Ali Bagherian kalat; Esmail Filekesh; Alireza Majidi
Abstract
Marl formations due to their unsuitable physico-chemical properties have low vegetation cover and so are highly erodible. These formations make up about 2000 km2 of lands in Sabzevar and Davarzan areas. In this research, geology, pedology and vegetation cover of marl formations were studied. Geologically, ...
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Marl formations due to their unsuitable physico-chemical properties have low vegetation cover and so are highly erodible. These formations make up about 2000 km2 of lands in Sabzevar and Davarzan areas. In this research, geology, pedology and vegetation cover of marl formations were studied. Geologically, there are two kinds of marl formations consisting salty and red gypsiferous marls. Marly lands in southern aspects usually have no vegetation but in northern aspects the vegetation varies between 0 to 27 percent. Three vegetation communities consisting of Salsola aucheri, Artemisia seiberi and Ephedra intermedia are stablished on marly soils. For recognizing soil factors of each vegetation community, studies localized in establishment area of Salsola, Ephedra and Artemisia vegetation types. Many soil profils were dug. Soil samples were taken from depth between zero and 40 cm of marly soils and were analyzed. Results showed that in all plant types with increasing of percent of plant cover from 0-10 to 10-24 percent, the main soil factors such as EC, pH, gypsum, silt an clay, Na+, K+, Mg2+, Cl-, So42-, total Cations and Anions and SAR were decreased and factors such as Organic carbon, N, P. T.N.V, Co3-1 and sand percent were increased. The statistical analysis of data was conducted with the SPSS software. This study showed that Artemisia and Ephedra had the highest and lowest vegetation percentages, respectively. Analyzing of data acording to Duncan Test showed that the differences between plant cover percent in three vegetation communities are very obvious (P<0.05). Meanwhile, the amount of EC and gypsum of marly soils were important soil factors that had the most roles in establishment of vegetation.
Abdolrasoul Shafiey Dastjerdi; Mohammad Hossein Mahdian; Kourosh Kamali; Hamid Hoseyni Marandi
Abstract
Entrance of high volume of floodwater containing huge amount of suspended sediments into the floodwater spreading networks which deposits sediments, as well as infiltration of soluble materials and fine grained, gradually changes the infiltration rate of soils. The aims of this project is to study the ...
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Entrance of high volume of floodwater containing huge amount of suspended sediments into the floodwater spreading networks which deposits sediments, as well as infiltration of soluble materials and fine grained, gradually changes the infiltration rate of soils. The aims of this project is to study the quantity and the process of changes made in the soil of Saravan floodwater spreading station. This research has tried to use direct method of infiltration rate measurement, using double ring infiltrometer in two separate time periods of one year each, and to compare it to the experimental area. In order to specify overall situation of infiltration rates in terms of increase or decrease in second period of measurement in comparison to the first one, and as far as data were not distributed normally, Wilcoxon signed-rank test was used. The results showed no significant difference between two separate measurement periods due to few number of floodwater occurrences (three times) in addition to short time interval of one year between the two measurement periods. To determine changing rate of infiltration between strips and between the strips and the experimental field, as far as abnormal distribution of data in this arrangement were concerned, Kruskal-Wallis test was used. Results indicated that the three strips of flood spreading area have no significant difference (at five percent probability level) in two periods of measurement, but the strip related to experimental area has significant difference with other three strips and in both measurement periods. In other words, infiltration rates of all strips under floodwater spreading have been decreased in relation to the experimental area. Moreover, the results were explanatory that only one of the rectangular in both measurement periods had significant difference with experimental rectangular (at five percent probability level) and all the other rectangular have had no significant differences with each other and in comparison to the experimental one, in none of periods of measurement. Main reason of this difference is also related to the thicker sediments deposits in rectangular location, compared to other blocks. Also, infiltration rate decreased by 55.94 percent in flood spreading area compared to experimental area during one-year timeframe and 3.23 percent of reduction.
Ebrahim Khalife; Mohammad Reza Kavianpour; Mojtaba Pakparvar; Aminollah Mottaghi
Volume 2, Issue 1 , May 2010, , Pages 44-55
Abstract
In view of the fact that extensive areas of ‘Iran’ are located in arid and semi arid regions, considerable damages on natural and economic resources by wind erosion and sand storms are expected annually. Lack of proper input data for physical and quantitative models and difficulties of access ...
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In view of the fact that extensive areas of ‘Iran’ are located in arid and semi arid regions, considerable damages on natural and economic resources by wind erosion and sand storms are expected annually. Lack of proper input data for physical and quantitative models and difficulties of access to these data can limit the models application. In these conditions it is necessary to devise an informative-computational model based on geographical information systems and use remote sensing to prepare as much as possible layers of parameters, accurately. Therefore, in this research a qualitative model for wind erosion assessment (IRIFR) has been embedded in geographical information system together with remote sensing to prepare layers of information and parameters. The major targets of this research are to get benefits of earlier approaches in relevant researches and compile relevant techniques and methods in GIS and RS to study wind erosion. The most important achievements of this research are; i) providing layers of information by remote sensing, ii) omitting primary common map of study units, iii) determining and defining separated maps of study units which are needed for a few parameters, iv) omitting the map of other parameters, and v) reducing uncertainties arising from experts judgment. Furthermore, the model could be repeated for any time duration. Consequently, investigations would be organized much better, more accurate and faster.
Mohammad Nekouiemehr; Said Naim Emami; Ravanbakhsh Raisian; Majid Soufi; Msoud Goodarzi
Abstract
Applied research about preventing gully initiation and expansion, needs basic knowledge about the types and morphometric characteristics of gullies. The purpose of current research is the classification of gullied regions based on morpho-climatic characteristics in Chaharmahal and Bakhtiary province. ...
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Applied research about preventing gully initiation and expansion, needs basic knowledge about the types and morphometric characteristics of gullies. The purpose of current research is the classification of gullied regions based on morpho-climatic characteristics in Chaharmahal and Bakhtiary province. In this research, two gullied regions covering an area about 500 ha were selected in each climate zone and three representative gullies were chosen in each region. The morphometric characteristics were measured in each studied area. Classification of gullied regions was done using cluster analysis based on quantitative characteristics. The results indicate that gullied regions in Chaharmahal and Bakhtiary province can be divided to three groups base on morpho-climatic characteristics. Maximum similarity level was 94.12 percent. A comparison of variance analysis and mean value of variables in groups shows that, annual rainfall, elevation above sea level, gully length, gullied region area and top width of gullies were the most important variables in separating of the groups. Generally, we can emphasize that among all morphometric characteristics; only gully length and top width have the main role in morpho-climatic classification.
Davood Nikkami; Hadi Chamheydar; Mohammad Hossein Mahdian; Ebrahim Pazira
Abstract
Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in ...
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Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in the area of soil nutrient evaluation with optimization models, the main objective of this research is determining the optimum level of land uses to minimize soil erosion and nutrients losses and maximize people incomes that live in a watershed. For this purpose, Abolabbas Watershed in the north-eastern part of Khouzestan Province was chosen for this research. A linear programming model was used in three different scenarios including current land use condition without land management, current land use condition with land management and standardized land use condition. Results demonstrated that the current land uses are not optimized for the least soil erosion and nutrient losses and high income. At optimized conditions, the area of forests and orchards increased by 1.81 and 55.7% respectively, rangelands with no changes, and irrigated and drylands decreased by 67.5 and 31.4% respectively. Also, results showed that land use optimization, in current land uses with no land management, decreases total soil erosion by 3.2% and total nutrient soil losses by 2.5 and increases total income by 29.7%, in current land uses with land management, decreases total soil erosion by 35.3% and total nutrient soil losses by 70.2 and increases total income by 37.2%, and in standardized land uses, total soil erosion by 47.2% and total nutrient soil losses by 70.4 and increases total income by 41.8%. Sensitivity analysis, also, showed that the change in the area of orchards and Irrigated lands has the most effects on increasing income and decreasing soil erosion and nutrients losses in Abolabbas watershed.
Akram Mirzaei; Ziaoddin Shoaei; Nader Jalali; Alireza Eslami
Volume 1, Issue 1 , May 2009, , Pages 53-60
Abstract
In this research, Hydro-physical model was used for estimating of potential sediment yield in sub- basin of Karaj watershed. In this model limited field survey is required and five main factors as vegetation cover, rainfall, erosion ability, topography and area were used. The results of comparison made ...
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In this research, Hydro-physical model was used for estimating of potential sediment yield in sub- basin of Karaj watershed. In this model limited field survey is required and five main factors as vegetation cover, rainfall, erosion ability, topography and area were used. The results of comparison made between the observed sediment yields in the gauged station of Siera with the estimation made by the model were highly correlated. Factor analysis by SPSS software was used for determining the role of those factors on erosion and sediment yield. The results showed those factors covered about 92% of sediment changing in sub-basins.
Ebrahim Karimi Sangchini; Majid Ownegh; Amir Sadoddin; Nasser Tahmasebi Pur; Hossein Rezaee
Abstract
This paper describes the utilization of a system dynamics model to predict the effects of vegetation-based management scenarios on structural landscape ecology in the Hablehrud River Basin. The river basin covers an area between Tehran and Semnan provinces. In this research, vegetative management scenarios ...
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This paper describes the utilization of a system dynamics model to predict the effects of vegetation-based management scenarios on structural landscape ecology in the Hablehrud River Basin. The river basin covers an area between Tehran and Semnan provinces. 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. In order to predict the effects, Weighted Mean Patch Size index (WMPSI), Weighted Land Cover Area Index (WLCAI) and Riparian Proportion Index (RPI) were quantified. Additionally, the model uncertainty analysis was conducted using bootstrap method. Ecological impacts of the scenarios using aforementioned indices were predicted and the best scenarios were chosen using system dynamics. Results suggest that considering WMPSI, tree plantation and riparian restoration scenarios are the preferred scenarios. Seeding and orchard development scenarios were considered to be the best scenarios based on WLCAI. Moreover, riparian restoration and saxaul plantation were chosen as the best scenarios considering RPI. Seeding and riparian restoration scenarios obtained the highest priority considering the combination of the indices. WLCAI and RPI have the minimum and maximum uncertainty levels with respect to coefficient of variation as 0.28 and 0.45, respectively. The system dynamics models are capable of predicting the effects of various management scenarios providing the information required for decision making and management at watershed scales.
Majid Hosseini
Abstract
In this study, a simulation has been performed using the Soil and Water Assessment Tool (SWAT) model with the data of the Ghare-sou watershed. The main objective of the study was testing the performance of SWAT and its feasibility to simulate the water balance in this watershed. Required data such as ...
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In this study, a simulation has been performed using the Soil and Water Assessment Tool (SWAT) model with the data of the Ghare-sou watershed. The main objective of the study was testing the performance of SWAT and its feasibility to simulate the water balance in this watershed. Required data such as soil properties, land use and topographic maps were collected from the Natural Resource Office of Kermanshah province, and the weather data, including daily rainfall, temperature, relative humidity and discharge were collected from Meteorology Agency and regional water company of the province. Before calibration, a sensitivity analysis has been performed for all parameters, using OAT (One parameter At a Time) method to evaluate and demonstrate the influences of the model parameters on four major components of water budget including surface runoff, lateral flow, groundwater and evapotranspiration. Calibration and validation of the model were performed using the SUFI2 algorithm. River discharge data from 1982 to 2000 were used for the calibration and those of 2001 to 2005 for the validation. Different criteria were used to evaluate the performance of the simulation. During calibration, the simulated flow matched the observed values with a Nash-Sutcliffe coefficient of 0.56 and a coefficient of determination (R2) of 0.6. These values were 0.6 and 0.65 during the validation. The calibrated SWAT model is suggested to be used in simulation of the monthly flow of the Ghare-Sou watershed, in order to assess the impacts of different management practices and environment changes on the flow.
Ali Forudi Khowr; Mahdi Azhdary Moghadam; Mojtaba Saneie
Abstract
This study aimed to analyse the design of spillway in curved plan and downward angle of convergence. In this plan the effective length of the spillway is reduced from the crest to the toe for several times. Tests were carried out in two stages. In the first stage, a physical model of the real sample ...
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This study aimed to analyse the design of spillway in curved plan and downward angle of convergence. In this plan the effective length of the spillway is reduced from the crest to the toe for several times. Tests were carried out in two stages. In the first stage, a physical model of the real sample was prepared for a specific site in the scale of 1:50. In this stage, experiments were performed for eight different discharges making up to 25 to 150% of the design discharge of the real sample. The spillway demonstrated a satisfactory performance up to the discharge of 1.13Qd (Design Discharge). Gradually an increase in the discharge led to a decrease in the performance of the spillway so that with a discharge of 1.26 Qd the spillway was fully submerged and the downstream channel took control of the discharge. Observations and experiments indicated that one of the factors contributing to the swamp of the spillway was a severe variant of the guide wall (120 degrees) as well as the considerable decrease in the ratio of channel length (Lch) to crest length (L), i.e. . In the second stage, the effect of variation of convergence angle of the guide walls of the spillway was studied. To this end, a physical model with three convergence angle of the guide walls, including a 0-degree angle and ratio of ; a 60-degree angle with ratio of ; and a 90-degree angle with ratio of was tested. The effect of variations of angles in discharge coefficient was reported to be negligible before the swap. At the 0-degree angle with ratio of , the highest discharge was 1.99 because the model was not submerged in a discharge equal to the PMF discharge of the real sample. In all angles, the static pressure on the crest was reduced while it was increased in the shoot and toe. So that, in the crest a ratio of was recorded for a discharge of 1.13 Qd. At the angles of 90 and 120 degree, higher discharges led to swamp of the spillway and a change of the current flowing on the spillway from supercritical to subcritical. The high pressure was reported to be of the 120-degree angle for a discharge of 1.5Qd. Since at the 60-degree angle ( ), the length of the crest was smaller (45% less than the 120-degree angle with ), it was selected as the proper angle.
Abdolnabi Kolahchi; Mohamamd Eftekhar Dadkhah; Mehdi Mirzai
Abstract
The effects of drought on water resources in mountainous areas in Iran, is very difficult, due to lack of proper distribution of the station as well as lack of long-term data. The main objective of this study is to investigate the droughts in Kermanshah. The data used included the precipitation data ...
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The effects of drought on water resources in mountainous areas in Iran, is very difficult, due to lack of proper distribution of the station as well as lack of long-term data. The main objective of this study is to investigate the droughts in Kermanshah. The data used included the precipitation data of 42 points of the TRMM model with a spatial accuracy of 0.25 × 0.25 degrees, precipitation data of ground stations for the 15-year period (2014-2000) and the discharge of karst springs. The accuracy of data from two databases was evaluated by using R, R2, EF, IA, Slope, NRMSE and Bias statistics in the MATLAB software. The evaluation of the TRMM model's accuracy in comparison with the recorded rainfall data of ground stations on a monthly scale showed that the satellite data is very accurate and 70 to 80 percent of the precipitation data variance is explained by satellite rainfall data. Also, the amount of satellite data deviation from the station data is negligible and less than 10 mm. Drought monitoring using TRMM data and SPI index in monthly, seasonal and annual measurements showed that the frequency of drought in this province is usually more than wet, but the severity of the dry periods is less than wet periods and some dry periods are compensated by a wet period. The time distribution of SPI showed that wet and dry periods are more concentrated at the beginning and the end of the study respectively. Therefore, rainfall is decreasing and the contribution of spring rainfall is rising relative to fall and winter rainfall. The correlation coefficient (R) between precipitation and discharge of selected karst springs is between 0.77 and 0.88 where the highest coefficient of determination (R2 = 0.77) occurred in Ravansar station.
Reza Chamani; Seyed Hamidreza Sadeghi; Mehdi Vafakhah; Maryam Naghdi
Abstract
Drought is one of the natural disasters related to climate and one of the most important threats to human survival leading to adverse effects on social, economic, and environmental sustainability. In this study, it has been tried to evaluate the changes in reliability, resilience, and vulnerability of ...
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Drought is one of the natural disasters related to climate and one of the most important threats to human survival leading to adverse effects on social, economic, and environmental sustainability. In this study, it has been tried to evaluate the changes in reliability, resilience, and vulnerability of the Chalous Watershed under the influence of drought in the period of 1982-2017. In this vein, rainfall data of nine stations were interpolated using invers distance squared method to the whole watershed. The SPI drought index was then determined through determining the mean and standard deviation of the data. To calculate Rel, Res and Vul indices, the mean value of SPI Index was used. By calculating the geometric mean value of these indicators, the general health status of the watershed was determined and quantified. The results showed that the SPI Index in this period varied between -1.43 and 2.25. Drought index had a similar pattern to that of rainfall with an increasing trend at the end of the period. The watershed health assessment also showed that the indicators of reliability, resilience, and vulnerability were found 0.5, from 0.23 to 0.62 and from 0.06 to 1, respectively. The geometric mean of these indices was also ranged between 0.19 and 0.58. The overall health condition of the Chalous Watershed based on the dynamics of drought index with a mean index of 0.45 was classified as “moderate”. The findings of the current research will play an important role in explaining the methods of adaptive management of the watershed.
Hamid Darabi; Kaka Shahedi; Mehdi Mardian
Abstract
Because of data lacking in the most of watersheds, many researchers applied spatial analysis in GIS environment to study the hydrological and flooding condition. This study aims to map flood susceptibility through frequency ratio technique using some parameters such as digital elevation technique, slope, ...
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Because of data lacking in the most of watersheds, many researchers applied spatial analysis in GIS environment to study the hydrological and flooding condition. This study aims to map flood susceptibility through frequency ratio technique using some parameters such as digital elevation technique, slope, curvature, topographic wetness index, stream power index, average rainfall, distance from river, geology, soil type and land use in Pole-Doab, Shazand Watereshed, Makazi Province, Iran. First, digital map of all of the parameters were prepared based on raster format using Arc GIS 10.1 and SAGA GIS2 softwares. To prepare land-use map IRS-1C satellite image, ENVI 4.8 software and maximum likelihood algorithm were applied. Then flood inventory map was produced by mapping 95 flood prone locations in the study area using documented information on the May-2003, May-2004 and March-2004 floods. These 95 locations divided into two groups including 67 points (70%) and 28 points (30%) for calibration and validation, respectively. For calibration, flood prone locations defined as dependent variable and ten parameters that are affecting flooding condition were introduced to frequency ratio as independent variables. Then flood probability was determined for each class of each parameter. Finally, obtained weights for each class in GIS were implemented in corresponding layers and using the overlay algorithm, susceptibility and probability maps were prepared. Based on the susceptibility map, study area was divided into 5 classes as very high, high, medium, low and very low sensitivity. The findings of the assessment of frequency ratio histogram indicated that the likelihood of very high and very low flooding classes are equal to 67.86 and zero percent, respectively. Therefore, the obtained frequency ratio histogram confirms the adequacy of the implemented method in flood susceptibility and probability mapping for the case study.
hamzeh saeediyan; Hamidreza Moradi
Abstract
By determining the threshold of runoff and erosion by rain simulator, it can be determined rainfall amount that causes runoff in different conditions with more speed and accuracy and lower cost. After determining the threshold of runoff and erosion in each region, using biological methods and operations ...
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By determining the threshold of runoff and erosion by rain simulator, it can be determined rainfall amount that causes runoff in different conditions with more speed and accuracy and lower cost. After determining the threshold of runoff and erosion in each region, using biological methods and operations can prevent the conversion of runoff to flood. In this research, considering that the threshold of runoff and erosion occurs simultaneously and mistakenly only the term of runoff threshold is used in different researches and do care less about erosion threshold and in order to determine the most important factors affecting the simultaneous threshold of runoff and erosion of different land uses of Aghajari and Gachsaran formations, part of Margha and Kuhe Gach watersheds of Izeh city with an area of 1609 and 1202 Hectare selected. This study was conducted to determine the relationship between runoff and erosion threshold using a rain simulator with some soil physical and chemical properties such as very fine sand percentage, sand, clay, silt, pH, electrical conductance, moisture, calcium carbonate and organic matter in different land uses of Aghajari and Gachsaran formations. Then, sampling was done at 13 points and with three replicates in Aghajari and Gachsaran formations at different rainfall intensities of 0.75, 1, and 1.25 mm/min in 3 land uses of rangeland, residential area, and agricultural land using a rain simulator. SPSS and EXCEL soft wares were used for statistical analysis. The most important factors affecting runoff and erosion threshold were identified by multivariate regression. In general, in Gachsaran formation in all three land uses, clay and calcium carbonate showed the highest role in increasing the threshold of runoff and erosion. The most roles in reducing runoff and erosion threshold showed very fine sand and moisture content in Gachsaran Formation. However, in the Aghajari Formation, in all three land uses, the highest role in increasing the threshold of runoff and erosion, showed clay and organic matter. In addition, the most roles in reducing the threshold of runoff and erosion in the Aghajari formation showed very fine sand and soil sand and salinity.
Reza Chamani; Mahmood Azari; Sven Kralisch
Abstract
The hydrological effects of climate change are a great challenge for water resources management. Determining climate change impacts on hydrological processes is a prerequisite for adaptation strategies to climate change; which in turn is necessary for water scarcity crisis in future. The purpose of this ...
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The hydrological effects of climate change are a great challenge for water resources management. Determining climate change impacts on hydrological processes is a prerequisite for adaptation strategies to climate change; which in turn is necessary for water scarcity crisis in future. The purpose of this research is to determine climate change impacts on hydrological regime of the Chehelchay watershed in Golestan province. J2000 distributed process based model was used for simulation of the hydrological process. Output results of seven climate models including CanESM2, CCSM, BBC-CSM1.1, CESM1-BG, CESM1-CAM5, ICHEC- EC-EART and MPI-M-MPI-ESM-LR for two Representative Concentration Pathways scenarios (RCP 4.5 and RCP 8.5) for 2071-2100 were used for climate change impact analysis. Study results revealed that the maximum temperature for RCP 4.5 and RCP 8.5 in 2071-2100 will increase by 2.6 and 4.7 °C and the minimum temperature will increase by 2.4 and 4.5 °C respectively by the end of the 21st century. In addition, precipitation for RCP 4.5 will increase by 0.6 percent and for RCP 8.5 will decrease by 0.6 percent. Modeling results show these will lead to significant changes in the hydrological regime. In particular, evapotranspiration will increase by 9.6 and 16.7 percent and stream flow will decrease by 4.2 and 3.2 percent. The results of the hydrological changes will cause a decrease in stream flow in April –June and for RCP 8.5 will be continued till October.
Tayebeh Irani; Mir Hassan Miryaghoubzadeh
Abstract
Land use is referred to the use of land in existing condition that includes all uses in different parts. Land use change is affected by several factors. In this research, land use Changes in the Zarrinehroud watershed and its effect on water quality were investigated in three periods (1987, 2004 and ...
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Land use is referred to the use of land in existing condition that includes all uses in different parts. Land use change is affected by several factors. In this research, land use Changes in the Zarrinehroud watershed and its effect on water quality were investigated in three periods (1987, 2004 and 2013) using Landsat satellite TM and OLI sensors. The results indicate that land use changes in the watershed is going to reduce of pasture and increasing of agriculture. Wilcox and Schuler diagrams were used to evaluate the chemical quality of agricultural water, and drinking water, respectively. Based on the Wilcox diagram, only year 2004 (dry period) was on the C3-S1 class and the remaining years were on the C2-S1 class. Based on the Schuler diagram, the year 2004 (dry period) is considered acceptable in the drinking category and the remaining years are in good drinking category and have no restrictions on drinking. Water quality assessment of the Zarrinehroud watershed shows a decrease in water quality, as a result of increasing the EC, TDS and SAR characteristics in year 2004 that indicates a decrease in river water quality due to land use change and accordance with the occurrence of droughts in the year 2003-2004.
Rahim Kazemi; Jahangir Porhemmat
Abstract
Estimating the runoff coefficient that is influenced by morphometric, geologic and hydro-climatologically factors are the most important issues in hydrology and information of its role in the planning and management of water resources is more important. Clustering catchments is the best method for the ...
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Estimating the runoff coefficient that is influenced by morphometric, geologic and hydro-climatologically factors are the most important issues in hydrology and information of its role in the planning and management of water resources is more important. Clustering catchments is the best method for the analysis of hydrological parameters in the absence of full coverage of hydrological data. In this research, twenty two hydrometric stations with common period from 1974 to 1999 were selected. Physiographic parameters of the catchments were extracted. Runoff coefficient was calculated and then base flow was extracted from using one parameter recursive digital filters. Lithological units using digital geological map, with the scale of 1: 250,000, based on expert opinion divided on two classes and area covered by each unit in each catchment were calculated. Factor analysis using 15 parameters were conducted. Catchments using independent factors in different hierarchy methods includes: nearest neighbor, furthest neighbor, median clustering, centroid clustering and Ward method were classified. Then, the regional equations using linear regression at 1% significant level were determined. To compare and evaluate the accuracy and efficiency of the models, independence errors, colinerity and normal distribution of error were tested. The results of factor analysis showed that all variables are to be classified in terms of five factors which 85.9% of the variance was included. Results of homogeneity showed that the basins in homogeneous methods of nearest neighbor, furthest neighbor, centroid clustering and median clustering, were all the same and classified in two groups with the similar components. The results of accuracy assessment showed that the accuracy of nearest neighbor methods was more accurate, and because of low relative error (25.4%) and MAE of 7.85 and RMSE of 9.62 was diagnosed as the best method for regional analyzing of runoff coefficient in the study area.
Maryam Pournader; Hassan Ahmadi; Jamal Ghoddosi; Mohammad Reza Jafari
Abstract
According to abundant damages and the extension of mass sliding in the country, its zonation mapping and investigating effective factors on its occurrence is necessary for preventing and control. Therefore, a research has been conducted in the Ilam dam watershed to create geologic, physiographic, Land ...
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According to abundant damages and the extension of mass sliding in the country, its zonation mapping and investigating effective factors on its occurrence is necessary for preventing and control. Therefore, a research has been conducted in the Ilam dam watershed to create geologic, physiographic, Land use, vegetation cover, soil erosion, climatologic, pedologic and geomorphologic maps, using earth data layers, topographic maps, Geographic Information Systems (GIS) and field surveys. The methodology of this research has been accomplished base on distinction of geomorphologic units while using aerial photos and crossing basis maps. Then, the effective factors on mass movement occurrence were investigated using logistic regression equations. So that, the factors such as slope, geological formation, pedologic, climatic, etc. were considered as independent variables and the frequency of mass movement occurrence was considered as dependent variable. Results demonstrated that factors such as slope, geological formation, the kind and the amount of soil minerals, and land use are the most effective factors on frequency of land sliding in the watershed.
Seyed Hamid Reza Sadeghi; Bahar Salavati; Abdolrasoul Telvari
Volume 2, Issue 2 , July 2010, , Pages 111-115
Abstract
Population ever increasing and consequent demands in recent decade have encouraged farmers to utilize unsuitable and marginal lands such as forests and ranges for agricultural purposes. However, these lands have high soil erosion potential and low productivity and their proper management is therefore ...
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Population ever increasing and consequent demands in recent decade have encouraged farmers to utilize unsuitable and marginal lands such as forests and ranges for agricultural purposes. However, these lands have high soil erosion potential and low productivity and their proper management is therefore a vital task. In the present study, the land use areas have been evaluated in Garan watershed in Kordistan Province, Iran, from 1995 to 2002 by using three digitized images and corresponding changes have been then assessed. The effects of land use changes on changing annual runoff were ultimately evaluated with the help of moving average and hydrological regime analyses. The results of the study revealed that the variation in water discharge thoroughly followed the annual rainfall oscillation which itself affected land allocation to different land uses.
Ravanbakhsh Raisian; Amir Hossein Charkhabi; Mohammad Nekoueimehr
Abstract
One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes ...
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One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes on soil loss in Gorgak sub-watershed. The statistical design was split plot design with pasture and rain fed agriculture as main factors. A drop maker rainfall simulator with 40 mm/hr intensity and 30-minute rainfall period was used on five field locationsunder two soil moisture conditions of air-dry and field capacity and three slope classes of 10-20, 20-30, and 30-40%. A total of 180 sediment and runoff measurements were made using the above rainfall simulator under field conditions for two land use systems of rain fed cereal and overgrazed pastures. All the measurements were done in triplicates (5 fields x 2 land uses×2 moisture content×3 slope classes×3 replicates = 180 plots). The results showed the soil loss under overgrazed and air-dry soil condition was 45.6 times more than the rain fed agricultureunder the similar soil moisture condition. However, the results showed the soil loss under overgrazed and field capacity soil moisture condition was 2.33 times more than the rain fed agriculture under similar soil moisture condition. Once the soil loss was compared for different slope classes of 10-20, 20-30, and 30-40 slope percent, the results indicated the soil loss under overgrazed and air-dry soil condition were 4.77, 5.19, and 2.34 times more than the rain fed agriculture under similar soil moisture condition. Overall, soil loss under overgrazed conditionwas 3.38 times more than rain fed agriculture. Therefore, although most soil conservationists generally believe that the rain fed agriculture in Iran is very improper managed and it has high soil erosion rates but the results of this study showed the overgrazed pastures in the north Karoon watershed need much more priority for any soil loss measures and controls.
Seyed Hamid Reza Sadeghi; Sudabeh Gharemahmudli
Abstract
Awareness of particle size distribution of river bed material plays an important role in studies of the organizing and analysis behavior of rivers. The traditional separation of particle sediments needs a lot of cost, time and fieldwork. Therefore, new methods such as image processing separation, is ...
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Awareness of particle size distribution of river bed material plays an important role in studies of the organizing and analysis behavior of rivers. The traditional separation of particle sediments needs a lot of cost, time and fieldwork. Therefore, new methods such as image processing separation, is essential for studies on particle size distribution of riverbed sediments. It is necessary to maintain standards in reach to the goals and to justify the adoption of a new separation technique. Accordingly, the resolution of the camera is very important for standard image processing. However, it has not been considered, yet. Hence, the present study aimed to analyze the accuracy of the particle size distribution of bed sediments using the image processing of image taken by cameras with different resolutions. For this purpose, variety of cameras were applied to provide images with different resolutions. The direct samplings and measurement was also conducted for comparison purposes. The results showed that cameras with 3 and 10 megapixel resolutions had the highest and the lowest consistency with observed data with respective correlation coefficients of 0.65 and -0.51 for coarse sediment. The cameras with resolutions of 16 and 18 megapixel also had the highest and the lowest agreement with the observed data with correlation coefficients of 0.88 and 0.69 for fine-grained sediments, respectively. In principle, the results suggested that the most appropriate camera for image processing purposes born 10 to 16 megapixels of resolution. However, coarse-grained sediments ranged from 10 to 107 mm in diameter with the respective highest and the lowest standard deviation and mode of 98.455 and 89.7, and 21 and 14. The fine-grained sediments also ranged from 10 to 57 mm in diameter with the highest and the lowest standard deviation and mode of 33.143 and 17.10, and 12 and 48, respectively.
Hamid Reza Moradi; Nayereh Ghazanfarpour; Sadat Feiznia
Volume 1, Issue 2 , July 2009, , Pages 119-127
Abstract
One of the effective factors in soil erosion is geological formations of the drainage basin from the view points of their erodibility and the amount of runoff and sediment yield. In this investigation a part of Segzi- Kuhpayeh subdrainage, located in Zayandeh-Rood Drainage Basin with 67091.7 ha area ...
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One of the effective factors in soil erosion is geological formations of the drainage basin from the view points of their erodibility and the amount of runoff and sediment yield. In this investigation a part of Segzi- Kuhpayeh subdrainage, located in Zayandeh-Rood Drainage Basin with 67091.7 ha area was chosen for studying erodibility and sediment yield of Quaternary Formations. For doing this, the map of Quaternary Formations was prepared. Then in each unit a field rainfall simulator was used and runoff and sediment were collected from the plots and erodibility and sediment yield factors were obtained. Soil samples were taken adjacent to each micro plot for laboratory tests and the data were analyzed statistically. The results of regression analyses have shown that erodibility and sediment yield are significantly different in various Quaternary Formations. The most important physical and chemical parameters in sediment yield in different formations are Silt, Sand, very Fine Sand, Wetness, Caco3 and in erodibility of different formations are Silt+ very Fine Sand, Caco3, Silt, Clay, very Fine Sand and EC.
Bagher Ghermezcheshmeh; Aliakbar Rasuli; Majid Rezaei Banafsheh; Alireza Massah Bovani; Alimohammad Khorshiddust
Abstract
Increasing Green House Gases (GHG) may change the climate in different areas. Investigation of parameters are difficult due to induced changes in climate parameters, such as precipitation and temperature. For predicting global climate change, different climate scenarios are defined, using AOGCM models. ...
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Increasing Green House Gases (GHG) may change the climate in different areas. Investigation of parameters are difficult due to induced changes in climate parameters, such as precipitation and temperature. For predicting global climate change, different climate scenarios are defined, using AOGCM models. AOGCMs are able to simulate global atmospheric circulation patterns. However, the spatial resolutions of such models are coarse; for example HadCM3 has spatial resolutions of 3.75 and 2.5 in longitude and latitude, respectively. Therefore, to study climate change in a given area, the outputs of the used AOGCMs must be downscaled properly. For this reason, statistical and dynamical methods have been developed. Statistical methods establish a relationship between AOGCM outputs and climate parameters such as precipitation and temperature. For example, many statistical methods use multiple regressions to predict future climate parameters. However, the accuracy of downscaling procedure varies depending on the geographical position of the studied station in relative to the nearby AOGCM grids. In this research, the accuracy of SDSM was tested in different synoptic stations of northwest Iran. This area has a complex topography and climate due to intrusion of different rain bearing weather systems to the region. First of all, daily climate data (precipitation, maximum and minimum temperature) were collected and their time series created. HadCM3 data for the girds over the studied area was obtained and SDSM model was applied for each climate parameters of all synoptic stations in the region. Then, the difference between the SDSM outputs and observed parameters were evaluated for all the stations and the performance of the downscaled outputs were evaluated by comparing the mean and variance of the model outputs and those of the NCEP/NCAR for the present climate. The morpho-climatic parameters were derived for each station and their relations with the magnitude of the model error were evaluated. Results showed that the error in precipitation has significant relation with the distance to the grid center, whereas the error in maximum temperature is related to the difference between the elevation of a given station and the mean elevation of the HadCM3 grids. For example, in Urmia station, the error is the highest of 104 mm while in Saqez the error is the lowest of 9.4 mm. Also, the maximum temperature accuracy in stations with elevation near to mean elevation of the grid is higher. Pars Abad station with 32 m elevation and with high elevation difference with the grid mean elevation, showed 1.14 ºC of error and Tabriz station with less elevation difference to grid mean elevation, showed 0.0.08 ºC of error.
Ramin Salmasi; Hamid Reza Peyrowan
Abstract
The most of the soil erosion and sediment yield in the Talkheh Rood watershed are mainly related to marl formations. This study was conducted to evaluate physico- chemical properties of Talkheh Rood marl samples in rill, gully, mass and badland erosion types. For this purpose, marl samples were taken ...
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The most of the soil erosion and sediment yield in the Talkheh Rood watershed are mainly related to marl formations. This study was conducted to evaluate physico- chemical properties of Talkheh Rood marl samples in rill, gully, mass and badland erosion types. For this purpose, marl samples were taken from marl sediment of homogenous work units. Twenty four samples were selected, in total. Some of main physic - chemical properties of these marls were measured in lab. These properties were pH, EC, CEC, Lime, gypsum and OC content, SAR, Na, K, Cl, Ca, Mg, clay, silt and sand percentage. These data were interpreted by ANOVA and mean comparisons analysis methods. Results showed that pH, gypsum content and sand percentage had statistically significant differences between four erosion types. Mean comparison showed that significant difference of pH, was between mass and badland erosions, sand between badland and gully ones, and gypsum, rill and gully, also badland and gully ones.
Ali Akbar Abbasi; Mehdi Habibi
Volume 2, Issue 3 , October 2010, , Pages 170-178
Abstract
One of the usual methods for river banks protection is using Gabion groyne structures. If this permeable structure is designed and constructed appropriately, it will control bank erosion and reclaims flood plain areas. Since there are some uncertainties in the determination of length, space and shape ...
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One of the usual methods for river banks protection is using Gabion groyne structures. If this permeable structure is designed and constructed appropriately, it will control bank erosion and reclaims flood plain areas. Since there are some uncertainties in the determination of length, space and shape of Gabion groyne, this experimental project was performed. In this investigation a laboratory movable bed flume with 17m length, 1.5m width and 0.8m depth was used to study local scour near the head of unsubmerged Gabion groynes. The T shape and straight groynes were constructed perpendicular to the flume's wall. Groynes with two different lengths of 15.0 and 22.5 centimeter (i.e. two contraction ratios of 20% and 30%) and four different spaces (i.e. four ratios of space to length, S/L), were used with one constant bed material, one constant bed slope and three different discharges. Based on the experimental results, a dimensionless relationship was derived for estimation of Local Scour near the Head of straight and T shape Gabion groynes.
Gholamreza Ghahari; Amir Gandomkar
Abstract
In undeveloped and less developed countries of arid zones, the easiest way for water supply is withdrawal of groundwater. The negative perception of this method of water discharge is clear. Spreading floodwater is one of the water resources management strategies in arid and semi-arid zones that has positive ...
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In undeveloped and less developed countries of arid zones, the easiest way for water supply is withdrawal of groundwater. The negative perception of this method of water discharge is clear. Spreading floodwater is one of the water resources management strategies in arid and semi-arid zones that has positive impacts on groundwater resources. The aim of this research was to demonstrate the impact of floodwater spreading on quantity of groundwater in Gareh Bygone Plain, Fasa, Fars province, Iran. Annual changes of water level was determined by reviewing water level of monthly data (1992-2013) of four piezometric wells. Despite to the spreading floodwater, the general trend of groundwater level was declining. Thus, for demonstrating the role of the floodwater spreading in groundwater recharge, changes in groundwater levels were investigated in the years of increases and decreases of floodwater. Results showed that the least recession is in piezometric wells 1 and 3. Piezometric well 1 due to the effect of fault and piezometric well 3 due to the effect of floodwater spreading. Results of Principal Components Analysis (PCA) of monthly water level in four piezometric wells showed that the first component as the most important indicator of recession of water level in the region is more than 83% of the variance. Sorting PCA loadings on the first component, represents a high recession in piezometric wells 2 and 4 that corresponds with the results of recession map of the plain. Piezometric well 2 due to evapotranspiration of trees and piezometric well 4 due to excessive extraction of water for agriculture in the area showed the most recession.
