فهرست مطالب

  • Volume:3 Issue:1, 2015
  • تاریخ انتشار: 1394/06/09
  • تعداد عناوین: 7
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  • Elahe Goodarzi, Mohammadtaghi Dastorani, Alireza Massah Bavani, Ali Talebi Pages 833-846
    Prediction of climatic variables on a local scale by General Circulation Models of the atmosphere is impossible because the models have large-scale network of resolution. Therefore, downscaling methods are used to solve this problem. Since the climate change phenomenon can affect different systems such as, water resources, agriculture, environment, industry and economy as well, Selection of the most suitable downscaling method is very important. This study aims to evaluate performance of Change-Factor (CF) and LARS-WG downscaling methods in prediction of future climate variability of the Azam River Watershed, located in Yazd Province, Iran, for the period of 2010-2039. For this purpose, the CGCM3-AR4 model under the A2 emission scenario and also two methods of downscaling including statistical (LARS-WG) and proportional (CF) approaches were applied. The results showed increasing of temperature by both downscaling methods in the Azam River watershed in the future. Average temperature difference obtained from the two methods is about 3 to 4 percent. On the other hand, based on the climate condition, the amount of rainfall varied in the whole watershed, in a way that the future maximum precipitation difference calculated by two downscaling methods is about 30 percent.
    Keywords: CGCM3, AR4, Change, factor, Climate Change, Downscaling, LARS, WG
  • Mehdi Vafakhah, Ali Dastorani, Alireza Moghaddam Nia Pages 847-865
    Parameter estimation of the nonlinear Muskingum model is a highly nonlinear optimization problem. Although various techniques have been applied to optimize the coefficients of the nonlinear Muskingum flood routing models, but an efficient method for this purpose in the calibration process is still lacking. The accuracy of artificial bee colony (ABC) algorithm is investigated in this paper to optimize the coefficients of nonlinear Muskingum model. The performance of this algorithm was compared with other optimization techniques. For evaluating the ability of the ABC algorithm, several statistical criteria such as sum of the square error, sum of the absolute error, mean absolute error and mean relative error were used in the present study. ABC is an intelligent algorithm, which can effectively overcome the prematurity and slowed convergence speed of the traditional evolution algorithms. It determines the best parameter values in terms of the sum of square residual between the observed and routed outflows. The simulation results show that the performance of ABC algorithm with the sum of the square of the deviations between the computed and observed outflows (SSQ) of 35.62 m3 s-1, the sum of the absolute value of the deviations between the computed and observed outflows coefficients (SAD) of 23.2 m3 s-1, the mean absolute errors between the routed and observed outflows (MAE) of 1.05 m3 s-1 and the mean relative errors between the routed and observed outflows (MRE) of 2.9% is comparable to those of other algorithms. Thus ABC provided an efficient way for parameter optimization of the nonlinear Muskingum model.
    Keywords: Flood routing, Karoon River, Muskingum model, Parameters estimation, Parameters optimization
  • Mehdi Heydari, David Pothier, Elham Jaferyan, Vahid Merzaei, Amin Heidarpour Pages 867-879
    Redbud (Cercis griffithii) is an Iranian native species that plays a crucial role in protecting soil and water in Zagros forestsareas. Although many reforestation projects of this species in this area were unsuccessful, the restoration of redbud must continue using new applied studies to help conserve this precious resource. This can be achieved through increasing the quality and quantity of seedling production in nurseries. This study thus aimed to evaluate the effects of various organic amendments on growth and efficiency of redbud seedlings in a nursery. Four treatments viz.1) control (standard nursery mix) (C) 2) control: cattle manure (5:1) (CCM), 3) control: leaf composts (5:1) (CLC) and 4) control: cattle manure -leaf composts (5:1:1) (CCML)were applied for the present study. After one year, all growth indices were significantly increased by organic soil treatments compared to the standard nursery mix. Thegrowth characteristics such as height, root dry weight, length of the longest root, stem length to diameter ratio and relative height growth of redbud seedlings were associated with an organic soil treatment. These positive results on growth indices were explained by the reduction in EC and pH of planting bed induced by the organic soil amendments.
    Keywords: Biomass, Compost, Growth, Quality, Manure, Planting bed
  • Abbas Farshad Pages 881-899
    Soil, a 3-dimensional component of the landscape, or simply a natural body in a soilscape with a given geopedological setting, was modeled by Jenny as S = f (Climate, Organism, Relief, Parent material, Time). To map such a complex body, the concept ‗pedon’ –the smallest volume that can be recognized as a soil had to be defined. Classically, soil is known to function as provider, controller, regulator, mechanical support, and as a filter to protect the quality of water, air, and other resources. The intention of this paper is to argue, with the help of several examples of soilscape, in (semi-) arid regions of Tunisia, Morocco and Iran, some other functions of the soils, namely those of being an archive (‗history book of the landscape‘), a guide (in soil management), and a ‗predictor‘ (sensing soil health), in other words, soilscape speaks out: an account of the past, present and future.
    Keywords: Geopedology, Paleoecology, Soil conservation, Soil degradation, Soil management, Soil (land) scape
  • Davoud Akhzari, Mohammad Pessarakli, Farnaz Mahmoodi, Behnoush Farokhzadeh Pages 901-916
    Livestock grazing and rangelands fire are important ecological disturbances influencing the vegetation and soil properties in rangelands ecosystem. This study was conducted to determine the effects of different burned treatments and distances from the water sources on some soil and vegetation properties of rangelands ecosystem. The experiment was conducted in Lashgar Dar Rangelands. Vegetation samplings were done based on the randomized systematic method across transects. Fifty randomized quadrats were sampled at each transect. One hundred soil samples per each transect were systematically taken by auger along each transect. The ANOVA and Duncan tests were employed for statistical analyses. The results indicated that the highest and the lowest above-ground biomass production (630 and 117 kg ha-1), Shannon-Wiener diversity index (2.37 and 1.07), soil TOC (18.34 and 6.66 g kg-1), soil gravimetric water content (16.4 and 6 %) and soil porosity (69.43 and 57.74%) values were found in the unburned rangelands with 2000 m distance from the water source and the one year post burned rangelands with 10 m distance from the water source, respectively. Whereas, the maximum and the minimum values of soil bulk density and soil EC were seen in the one year post burn with 10 m distance from the water source and the unburned rangelands with 2000 m distance from the water source, respectively. There were no relations between the soil pH change trends and the different burned treatments or distances from the water source.
    Keywords: Burned rangelands diversity, Ecological disturbances, Soil management, Water resource
  • Mahdieh Ebrahimi, Alireza Masoodipour, Masood Rigi Pages 917-932
    The study was carried out to investigate the effective soil and topographic features on distribution of plant types in Sanib Taftan Watershed in Sistan-and-Balouchestan Province, Iran. Initially, land units map was specified by combining three maps of slope, aspect and altitude. Five types including Artemisia santolina- Hammada salicornica, Artemisia sieberi- Amygdalus lycioides, Artemisia lehmaniana- Amygdalu slycioides, Amygdalus lycioides-Amygdalus scoparia, Pistacia atlantica- Amygdalus scoparia were identified. Sampling of vegetation in the land units was conducted using linear transect method, so that presence and absence of the plant species, canopy cover, stone and pebbles, litter and bare soil percent were catculated in 50 or 100 m transects (2-4 m2 plots) in a randomized systematic method. Soil sampling was done with respect to the width of each land unit (from 0-30 cm depth). Principal component analysis (PCA) was conducted on vegetation and plant type-environmental variables matrix. The most important and effective factors in vegetation distribution of the studied area were slope, altitude, soil texture (silt and sand) and total nitrogen and the factors related to topography (slope and altitude) were more effective than those related to the soil.
    Keywords: Altitude, Plant community, Soil characteristics
  • Afshin Adeli, Mahya Namdar Pages 933-944
    World production of caviar from the farmed sturgeon has recently so increased that in addition to compensate reduction of natural resources of sturgeon, it has also increased its share in the world market for caviar and its substitutes. Although Belarus, China and Norway are currently considered as the main exporting countries of caviar and its substitutes but, Iran solely exports caviar from sturgeon species. Having a world reputation in caviar brand, as well as the decreased natural resources, Iran aims to develop sturgeon rearing as well as modern marketing along with global standards to stand its brand and reputation as well as its world market share. The present paper reviewed the caviar and caviar substitutes market with emphasis on sturgeon caviar. During 1991-2013, caviar export from Iran decreased by 21.2 % in quantity and decreased income by about 17.2 %. However, the caviar value increased from 231000 to 680000 USD per ton.
    Keywords: Caspian Sea, Caviar substitutes, Fishery products, IRAN, Marketing