Mohammad Ali Saremi Naeini
Abstract
Rapid population growth and the need to provide the necessities of life has caused human beings to change land use widely. In many cases these changes have been accompanied by disruption of balance in nature and providing the possibility of soil erosion. This study was carried out to investigate the ...
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Rapid population growth and the need to provide the necessities of life has caused human beings to change land use widely. In many cases these changes have been accompanied by disruption of balance in nature and providing the possibility of soil erosion. This study was carried out to investigate the effect of land use changes on increasing the intensity of wind erosion. Landsat satellite imagery and implementation of supervised classification by using SVMs were used to prepare land use map. Ground surface temperature was calculated, as one of the effective factors in wind formation, with single channel and split window algorithms in different land uses. In order to make connections between land use changes and wind erosion, effective climatic parameters such as temperature, relative humidity and maximum wind speed were investigated. The highest surface temperature was observed in poor and non-vegetation areas, and the lowest temperature was estimated in highlands and rangelands. Results showed an increase in average temperature as well as maximum and minimum absolute temperature and decrease in relative humidity. Over the past decade, the maximum wind speed in the study area showed a significant increase, and it has increased from eight m/s in 1990 to more than 20 m/s in the last decade. This shows that land use change by removing vegetation cover, as well as the uncontrolled increase of human constructions and creating thermal islands in the last 30 years, has a significant impact on the emergence of climate change and increasing wind speed.
Khosro Shahbazi; Ali Salagegheh; Mohammad Jaafari; Mohammad Khosroshahi
Abstract
Gully erosion affects land degradation, particularly in the semiarid reigns. Topographic thresholds are strongly affected by landuse change and destroy of vegetation. The objective of this study was to evaluate topographic thresholds of gully erosion in different landuse including agriculture (AG), fair ...
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Gully erosion affects land degradation, particularly in the semiarid reigns. Topographic thresholds are strongly affected by landuse change and destroy of vegetation. The objective of this study was to evaluate topographic thresholds of gully erosion in different landuse including agriculture (AG), fair rangeland (FR) and weak rangeland (WR) which carried out in Ghasreshirin, Kermanshah, Iran. The topographical parameters were measured in the field and relationship between gully catchment area and slope was analyzed for each landuse. The results revealed that some main topographic characteristics mainly cross-section, width, depth and gully branches length in the FR was significantly lower than in the AG and WR (p<0.05). Furthermore, analysis of gully threshold based on catchment area-slope showed that the critical area for gully formation in AG, FR and WR was 1300, 1689 and 1233 m2, respectively which was significantly lower in FR reducing by vegetation cover. The respective slope threshed was 1, 3 and 3 percent in AG, FR and WR. However, the affected area by gully erosion in AG, FR and WR was 12.4, 14.1 and 21%, respectively. The gully in the agricultural land was more dipper compared with other land uses. The volume of gully channels in FR was 3.4 and 2.2 times less than AG and WR, respectively. It is concluded that rangeland degradation and thereby removing vegetation attribute to severe gully erosion and consequently environmental problems such as soil carbon dioxide emission.
H. Mohammadi; H. R. Karimzadeh; S. J. Khajeddin
Volume 62, Issue 1 , June 2009, , Pages 125-137
Abstract
Study of soil and plant relationships is nessesery for ecological- based and appropriate management. The objective of this study is to determine the influence of edaphic properties on Haloxylon persicum growth and also, indentifing growth limiting soil properties for saxaul. The study was performed through ...
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Study of soil and plant relationships is nessesery for ecological- based and appropriate management. The objective of this study is to determine the influence of edaphic properties on Haloxylon persicum growth and also, indentifing growth limiting soil properties for saxaul. The study was performed through the stratified random sampling and 3 sites were selected as follow: planted strong saxaul, planted weak saxaul, rangeland without saxaul. Then 6 samples of Haloxylon persiocum were selected in each region, meanwhile, plant parameters including canopy cover area, canopy cover perimeter, the smallest and the largest canopy cover diameter, average of canopy cover diameter, height, basal area and diameter were considered. Also, 9 profiles in sites were sampled and the followiong properties: pH, SP, EC, Ca+Mg, Cl-, CO3--,HCO3-, SO4--, gravel, CaCO3, CaSO4, organic matter, clay, silt, sand, available phosphorous, Na+, K+, CEC, SAR, ESP, PSS, PSW and TDS were measured. Ordination method was used for data analysis. Accordiong to the results, plant parameters have significant diffirences in saxaul sites with the same age. Soil physical characteristics including soil texture and chemical characteristics such as organic matter, available phosphorous, CEC, salinity, CaSO4 and CaCO3 content showed the highest influence on saxaul growth parameters.
Mehrnoosh Ghadimi; sasan zangenetabar
Abstract
One important approach in the management of karst water resources is mapping of karstic aquifers. Vulnerability mapping enables identification of the groundwater resources that are subjected to contamination. The Gilangharb karst aquifer as part of the folded Zagros zone feeds the Gilangharb karstic ...
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One important approach in the management of karst water resources is mapping of karstic aquifers. Vulnerability mapping enables identification of the groundwater resources that are subjected to contamination. The Gilangharb karst aquifer as part of the folded Zagros zone feeds the Gilangharb karstic aquifer. Field visits and examination of chemical properties of the Gilangharb spring all confirm the karstic nature of the study area. In this study, in order to evaluate the vulnerability of the Gilangharb karstic aquifer, the EPIK method consisting of four layers of E (epikarst), P (protective coating), I (penetration) and K (karst network) and also the KDI method based on land use were employed. The former method is one of the inherent vulnerability methods developed especially for the karst areas based on different weight and ranking parameters. After executing the model and preparing the vulnerability map, the EPIK index was calculated between 12 and 26. The spatial distribution of the final vulnerability map classes from the EPIK model shows that 14.24, 14.56, 47.17 and 24.03% of the study area, is located in the low, medium, high and very high vulnerability zones, respectively. According to this map, about 71% of the study area shows high and very high vulnerability indicating high vulnerability of this aquifer. According to the results of the KDI method, 7.54%, 9.49%, 2.9%, 77.89% and 2.18% of the study area had high, medium, low, very low and intact, respectively that shows low vulnerability of the Gilangharb karstic aquifer.
A. Salajegheh; A. Fathabadi
Volume 62, Issue 2 , October 2009, , Pages 271-282
Abstract
Correct estimation of suspended sediment transported by a river is an important practice in water structure design, environmental problems and water quality issues. Conventionally, sediment rating curve used for suspended sediment estimation in rivers. In this method discharge and sediment discharge ...
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Correct estimation of suspended sediment transported by a river is an important practice in water structure design, environmental problems and water quality issues. Conventionally, sediment rating curve used for suspended sediment estimation in rivers. In this method discharge and sediment discharge or concentration related using regression relation that generally is exponential model. Respect to uncertainty and nonlinear relation between discharge and sediment concentration, sediment rating curve has not enough efficiency for this purpose. In this study using Artificial Intelligent (Fuzzy Logic and Artificial Neural Network), suspended sediment in Karaj River was estimated. First, various neural network and fuzzy logic models established. For neural network and fuzzy logic, models with four neuron in hidden layers and FIS (Fuzzy Inference System) with four Gaussian membership functions, respectively were selected as the best structure. Finally, the results showed that fuzzy logic estimates the suspended sediment loud better than the other techniques and therefore is suggested for estimation of suspended sediment load.
Hamid Reza Saeidi Goraghani; Ghodrat alah Heydari; Hossein Barani; Zakaria Alavi
Abstract
This study is trying to exploitations view point and permanent management problems of rangeland to evaluate in ranches Damavand Summer Rangeland in Amol County. Statistical Society are utilizations 15 ranch that with three methods, collective property, private property and council property from rangeland ...
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This study is trying to exploitations view point and permanent management problems of rangeland to evaluate in ranches Damavand Summer Rangeland in Amol County. Statistical Society are utilizations 15 ranch that with three methods, collective property, private property and council property from rangeland utilization and randomly from among their number 88 was selected. The research tool was a questionnaire that among exploitations through direct interviews have been completed. To assess problems permanent management of rangeland in the area with pivotal effect of the structure of exploitation methods, index nine selection and with spectrum from exploitations view point and were measured. The results showed different methods on among permanent management of rangeland effect means confidence level 99 percent. Duncan comparison test showed that permanent management problems private property exploitation methods are low from exploitation methods collective property and council property. So Friedman test results showed that with the rank category index of problems permanent management of rangeland time stop livestock mid excessive pasture with average 9.23 and the number of livestock over rangeland capacity in the region with average 8.01, respectively, the uttermost rank or impacts than the other indexes on rangeland permanent management in watershed land. So with use from Kruskal Wallis test evaluated and compared each one of rangeland permanent management indexes in exploitation different methods. Generally recommended to reduce problems in watershed areas of before Projects of reform and reducing, recognizing systems, common law and the demands of exploitation more attention and emphasis management and experts.
Bahram Gholinejad; Mohammad Jaffari; Mohammad Ali Zarechahuki; Hossein Azarniuand; Hassan Pourbabaei
Abstract
This research has been done with the aim of explaining environmental and managerial factors that affects on rangeland vegetation distribution in Saral rangelands of Kurdistan province. After selecting plant types as working area were done sampling from plant types and determined some of plants parameters ...
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This research has been done with the aim of explaining environmental and managerial factors that affects on rangeland vegetation distribution in Saral rangelands of Kurdistan province. After selecting plant types as working area were done sampling from plant types and determined some of plants parameters such as kind and number of plants and cover percentage. Various environmental factors such as topographic factors (slope, slope direction and elevation), soil physical factors (depths, soil texture, gravel and saturation moisture) and various chemical factors such as acidity, electrical conductivity, lime, gypsum percentage, organic material, nitrogen, phosphor and potassium) were measured and grazing intensity were considered as managerial factors. After collecting data, the Principal Component Analysis (PCA) was used to determine relationship between vegetation cover and environmental factors by PC-ORD software. The results showed that among various environmental and managerial factors affecting in plant distribution, soil depth, grazing intensity, elevation, sand, gravel and silt percentage have the highest correlation with Principal Component Analyses. These factors are the most effective factors on plants type distribution in rangeland ecosystems. Among effective soil factors on distribution of plant communities in this study, soil physical factors have greater impact than soil chemical properties. Physiographic factors including elevation and managerial factors including grazing intensity have considering effect on distribution of plant communities.
Saeedreza Moazeni-Noghondar; Faeze Alikhani; Abuzar Hatami Yazd
Abstract
Unprincipled exploitation of water and soil resources, while increasing the likelihood of floods and increasing the rate of sedimentation, has reduced agricultural products and losses of national capital. Due to the destruction of Nakhab watershed in recent years, watershed management operations have ...
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Unprincipled exploitation of water and soil resources, while increasing the likelihood of floods and increasing the rate of sedimentation, has reduced agricultural products and losses of national capital. Due to the destruction of Nakhab watershed in recent years, watershed management operations have been carried out in this watershed. The purpose of this study is to investigate the role of operations in runoff and soil erosion control. For this purpose, HEC-HMS model was used to determine the rate of reduction of flood peak discharge and MPSIAC model was used to determine the rate of erosion and sediment change in both cases before and after the operation. According to the results, the implementation of operations increased the flood peak time by 60 and 30 minutes and also reduced the peak discharge by 54% and 28% for the return period of 2 and 100 years, respectively. In addition, if the reservoir of structures is filled with sediments, they still have a significant effect on increasing the peak discharge time and reducing the volume and peak discharge of flood. The results of erosion and sedimentation show that due to the implementation of operations, special erosion has decreased from 10.18 to 9.8 tons per hectare per year and special sedimentation of the watershed from 3.16 to 2.9 tons per hectare per year. Since the watershed is a complex system, it is suggested that in order to achieve sustainable development, integrated management of all resources and the policy approach should be considered as an unavoidable necessity.
Ali Fathzadeh; Somayeh Ebdam
Abstract
[1] Ahmad, S. and Simonovic, S.P. (2005). An artificial neural network model for generating hydrograph from hydrometeorological parameters, J. Hydrol, 315, 236-251.
[2] Agarwal, A., Mishra, S.K., Ram, S. and Singh, J.K. (2006). Simulation of runoff and sediment yield using artificial neural ...
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[1] Ahmad, S. and Simonovic, S.P. (2005). An artificial neural network model for generating hydrograph from hydrometeorological parameters, J. Hydrol, 315, 236-251.
[2] Agarwal, A., Mishra, S.K., Ram, S. and Singh, J.K. (2006). Simulation of runoff and sediment yield using artificial neural networks, Biosys. Eng, 94(4), 597-613.
[3] Amini, M., Abbaspour, K.C., Khademi, H., Fathianpour, N., Afyuni, M. and Schulin, R. (2005). Neural network models to predict cation exchange capacity in arid regions of Iran, European Journal of Soil Science, 53, 748-757.
[4] Balk, B. and Elder, K. (2000). Combining binary decision tree and geostatistical methods to estimate snow distribution in a mountain watershed, Water Resources Research, 36, 13-26.
[5] Bagheri Fahrji, R. (2011). Estimating the satial distribution of snow water equivalent in mountain watersheds using geostatistic methods (Case study: Bidakhovid), M.Sc. thesis, Islamic Azad University Maybod branch.
[6] Carrol, S.S. and Cressie, N. (1996). Acomparison of geostatistical methodologies used to estimate snow water equivalent, Water Resources Bull., 32, 267-278.
[7] Chen, J. and Adams, B.J. (2006). Integration of artificial neural networks with conceptual models in rainfall-runoff modeling, J. Hydrol, 318, 232-249.
[8] Elder, K., Dozier, G. and Michaelsen, J. (1991). Snow Accumulation and Distribution in an Alpine Watershed, Water Resources Research, 27(7), 1541-1552.
[9] Elder, K., Michaelsen, J. and Dozzier, J. (1995). Small basin modeling of snow water equivalence using binary regression tree methods, IAHS Publ., No. 228.
[10] Elder, K., Rosenthal, R. and Davis, R.E. (1998). Estimating the spatial distribution of snow water equivalence in a mountain watershed, Hydrological Processes, 12, 1793-1808.
[11] Erickson, T.A., Williams, M.W. and Winstral, A. (2005). Persistence of topographic controls on the spatial distribution of snow in rugged mountain, Colorado, United States, Water Resources Research, 41, 1-17.
[12] Erxleben, J., Elder, K. and Davis, R. (2002). Comparison of spatial interpolation methods for estimating snow stribution in Colorado Rocky Mountains, Hydrological Processes, 16, 3627-3649.
[13] Fathzadeh, A. (2008). Estimating the spatial distribution of snow water equivalent in Karaj watershed using remote sensing and energy balance model, PhD thesis, Tehran University.
[14] Gayoor, H., Kavyani, M., Mohseni, B. (2004). Estimates of coverage and the amount of snowfall in the mountains north of Tehran Case Study: River Basin Rehabilitation (Darband and Glabdarh), Journal of Geographical Research.
[15] Hassani Pak, A. (1998). Geostatistics, Tehran University Publications.
[16] Hosang, J. and Dettwiler, K. (1991). Evalution of a water equivalent of snow cover map in a small catchment area using a geostatistical approach, Hydrological Processes, 5, 283-290.
[17] Huang, M., Peng, G., Zhang, J. and Zhang, S. (2006). Application of artificial neuralnetworks to the prediction of dust storms in Northwest China, Global and Plantetary Change, 52, 216-224.
[18] Marchand, W.D. and Killingtveit, A. (2001). Analyses of the Relation between Spatial Snow Distribution and Terrain Characteristics, 58th Estern Snow Conference Ottawa, Ontario, Canada.
[19] Marchand, W.D. and Killingtveit, A. (2005). Statistical probability distribution of snow depth at the model sub-grid cell spatial scale, Hydrological Processes, 19, 355-369.
[20] Menhaj, M. (2007). Fundamental of Artificial neural networks, Amirkabir Press.
[21] Mohammadi, J. (2001). Considering geostatistics and its application in soil science, Journal of Soil & Water Science, 15(1), 99-121 (In Farsi).
[22] Molotch, N.P., Colee, M.T., Bales, R.C. and Dozier, J. (2005). Estimating the spatial distribution of snow water equivalent in an alpine basin using binary regrnion tree models: the impact of digital elevation data independent variable selection, Hydrological Processes, 19, 1459-1479.
[23] Najafi, M., Sheykhivand, J. and Porhemat, J. (2006). Runoff from melting snow in snowy areas using SRM (Case Study Mahabad), Journal of Agricultural Sciences and Natural Resources (In Farsi).
[24] Roebber, P.J., Bruening, S.L., Schultz, D.M. and Cortinas JR., J.V. (2002). Improving snowfall forecasting by diagnosing snow density, Weather and Forecast, 18, 264-287.
[25] Sharifi, M.R., Akhund Ali, M. and Porhemat, J. (2007). Assess the linear correlation and ordinary kriging method to estimate the spatial distribution of snow depth in the watershed Samsami, Journal of Watershed Management Science & Engineering, 1(1), 24-38 (In Farsi).
[26] Topsoba, D., Fortin, V., Anctil, F. and Hache, M. (2008). Use of the kriging technique with external drift for a map of the water equivalent of snow: application to the Gatineau River Basin, 32(1), 289-297.
[27] Tedesco, M., Pulliainen, J., Takala, M., Hallikainen, M. and Pampaloni, P. (2004). Artificial neural network-based techniques for the retrieval of SWE and snow depth from SSM/I data, Remote Sens. Environ, 90, 76-85.
[28] Tryhorn, L. and DeGaetano, Art (2012). A methodology for statistically downscaling seasonal snow cover characteristics over the Northeastern United States, 10. 1002/joc. 3626.
[29] Vafakhah, M., Mohseni Saravi, M., Mahdavi, M., Alavi Panah, S.k. (2008). Geostatistics application to estimate snow depth and density in the watershed Ourazan, Journal of Watershed Management Science & Engineering, 4(2), 49-55 (In Farsi).
[30] Vaziri, F. (2003). Applied hydrology in Iran-The second book: Identification of glaciers in Iran, Publication Management and Planning Organization.
[31] Zareabyaneh, H. (2012). Estimating the spatial distribution of snow water equivalent and snow density using ANN method (Case study watershed Azarbayejan), Journal of Water Resources Engineering, 5(15), 1-12 (In Farsi).
Sahar Zakeri Anaraki; Gholamreza Zehtabian; Hassan Khosravi; Hossein Azarnivand; Arash Malekian
Abstract
Intergovernmental Panel on Climate Change report shows that the world average temperature has increased to 0.6 ° C ± 0.2 ° C in the twentieth century. Therefore, long-term prediction of climate variables and the consideration of measures to mitigate the adverse effects of climate change ...
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Intergovernmental Panel on Climate Change report shows that the world average temperature has increased to 0.6 ° C ± 0.2 ° C in the twentieth century. Therefore, long-term prediction of climate variables and the consideration of measures to mitigate the adverse effects of climate change is evident. The SDSM model was used to downscale observation data of the minimum and maximum temperatures of the Vazvan Meyme station in Isfahan province. The CanESM2 global model data under new emission scenarios: RCP2.6, RCP4.5, and RCP8.5 are used to predict the near future (2006-2036), mid-term (2037-2078) and far-away future (2079-2100). The studies show the ability of the SDSM model to model maximum and minimum temperatures in the base period. The results of this study necessary indicate that as we get closer to the 21st century, the minimum and the maximum temperatures increase in the area of study. The average maximum temperature changes will have the highest increase under the RCP8.5 scenarios in the (2079-2100), in July, which will reach 7.9 ° C. The average changes in minimum temperature show the highest increase in August under the RCP8.5 scenarios. Therefore, considering that this temperature increase in future periods will affect the status of the study area, water resources, and natural resources. Planners and authorities of the relevant departments will take the necessary measures, such as measures to correct irrigation systems, methods for reducing evaporation and improving the cultivation system, to adjust the damage caused by heating or adapt to the new climatic conditions.
M Zare; Aliakbar Nazari Samani; shahram khalighi; javad bazrafshan; mohsen hasan joury
Abstract
Land use Changes have recently been increasing due to anthropogenic and climatic factors. Natural resources management critically needs land use maps and simulation of its changes for understanding the interaction and relationship between humans and natural phenomena, as well as for making premium decisions. ...
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Land use Changes have recently been increasing due to anthropogenic and climatic factors. Natural resources management critically needs land use maps and simulation of its changes for understanding the interaction and relationship between humans and natural phenomena, as well as for making premium decisions. Accordingly, present study has dealth with simulation of future changes land use of Kessillian watershed. Hence, land-use and land cover maps of the catchment was prepared by using multi-period Landsat images captured in 1986, 2000, and 2011. Then, applying cellular automaton and Markov model, the land-use/land cover condition in 2011 was predicted 0.9 using ROC. Thereafter, this model was run for simulating land-use/land cover changes in 2030. According to the results of detection and simulation of changes, forest land reduction trend will continue but the area of rangelands and inhabited areas will expand. Agricultural lands will not seriously change due to steep slope and low fertility after several consequent plantings. In most cases, maximum changes occurred around the forest and rangeland areas and changes will decrease far from these margins. Markov model can precisely show the land changes in the area via time period and can anticipate the future of them. Therefore, this model can be applied in order to manage the land.
Foroud Sharifi
Abstract
This paper has focused on the application of hydro- geochemical techniques in conceptualizing of groundwater and to estimate recharge/discharge and the renewability of aquifer in Hashtgerd Watershed, Iran. At first, the aquifer boundary was defined based on data of existing wells and basin morphologic ...
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This paper has focused on the application of hydro- geochemical techniques in conceptualizing of groundwater and to estimate recharge/discharge and the renewability of aquifer in Hashtgerd Watershed, Iran. At first, the aquifer boundary was defined based on data of existing wells and basin morphologic conditions. Estimation of recharge rate at different depth intervals by using tracer mass balance was done for 291 representative groundwater samples which includes 195 samples from soil and water of unsaturated zone in depths of 30 to 90 m (sampling in each meter), 10 samples were taken from rainfall, five samples from Qanats and 21 samples from wells and 60 samples taken from surface water in the study area. Based on water balance technique applying to a 7 year measured data and evaluation of hydrological and hydro- geological processes in the Watershed, average groundwater depletion was calculated at 0.37 m/year that indicated annual recharge rate of 245 million cubic meter (mcm) and over use of storage capacity of the aquifer. The groundwater studies showed that the natural recharge from direct rainfall is about 2% of total recharge. The annual recharge rate over an area of 752 km2 varies from 2.3 to 15.1 mm/yr. The required time for aquifer recharge from rainfall for the aquifer of 30 m thickness in the southern part of the aquifer is 1200 years while for aquifer of 90 m thickness in the north, recharge time is around 1100 years. On the other hand, in north and south of the aquifer, transitivity rates are 2500 and 300 m2/day, respectively with the groundwater renewability of 2.92 years which shows the importance of renewability of groundwater via concentrated/linear recharge from fractured zones. Studies of direct recharge in other parts of the world have shown that direct recharge rates may vary from zero to around 40% of mean rainfall volume. The results of this study revealed that around 98% of aquifer recharge occurs via concentrated/linear recharge from fractured zones with the average renewability of three years. Then it is recommended to consider the above mentioned geologic features in concentrated recharge of aquifer in saturated zone by watershed management, floodwater spreading and vegetation cover improvement projects.
Fatemeh Salarian; Jamshid Ghorbani; Ghodratolah Heydari; Nosratolah Safaian
Abstract
Conservation and restoration of biodiversity is very important for degraded rangeland ecosystems. It is necessary to assess the potential of soil seed bank as a major source of species. In this study, the soil seed bank size and composition were compared between exclosure and grazed areas. This was done ...
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Conservation and restoration of biodiversity is very important for degraded rangeland ecosystems. It is necessary to assess the potential of soil seed bank as a major source of species. In this study, the soil seed bank size and composition were compared between exclosure and grazed areas. This was done in Chahar-Bagh rangelands in Golestan province. Soil was sampled in Exclosure and Grazing from 0-5 and 5-10 cm depths in 90 quadrates of 1 m2. Then seed bank composition was identified after seed germination in glasshouse. A total of 28 species from 15 families were found in soil seed bank flora of both exclosure and grazed areas. Compositae, Gramineae, and Rosaceae were dominant in soil seed bank. Also, hemicryptophyte, Forbs and perennials were abundant in the seed bank of both areas. Exclosure significantly increased the seed density of Digitaria sanguinalis, Potentilla canescens, Stellaria media, Sonchus oleraceusand Galium verum in the seed bank. The species richness and diversity indices were not significantly different between two areas. These indices significantly increased in upper soil layer in exclosure while these indices were not significantly different between two soil depths in grazed area. The result of this study showed that exclosure influenced the soil seed banks, however, there was no evidence of positive changes in species richness and diversity indices and also an increase of grasses in soil seed bank.
E Ghehsareh Ardestani; M Bassiri; M Tarkesh; M Borhani
Volume 63, Issue 3 , December 2010, , Pages 387-397
Abstract
Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. ...
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Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. Many of researchers think of higher species diversity as an index of bio-system’s stability. This research aimed to study parametric models of species diversity on range vegetations of study sites and relationship of ecological factors such as climate, soil and topography with diversity index. Four range sites were selected on different geographic areas in Isfahan province and randomly- systematic sampling was conducted to collect density data on plant species by quadrates along transects of each site during six years (2002-2007). Broken stick, log normal, logarithmic series and geometric series models were fitted for each site, and log normal showed to be the most proper model of distribution with P>0.05. LSD’s test indicated a significant different at ?=1% level between species diversity of steppe1 and semi-steppe2 sites. Log normal model seemed to be the most proper model in all sites. Generally, when this model is fitted successfully communities are considered stable. On the basis of some related studies with this research, Hill ( ) showed to be most proper index for species diversity in study sites, therefore effects of ecological factors such as soil, climate and topography on this index were studied by CCA method. Results of CCA revealed a high positive correlation between species diversity and percent organic matters of soil as well as precipitation levels and negative correlation with temperature.
Seyed Hamidreza Sadeghi; Zahra Hashemi Ariyan; Mehdi Vafakhah; Zeinab Karimi
Abstract
Studying temporal and spatial variations of soil erosion and the effective factors is very important for providing appropriate solutions to properly plan the utilization of watershed resources. However, few studies have attempted to examine temporal and spatial variations of soil erosion. In this study, ...
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Studying temporal and spatial variations of soil erosion and the effective factors is very important for providing appropriate solutions to properly plan the utilization of watershed resources. However, few studies have attempted to examine temporal and spatial variations of soil erosion. In this study, the temporal variability of spatial participation of soil erosion has therefore been investigated in the Gonbad representative and treated watersheds in Hamedan Province with an area of 300 ha. For this purpose, the work units were designated through overlaying land cover type, soil texture, and slope maps. The soil erosion was then measured in each work unit using rainfall simulator with intensity of 50 mmh-1 during 30 minute in two main rainy months of November and October 2014. Then, three points with relatively similar characteristics and representing each work unit were determined in the specific outlines of the equilateral triangle. The soil erosion was consequently measured with five minutes interval after the beginning and ending of rainfall simulation. The results of analysis of variance verified a significant difference (P<0.01) among different work units in soil erosion in both representative and control watersheds verifying spatial variation of different parts of the watersheds in soil erosion and consequent sediment yield. While, no significant difference was found using t-test between soil erosion during November and October 2014.
Nafiseh Seyyed Nezhad Golkhatmi; Javad Bazrafshan; Arezo Nazi Ghameshlou; Parviz Irannejad
Abstract
North Atlantic Oscillation (NAO) is one of large-scale signal that affects the north hemisphere. Various studies have investigated the correlations between Iran’s precipitations and North Atlantic Oscillation from monthly to yearly scales. This study has considered weekly time scale. The daily ...
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North Atlantic Oscillation (NAO) is one of large-scale signal that affects the north hemisphere. Various studies have investigated the correlations between Iran’s precipitations and North Atlantic Oscillation from monthly to yearly scales. This study has considered weekly time scale. The daily precipitation variable was obtained from the ERA-Interim database (grid) and its compliance with ground reference points (synoptic) were investigated (1979-2016). The results showed that the amount of annual precipitation in regions with more humidity, especially in the Caspian region, is underestimated. Also, the correlation between grid and synoptic precipitation data in the western, northeastern and southeastern area of the country is the highest and in the strip parallel to the western-eastern line (the middle areas) is the lowest (weekly average). This correlation decreases from winter to autumn and spring, respectively. A review of the time series of the sever events of NAO during the year with the weekly scale showed that this signal had two peaks, which was used to select the time period of assessing the relationship between precipitation in Iran and NAO. The results showed that the correlation between grid precipitation and NAO is not completely direct and relative frequency of direct correlation is more than non-direct type and decreases from north to south.
Akram Arefi Asl; Ali Najafinejad; Farshad Kiani; Abdolrassoul Salmanmahiny
Abstract
Runoff and sediment measurement is difficult in mountain watershed because of many different problems such as time and financial limitations. So using simulation model is necessary in this regard. Accuracy and precision evaluation of models for different watershed of Iran is necessary. The aim of this ...
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Runoff and sediment measurement is difficult in mountain watershed because of many different problems such as time and financial limitations. So using simulation model is necessary in this regard. Accuracy and precision evaluation of models for different watershed of Iran is necessary. The aim of this study was the evaluation of SWAT model efficiency in simulation of runoff and sediment yield in Chelchay watershed in Golestan province, Iran and also calibration and validation of SWAT. SUFI2 algorithm was used for calibration and validation. Nash-Sutcliff for calibration period (2001-2005) and validation period (2006-2009) for average daily discharge was 0.5 and 0.4 respectively and for sediment concentration was 0.71 and 0.92 that is good according to past research results. Because SWAT is complex and integrated model and can be used as a management tool in watershed management so it is suggested that it would be used for evaluation of management activities effects in Chelchay watershed.
Ahmad Sadeghipour; nadia kamali; Paria Kamali; Hamed Joneidi
Abstract
This study investigates monthly and seasonal variations of carbon emission from the soil at different grazing intensities. Three areas of exclosure, low and high grazing intensities were selected in Ghoosheh region of Semnan province. Carbon emission was measured monthly, in each treatment applying alkali ...
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This study investigates monthly and seasonal variations of carbon emission from the soil at different grazing intensities. Three areas of exclosure, low and high grazing intensities were selected in Ghoosheh region of Semnan province. Carbon emission was measured monthly, in each treatment applying alkali traps (CSC) during a year. Emission and grazing data were analyzed, using a factorial experiment in a completely randomized design with four replications. To investigate the relation of soil moisture and air temperature with carbon emissions in each area, Pearson correlation was used. Results showed that the emission levels under different grazing intensities had significant difference. The highest emission occurred in high grazing intensity, in August (3.34 g C m-2 day-1) and lowest in February (0.033 g C m-2 day-1) in exclosure. The seasonal distribution of emission showed the highest amount, in summer, autumn, winter and spring respectively. There was also a negative correlation between carbon emissions and soil moisture.
D. Askarizadeh; Gh. A. Heshmati
Abstract
Abiotic factors, as topographic and physicochemical properties of soil, are the most important effective factor on vegetation in rangeland ecosystems which have the most important performances to forming and succession of plant vegetation. Ecologic management of rangelands can be desired by better understanding ...
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Abiotic factors, as topographic and physicochemical properties of soil, are the most important effective factor on vegetation in rangeland ecosystems which have the most important performances to forming and succession of plant vegetation. Ecologic management of rangelands can be desired by better understanding of these effective factors. Then, rangeland of Javaherdeh (Ramsar) in the northern Alborz Mountains ranging 2000-3200 m a.s.l. was selected in this study and altitudinal classes of 300 meter were selected to obtain field records on the basis of field monitoring and plants structures. About 15 plots (1 m2) in each altitudinal class were considered in order to obtain the field data, e.g. percentage of life-form covers. It was also chosen five plots to gather soil samples. Statistical analyses, using cluster analysis, DCA and CCA, were done by PC-Ord V.5.1 software. The results showed that life forms of plant under 183 species and 33 families have been divided into five sub-associations so that their segregation is done based upon elevation, aspect, and soil properties. Multivariate analysis (CCA) also can as well divide the life forms of plants based on their ecological requirements into subgroups include annual and perennial grasses with perennial forbs, annual forbs, shrubs, and bushy trees. These life forms are also found different ecologic niches funded upon influence of the topographic factors and physicochemical properties of soils. Hence, ecologic management of terrestrial ecosystems needs to knowing and understanding of vegetation structures under different environmental factors.
Parivash Toufani; Ahmad Fakheri fard; Abolfazl Mosaedi; AmirAhmad Dehghani
Abstract
Prediction of Precipitation is very important. Regarding to the non- linear relationships and uncertainty of models, there is no superior and persuasive model among various proposed models to simulate precise precipitation and its amount. Wavelet is one of the novel and very effective methods in time ...
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Prediction of Precipitation is very important. Regarding to the non- linear relationships and uncertainty of models, there is no superior and persuasive model among various proposed models to simulate precise precipitation and its amount. Wavelet is one of the novel and very effective methods in time series and signals analyzing, that has been considered in the field of hydrology in recent years. In this research, precipitation signal has been decomposed via selected mother wavelet, and then the resulted data are used by fitting direct equations and nero-wavelet hybrid in order to anticipate the precipitation. The mentioned method was applied in Zarringol station (Iran) to predict monthly precipitation since 1975-76 until 2007-2008 for the period of 33 years. The results showed that, by decomposing signal via wavelet, the correlation among observed and calculated data were significantly increased, and the precision of prediction was improved. So that in direct method the value of R2 is equal to 0.74 and in nero-wavelet hybrid in the best case and for 4 level decomposition the value is equal to 0.95. This shows the capability of wavelet in simplifying of signal and intensification of accuracy random data in prediction of precipitation. Moreover, the meaningless F test, verifies the mentioned object. Keywords: Precipitation, prediction, Signal, Wavelet theory, Nero-wavelet hybrid, Zarringol. Prediction of Precipitation is very important. Regarding to the non- linear relationships and uncertainty of models, there is no superior and persuasive model among various proposed models to simulate precise precipitation and its amount. Wavelet is one of the novel and very effective methods in time series and signals analyzing, that has been considered in the field of hydrology in recent years. In this research, precipitation signal has been decomposed via selected mother wavelet, and then the resulted data are used by fitting direct equations and nero-wavelet hybrid in order to anticipate the precipitation. The mentioned method was applied in Zarringol station (Iran) to predict monthly precipitation since 1975-76 until 2007-2008 for the period of 33 years. The results showed that, by decomposing signal via wavelet, the correlation among observed and calculated data were significantly increased, and the precision of prediction was improved. So that in direct method the value of R2 is equal to 0.74 and in nero-wavelet hybrid in the best case and for 4 level decomposition the value is equal to 0.95. This shows the capability of wavelet in simplifying of signal and intensification of accuracy random data in prediction of precipitation. Moreover, the meaningless F test, verifies the mentioned object.
Ebrahim Gavili; Mohamad Reza Vahabi; Fazel Amiri; Hossain Arzani
Abstract
This research was conducted to recognize Sibak-Sardab watershed rangeland potentials, evaluate and determine of suitability classes for sheep grazing. In this research, we used the proposed method of FAO (1992) and for information layers crossing used in Geographical Information System (GIS). In this ...
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This research was conducted to recognize Sibak-Sardab watershed rangeland potentials, evaluate and determine of suitability classes for sheep grazing. In this research, we used the proposed method of FAO (1992) and for information layers crossing used in Geographical Information System (GIS). In this research, sensitivity to erosion, water resources and forage production are three basic components of this study. We used the MPSIAC model for the sensitivity to erosion. The model of water resource suitability consists of three parameters, quantity, quality and water resource's accessibility. In the forage production model, we estimated the ratio of available forage to the whole produced forage in each vegetation type. According to the result 96% of the rangeland was in low suitability class (S3) and only 4% were in medium suitability class (S2). The most important factors causing the decrease in suitability were lower rates of available forage for the livestock, low forage production of classes, I, II and low palatability percentage. According to Actual use (22170 animal units in season grazing); and grazing capacity (15989 animal units) and also according to the high destruction because of heavy grazing; using a management method that can help to improve the rangeland condition is suggestion.
zahra giveiiashraf; Mohammad Ali Hakimzade; Mohammad Zare; Zohre Ebrahimi Khusfii; Kazem Dashtakian
Abstract
Desertification relates to the both the process and end state of drylands degradation. Salinization and alkalinization are two indicators of soil degradation in arid and semi-arid regions. The main objectives of this research is monitoring of soil salinity using high spectral and spatial resolution of ...
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Desertification relates to the both the process and end state of drylands degradation. Salinization and alkalinization are two indicators of soil degradation in arid and semi-arid regions. The main objectives of this research is monitoring of soil salinity using high spectral and spatial resolution of remote sensing to assess desertification in the Marvast plain, Yazd province. Two images of Terra satellite, ASTER synchronous to 2003 and 2010 are used. After preprocessing and analyzing of the images, relationship between parameters of soil salinity (i.e. SAR and EC) and spectral reflections were determined and, both two satellite images were classified using maximum likelihood method. Then, the surface area of each class and the amount of its changes were calculated. Results showed that during the period of 7 years (2003-2010), area of non-saline lands has decreased while, the area of saline land has increased, which leads to the salinization of agricultural lands, reduction of its yield and also extent of desertification in this region. Accuracy of EC map classification for 2003 and 2010 images are 87.5% and, 82.5%, respectively. Kappa coefficients for both images are 0.83 and 0.76. Accuracy of SAR map classification for 2003 and 2010images are 87.5% and 87.5%, respectively. Kappa coefficients for these two images are 0.81 and 0.77, respectively. Generally, it can be conclude that using of remote sensing data, especially ASTER images has high efficiency for change detection analysis in soil salinity and natural resources management.
jalil farzadmehr; payam Ebrahimi; mehdi Eslah
Abstract
Predicting the hydraulic behavior of the river and flood zone determination to reduce probable damages, are among measures which in recent years has been the attention of many researchers. Mazandaran province, especially the city of Neka, each year is affected by the floods with different return periods; ...
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Predicting the hydraulic behavior of the river and flood zone determination to reduce probable damages, are among measures which in recent years has been the attention of many researchers. Mazandaran province, especially the city of Neka, each year is affected by the floods with different return periods; therefore, land use changes and the role of these changes were evaluated in flood zones. In this study, with integration of river system analysis, GIS and Remote Sensing, images of the years 2000 and 2011 were processed and Neka river hydrological response was determined in specified return periods. The results showed Pearson type 3 distribution, roughness coefficient determined by Cowan’s method and IRS image in comparison with ETM+ image, have good accuracy. With determining land use changes in the years 2000 and 2011, the area of each land use class was specified in GIS, and then attached to the HEC-GeoRAS. By determining two flood maps with return periods of 2 to 200 years, the difference of each layer was determined. Many studies determined land use only; but according to the results of this study and impact of the 14.60-percent increase in flood area, the role of changes is noticeable. This study suggests that in the flood zone determination, addition to land use designation, we should pay special attention to its changes and hydrological response of the total area to these changes, and its role in the flood zones. The simulation of river bed and flood zone in forest areas depends on land use, and deforestation in this river is one of the most important factors.
shahla dehghan pir; omonabin bazrafshan; arashk hlizadeh
Abstract
Ground water depletion and water shortage are two problems in Hormozgan province which have occurred due to the irregular use and inappropriate management of demand and supply of water in agricultural sector. This research explored the balance of agriculture virtual water trade (imports and exports of ...
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Ground water depletion and water shortage are two problems in Hormozgan province which have occurred due to the irregular use and inappropriate management of demand and supply of water in agricultural sector. This research explored the balance of agriculture virtual water trade (imports and exports of virtual water) and its value in two catchments with different climate in north (Baraftab catchment in Hajiabad) and east (Payab-E Roodan catchment) of Hormozgan province. Based on the results, most of the volume of virtual water in northern catchment is related to wheat and Palm fruit with the amounts of 14 and 0.18 million cubic meters, respectively. Most of the volume of virtual water in the eastern catchment of province is related to Palm fruit (0.8 million cubic meters) and citrus (0.6 million cubic meters) and most of the volume of imported virtual water is related to wheat and rice. Also, Baraftab and Payab catchments are the exporter and importer of virtual water, respectively so that the amount of the balance of trade of virtual water in two mentioned catchments are -11.94 and 17.83, respectively. 64% and 67 % of fresh water in two Baraftab and Payab catchments is consumed to produce the agricultural products. The amount of water self-sufficiency index of virtual water is 86% and 81% and the amount of water shortage index is 66% and 69% in Baraftab and Payab catchments, respectively. These results reveal the severe water shortage in these two catchments.
hosien شظهیه; omonabin bazrafshan; Abdolreza Bahremend; Arash Malekian
Abstract
The purpose of this study is the effects of the morphometric factors on peak discharge in 108 hydrometric stations in the southern watersheds, Iran. After homogeneous tests and random data, a time period (from 1983-1984 to 2013-2014 was chosen and used to choose the best probability distribution function. ...
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The purpose of this study is the effects of the morphometric factors on peak discharge in 108 hydrometric stations in the southern watersheds, Iran. After homogeneous tests and random data, a time period (from 1983-1984 to 2013-2014 was chosen and used to choose the best probability distribution function. Overall, the 84 morphometric and geometric parameters were calculated in ARC GIS software. In this research, the structural equation modeling with the least approach in smart – PLS software was used to check the most effective factors on the annual maximum discharge. 18 variables were identified as effective factors on the maximum discharge. between more than 84 structures, the effect of the focus time structures, positive height ratio, miller slenderness ratio structures ,the main river- slope characteristics , elevation number and the main river-slope height properties are negative than can predict overall the %46 of the annual maximum discharge changes in the watershed areas of Iran s southern parts. These factors affect directly on the flood in the total focus time about %38 thus, the most effective factor on the flood discharge is the focus time factor that should be considered in the flood management in Iran s southern areas.
