more than others due to the human impacts. In order to study the relationship between land use change and soil erosion, the Manderijan watershed located upstream of Zayandehrud dam basin, comprises 23000 ha, was selected. The satellite images of MSS1979, TM1990, TM1998 and ETM2002 were used to map land use as well as soil erosion features during the study periods. The relationship between the existence as well as areas of each particular soil erosion feature and land use was also investigated using regression and Chi-square analyses. The results of the study verified a significant relationship between areas of land uses and soil erosion features. The moderate sheet erosion was further related to the land use changes in particular in the form of cubic regression equation having the determination coefficient of less than 81% and relative error of below 39.65%. The Chi-square analysis was also certified the insignificant relationship between existence of each particular soil erosion feature and land use whereas the relationship between land use and soil erosion areas could be significantly approved. The results of the study therefore can be utilized for proper management of the area through devoting necessary attention into the land uses.
Jamal mosaffaie; Majid Ownegh
Abstract
Landslide is one of the natural hazards that makes numerous financial and life damages each year. By landslide hazard zonation, we able to detect susceptible areas to landslide and with applying developed methods and suitable management the abundance of land sliding and the amount of damages will be ...
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Landslide is one of the natural hazards that makes numerous financial and life damages each year. By landslide hazard zonation, we able to detect susceptible areas to landslide and with applying developed methods and suitable management the abundance of land sliding and the amount of damages will be reduced. In this study potential landslide hazard evaluated using multivariate regression model at a part of Alamout watershed in general level (1:50000 scale). So first, landslide distribution map of area prepared using study of air photos and field surveying. After reviewing available resources along with reviewing the benefit of experts, all factors that can affect landslide were extracted and among them eight parameters including (lithology, slope percent, aspect, height, distance to fault, land use, rainfall and earthquake acceleration) were selected as landslide effective factors. AHP and pair comparing technique were used for numerical weighting to qualitative categories of land use, aspect, and lithology parameters. Homogeneous units map prepared using overlaying 8 maps of landslide key factors, and by crossing of homogeneous map and landslide distribution map. Categories of each parameter were detected in each landslide, and with weighting average of them, the effect of each parameter was determined in each landslide. Therefore 84 observations prepared for statistical analysis of landslides. Results showed that 5 parameters including lithology, slope, height, distance to fault and land use have meaningful relation with landslides that determining coefficient between these parameters as independent variables and logarithm of landslides area as dependent variable was 60.7%. Landslide hazard zonation map and landslide distribution map were crossed and efficiency of model was evaluated. The Chi square test was used for comparing of difference between hazard classes of model. Results show that model has higher efficiency in higher classes of hazard. Results show also measured chi square rate is meaningful at 99% of confidence interval, and there is suitable separation among landslide hazard classes.
Hamidreza Peyrowan; Ali Jafari Ardekani; Mohsen Shariat Jafari
Abstract
This research has been done for the study of morphology of Ghezel Ouzan River from Ostoor to Manjil dams in two gorge and floodplain basins at 37 years period based on aerial photos, topographic maps and field surveying. The results showed the mean sinuosity ratios of, 1.46 and 1.22 for gorges and floodplain ...
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This research has been done for the study of morphology of Ghezel Ouzan River from Ostoor to Manjil dams in two gorge and floodplain basins at 37 years period based on aerial photos, topographic maps and field surveying. The results showed the mean sinuosity ratios of, 1.46 and 1.22 for gorges and floodplain basins so that they can be classified as meandering and sinuous river reaches respectively. More sinuosity at gorge basin is due to the geological and tectonically factors. In the other words, the river plan initiate and mature based on rock canal that originated from above mentioned geological factors. At floodplain basin in Pavehrood to manjil dam with 60 km length river reach, the river showed three obvious sinuous canaliform, sinuous point bar, sinuous braided and braided and anastomising plan . At period 37 years braiding extend in the boundary about 1.2 km widths in Hezarrood area. If the rate of widening of the river in this basin presumes in uniform rate, the velocity of the river widening is about 32 meters per year that is noticeable. Bank erosion with meandering form of the river in Haroonabad area through meandering growth and extensions of the loops occurred up to 850 meters at the mentioned periods. Based on central angel of meanders loops, 57.72 percents of loops are extended modes, 25.93 % very extended, 16.05 of others are new so the river has meandering hazard. Extension mode of the loop growth is the main mode with 56% frequency and based on water shear stress distribution, geometry of loops and relative radius of the loops, consequently accumulation point of the shear stress, the modes of translations, rotation, compounding and chute and neck cut off are observed. More than 75 % of canal shifting cases of the river is toward left bank so that the construction of any structures on the left bank of the river would be dangerous.
Rahim Kazemi; Jahangir Porhemmat; Bagher Ghermez Cheshme
Abstract
Understanding the interaction of drought phenomenon and hydrological response of catchments can lead to obtaining some information for optimal water resource management. The aim of this study was to investigate the temporal relationship between drought and groundwater contribution to stream flow, in ...
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Understanding the interaction of drought phenomenon and hydrological response of catchments can lead to obtaining some information for optimal water resource management. The aim of this study was to investigate the temporal relationship between drought and groundwater contribution to stream flow, in Kaka–Reza Sub-catchment. In this study, the common period of 1382-2017 was considered for the corresponding hydrometric and rain gauge stations. The Standardized Precipitation Index (SPI) was then calculated at time scales of three, six, nine, 12, 18 and 24 months. Base flow and related index were calculated by B-Flow-Line and Halick digital filter method in monthly, annual and total time bases. Then the Standardized Base Flow Index (SBFI), the Base Flow Duration Curve (BFDC) and the base flow duration curve shape index (SBFDC) was calculated. Changes in BFDC and the corresponding shape index and the relationships between SPI and SBFI were investigated and analyzed using the correlation method. The results showed that the average Base Flow Index during the research period was equal to 0.52 and its minimum and maximum were equal to 0.46 and 0.57, respectively. Also, the trend of bas flow changes is a decreasing trend with a low slope. The trend of changes SBFDC decreases over study period with a low slope. The rate of slope change is also from one to three percent, and close to the straight line, which indicates the tendency for base flow to be stable in the long time. The greatest impact of the drought phenomenon on the river base flow is in the time step of nine and twelve months. The correlation between SPI and SBFI with a coefficient of determination 0.87 confirms the increase in the groundwater contribution to base flow, with a delay of nine to twelve months.
Mohsen Tavakoli; Haji Karimi; Hadi Norollahi
Abstract
Climate change and global warming is one of the most important issues in the world that is discussed in public and professional meetings. Long term climate change forecasting has an important role on water resources planning and management, due to fragile climate of our country. The present study aimed ...
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Climate change and global warming is one of the most important issues in the world that is discussed in public and professional meetings. Long term climate change forecasting has an important role on water resources planning and management, due to fragile climate of our country. The present study aimed to investigate the effects of climate change on discharge changes in Golgol Watershed as one of the Ilam dam sub-watersheds. In this research, first, temperature, precipitation and potential evapotranspiration data were downscaled and then, hydrological condition of the watershed is simulated using SWAT hydrological model. Next, the results of downscaled HadCM3 data under two scenarios of A2 and B2 were downscaled using SDSM and in the next step stream flow of three period including 2010-2039 (2020s), 2040-2069 (2050s), 2070-2099 (2080s) and base period of 1990-1961 (Baseline), simulated using SWAT model. Finally, the effects of climate change assessed until the end of the century. The results indicated that annual discharge will decrease for 2020s, 2050s and 2080s under A2 scenario by 6.3, 16.9 and 24.1percent, and will decrease under B2 scenario by 10.9, 8.8 and 13.2 percent, respectively. Resualts demonstrated that climate change as one of the negative phenomena that affects on the amount of water in Ilam Dam should be considered by managers and planners.
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.
Alireza Zarei Ghorkhodi; Maryam Mirhashemi; Ali Shahnazari
Abstract
Extended abstract
Introduction
Indiscriminate and non-technical extraction of sand and gravel from rivers has brought many adverse morphological and environmental effects. The negative consequences of river materials mining occur under the influence of various factors. Examining the system of exploitation ...
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Extended abstract
Introduction
Indiscriminate and non-technical extraction of sand and gravel from rivers has brought many adverse morphological and environmental effects. The negative consequences of river materials mining occur under the influence of various factors. Examining the system of exploitation of materials from the river also indicates the existence of many problems in different technical, legal, socio-economic and environmental aspects. In this regard, the present research was carried out with the aim of identifying and prioritizing factors affecting river materials mining and providing optimal river materials mining management indicators.
Materials and methods
The watersheds studied in this research include Lake Urmia, Sefidroud and Heraz, Heraz and Qarasu, Kerganrud, Karkhe, Karun and Sefidroud Bozorg. The required information has been obtained through survey-type field research, by conducting face-to-face interviews and using questionnaires. The studied statistical group consists of experts, specialists and experts of regional water companies all over the country. The research tool was a questionnaire whose content validity was obtained by obtaining the opinions of relevant experts and university professors and applying the necessary corrections. Cronbach's alpha coefficient and SPSS software were used for the reliability of the research tool and its figure was equal to 0.811. The items examined in the questionnaire were measured in three main sections, including river characteristics, the status of material harvesting, the evaluation of technical, legal, socio-economic, and environmental indicators of the effects of river material harvesting, and two general sections, including the identification of the main indicators of optimal river material harvesting and the extent of the impact of clause "and" of Note 8 of the 2021 National Budget Law on reducing or increasing the effects of river material harvesting.
Results and discussion
The examination of technical factors showed that T3 items (river stability, hydraulic structures and their lifespan) with a frequency of 16.92% and item T5 (changes in the level of underground water in aquifers adjacent to the river) with a frequency of 4.61% are the most important respectively. And they are the least important factor in River materials mining. Among the legal components of item L1 (weakness in providing the necessary infrastructure for the establishment of control laws and regulations) and item L6 (lack of suitable infrastructure for crisis management in times of need) respectively with the frequencies of 18.69% and 8.46% of the first priorities and finally, they have assigned the factors affecting the river materials mining. The results of the study of socio-economic factors affecting the river materials mining showed that item S1 (lack of laws and regulations to control the price and price fluctuations of river materials) with a frequency of 15.38% is the first priority of socio-economic factors affecting the river materials mining and Item S3 (migration process from (to) the region) is the least important factor (6.17%) in river materials mining. On the other hand, item E2 (environmental effects of river materials mining on the water environment of the river (plant and animal community)) is the most important influencing factor in river materials mining with a frequency of 23.08% and item E5 (effect of river materials mining on floodplains) with a frequency of 15 16% is the least important factor among environmental components. Based on experts' point of view, indicators such as appropriate depth of river materials mining, distance of river materials mining from upstream and downstream structures, finding the potential of a suitable river materials mining location, estimating the annual sediment load of rivers, determining suitable river materials mining sizes according to the surplus materials of the river are the most important indicators affecting the optimal river materials mining.
Conclusion
The results of the general investigation of legal, technical, socio-economic and environmental factors indicate that the weakness of the legal components is the most effective factor in aggravating the negative consequences caused by the river materials mining. Lack of sufficient and effective supervision at the stage of issuing operating licenses, weakness in providing the infrastructure needed to enact laws and regulations, lack of price control laws and regulations are the most challenging issues among the criteria. Therefore, creating laws without parallel work, placing the regional water company in charge of all stages of issuing operating licenses, and establishing strict rules in dealing with violators and continuous monitoring of river materials mining operations can reduce the damages caused by the river materials mining in technical, socio-economic and environmental sectors also reduce.
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.
