Suma Mohamadpur; Hamed Rouhani; Hojat Ghorbani Vaghei; Seyed Morteza Seyedian; Abulhasan Fath Abadi
Abstract
In many semi-arid regions of Iran, soil erosion has turned into a serious environmental problem affecting land productivity, nutrient loss, water quality, and fresh water ecosystems. Rates of soil loss differ according to erosion type and land degradation processes. Rill erosion is commonly observed ...
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In many semi-arid regions of Iran, soil erosion has turned into a serious environmental problem affecting land productivity, nutrient loss, water quality, and fresh water ecosystems. Rates of soil loss differ according to erosion type and land degradation processes. Rill erosion is commonly observed when rainstorms occur on steep slopes and sediment transport in rill flows exhibits the characteristics of non-equilibrium transport. In this paper, sediment concentration of rill flow is estimated by adaptive neuro-fuzzy inference system (ANFIS). A series of mathematical equations and parameters affecting rill hydrodynamics and soil detachment were used for well-defined rill sediment concentration. A series of filed experiments were performed to evaluate the model. The stepwise method was used to select the most important and effective input variables from measured input parameters of soil properties, topographic and vegetation attributes affecting sediment concentration of rill flow. Based on the stepwise procedure, the most significant parameters in the model predications were steep slope, vegetation percentage, clay percentage, and shear stress parameters. The values of sediment concentration simulated by the model were in agreement with observed values with Coefficient of Correlation (R2), Root Mean Square Error (RMSE) and Mean Bias Error (MBE) of 0.697, 30.5 and 1.0, respectively. The results of the investigation shows that the data-driven ANFIS modeling approach can be a powerful alternative technique for correctly estimating rill sediment concentration.
AliB. Mirgalili; MohammadR. Fazelpoor; fariba zakizadeh
Abstract
Grazing animals affect rangeland vegetation structure and function both directly and indirectly.These effects can be assessed in exclosures. In this study, vegetation changes inside and outside ofexclosures of Tanglaybid rangelands, located in south-western part of Yazd province, have beeninvestigated. ...
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Grazing animals affect rangeland vegetation structure and function both directly and indirectly.These effects can be assessed in exclosures. In this study, vegetation changes inside and outside ofexclosures of Tanglaybid rangelands, located in south-western part of Yazd province, have beeninvestigated. Vegetation changes study was carried out in 3 key areas inside and also 3 key areasoutside of exclosure and lasted for 5 years (2000-2005). Every key area included 3 transects of 100meters long and 40 meters intervals. The transects were selected vertical to slope, including 10fixed plots (2×1 m2). Vegetation cover, density and frequency percentage of each plot species weremeasured annually. The random- systematic method was applied as a sampling method. Vegetationchanges inside and outside of exclosure were assessed, in a completely random plan, applyingDuncan's test (P < 0.05). The results showed that vegetation cover percentages increasedsignificantly (P < 0.05), inside the exclosure comparing to outside of it. Mean coverage of annualand perennial grasses and also bushes, inside the exclosure comparing to its outside increased 47,38 and 7%, respectively. Thus, in present research, exclosure has positive effects on vegetationcover changes of several species. Frequency percentage results showed that there was no significantdifference, inside against outside the exclosure in 2000, 2001, 2002, 2003, and 2004. Regardingdensity, there was significant difference only in 2001.The results can be considered in futuremanagement of the area's rangelands and similar regions throughout Iran
Mehdi Ghorbani; leila avazpour; sadegh heydari
Abstract
Governance of natural resources is currently hampered by abundant challenges. The way out of this dead-end is injecting kind of capital derived from people per se i.e. social capital which is unfortunately the missing part of collaborative governance of natural resources. The present study was an attempt ...
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Governance of natural resources is currently hampered by abundant challenges. The way out of this dead-end is injecting kind of capital derived from people per se i.e. social capital which is unfortunately the missing part of collaborative governance of natural resources. The present study was an attempt to evaluate the structural characteristics of out-group social capital in local beneficiaries’ network, in keeping with natural resource governance. It was conducted under the international RFLDL project in four regions of South Khorasan province. To measure the structural features of out-group social capital of local beneficiaries of each region, network analysis questionnaires were applied and there was a direct interview with network actors (heads of rural development micro committees) and their trust an participation ties were investigated. It was found out that post-RFLDL project implementation, trust and participation level or in other words the out-group social capital of each four regions escalated among heads of rural development micro committees. It can be asserted that natural resource governance will not actualize utterly and natural resource management will come to halt in a limited and stagnant framework, void of the participation of communities, where a mono-lateral power is exerted over decision-making around natural resource issues unless social capital develops among actors and they participate actively in this process.
Somayeh Movahedi; aboalhasan fathabadi; null null; Ali Heshmatpour
Abstract
In this study using Frequency Ratio (FR), Statistical Index (SI), Weights Of Evidence(WOF), Logistic Regression (LR), Random Forest (RF) models the probability of gully formation was calculated in Aytamar watershed and susceptibility maps was prepared. First the thematic maps of 13 gully conditioning ...
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In this study using Frequency Ratio (FR), Statistical Index (SI), Weights Of Evidence(WOF), Logistic Regression (LR), Random Forest (RF) models the probability of gully formation was calculated in Aytamar watershed and susceptibility maps was prepared. First the thematic maps of 13 gully conditioning factors including lithological formations, distance to faults, faults density, altitude, slope-length, slope angle, slope aspect, plan curvature, profile curvature, distance to roads, land use, distance to rivers, stream power index and topographic wetness index was prepared. Then landslide inventory map was combined with each gully conditioning factor and all models weights and parameters were calculated. Area under curve for test data was calculated as 0.74, 0.78, 0.75, 0.86 and 0.96 for Frequency Ratio (FR), Statistical Index (SI), Weights Of Evidence(WOF), Logistic Regression (LR), Random Forest (RF) models, respectively. Random forest, Frequency Ratio and Logistic Regression have the least the area of high susceptibility zone, respectively. With respect three validation criteria multivariate methods including Random Forest and Logistic Regression had the best performance among all models.
Kobra Karimi; esmaeel karami dehkordi; khalil aghajanlu
Abstract
Assessment of rangeland management projects enables policy makers and planners to understand their impacts from different environmental, social, human, and economic aspects. The aim of this research is to assess rural households’ perspective regarding the impact of rangeland management projects ...
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Assessment of rangeland management projects enables policy makers and planners to understand their impacts from different environmental, social, human, and economic aspects. The aim of this research is to assess rural households’ perspective regarding the impact of rangeland management projects on their social capital. Using a survey methodology, respondents were asked to assess the indicators before and after the implementation of the projects. A randomized multi-stage sampling technique was utilized to select a sample of 204 out of 1280 rural pastoralists in Mahneshan County of Zanjan Province. Data was collected utilizing a structured interview technique and questionnaire. From pastoralists’ points of view, these projects have had considerable impacts on increasing relationships, collaboration, and social norms for collective actions. They have also been slightly effective in terms of reducing emigration, increasing job opportunities and participation in decision-making. Nevertheless, these projects had no effect in establishing or strengthening non-governmental organizations. Therefore, planning for rangeland management projects necessitates more attention to improving their effectiveness and their social institutionalization potential.
Yosef Nabipour; Mahadi Vatakhah
Abstract
Rainfall spatial analysis methods are very helpful since there are not enough rainfall gauge stations and watersheds are scattered in large extent. There are many different methods for estimating average precipitation such as; arithmetic method and Thiessen polygon. However, the arrangement and location ...
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Rainfall spatial analysis methods are very helpful since there are not enough rainfall gauge stations and watersheds are scattered in large extent. There are many different methods for estimating average precipitation such as; arithmetic method and Thiessen polygon. However, the arrangement and location of data and their correlations are not considered by classic methods. Thus, geostatistical techniques are applied instead. In the present article, 22 meteorological stations from within and around the basin with data collection period of 30 years were selected for the analysis. The geostatistic analysis methods including ordinary kriging, simple cokriging, ordinary cokriging, standardized ordinary kriging, moving average using inverse distance with powers of 1 to 5 were applied for spatial analysis of annual, monthly and 24 hourly maximum rainfall data in Hajighoshan watershed located in northeast of Iran. For this reason, rainfall data were fitted to different methods and compared using cross validation by removes rainfall values of each station, one at a time, and predicts the associated data value. The results of geostatistic analysis showed that ordinary kriging is the best method with MBE=34.26 for annual rainfall while moving average using inverse distance with power of 5 is the best method for monthly and 24 hourly maximum rainfall. According to the results obtained through analysis of variogram model, gaussian model are supposed as the best models for annual, monthly and 24 hourly maximum rainfall data.
TAYYEBEH MESBAHZADEH; farshad soleimani sardou
Abstract
Due to incorrect policies in the water resources sector and excessive withdrawal of groundwater resources, water quality in most plains of the country has decreased. Therefore, the quality of water for drinking and agriculture is important in qualitative terms.With this aim in this study, the desertification ...
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Due to incorrect policies in the water resources sector and excessive withdrawal of groundwater resources, water quality in most plains of the country has decreased. Therefore, the quality of water for drinking and agriculture is important in qualitative terms.With this aim in this study, the desertification changes in Khash plain were studied using two criteria of groundwater and vegetation. Shooler and Wilcox diagrams were drawn up for AquaChem software for the years of 2001, 2008 and 2015. Also, spatial variations were made on Arctic plain surface using Arc GIS software and vegetation changes trend were also done using MOD13A2 sensor images and remote sensing techniques. The results showed that the number of wells that have an unpredictable TDS in the years 2008 and 2015 compared to 2001 have been increased by comparing the Schuler diagram. However, the level of lands with good drinking status decreased during the years 1387 and 1394 compared to 1380 and was increased by the level of acceptable drinking water. According to Wilcox's diagram, the result is that most wells are salty to very salty and their use is harmful to agriculture or requires measures. The results of the vegetation change trend also indicated that the trend is to reduce vegetation and the average level of the NDVI index decreases with the passage of time.
Zhila Ghorbani; Kiomars Sefidi; Farshad Keivan Behjou; Mehdi Moameri; Ali Ashraf Soltani Tolarod
Abstract
The most current way for measuring the soil fragmentation is determination of mean weight diameter (MWD). In this study, the adaptive neuro-fuzzy inference system (ANFIS) was used to predict of range soil fragmentation affected by different grazing intensities, distance from village and sampling depth. ...
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The most current way for measuring the soil fragmentation is determination of mean weight diameter (MWD). In this study, the adaptive neuro-fuzzy inference system (ANFIS) was used to predict of range soil fragmentation affected by different grazing intensities, distance from village and sampling depth. Present study conducted at 2015 in 3 adjacent rural areas (Alvars, Aldashin and Asbe marz) in Darvishchai watershed in Ardabil County. The studied parameters on the soil fragmentation including different grazing intensities in 3 levels (low, medium and high intensity), distance from village in 3 levels (200, 400 and 600 meters) and the soil sampling depths in 2 levels (0-15cm and 15-30cm). Obtained data were transferred to MATLAB software for the development of ANFIS models. For evaluating the models operation, mean squares error (MSE) and correlation (R2) were used. The result of best ANFIS model in prediction of soil fragmentation was compared with results of regression model. The results show that different grazing intensities, distance from village, sampling depth and their combinations had significant effect on the soil fragmentation. Increase of grazing intensity resulted in increment of soil fragmentation. With increment the distance from village from 200 to 400 meters, soil fragmentation decreased but with increment of distance, increased. Soil fragmentation in all conditions was higher at depth of 0-15 cm than depth of 15-30 cm. ANFIS model had more precision in prediction of soil fragmentation (R2=0.96) relative to regression model (R2=0.76).
Mojtaba Nassaji zavareh; Ali Khorshiddoust; Ali Rasouli; Ali Salajegheh
Abstract
Temperature and precipitation are among important atmospheric parameters for watershed planning. Assessment of temperature and precipitation trends is very important for future watershed planning. In this paper, trends of atmospheric parameters such as seasonal and annual temperature and precipitation ...
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Temperature and precipitation are among important atmospheric parameters for watershed planning. Assessment of temperature and precipitation trends is very important for future watershed planning. In this paper, trends of atmospheric parameters such as seasonal and annual temperature and precipitation were examined for the synoptic stations of Bandar Anzali, Rasht, Ramsar, Babolsar and Gorgan. In order to detect temperature and precipitation trends, homogeneous time series are needed. Expert judgment, metadata and standard normal homogeneity test (SNHT) were used to assess homogeneity of seasonal and annual time series. Some seasonal and annual time series were heterogeneous which were adjusted to homogeneous time series. The results show positive trends of annual and seasonal maximum and minimum temperature, and negative trends of annual and seasonal maximum and minimum precipitation. Also the trend of minimum temperature is higher than the trend of maximum temperature. Mean trends of annual minimum and maximum temperature and annual precipitation are 0.39 ◦c/decade, 0.05◦c/decade and -31/8mm/decade, respectively. The highest average trend of seasonal maximum and minimum temperature is related to the summer season, whereas the highest of average trend of seasonal precipitation is related to the winter season.
The lowest of average seasonal trend of minimum and maximum temperatures are related to the winter and spring seasons, respectively. Mean of seasonal precipitation trends of spring, summer and autumn are almost similar each other.
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.
Javad Motamedi; Tayebeh Tofighi azar; Morteza Molaei
Abstract
Functions of a natural resource, including rangeland ecosystems, can be divided into four groups of regulatory, habitat, production and information functions. Therefore, in this study, the economic valuation of forage production function and utilization of rhizome orchid were in terms of performance ...
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Functions of a natural resource, including rangeland ecosystems, can be divided into four groups of regulatory, habitat, production and information functions. Therefore, in this study, the economic valuation of forage production function and utilization of rhizome orchid were in terms of performance and utilization of orchid feed, studied in Trgvr grasslands of Urmia. For this purpose among, the distribution areas of orchids in the grasslands area, six locations with a total area of 120 hectares with different water levels that are representative of a wide range of grassland area, were selected. Then, The production of different vegetation forms and the amount of orchids production was measured in represetive sample, and the economic value was estimated by marketing method according to the results each hectare of grassland area is able to produce 1731.78 kg forage and 4.02 kg orchids in a growing season, whit it's economic value of each hectare of forage production and utilization of orchids in terms of function, respectively equal to 16.88 and 44.72 IRR. The results of the study are useful in determine the acceptable level of damages grassland area and to calculated and green national accounts.
mohsen kazemi; sadegh naji; Sadat Feiznia; Hassan Khosravi
Abstract
One of the strategies to achieve sustainable management of lakes and wetlands is change detection of lakes, wetlands and their surrounding landuses during the specific time periods. In this research, the satellite images from 1381 to 1394 applying geometric and atmospheric corrections were used in order ...
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One of the strategies to achieve sustainable management of lakes and wetlands is change detection of lakes, wetlands and their surrounding landuses during the specific time periods. In this research, the satellite images from 1381 to 1394 applying geometric and atmospheric corrections were used in order to monitor the changes of the Maharloo Lake level and its surrounding lands Image subtraction techniques, the principle component analysis (PCA) and fuzzy logic were used for providing the maps of landuse changes and drastically changes. The obtained results of Maharloo landuse changes showed that the lake water level has decreased 78 percent during 1381 to 1394. Reducing the lake water level, the landuses of bare and saline lands increased 46 and 58 percent respectively. The obtained results of the drastic changes showed that 82% of the changes have had the intensity between 50-100 percent. The most intensity of the changes with reduction of 22 percent was related to water body of Maharloo. The reduction of Maharlu Lake water level have different consequences therefore management planning is necessary to prevent its ecosystem degradation and Risks of reduced water levels in recent years.
yaser ghasemi aryan; yaser Ghasemi aAryan; ali kiani rad
mahboobeh moatamednia; ahmad nohegar; arash malekian; maryam saberi anari
Abstract
One of the most important of hydrological computing in ecosystem is estimation of the relationship between rainfall and runoff. So that investigation occurred processes in it and the estimate of important outputs such as flood and sediment is considered one the most important mission of a watershed project. ...
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One of the most important of hydrological computing in ecosystem is estimation of the relationship between rainfall and runoff. So that investigation occurred processes in it and the estimate of important outputs such as flood and sediment is considered one the most important mission of a watershed project. Because of variable spatial and temporal characteristics of incident in the water cycle and the nonlinear relationship and uncertainties, none of the statistical and conceptual models are able to be a better and capable model for that. But today using nonlinear networks as intelligent system for forecasting such complicated event can be efficient and effective in many problems of ecology. For this aim it is used variables such as precipitation, temperature, evartanspiration, relative humidity and discharges in daily scale over 42 years period and assessment 62 different suggested structures for surveying river flow in Amame representative watershed. For comparison it used Multi Layer Perceptoron (MLP) and Radial Basis Function (RBF).The results show that out of 6000 available models for estimation river flow model number 54 with 8-9-8-1 network structure and 8 types of input variable such as precipitation (Pt), precipitation with two lags (Pt-1 and Pt-2), temperature (Tt), evartanspiration (ETt), relative humidity (Rht), and discharge with two lags (Qt-1 and Qt-2) with Multi Layer Perceptoron method has the best function. The error of model was 0.03, 0.18 and 0.04 in training and 0.02, 0.14 and 0.02 for testing stage for MSE, RMSE and MAE, respectively.
Asghar Kouhpeima; Sadat Feiznia
Abstract
Landslide causes many social and economic losses in many parts of the world every year. These losses can be greatly reduced by using appropriate management measures such as mapping landslide susceptibility mapping in the basin. The aim of this study is landslide susceptibility mapping using Mahalanobis ...
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Landslide causes many social and economic losses in many parts of the world every year. These losses can be greatly reduced by using appropriate management measures such as mapping landslide susceptibility mapping in the basin. The aim of this study is landslide susceptibility mapping using Mahalanobis distance in the Latyan catchment. First, a total of 208 cases of landslides identificated and geo-referenced using geographic information systems based on an interpretation of aerial photographs and extensive field surveys and provided a landslide inventory map. The map of 12 factors, including rainfall, land use, distance to fault, distance from river, distance from road, lithology, altitude, slope, aspect, plan curvature, Peak Ground Acceleration and topographic wetness index as the most important factors in landslides was prepared. Then the correlating each factor and the landslide was examined. Finally landslide susceptibility zoning map was provided based on the Mahalanobis distance in Latyan catchment. To evaluate the results, the ROC and chi-square tests were used. The results show more than 80 % of the catchment located in range of high and very high susceptibility classes and need to suitable management operations. AUC index (area under the curve ROC) for this model is achieved to 0.896 or 89.6% which represent capability and high accuracy. Chi-square test results also reflect the proper separation of landslide susceptibility classes by model.
sadaf sayadi; siavash naghizadeh; Hossein moradi zeinab; ahmadreza mehrabian; hossein mostafavi
Abstract
The climate change is the greatest environmental challenge facing the world today. The prediction of the effect of climate change on the distribution of sensitive and valuable plant species is considered important in the management and conservation of them. Onosma L. as a very rich taxa from Lithospermeae ...
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The climate change is the greatest environmental challenge facing the world today. The prediction of the effect of climate change on the distribution of sensitive and valuable plant species is considered important in the management and conservation of them. Onosma L. as a very rich taxa from Lithospermeae Dumort. tribe in Boraginaceae family including 52 species in Iran wich more than half of them are endemic to Iran. The Onosma sabalanica Ponert. and Onosma cornuta H. Riedl. are the rare and endemic species of Onosma L. in Iran. Objective of the present study was to predict the effects of the climate change on the spatial distribution of these plants at future. In this regard, with using species distribution model's tool (SDM), different algorithms (GLM, GAM, GBM, RF, CTA, FDA, MARS, ANN, SRE) in different optimistic (RCP2.6) and pessimistic (RCP8.5) scenarios predicted the future spatial distribution of this species for 2050 by an ensemble model in R statistical software. The results showed that the performance of all models based on TSS index was excellent and modeling of the distribution of the species had been done with high statistical reliability. The results also represented that the distribution of these species in both optimistic and pessimistic scenarios of 2050 had been significantly reduced which requires to apply strategies for protecting of this valuable plants.
mohammad moazami; Sadat Feiznia; Majid Khayyat Kholghi; Arash Malekian
Abstract
Hydraulic conductivity is an important parameter for controling water flow through porous media. Hence, accurate estimation of this parameter is important for evaluating flow exchange between surface water and groundwater. In this study, 12 empirical formulae based on grain-size and 4 infiltration equations ...
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Hydraulic conductivity is an important parameter for controling water flow through porous media. Hence, accurate estimation of this parameter is important for evaluating flow exchange between surface water and groundwater. In this study, 12 empirical formulae based on grain-size and 4 infiltration equations were used for estimating hydraulic conductivity on 3 sites in Jarmeh flood spreading system, Khuzestan Province. Results were evaluated using measured hydraulic conductivity by double rings infiltrometer. The results of the empirical formulae showed that 9 formulae were overestimated or underestimated and 3 formulae were close to measured values. Hazen formula gave the largest overestimation and Slitcher formula gave the largest underestimation and Shepherd formula is the best one. Generally, empirical formulae applicability requires the calibration of C coefficients. The results of the infiltration equations showed that all of 4 equations estimated hydraulic conductivity appropriately and there are no significant differences between them. Among the equations, Kastiakov and Green-Ampt were the best.
Mostafa Naderi; Asghar Mosleh arany; Gholamhosein Moradi; Abdosalam Piri; Mehrdad Kuhzadian; Hamid Azimzadeh
Abstract
This research aimed at studying the vegetation and investigating the effects of physiographic,edaphic and geological factors upon distribution of plant communities in Manesht district in Ilamprovince. Sampling was done based on plant types and land unit map. The number of samples wasdetermined by Krebs ...
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This research aimed at studying the vegetation and investigating the effects of physiographic,edaphic and geological factors upon distribution of plant communities in Manesht district in Ilamprovince. Sampling was done based on plant types and land unit map. The number of samples wasdetermined by Krebs method. In total, 125 square sampling plots of 400 2 m area were selected byrandom systematic method. To determine soil factors, two soil samples (0–30, 30-90 cm deep) werecollected from each land unit and physico-chemical parameters were measured. Using TWINSPAN,vegetation of study area was classified and then PCA and CCA were used to investigate therelationship between vegetation and environmental factors. Based on TWINSPAN, four vegetationgroups were recognized. According to TWINSPAN results, four ecological groups were identifiedthat first and second groups with 31 and 46 sample plots, respectively and by Quercus barantti,Crataegus pontica and Acer monspessulanum, as indicator species, are more calciphiles thananother groups. The first three axes of the PCA accounted for 62.83%, 23.45% and 13.72% of thetotal plant cover variability, respectively. Also based on Mont Carlo analysis, first and second axeswith 0.68 and 0.48 eigenvalue, accounted for 28% and 19% of the variability, respectively and thecorrelation coefficient of axes and species is 0.98. According to PCA and CCA, Formation, organicmatter and lime were the most important factors on establishing of ecological groups.
Ataolah Kavian; 1 1; 1 1; 1 1; 1 1; 1 1; 1 1
Abstract
Small and portable rainfall simulators are essential tools in study of soil erosion and surface hydrology and it provide to repeat natural rainfall characteristics. In addition to the introduction of this device, calibration tests were performed including nozzles discharge evaluation, uniformity test ...
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Small and portable rainfall simulators are essential tools in study of soil erosion and surface hydrology and it provide to repeat natural rainfall characteristics. In addition to the introduction of this device, calibration tests were performed including nozzles discharge evaluation, uniformity test over the plots and raindrop size distribution. The results of nozzles discharge calibration showed that two nozzles discharge at 20, 40, 60 and 80 KPa pressure are similar and there isn't any significant difference between them. To achieve the optimum uniformity of simulated rainfall over the plot uniformity test was performed with changing nozzle distance (50, 60 and 70 cm) and oscillation of nozzles (30, 45 and 60 degrees) at constant operational pressure of 60 KPa. The results showed that the uniformity coefficient at 2m2 plot obtained from 57% to 61% and rainfall intensity changes from 48 to 101 mm/hr. The results of high velocity photography revealed median diameter of raindrop as 2.4 to 2.6 mm.
Sina NabiZadeh; Ataollah Ebrahimi; Masoumeh Aghababaei; Iraj Rahimi
Abstract
The land use of the watersheds is one of the most affected and highly vulnerable due to developmental process which effect on the other variables such as the hydrological function. The purpose of this research is to monitor land use changes in the past and to investigate predictability of its future ...
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The land use of the watersheds is one of the most affected and highly vulnerable due to developmental process which effect on the other variables such as the hydrological function. The purpose of this research is to monitor land use changes in the past and to investigate predictability of its future using Land Change Modeler (LCM) in the watershed of Farsan County of Chaharmahal-va-Bakhtiari province. For this purpose, the Landsat-5 TM images of 1986 and 2009 as well as the Landsat-8 OLI images of 2017 were analyzed. Land covers including residential areas, agricultural land, dryland farming, rangelands, rocks, water bodies, bare-land and snow were classified for the three periods. The prediction of land cover of 2017 was done using the LCM model based on Artificial Neural Network and Markov chain analysis after assessing model’s accuracy based on Kappa index. The land cover of 2027 was also predicted using a change probability table extracted from occurred changes from 1986-2017. The results show that the rangeland decreased by 4379-ha in the years 1986 to 2017, but the agricultural land increased by 1922-ha. This study proved that the LCM could accurately forecast future changes (85% overall accuracy). An increase of 149-ha of residential area and 100-ha decrease of rangelands in the study area was predicted for 2027. Therefore, while emphasizing the conservation of rangelands, it is necessary to study and use this technique to predict changes, its causes, as well as the consequences of land use changes at the broader scales.
Shirin Mohammadkhan
Abstract
The phenomenon of dust storm causes a number of damages such as aggravation of heart or lung disease, air and land traffic. Occurrence of dust storm has been growing inrecent years and has created many problems in some cities of Iran. Dust storms of Iran arise either from internal or external sources. ...
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The phenomenon of dust storm causes a number of damages such as aggravation of heart or lung disease, air and land traffic. Occurrence of dust storm has been growing inrecent years and has created many problems in some cities of Iran. Dust storms of Iran arise either from internal or external sources. In this paper, Climatology of dust storms in Iran is compiled based on observational data of 112 meteorological stations from 1985 to 2005. Results show that the total number of dust stormy days varies from 11 to 3833. Accordingly, we have identified five types of cities; 1- less than 492 days; 2- from 588 to 1153 days; 3- from 1243 to 1757 4 days; from 2007 to 2239 5 days; 5- more than 3832 days. Afterwards, we examined each of them separately. The first group is fixed. Cities of this group are located mostly in North, East and Center of Iran. The second group contains three parts:First, an ascending trend to 1992 and then a descending part to 1998 and again,an ascending part to 2005. Cities of second group are located in the southern pasrt of the country. The third group contains four parts: First, a down trend to 1990 and then an ascending part to 1993 and again, a descending part to 1998 and finally, a branch of the ascending to 2005. Cities of the third group are located almost in the southwest. The cities of the fourth group are located in Sistan&Baloochestan province and are affected by the120-day wind. The occurrence of dust storm in the fourth group is ascending. Finally, using GIS and interpolation systems, we have plotted dust storm zone classification map of Iran from 1998 to 2005.
Mojtaba Nassaji zavareh; Bagher Ghermezcheshmeh; Fatemeh Rahimzadeh
Abstract
Daily constant discharges are needed estimating daily discharge in the hydrological model. The different number of statistical years, statistical deficiencies, and measurement error leads to the formation of time series with an uncommon time base. Hence the reconstruction of daily discharge data is of ...
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Daily constant discharges are needed estimating daily discharge in the hydrological model. The different number of statistical years, statistical deficiencies, and measurement error leads to the formation of time series with an uncommon time base. Hence the reconstruction of daily discharge data is of paramount importance. In this research, daily discharge was reconstructed in two stages in one of the upstream of Karoun River. In both stages of research, daily discharge data from two upstream stations were used to reconstruct daily discharge of the downstream station using artificial neural networks, neuro-fuzzy and two variables regression methods. In the second stage, the magnitudes of discharge, based on dry, normal and wet years was used to reconstruct the daily discharge. The results showed higher accuracy in the artificial neural network and neuro-fuzzy methods compared to two variable regression methods in the reconstruction of daily discharge. Multi-layer perceptron model has better potential among all different method of artificial neural network and neuro-fuzzy models. Classification of discharge into dry, normal, and wet years decreases error in the reconstruction of daily discharge. Based on the mean relative error (MRE), error in reconstruction of daily discharge is the least in normal, wet, and dry years, respectively
seyedeh khadijeh mahdavi; gholamreza houseynibamrooud; mouhamadhasan jouri; houseyn tavakouli
Abstract
Calligonum eriopodum is the only psammophyte shrub in Iran, which was reported from South Korassan. Searching of environmental limitation of the species was the goal of current research that has been done on dune lands around the east direction of the Qaen city in south Khorassan. First of all, the habitat ...
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Calligonum eriopodum is the only psammophyte shrub in Iran, which was reported from South Korassan. Searching of environmental limitation of the species was the goal of current research that has been done on dune lands around the east direction of the Qaen city in south Khorassan. First of all, the habitat boundary was cleared by field monitoring and GPS recording of points and the species distribution, and then was pointed at map scale 1:50,000. Sampling in inside and outside by using three 1000-meter transects were laid down on the land, and the soil and plant samples were selected using five by five meter plots. The soil samples were taken from the fifth plot in each transects. The water samples were obtained. The t test was done to compare the soil and water samples from two habitats. Results showed that the soil and vegetation conditions were statistically the same inside and outside the habitat. However, EC and TDS of water samples were significantly different two habitat (P-value<0.05). The EC rate of the water resources was less in the inside habitat position than the outside of the species habitat. The water table level (WTL) in the inside limatation in close to the surface was (less than five meters) while it was between twenty five to thirty two meters in the outside land. It can be stated in among environmental factors the WTL and the quality of water resources were the cause of establishing of the species in the dune lands.
Hamidreza Mirdavoodi; Adele Jalili; Ziba Jamzad; Ali Famaheini
Abstract
Classification of species in plant functional types (PFTs) according to Grime’s CSR theory has been found useful in understanding ecosystem functioning and processes and in quantifying variation along environmental gradients. The aim of this study was to assess variations in CSR strategies along ...
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Classification of species in plant functional types (PFTs) according to Grime’s CSR theory has been found useful in understanding ecosystem functioning and processes and in quantifying variation along environmental gradients. The aim of this study was to assess variations in CSR strategies along stress and grazing gradients in Meyghan playa of Arak. The strategy of plant species was determined according to the Grime’s CSR strategies, based on Pierce’s method. Random- Systematic design was applied to sampling. Two-way indicator species analysis (TWINSPAN) was applied to classification of the ecological plant groups, and partial canonical correspondence analysis (pCCA) was used to identify relationship between environment factors, disturbance and the plant groups studied, using the PC-ORD4.17 and CANOCO4.5 software, respectively. Among the factors that affect plant functional types and the structure of vegetation, soil salinity as a stress factor and grazing as a kind of disturbance were studied. Results showed that stress-tolerant peaked in conditions of high salinity. Competitors with a frequency of 14.3% were mostly present in conditions of low salinity and disturbance/light grazing. Ruderals with a frequency of 7.1% were mostly present in condition of overgrazing. The presences of competitor in protected areas with low soil salinity confirmed the theory of appearance of competitive strategy in low/stress-free areas and light/graze-free. Therefore, it may be possible to use Grimes’s PFTs for assessing environmental constraints and predicting whether a species with a specific strategy is likely to be positively or negatively affected by changes in environmental stress due, for instance, to climate change.
kazem Nosrati; Saeedeh Jalali
Abstract
Identifying sediment sources is one of important factors in selecting of appropriate method of erosion control and soil conservation. The main objective of this study is to estimateuncertainty and contribution of forest roads to sediment yield in Ziarat Drainage Basin, Gorgan city using geochemical tracers. ...
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Identifying sediment sources is one of important factors in selecting of appropriate method of erosion control and soil conservation. The main objective of this study is to estimateuncertainty and contribution of forest roads to sediment yield in Ziarat Drainage Basin, Gorgan city using geochemical tracers. For this purpose, 47 soil samples were collected from different sources with different land uses and 14 suspended sediment samples collected from basin outlet. In order to identify sources of basin sediment yield and determine individual contribution of each source, 11 geochemical tracers including OC (Organic Carbon), Sr, Ni, Na, K, Cu, Fe, Mn, Ca, Mg, and Pb were measured in sediment and suspended-sediment samples. By comparing the tracers in the sediment sources and using statistical analyses of Kruskall-Wallis test and discriminant function analysis (DFA), three tracers of OC, Cu, and Fe were selected as optimum set of tracers in separating sediment sources. Eventually, using Bayesian model, land uses of agriculture, road construction and forest with 67.1(61.6-71.8), 31.4(27.1-35.9), and 1.2(0.1-5.1) percent, respectively were determined as the relative contribution from each source in sediment yield, and the highest uncertainty is related to the agricultural land use. The results of this study can be used to select the best appropriate method of erosion control in the study area and similar areas.
