جستجوی مقالات مرتبط با کلیدواژه « طالقان » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

The loss of biodiversity worldwide and its impact on ecosystems' functions and performance over the past few decades has led to the conduct of many studies in this regard. On the other hand, identifying the reasons behind and the processes involved in changes made in species diversity has remained a challenge in ecological research. However, as vegetation is one of the factors that affect the richness of species, this study sought to investigate the relationship between species richness and vegetation percentage in the middle Taleghan rangelands.

considering the effects of livestock grazing, pasture condition and tendency, soil erosion, soil depth, and the percentage of rocks and pebbles at each site, the researchers of this study identified five levels of turbulence and stress in order of importance, including high turbulence and medium stress, medium turbulence and medium stress, medium turbulence and low stress, low turbulence, and moderate stress and low turbulence and low stress. To this end, random-systematic sampling was performed on the representative areas of each sampling unit to collect the required samples. Moreover, the number of plots was determined via the statistical method of 21 (one square meter) and the sampling was performed along two to three transects (100 to 150 meters long) in the representative areas of the study sites (a total of 735 plots). In each plot, first, the list of plants was recorded and their life forms were identified individually. Furthermore, different regression models were used to investigate the relationship between canopy cover percentage and species richness. These models were developed in such a way that the researchers were able to insert the amount of species richness (species per square meter) as a dependent variable (response) and the percentage of vegetation canopy as an independent variable in the relevant equations. On the other hand, to investigate the relationship between species richness and canopy cover percentage of plant species, first, the matrix of the data regarding the plant species cover percentage in different plots and sites was produced, followed by the modeling of regression equations via vegan and IME 4 packages in R software. Moreover, this study used a hybrid model to model the regression relationships between species richness and vegetation percentage. To this end, the best model was selected based on AIC standard statistics from among different regression models fitted on species richness and percentage of the vegetation canopy. It should be noted that as the results of such a statistic are separately calculated for each effect, and that the best model is selected based on the lowest value of the statistic, two or more models are selected as the best model in cases where the difference of the statistic is less than 2 in two or more models. Finally, R2C and R2m values were calculated for the best model using the MuMIn package in R software.      

The study's results indicated that the logarithm-quadratic model was the best-fitted model for the relationships between species richness and percentage of vegetation canopy for forbs, grasses, and shrubs. It was also found that the highest variance in modeling was explained by the fixed effect (based on R2m values). Therefore, the broad-leaf weeds and the shrubs had the highest and lowest variance, respectively. The results also showed that the relationship between species richness in different vegetative forms and the percentage of vegetation canopy were Gaussian but not complete. Moreover, the Gaussian model was observed more on the left side of the curve. Furthermore, in the broad-leaf weeds, the highest species richness was observed in moderate turbulence and stress and the lowest one was found in low turbulence and stress. On the other hand, in wheatgrass plants, the highest species richness was observed at high turbulence levels and the lowest one was found at low turbulence and stress. According to the study's results, the quadratic model was identified as the best-fitted model for the relationships between species richness and canopy cover percentage. Also, it was found that species richness was increased with increasing vegetation percentage and that the species richness decreased (Gaussian relationship) with increased vegetation percentage. Moreover, the highest amount of species richness was found in low turbulence and moderate stress and medium turbulence and low stress, and its lowest amount was observed in low turbulence and low stress. Furthermore, the highest species richness was found in 60-65% of the vegetation.

The results showed that the relationship between species richness and canopy cover percentage was of Gaussian type and that the amount of species richness increased with an increase in the percentage of vegetation, and this increasing trend continued almost to 60% of the vegetation. Moreover, it was found that the species richness decreased with an increase in the percentage of vegetation (more than 60% of vegetation), which may be attributed to reduced light intake, which, in turn, would lead to a Gaussian relationship. Furthermore, according to the study's results, the highest species richness was observed at moderate turbulence and stress, and the lowest was observed at the level of low turbulence and stress. On the other hand, in wheatgrass plants, the highest species richness was observed at a high turbulence level, which could be due to the effect of grazing intensity and turbulence on species of the wheatgrass family. In general, a Gaussian relationship was observed in the whole study area between species richness and vegetation. Therefore, as measuring vegetation is easier and more accessible than other parameters such as biomass, it can be used as a parameter to predict species richness in rangelands. Moreover, considering the fact that a few studies have so far been conducted on the investigation of such a relationship in Iranian rangelands, and on the threshold at which vegetation is at its maximum species richness, examining such a relationship can help the relevant officials manage and maintain vegetation as much as possible so that that optimal species richness is obtained in the ecosystem.

Flood zonation mapping is one of the priorities for the soil and water management, which Remote Sensing (RS) capabilities are very applicable to this issue. The main objective of this research was study of accuracy of the Object oriented and Pixel based methods for flood zonation mapping in the Taleghan River basin. Therefore, the Sentinel 2A satellite image of the study area classified using supervised classification method based on the both Object oriented and Pixel based approaches, with the Random Forrest (RF) and Support Vector Machine (SVM) algorithms. The overall precision and Kapa Coefficient of the RF algorithm based on Object oriented method were 89 percent and 0.82 and based on Pixel based method 88.5 percent and 0.75 respectively. The results of the overall precision and Kapa Coefficient for the SVM algorithm based on Pixel based method were 84.5 percent and 0.73 and based on Object oriented method were 86 percent and 0.78 respectively. In order to verification of the generated flooding zone maps, the flooding zone maps resulted from the hydraulic flood zonation mapping method with 2,5,10, 25 and 100 year return periods have been used. The results shown that, the generated maps of the both RF and SVM algorithms based on object oriented method; have the most suitable overlaps with the all-return periods flooding zone maps

Rainwater harvesting (RWH) in arid and semi-arid regions using micro-catchments (MCS) is an appropriate technique to produce crops and to deal with water shortages. Potential of RWH on the Taleghan Watershed was investigated using MCS covering areas of 100, 25 and 6.25 m2 under three treatments: furrowing, surface compaction and control (no treatment) during the 2016/2017 hydrological year. The experimental design was complete randomized block in factorial manner with three replications. Volume of the collected runoff was measured after each precipitation event in different seasons. The relationship between the amount and coefficient of runoff (R and Cr, respectively) with precipitation and the threshold of precipitation for runoff production (TPR) was determined. Results showed that the spring precipitation produced 62.5 and 65.5% higher R than the winter and autumn rainfall, respectively. Moreover, surface compaction produced 17.3 and 19.8% higher R and Cr than the control, respectively; it also reduced TPR by 7%. However, under furrowing, the R and Cr values decreased by 22 and 20%, respectively; while, TPR increased by 4% more than the control. Furthermore, the values of R and TPR in larger MCS were less than those of the smaller MCS. Overall, the use of MCS for R harvesting and plant cultivation with surface soil compaction (increasing bulk density by 7%) is recommended in regions where their areas is determined by the plant type.

One of the important criteria for quality of life is the health of the watershed. Researches in this field show that in Iran, a model for assessing the health of the watershed is not prepared. So, In this study, using the statistical data of 27 years (1990-2016) 5 environmental variables in the Taleghan watershed in the province of Alborz is estimated using gene expression and Bayesian network techniques. By using the gene expression programming and the Bayesian network of each variable, the years from 1991 to 2006 selected as a training data and 2006 to 2014 as test data, and from 2014 to 2016 selected as validation period (predictive accuracy). In comparison, the estimation accuracy of the gene expression and Bayesian network, the mean correlation values of 5 variables are 0.87 and 0.78, respectively. In the case of the gene expression model, the values of the coefficient of determination in the training section were: 0.87 for discharge, sediment, 0.92, precipitation, 89.9, temperature 0.91 and evaporation 0.77, and also in the Bayesian network, the values were 0.73, 0.88, 0.78, 0.71 and 0.81. The amount of gene expression scheduling will have a high power in simulating future values, given the generation of a generation of 200,000 times. The results of this study indicate that the health state of the watershed with a score of 8 in 2016 has advanced cancer status, and according to the results of the model in 2017, it can be in the recurrence of cancer.

There is a multifaceted approach of water resource in a watershed, which is accompanied by complexity and issues such as the interaction of natural and human systems. Achieving the consistent governance of water resources is one of the most important management approaches in the water sector, which requires a coherent structure of knowledge transfer and information on the organizations stakeholders’ network associated with water resources. In this research has been studied in Taleghan watershed to measure cooperation relations (transfer of water resources management knowledge), between 28 organizational practitioners (Including development, protective, and mediation organizations). In this study data were collected based on the questionnaire analysis questionnaire. The results show that the knowledge structure of water resources management in Taleghan watershed is highly integrated among organizational stakeholders and the type of knowledge management is currently not based on negotiation. On this basis, it can be claimed that based on the bonding social capital index (relationships of each of the sub- groups) is modest and based on the E - I index, bridging relations (relations between different subgroups) have a weak rate. it can be concluded that the relationship between water resource management and water resources management in Taleghan district level is an essential step to establish a cooperative governance of water resources.

Salvia limbata is an herbaceous plant which belongs to Lamiaceae family and is native to Iran. In this study, essential oils and variety of chemical compounds of Salvia limbata in flowering stage in different altitudes in July were studied. In order to study the active ingredients of plant in studied sites in flowering stage nine plant samples were examined for phytochemical analysis. Identification of the basic constituents (quantity and quality) with GC / MS and GC-FID (gas chromatography coupled to mass spectrometer) has been done. The yield of essential oils in flowering stage in Paeein Taleghan 0.34% in Mian Taleghan 0.34% and in Bala Taleghan is 0.46%. According to the results, difference in altitudes in three habitats shows a significant difference among the percentages of the obtained compounds. The most important constituents of essential oil include α-Pinene, β-Pinene, allo-aromadendrene and Spathulonol. Also, Salvia is reported as one of the sources for the extraction of α -pinene.

Rrecently, rangeland multiple use has been found to be one of the primary solutions to alleviate livestock grazing pressure while improving stakeholder's welfare and per capita income and sustainable management and development. Beekeeping in rangeland as a profitable approach and one of multiple use components in upper Taleghan basin and Saman Orfi of Narian, Dizan and Mehran were studied. The present study was aimed to determine beekeeping suitability as well as ecological and social issues. According to permanent standards and resource sites priority for comprising of these Samans Orfi reserves 4 criteria to be considered such as vegetation,environmental, physical and social issues.These criteria are included overall 14 sub criteria. So Multi-Criteria Decision Making Methods (MCDM) has used because of problem complexity. The hierarchical formed in the 4 levels that is purpose, criteria, sub criteria and options. One of the criteria were qualitative. For accessing logical results, we benefit specialist cooperation. The results showed that social problem are more important than the other criteria in priority. Also, final results of Analytical Hierarchy Process (AHP) indicated that Saman Orfi Narian, and Mehran and Dizin were fall into first to third priorities respectively.

Soil is one of the most vital natural resources in any country. Nowadays, lands are rarely found worldwide without having severe erosion problem. Landslide is one of the soil erosion processes in which a huge volume of soil is washed away. SHETRAN Model was used in this study to assess the landslides being occurred in Zidasht catchment, Taleghan. At the first stage, sediment-water mixed samples were gathered at the outlet of the Catchment for calibration purpose in 2011. To run the model, regions undergoing landslide were identified using GISLIP sub-model. Secondly, after hydrological and sediment production simulations in a sub-model of SHETRAN for the region, calibration was made for spring season. After the calibration process, the model was run again, this time for the regions having landslide (for 418 spots), and in regions where landslide sediments do not pour into water courses, these regions were omitted, the final amount of sediment was calculated using SHETRAN sub-model and the results were compared with the previous studies. The results show that 19.75% of the total sediment belongs to landslides. With regard to the current sediment quantity of about 111248 kg, total sediment in landslides was estimated to be around 120668kg.

Overgrazing and inappropriate use of Taleghan rangelands has led to poor and very poor condition for almost all vegetation types. Taking the importance of rangelands in forage production and other benefits into consideration, management of these rangelands and improving their condition seems essential. The present research was conducted using data integration of vegetation, condition, slope, soil, precipitation, etc. in a Geographic Information System (GIS) environment. Our study area was located in 50˚, 36ó, 43ð - 50˚, 53ó, 23ð longitude and 36˚, 5ó, 19 ð - 36˚, 19ó, 19ð latitude in the middle area of Taleghan watershed with the area of 37977 hectares. According to the results, improving methods and reforming activities could be suggested including prevention of livestock grazing (enclosure), sowing, inter seeding, broad casting and hoe sowing in areas which have poor and very poor condition (in 6621.325, 1274.381, 694.561, 1215.254 and 2368.101 hectares (areas), respectively). Such activities may improve livestock grazing management as well as watershed conditions, wildlife habitat or other similar purposes.

Estimation of fine suspended load rivers is important in designing reserves, transition volume of sediment, and estimating lake pollution. Thus, some methods are needed for determining damages caused by sedimentations in environment and determining its effects on the watersheds. There are many methods for estimating suspended load, one of these methods that solves the problems of sediment discharge and can predict it is using Neuro fuzzy or ANFIS (Adaptive Network Fuzzy Inference System), and ANN (Artificial Neural Network) methods. These make a function between sediment and simultaneous discharge by use of different algorithms. The goal of this research is comparing the effectiveness of Neuro fuzzy, neural network artificial and statistical methods for estimating suspended load river in Glinak station of Taleghan Basin. It was found out that suspended load estimations of Nero fuzzy method with MAE 1006 ton/day, and correlation efficiency (R) 77%, RMSE 2621 ton/day and Nash-Sutcliff error (NS) 0.51 is better than Neural Network Artificial and Statistical methods and Artificial Neural Network method rather than Statistical Method are more proper. Also, contracting both neural networks artificial to fuzzy laws can be illustrated better than other methods, variation of sediment Load River. One more merit of this method is that it is not sensitive to few errors in early statistical data and this fact enables better estimation of neural network model in comparison with statistical model. Finally, Neuro fuzzy method works better as the percent of train data to test data increases.

Landslide occurs inevitably and naturally in many slopes due to sensitive formations, moisture, and other factors. Taleghan watershed is prone to landslide due to the presence of huge Miocene marl masses. After construction of Taleghan reservoir dam, moisture and ecological condition of the region changed. In this paper, factors impacting upon landslide hazard (slope, aspect, hypsometry, geology, land use, distance to road, distance to lake) were studied and their role and importance on this phenomenon were verified in a large (maximum distance of 1500 meter from lake) and a small (maximum distance of 450 meter from lake) spatial scale. Thus, GIS maps of the above mentioned parameters were provided using satellite and aerial images and field activities. All maps were crossed with a resolution of 100m*100m. It was found out that the distance to the lake didn’t influence upon landslide in a large spatial scale but it falls effective as the distance to the lake reduces. In fact lake has a local effect and mostly influences at maximum 200 meter distance.

Due to the constraints in determining of soil susceptibility to water erosion or soil erodibility through field tests, use of laboratory methods on small soil samples, are easy to implement and far less expensive and time-consuming. among different laboratory methods based on the soil properties, those relating to aggregate stability have received much attention. In this study, by relying on observations and changes in the macroscopic scale of homogeneous work units in marly soils of taleghan watershed, with 3260 hectares in area, 84 points as the soil sampling points were selected.
In order to distinction between aggregate breakdown mechanisms and assessing of soil structural behavior in different environmental conditions, aggregate stability is measured with respect to three treatments fast wetting, slow wetting and stirring after pre-wetting using Le Bissonnais method. Results showed that aggregate breakdown mechanisms have a significant influence on aggregate stability. The instability main mechanism of marly soils in Taleghan watershed is slaking that caused by the compression of entrapped air during fast wetting and this situation can occur during rain storms on dry soils and irrigation flooding. So it seems that the method of agricultural land irrigation can be one of the most important soil erosion factors in the study area.

When watershed input, evatransporation and ground water usage be limitated, recession curve showed storage–output relationship for basin. This relationship can help us in low flow forecasting, decision and management of water resources; hydrological models calibration and etc. In this study recession curve were modelled in Taleghan, Jajrod and Khoramdare rivers. At the first by consideration of annul hydrographs, recession lamb were separated then by doing some pre-processing recession curve get prepared for fitting various models. For each recession eight models were fitted. Result showed that for Jajrod and Talaghan, Barnes, Drogue, Coutagne and Wittenberg had better application, respectively. For Khoramdare river Horton, Barnes and Drogue had better performance with compared to others models. For Barnes model average value of K coefficient for Jajrod 0.97, 0.975 and 0.99, for Taleghan 0.967, 0.974 and 0.987 and for Khoramdare river 0.931, 0.945, 0.972 were obtained.

Land use optimization is one of the suitable methods for soil conservation. The present research with objective of land use optimization for soil erosion minimization and pure income maximization was conducted in the part of Taleghan Watershed which comprises 80427. 23 ha in area. To achieve this propose، area، erosion rate and net income value of each land uses according to requiring standards of each land uses area was extracted. Then، limitations and two objective functions were determined and optimization problem was solved by using ADBASE software. The results revealed that the optimization decrease 6. 99 percent of erosion rate (6. 28 ton/ha/year to 5. 84 ton/ha/year) and 4. 65 percent of pure income (118174. 38 to 112681. 02 million Rials). Also، the results proposed that drylands farming are changed to garden and orchard and rangelands.

This study was aimed to assess the applicability of LANDSAT ETM+ satellite images for estimating vegetation production and cover. The images were digitized using topographic maps and geometrized in 1:25000 scales. Required processes such as spectral ratio measurement and vegetation indices were applied on the images. Collection was carried out for vegetation cover and production in various vegetation types in homogeneous units. Sampling points'' locations were recorded with GPS. Sampling method was random-systematic in such a way that in each unit، a circle with 20 meters radius was considered. One and 9 sampling plots were placed on the centre and on the perimeter، respectively. The plot size was 1m * 1m. In each plot، vegetation percentage was estimated and the production was calculated using double sampling method. Then، DN values for each sampling unit (9 pixels for one unit) were elicited in respect to primary bands'' images، vegetation indices and spectral ratios. Correlation and regression analyses between geo-information and satellite information (Digital numbers) were carried out. Results revealed that 7th and 5th Bands and IR1، MIRV2 and VNIR2 indices had a significant correlation with production and given parameter could be estimated through regression models. Likewise، RA، IR1 and TVI indices had a significant correlation with vegetation percentage and this parameter could be estimated through regression models.

Natural landscape alternation is a problem that has been under debate for a long time. Land utilization techniques like agriculture، forest and rangelands، residential and urban are among influential criteria affecting erosion severity and sediment yield in a given region. In this respect، land management is a promising option to mitigate it. Thus، acquaintance with quantitative soil erosion owing to land-use changes is of great importance for estimating disadvantages and latent and intangible symptoms of erosion. Strategic planning for sustainable development could be benefited from such knowledge. The current research considered a statistical period from 1970 to 2004. This period was sub-divided into two separate periods from 1970 to 1987 and from 1987 to 2004. During these periods، statistics relating to sedimentation، climatology (precipitation) and hydrology were analyzed. Results revealed that the sediment reduction in these two periods under similar rainfall would be as a result of an increase in abandoned areas.

It is necessary to use empirical models for estimating of instantaneous peak discharge because of deficit of gauging stations in the country. Hence, at present study, two models including Artificial Neural Networks and nonlinear multivariate regression were used to predict peak discharge in Taleghan watershed. Maximum daily mean discharge and corresponding daily rainfall, one day antecedent and five days antecedent rainfall, sum of five days antecedent rainfall and monthly mean temperature were extracted in Gatehdeh, Mehran, Alizan, Joestan and Gelinak hydrological units and entered into neural network model (from upstream to downstream, respectively). The feed forward network was used with one hidden layer and back-propagation algorithm. Then, the models were trained, validated and tested in three stages. The observed and estimated peak discharges of the models were compared based on RMSE and r. The results showed that neural network has better performance than nonlinear multivariate regression.

The goal of this research is to compare the quality of litter and aerial organs in three rangeland species including Bromus tomentellus, Agropyron tauri and Psathyrostachys fragilis on the basis of nitrogen, phosphorous, potassium, carbon amounts and C/N proportion. After recognition of the species sites in Taleghan Watershed, litter and aerial organs of the mentioned species were collected. Sampling was done in key areas of each site along four transects using randomized-systematic method. Transect length was determined according to the area and variation of the key region.. Ten plots were placed along each transect and the dimensions of sampling plots were selected on the basis of species type and distribution using minimal area method. The obtained results of analysis of variance and comparison of means showed that B. tomentellus has maximum amounts of carbon and C/N proportion in its litter while P. fragilis has maximum amount of phosphorous and finally the maximum amount of nitrogen in litter is related to A. tauri. Meanwhile, P. fragilis showed maximum amounts of nitrogen, carbon and C/N proportion in its areal organs. The highest amounts of phosphorous and potassium are related to B. tomentellus. Totally A. tauri species showed the better condition than other species based on quality of litter and aerial organs.

Iran with its special geographical position mainly has an arid and semi-arid climate. The average annual rainfall in Iran is about 240 mm equivalent to one-fourth of the world average rainfall. In addition, irregular spatial and temporal distribution of rainfall has caused problems in natural resources and agriculture and annually huge amount of our water and soil resources are degraded. Since the advent of the farming activities until the present, human needs have been based upon farming activities. Considering the growing population and the social and economic developments, most of rangelands have been subject to rainfed cultivation. Therefore, to prevent further degradation of soil in these regions research should be conducted on agricultural lands and the exploitation methods. For this reason, Taleghan was selected as the study area. Map of the area, including soil maps, land types and the current land use were produced by GIS. After determining the main treatments, soil samples were taken in every part of the area and in agricultural area and soil factors were measured within two groups of soil improvement factors including nitrogen, phosphorus, potassium, humus and lime and soil degradation factors including acidity, sodium adsorption ratio (SAR) and salinity in two depths of 0-10 and >10 cm. These factors were studied in a split-plot design. The results showed significant differences among treatments. According to the results of soil improvement and degradation factors, orchards and rangelands are in an ideal condition and monoculture treatment decreases the performance of the products.

The object of this research was to compare the amount of N، P، K، C and C/N in litter of three range species including Bromus tomentellus، Agropyron tauri and Psatyrostachys fragilis in order to determine the influences of these elements on soil quality indexes. Soil and litter sampling was done at the end of growing season (summer 2009) after identification the sites of these species in Taleghan. Sampling were conducted in the key area of each site based on random-systemic method. The samples were collected and transferred to laboratory، the amount of C، N، K، P، C/N ratio in litter and pH، EC، Lime and texture in soil were determined. After investigation of data، their analyses were performed by T. test analysis، analysis of variance and Duncan. The result of variance analysis showed that there was significant deference between of C، N and C/N ratio in litter of these species. The maximum of N was related to A. tauri and the maximum of C and C/N ratio was related to B. tomentellus. Comparison of under plant soil and control area showed that there was significant deference between under plant soil and control area and above species was increased soil fertility. In generality A. tauri was better than two other species in litter quality، speed of degrade ability and its effect on soil conditions.