Ommolbanin Kazemi Gordgi; Hasan Ahmadi; Mohammad Jafari
Abstract
The ultimate aim of any research on the mass movement processes is to prepare zonation map and classify area into different degrees of hazard in order to mitigating related damages. This study was undertaken using F-AHP & GIS within Nekaroud watershed in Mazandaran province. Pairwise comparisons ...
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The ultimate aim of any research on the mass movement processes is to prepare zonation map and classify area into different degrees of hazard in order to mitigating related damages. This study was undertaken using F-AHP & GIS within Nekaroud watershed in Mazandaran province. Pairwise comparisons showed that sub-criteria’s Slope (>30%), elevation (> 1700 m), distance from fault (0-200 meter), distance from river, residual land-use and precipitation (>600 mm) have high weight than others in their group which lead to increasing occurrence of landslides. In the study area much amount of lime stone was found which is effective in reducing landslide. Major parts of central areas of watershed are prone to the most dangerous and high frequency landslides, other parts of watershed classified into medium and a little part is in low danger class.
golaleh ghaffari; Hasan Ahmadi; Omid Bahmani; Ali Akbar Nazari Samani
Abstract
Although more than 45 years has passed since the first time operating watershed projects were run inside the country and considering the increasing budget that is being allocated to such projects, terrible soil erosion, natural resource degradation and the dazzling and painful consequences of such events ...
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Although more than 45 years has passed since the first time operating watershed projects were run inside the country and considering the increasing budget that is being allocated to such projects, terrible soil erosion, natural resource degradation and the dazzling and painful consequences of such events are indicative of low efficiency and failure of natural resource protection projects. Therefore, since watershed projects involve many agents and management needs to be as effective as possible, assessment of how suuccessfully the project objectives have been realized is essential. The sologhan aquifer’s basin with an area of 20571 hectar is one of the basins in which watershed project was carried out in winter 2000. To assess the effectiveness of the above mentioned project, required statics and data was collected and the accuracy of meteorology and hydrology data was examined and the double mass curve, annual hydrograph comparisons, hydrologic analysis, sediment examination in dry and moist periods, sediment graph, studding the amount of sediment in precipitation periods prior and post projects implementation were considered and used. Double mass curve shows the positive effects of this operation on the amount of runoff and sediment. Hydrologic regime curves show as well that watershed operations had positive impacts upon the basins hydrologic reaction to rain so that the amount of runoff as a result of similar amount of precipitation has decreased. Furthermore, the amount of annual suspended load has decreased from 47892.56 to 22365 tons, so did the amount of Debbi and sediment. Above results prove the positive effects of watershed projects.
Maryam Azarakhshi; Mohammad Mahdavi; Hasan Ahmadi; Hosein Arzani; Jalil Farzadmehr
Abstract
Plants cover composition, condition, trend, production, and grazing capacity of the rangeland change annually. In this research, the role of temporal rainfall distribution on rangeland production was assessed. This research had down in the rangelands of Ilam (with semiarid to semi humid climate) and ...
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Plants cover composition, condition, trend, production, and grazing capacity of the rangeland change annually. In this research, the role of temporal rainfall distribution on rangeland production was assessed. This research had down in the rangelands of Ilam (with semiarid to semi humid climate) and Qom and Markazi (with arid to semiarid climate) provinces. By attention on plant cover maps in each province 10 main types of plant cover in Ilam, 8 types in Qom and 10 types in Markazi were selected. In these sites, relative factor to plant cover and soil contains: canopy cover, density, production, germination and, soil cover were measured along four 400m transects into 60 plots .the production of the graze able species was measured by clipping and weighting method. The regression techniques and correlation coefficient were used to the relation between production and precipitation. to determination the role of the temporal distribution of rainfall of the rangeland production, the relationship between rainfall and production was calculated in seven time steps contains. The results show that only 4% of the total forage production is explained by annual precipitation but in 96% cases there were related with start of growth season (March) and growth season(early March to late July).this result shows the importance of growth season precipitation on the forage yield in rangelands.
kazem Nosrati; Mohsen Mohseni Saravi; Hasan Ahmadi; Hosein Aghighi
Abstract
Estimation of evapo-transpiration is necessary in cases such as irrigation planning, determining of evaporation of the water bodies, water balance assessment, estimation of runoff and watershed management and ecological and meteorological studies. Evapo-transpiration can be determined precisely using ...
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Estimation of evapo-transpiration is necessary in cases such as irrigation planning, determining of evaporation of the water bodies, water balance assessment, estimation of runoff and watershed management and ecological and meteorological studies. Evapo-transpiration can be determined precisely using field measurements. However, these methods provide evapo-transpiration just for limited areas from spatial point of view. This limitation has motivated the development of using remote sensing data to evaluate evapo-transpiration over vast area. Surface Energy Balance Algorithm for Land (SEBAL) is a new model that has been used at different areas all over the world for estimating of evapotranspiration. Due to the fact that no written report in evapo-transpiration estimation using this algorithm in the country has been published yet, the objective of this study is to investigate the validation of revised SEBAL model in mountainous region. In this project, actual evapo-transpiration values were estimated using MODIS image data and revised SEBAL model for mountainous region in 22 different dates in 2006 in Taleghan Drainage Basin. The result showed that the correlation between estimated and measured values is significant (R2=0.88, p<0.001). Thus, MODIS image data and revised SEBAL model were able to estimate actual daily evapo-transpiration values in Taleghan Drainage Basin. Therefore this revised algorithm could recommend as suitable method for further studies in different area with variation topography.
Mohammad Nohtani; Sadat Feiznia; Hasan Ahmadi; Hamidreza Peirovan
Abstract
Loess Deposit is one of the most important Quaternary Deposits of northeastern parts of Iran which have high erosion rate. This study was performed with field- Rainfall- Simulator which has a plot area of 1 m2 in Gorganrood Drainage Basin to determine the effective factors on sediment yield. Landuse, ...
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Loess Deposit is one of the most important Quaternary Deposits of northeastern parts of Iran which have high erosion rate. This study was performed with field- Rainfall- Simulator which has a plot area of 1 m2 in Gorganrood Drainage Basin to determine the effective factors on sediment yield. Landuse, slope and erosion feature maps were overlaid in GIS to obtain land unit map. Then on work units, rainfall simulator analyses were performed. The produced runoff and sediment in 69 points on work units were collected and were measured. Adjacent to each rainfall simulator plot, samples of surface material were collected in the field to analyze for physical and chemical characteristics. In the field, descriptive tables were prepared for different work units in which locality, slope percentage, elevation, depth of A horizon of the soil and other necessary informations were recorded. In order to determine logical relationship between different variables, regression and correlation analyses were performed. In statistical analyses, it was found that slope percentage has the highest correlation coefficient and has the highest direct relationship with sediment yield and sediment production and silt amount is the second factor. The investigation of multiple regression analyses generated a model which shows %80 of sediment production variations. In this model slope percentage, cation exchange capacity and silt have possitive relationship and Calcium cation has negetive relationship with sediment yield.
mohsen padyab; Sadat Feiznia; Hasan Ahmadi; Ardeshir Shafei
Abstract
Evaluation of changes present in soil and water resources due to operation implement of floodwater spreading is necessary to assess their positive or negative resultant effect. Rate of the internal sediment to diversion spreader channels, surface sedimentation and aggregation of the spreading field depth ...
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Evaluation of changes present in soil and water resources due to operation implement of floodwater spreading is necessary to assess their positive or negative resultant effect. Rate of the internal sediment to diversion spreader channels, surface sedimentation and aggregation of the spreading field depth are most important effective attributes on the yield of floodwater spreading systems. These factors can change physical and chemical properties of studied field, as, by measuring of the infiltrate depth sedimentation of can achieve influencing depth of floodwater. To determine the effect of flooding spread on the sediment infiltrate rate in the field depth of Gachsaran floodwater spreading, from 0-15, 30-15, 30-45 and 45-60cm of the soil surface of spreading field and control were sampled. Granulometry of all samples was done using dry sieve and hydrometric analysis and then percent of the sediment grains with size of less than two millimeters were subjected to analysis of variance (ANOVA) by Duncan t-student test for 80 sampled samples. Results showed that deep entering of the sediments into drilled profiles to 30-45cm was completely distinct which can affect on the soil physical and mechanical properties. However, after the 30-45cm depth, the impact of floodwater spreading was minimal. The infiltration of each studied layer is the most important feature which will change from surface to the depth of spreading belts, so that by increasing infiltrated fine particles in the depth and blocking pores, the soil layers are clogged and in result reduce the infiltration rate, sharply. This state was more remarkable in the spreader belts surface. Furthermore, by depositing the sediments in the surface (0-15cm depth), an impermeable and earthen layer is created which prevent from infiltrate the particles and even water into soil depth. Generally, with determine of the deposited sediment level in the spreading belts and also its deep infiltrate rate can provide effective and practical decision to improve efficiency and easy maintenance of the floodwater spreading systems or even not use this method.
Sadat Feiznia; Asghar Kouhpeima; Hasan Ahmadi; Ali Asghar Hashemi
Abstract
Due to successes of fingerprinting method in producing rapid and low-cost information of sediment sources, in this research this method was used in three sub-cathments of Chasht-Khoran Basin in Semnan Province: Amrovan, Atari and Ali-Abad. Samples below 63 μm were separated and 15 fingerprinting propertis ...
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Due to successes of fingerprinting method in producing rapid and low-cost information of sediment sources, in this research this method was used in three sub-cathments of Chasht-Khoran Basin in Semnan Province: Amrovan, Atari and Ali-Abad. Samples below 63 μm were separated and 15 fingerprinting propertis was measured. In the first stage comparison of means and differentiation analysis were used for determination of the characteristics that can differentiate sediment source as well as possible. In second stage, by minimizing composite multivariate model by optimization methods, the share of each source was determined. The results shown that, in Amrovan Catchment, For properties consisting of Co, Ph , Kaolinite and K were recognized as optimum composition of sediment tracers which could differentiate sediment source completely. In Atary Catchment, the optimum composition of tracers are Na, Co, XLF and kaolinite which differentiate source by %91.7. In Ali-Abad Catchment five parameters were recognized as optimum composite which are :Na, XLF, Ca, Co and smectit which completely differentiated sediment sources. The results of calculated composite multivariate model have shown that Upper Red formation in Amrovan, Atari and Ali-Abad Sub-Catchment has the highest share in sediment production. The sediment production in these three sub catchment are as follows:35.9, 23.53 and 86.64% respectively. Therefore sediment management and control strategies should be performed on these sources.
Tayyebeh Mesbahzadeh; Hassan Ahmadi
Abstract
Sand dunes mobility is one of the serious problems in arid regions. Since wind regime is one of the important factors in sand dunes formation, its frequency, direction and magnitude can be effective. Amount of wind energy and its directional variability (wind regime) have significant control on the morphology ...
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Sand dunes mobility is one of the serious problems in arid regions. Since wind regime is one of the important factors in sand dunes formation, its frequency, direction and magnitude can be effective. Amount of wind energy and its directional variability (wind regime) have significant control on the morphology and maintenance of aeolian landforms. By recognizing of morphometric and morphodynamic characteristics, it is possible to control soil erosion. Thus, statistical analysis of wind data using Tsoar index (sand dunes mobility index) in the study area was considered to understand wind regime role in volume and direction of transported sediments. Sand drift potential amount of the study area is 100.8 v.u. and sand flux is 2.358 m3/m.year resulted from Lettau – Lettau equation. Considering wind erosion power, the study area is in low class based on Fryberger & Dyne (1979) classification. In spring the wind blowing pattern has west direction and is different from other seasons. Also, the most frequency of blowing wind higher than threshold velocity occurs in this season. Unidirectional index value is 0.64 for this region that results formation of transverse dunes (barkhanoid).
Maryam Azarakhshi; Behnoush Farokhzadeh; Mohammad Mahdavi; Hossein Arzani; Hassan Ahmadi
Abstract
Iran is located in dry belt of the earth and always involved with drought in different sections. Drought has already caused many losses to natural plant cover, agriculture and human society. For drought monitoring, we can use some drought indecies. In this research, the Standard Index of Annual Precipitation)SIAP),Sandardized ...
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Iran is located in dry belt of the earth and always involved with drought in different sections. Drought has already caused many losses to natural plant cover, agriculture and human society. For drought monitoring, we can use some drought indecies. In this research, the Standard Index of Annual Precipitation)SIAP),Sandardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI) were used for assessment of drought effects on rangeland plant production. The research area is located in Qom province that contains eight rangeland sites. Plant production and soil factors were measured in rangeland readiness period from 1997-1998 to 2005-2006 annualy. Regression techniques were used between drought indices and total production and also production of different vegetation forms in seven time scales (early March to late July (growth season) and early February to late July (growth season and the previous month), March to June, March to May, March to April and March (start of growth season). The best drought index was then selected based on the highest correlation coefficient and lowest standard error. The result showed that the best drought indices in Qom rangelands are SPI-3, PDSI, SPI-24 and SPI-6, respectively. Also the most significant time step was resulted growth season and specially early stage of growth season.
T Mesbahzadeh; H Ahmadi; Gh Zehtabian; F Sarmadian
Volume 63, Issue 3 , December 2010, , Pages 399-415
Abstract
Investigation and preparing of wind erosion intensity maps are the main objectives of this research. In this research, the working unit map was prepared and then nine effective factors in wind erosion according to IRIFR.E.A model are determined at each of seven homogeneous units. According to the results, ...
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Investigation and preparing of wind erosion intensity maps are the main objectives of this research. In this research, the working unit map was prepared and then nine effective factors in wind erosion according to IRIFR.E.A model are determined at each of seven homogeneous units. According to the results, active sand dunes and landuse change showed the highest value with the rate of annual sedimentation more than 6000 ton/km2 while lands surrounding the villages showed the least value with an annual rate of sedimentation of 150-500 ton/km2. Also considering whole area which is about 16161 hectares, around 1978 hectares are classified in low class of desertification; 7430 hectares in medium class while 6753 hectares in high and very high classes.
S.M Soleimanpour; majid Soufi; hassan Ahmadi
Volume 63, Issue 1 , June 2010, , Pages 41-52
Abstract
Gully erosion has an important role in Fars province due to sediment production and enormous damages to land, roads and infrastructures. In this research, 15 gullies were selected to measure their morphometric characteristics. The length, depth, top and bottom width and volume of gully erosion were then ...
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Gully erosion has an important role in Fars province due to sediment production and enormous damages to land, roads and infrastructures. In this research, 15 gullies were selected to measure their morphometric characteristics. The length, depth, top and bottom width and volume of gully erosion were then measured. Influential factors on the sediment production and gully development were analyzed and determined by using stepwise method in SPSS software. The results indicate that sediment production due to gully development is related to three variables including drainage area, silt and the sand percent of the watershed above the gully heads. These results imply that surface runoff is acting as dominant hydrologic process on gully development. Investigation on the topographic threshold reveals that drainage area exponent (b) is negative and these results are in the same line with the results of some recent relevant studies. The results also indicate the watershed characteristics and geological formation impact on the gully sediment production. Gully development could be reduced by decreasing the area of bare land as the main source of surface runoff by vegetation planting and terracing. Constructing of small earth dams at the end of gullies collect surface runoff and provides better situations for vegetation establishment around gullies.
B. Motamedvaziri; H. Ahmadi; M. Mahdavi; F. Sharifi; N. Javaheri
Volume 62, Issue 2 , October 2009, , Pages 283-298
Abstract
Estimation of river sediment load is one of the most important issues in design of hydraulic structures, investigating water quality, conserving fish habitat, estimating erosion and determining watershed management effects. There are two methods for estimating sediment load: empirical and hydrological ...
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Estimation of river sediment load is one of the most important issues in design of hydraulic structures, investigating water quality, conserving fish habitat, estimating erosion and determining watershed management effects. There are two methods for estimating sediment load: empirical and hydrological methods. Existence of numerous empirical methods for estimation of river sediment load and a wide range of calibration coefficients shows that a suitable analytical or empirical method does not yet exist to accurately estimate the sediment load. Also, hydrological methods are not able to recognize and separate the specific data measuring conditions and they can not show the temporal variation of sediment loads. In spite of these problems, nowadays, researchers are using Artificial Intelligence methods such as Fuzzy Logic. In this study, the measured suspended sediment load at hydrometric station of Sarcham located on Zanjanroud river is analyzed using USBR and FAO methods (common hydrological methods). Furthermore, suspended sediment load are estimated with a model developed based on Fuzzy Logic rules. In order to estimate suspended load using fuzzy method, one method named Supervised Fuzzy C- mean Clustering Method, is used. Then the results of hydrological and fuzzy methods are compared. The results showed that the temporal variation of sediment loads can be analyzed using a fuzzy method. Also the results obtained using the fuzzy method in comparison with the corresponding values obtained using the usual hydrological methods shows a better correlation with the observed values.
H. Saadati; F. Sharifi; M. Mahdavi; H. Ahmadi; M. Mohseni Saravi
Volume 62, Issue 1 , June 2009
Abstract
The main structure of this study includes; isotopic tracer evaluation and measuring, to identify and origin of groundwater recharge, contributions determine of diffused recharge (DR) and concentrated recharge (CR) as well as determine drought and wet periods in Hashtgerd plain. The hydrochemical study ...
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The main structure of this study includes; isotopic tracer evaluation and measuring, to identify and origin of groundwater recharge, contributions determine of diffused recharge (DR) and concentrated recharge (CR) as well as determine drought and wet periods in Hashtgerd plain. The hydrochemical study which involved collection and analysis of water samples from the deep and dug wells, springs, tap water and rainwater showed that the rainwater is little source of groundwater recharge. The isotopical study aimed to determine the origin of the groundwater bodies and to offer support for the hydrochemical analysis. To achieve this purpose samples analyzed for H2 and O18 and data was quoted from literature about the isotopic composition of precipitation. The study shows that the isotopic composition during the rainy season ranges for ?O18 between -6/05 ‰ and -6/92 ‰ and for ?H2 between-45/92 ‰ and -52/27 ‰. The changes in ?O18 are correlated with those of ?H2 with R2 =0.9 that was similar to GMWL line. proving their meteoric origin. Cluster analysis supported by the Hierarchical Cluster Analyze, Chebychev and Mann-Whitney tests classified the analyzed rivers water samples into two main groups: the first cluster was included Kordan, Aqasht, Sorheh and Khor rivers. Because of the low runoff and high infiltration these rivers are recharged through groundwater. The second cluster was consisted Valian, Fashand and Hiv-shalamzar rivers. Because of the low infiltration these rivers are recharged through runoff. Cluster Analysis shows that the samples of groundwater of Hashtgerd plain were divided into three clusters. The first cluster was included west and north-east of Hashtgerd plain (Nazarabad, Hashtgerd town, Baraghan and Kordan) were recharged through surface water and rainfall. The second cluster was included north and center of Hashtgerd plain were recharged through surface and groundwater. The third cluster was included south-west and south-east of Hashtgerd plain which were recharged through groundwater. The results show that concentrated recharge (CR) supply groundwater more than diffused recharge (CR). Concentrated recharge was performed by watersheds and flood spreading. Using isotopic method, mean values of ? O18 and ? H2 in a mass-balance equation, the relative contributions of diffused recharge (DR) and concentrated recharge (CR), to groundwater were estimated to be 78 درصد and 22 درصد, respectively. According to results of this study, groundwater resource level decrease and there is a drought period in Hashtgerd plain.
