Maryam Azarakhshi; Jalil Farzadmehr; Mahdi Eslah; Hossein Sahabi
Abstract
Climate change is defined as long term and irreversible changes in the climatic behaviorof a region. Many studies have been conducted in different regions of the world on climatechange. The results of these studies show considerable changes in climatic factors especiallyin precipitation and temperature. ...
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Climate change is defined as long term and irreversible changes in the climatic behaviorof a region. Many studies have been conducted in different regions of the world on climatechange. The results of these studies show considerable changes in climatic factors especiallyin precipitation and temperature. In this research, the trend of changes in annual and seasonalrainfall and temperature in 24 synoptic stations over a 50-year data period (1956-2005) wasinvestigated in Iran. The Mann- Kendall test and linear regression technique were used to analyzethe trend of changes in climatic factors. The results showed both increasing and decreasingtrends in annual rainfall at various regions of Iran. Annual rainfall in northern slopes of Alborzand western slopes of the Zagros Mountain as well as in eastern and southeast parts of Iran hada decreasing trend while in the central of Iran the trend of changes was increasing. In southernregion of Iran the rainfall had an increasing trend. The results also showed that temperature inmost of the studied stations over the considered period was increasing. The highest and lowestchanges in temperature were seen in the mean temperature of summer and winter, respectively.Ahwaz and Khorramabad stations had a decreasing trend and over all seasons would go towardmore cooling. The temperature trend in Oromiye was decreasing in autumn and summer whileShahrekord and Bandar abbas had the same trend in summer and winter.
Iman Islami; Ali Akbar Mehrabi; Gholam Reza Zehtabian; Mehdi Ghorbani
Abstract
Agriculture sector is the main consumer of water in the world. In productive sectors likeagriculture, water is considered as a valuable mediatory commodity or production input.Demand for agriculture water comes from consumers› (agriculture products›) behavior. Thisstudy aims to evaluate ...
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Agriculture sector is the main consumer of water in the world. In productive sectors likeagriculture, water is considered as a valuable mediatory commodity or production input.Demand for agriculture water comes from consumers› (agriculture products›) behavior. Thisstudy aims to evaluate water use optimality in Pomegranate Arbors at the Charkhab village inthe Yazd province. The data was randomly collected from 95 people of 153 beneficiaries inthe study area. This study surveys water demand variations in the case of one percent changein water procurement expenses in Yazd. Elasticity estimation revealed that pomegranateproducers› sensitivity to agriculture water price changes is high. To be specific, one percentincrease in the price of agriculture water would decrease water demand by 24.32 percentamongst pomegranate producers in Yazd. Production elasticity of water input was obtained0.0565 which is located in the third part of production region and means over-consumption ofwater by producers due to its low price. Given high demand for water in this arid area havingappropriate polices in water pricing for optimal water consumption is needed.
Leila Bakhshandehmehr; Saeid Soltani; Adel Sepehr
Abstract
According to the UNCCD definition, “Desertification” is land degradation in arid, semi-aridand dry sub-humid areas resulting from various factors, including climatic variations andhuman activities. It has been recognized as a major economic, social, and environmentalproblem in many countries ...
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According to the UNCCD definition, “Desertification” is land degradation in arid, semi-aridand dry sub-humid areas resulting from various factors, including climatic variations andhuman activities. It has been recognized as a major economic, social, and environmentalproblem in many countries of the world. The MEDALUS methodology is a practical approachto assess the present status of desertification and evaluate the desertification risk. In this study,a regional model has been developed to desertification assessment and mapping in the SEGZIplain (Eastern Isfahan) based on the MEDALUS methodology. At first step, seven criteriaincluding climate, soil, vegetation cover, ground water, water erosion, wind erosion and policyand management were recognized according to the local condition. Each criterion includedseveral indicators accounting as factor quality determination. These indicators quantified basedon their influences on desertification process. For each indicator a score ranging from 100 to200 were assigned and desertification weighting was finally extracted. The weight of eachfactor and the weight of desertification status was calculated by geometric mean. Ultimately,desertification status was classified in four levels including low, moderate, severe and highsevere. At last the maps of these results was produced by geographical information system.Results showed that 2% of the study area was classified as moderate class, 35% classified assevere and 63% involved high severe class. Climate, policy and management are the mostimportant factors have led to desertification process in this region.
Mahbobe Hajibigloo; Mohammadtaghi Dastorani; Abbas Ali Ghezelsofloo; Mohammad Reza Ekhtesasi
Abstract
The morphology of a river system is affected by dominant watershed processes includingclimatic, hydrologic, hydraulic, erosion and sedimentation, geological and topographicalcharacteristics of the river environment and watershed. Understanding the interaction betweenthe river form and dominant watershed ...
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The morphology of a river system is affected by dominant watershed processes includingclimatic, hydrologic, hydraulic, erosion and sedimentation, geological and topographicalcharacteristics of the river environment and watershed. Understanding the interaction betweenthe river form and dominant watershed processes in river systems is necessary for recognitionof river behavior and of importance for developing river environments conceptual models.In this research the aim was to evaluate morphological characteristics caused by dominantwatershed processes in the Firoozeh-shahjoob river of north Khorasan and extract equations inorder to mathematically link between the river physical features and watershed processes. Forthis purpose, the HEC-RAS hydraulic model after doing sensitivity analysis and calibrationprocess was used to simulate the relation between dominant watershed processes and riverphysical factors for 37 reaches of this river. Considering the standard error, level of confidenceand coefficient of determination, compared to simple linear models, second order (quadratic)and third order (cubic) models, exponential models were the most suitable ones to extract themathematical relation between geometrical characteristics and the related dominant processesin this river system.
Sayed Hamzeh Hosseini; Reza Erfanzadeh; Paria Kamali
Abstract
The study on the livestock dietary and preference value of different species are essential forrangeland management. Therefore, this study was carried out to evaluate the preference indicesof 14 plant species in Kahnuj, during two different phenological stages (vegetative growth andafter-seed-dispersal). ...
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The study on the livestock dietary and preference value of different species are essential forrangeland management. Therefore, this study was carried out to evaluate the preference indicesof 14 plant species in Kahnuj, during two different phenological stages (vegetative growth andafter-seed-dispersal). The close observation method was used to measure the preference indexfor three age classes of Rainian goat (one, three and five years). The results showed that mainand interaction effects of goat age, plant phenological stage and the kind of plant species onpreference values were significant. Older goat consumed a higher time to graze in the studyarea. Stipa capensis had the highest preference index and Rhazya stricta had the lowest. Thepreference index of most plant species was significantly variable between two phenologicalstages. In addition, in each phenological stage, the preference value of plant species wassignificantly different. In the vegetative growth stage that annual plant species were abundant,goats mostly focused on these plant species for grazing. However, in the after-seed-dispersalstage in which the annual cover decreased, goats (particularly older ones) focused on shrubs forbrowsing. As a result, Rainian goat is a grazer in the normal situation and he can be a browserin the hard condition. It was suggested that the cover of Taverniera cuneifolia to be increased inthe study area in order to compensate the deficiency of forage in long term. Artificial foragingis useful to reserve the performance of goats (particularly younger ones) in short term.
Morteza Dehghani; Hosein Ghasemi; Arash Malekian
Abstract
Nowadays, watershed management practices are undertaken based on selective criteria and/or a specific purpose such as a decrease in flood risk, soil erosion and the like. In this respect,fuzzy logic has the ability to manage a wide range of options for decision making. This researchaimed to use the fuzzy ...
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Nowadays, watershed management practices are undertaken based on selective criteria and/or a specific purpose such as a decrease in flood risk, soil erosion and the like. In this respect,fuzzy logic has the ability to manage a wide range of options for decision making. This researchaimed to use the fuzzy logic theory to priorities watershed management practices consideringtime and budget constraints in catchments with high sediment production and flood risk. Thisresearch was carried out in the Foorg watershed of Darmian town with an area of 11137 ha. Allparameters related to soil erosion and flood risk were determined using the standard methods.Fuzzy score for each mentioned factor was then determined. Finally watershed managementpractices using the fuzzy theory and GIS were prioritized.
Shahrebanoo Rahmani; Ataollah Ebrahimi; Alireza Davoudian
Abstract
The analysis of the relationship between spatial distribution of environmental factors andvegetation types is crucial for understanding mountainous ecosystems. In this research aGIS based approach was used to produce a vegetation map for Sabzkouh protected area inthe Chaharmahal-Va-Bakhtiari province. ...
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The analysis of the relationship between spatial distribution of environmental factors andvegetation types is crucial for understanding mountainous ecosystems. In this research aGIS based approach was used to produce a vegetation map for Sabzkouh protected area inthe Chaharmahal-Va-Bakhtiari province. To identify environmental parameters affecting thevegetation cover, 6 primary and secondary environmental parameters including hypsometric,slope steepness, slope direction, annual precipitation, temperature and sun radiation maps werederived from the study area DEM. To investigate the relationship between these factors andthe spatial distribution of vegetation cover, quantitative analyses using statistical techniqueslike Principal Components Analysis(PCA) were undertaken. Then, the spatial distributionof vegetation types was predicted using a multi-logistic regression. Results showed thattopographic variables derived from the DEM were very useful for indicating habitats ofrange and forest types. Although lack of information on the anthropogenic effects led to someuncertainties in the interpretation of spatial pattern of vegetation types, the topographic andclimatic variables, derived from the DEM, were considerably effective in modelling the spatialdistribution of vegetation types.
Valiollah Raufirad; Ataollah Ebrahimi; Hossein Arzani; Zahra Shojaei Asadeiye
Abstract
Palatability includes plants physical and chemical property that encourages an animal selecta plant for grazing. This study is an attempt for intruducing an indicator for determining thepalatability of rangeland plants. To do this, the relationship between palatability and foragequality of rangeland ...
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Palatability includes plants physical and chemical property that encourages an animal selecta plant for grazing. This study is an attempt for intruducing an indicator for determining thepalatability of rangeland plants. To do this, the relationship between palatability and foragequality of rangeland plants in Karsanak rangelands of the Chaharmahal-va-Bakhtiari provincewas studied. First, plant composition based on plant canopy cover and production wasdetermined using of the systematic random sampling method (in each plant type there are2 transects of 200 m and 15 plots along each transect). Also, the percentage of present eachplant in the livestock diet (sheep and goat) was determined using the filming method. Then,the selection index of each plant species by sheep and goat was determined. In the next stage,the forage quality of some plant species was determined by determining the percentage ofCP, ADF, DMD and ME. Finally, the relationship between plant quality indices (independentvariables) and the selection index of plant species by sheep and goats (dependent variable)was determined using the SPSS software (Ver.15). Results showed that there is a significantrelationship between the selection index of each species (both percentage canopy cover andproduction) and ADF, DMD, and ME by the sheep (P ≤0.05). However, such a significantrelationship was not found for CP. And, there is not a significant relationship between theselection index of each species (both percentage canopy cover and production) and ADF,DMD, ME and CP by the goat (P ≤0.05). Considering the results, the quality of forage can be an indicator in determining their palatability.
Mohammad Sharifi Yazdi; Farhang Ghasriani; Mina Bayat
Abstract
The present research was done in steppic rangelands of Dehno, Kerman province to study theeffects of different harvesting intensities of Artemisia sieberi applying simulation method. Theexperiment was conducted using split plots in a completely randomized experimental designof ten replications to find ...
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The present research was done in steppic rangelands of Dehno, Kerman province to study theeffects of different harvesting intensities of Artemisia sieberi applying simulation method. Theexperiment was conducted using split plots in a completely randomized experimental designof ten replications to find the best grazing intensity. Treatments are including no harvest (as acontrol), 25, 50 and 75% harvest. In each treatment, 10 similar and average plant species wereselected as replications. All dependent variables were evaluated during the study and resultswere analyzed in SAS software. Results showed Minimum and maximum forage productionwas obtained at 25% harvest in 2008 and no harvest treatment in 2009, respectively. Regardingto the obtained results and soil condition, the 50% harvesting intensity is recommended inDehno site to maintain the vigority of Artemisia sieberi that is not dangerous for its survival,healthiness and vigority even in drought conditions.
Ataolah Kavian; Fatemeh Adineh; Gorban Vahabzadeh; Abdolvahed Khaledi Darvishan
Abstract
Investigating downstream changes in bed load shape can be useful to detect watershedhydrological processes and it is very important to design hydraulic structures and to managecapacity of large storage dams, properly. Regarding to doing of enforcement studies, thisresearch was conducted in Qalesar River ...
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Investigating downstream changes in bed load shape can be useful to detect watershedhydrological processes and it is very important to design hydraulic structures and to managecapacity of large storage dams, properly. Regarding to doing of enforcement studies, thisresearch was conducted in Qalesar River in upstream of Chahardangeh watershed in MazandaranProvince. After recognition of the study area, 6 sections were selected towards downstreamfor bed load sampling. Laboratory analysis were done to measure and calculate some bedload shape characteristics including skewness, kurtosis, mean, mode, percent of sand, finegravel, silt and clay, sediment texture, small, medium and large diameters, nominal diameter,sphericity, rounding, width ratio, shape factor and D10, D50 and D90. Results indicated adecreasing trend in shape factor and sphericity, an increasing trend in mean diameters androundness, a complex trend in width ratio and a uniform trend in 3 axes. Our finding alsoindicated that this variations may be affected by physiographic, lithologic and geotechnicalcharacteristics of the study area.
Alibeman Mirjalili; Mohammad Musaei Sanjeraei; Shahabodin Zarezadeh Mehrizi
Abstract
A better understanding of rangeland vegetation cover and its variation in different years basedon wetness and droughtiness fluctuations is a great importance. Economical priority setting ofrangelands is based on variations in rainfall and drought patterns, because it yields to bettercharacterization ...
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A better understanding of rangeland vegetation cover and its variation in different years basedon wetness and droughtiness fluctuations is a great importance. Economical priority setting ofrangelands is based on variations in rainfall and drought patterns, because it yields to bettercharacterization of vegetative cover. Yet a comprehensive and continuous monitoring ofvegetative cover of rangelands has not been established. To study the influence of droughtinessand wetness on vegetation cover and production forage, 11 sampling areas and 3 referenceareas were selected in Herat. Three 100-m transects were located 25-m apart within eachsampling area. Production and cover were estimated within 10 located 2- plots along eachtransect. Data were analyzed using Duncan›s test Design a completely random with a factorialGLM procedure at 99% and 95% confidence levels. Results showed that the vegetation coverand production in wetness were significantly different from those in droughtiness (P<0.01).The vegetation production and cover increased by 36.3% and 34% respectively in the wetnesscompared to the droughtiness. The influence on production and cover was positive and efficientin the wetness with the average rainfall higher than the 30-yr average. Finally, the results offlood spreading increased vegetation cover and production forage in dams.
Aliakbar Nazari Samani; Hesam Heravi; Mehdi Panahi; Masoud Jafari Shalamzari
Abstract
Natural landscape alternation is a problem that has been under debate for a long time. Landutilization techniques like agriculture, forest and rangelands, residential and urban are amonginfluential criteria affecting erosion severity and sediment yield in a given region. In this respect,land management ...
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Natural landscape alternation is a problem that has been under debate for a long time. Landutilization techniques like agriculture, forest and rangelands, residential and urban are amonginfluential 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 soilerosion owing to land-use changes is of great importance for estimating disadvantages andlatent and intangible symptoms of erosion. Strategic planning for sustainable developmentcould be benefited from such knowledge. The current research considered a statistical periodfrom 1970 to 2004. This period was sub-divided into two separate periods from 1970 to 1987and from 1987 to 2004. During these periods, statistics relating to sedimentation, climatology(precipitation) and hydrology were analyzed. Results revealed that the sediment reduction inthese two periods under similar rainfall would be as a result of an increase in abandoned areas.
