فهرست مطالب

  • Volume:6 Issue:4, 2018
  • تاریخ انتشار: 1397/08/01
  • تعداد عناوین: 7
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  • A. Sardar Shahraki*, J. Shahraki , S.A. Hashemi Monfared S.A. Pages 205-214
     
    Aims
    Water is a basic demand of sustainable development in every region of the world. Hirmand catchment is one of the most important cross-border of Iran basins affected by the recent drought periods from water scarcity and caused severe crisis in the Sistan region. Fuzzy theory is able to convert most incorrect and enigmatic concepts, variables and systems into a mathematical form and set the context for reasoning, deduction and decision making at uncertainty conditions. The aim of this study was to simulate the Hirmand catchment by Water Evaluation and Planning System (WEAP) model and prioritization of the implementation of agriculture development projects in Hirmand catchment.
    Materials & Methods
    In this analytical-computational study, water development projects in the study area were predicted. The effects of the water development projects predicted using WEAP model and the projects according to the economic criteria was evaluated and prioritized with Fuzzy Technique for Order Preference by Similarity to Ideal Situation (TOPSIS). Ten water development projects and criteria including 5 economic indexes were considered.
    Findings: Water transfer project to agricultural field called Zehak and Sistan were the first priorities which is needed for noticing target population to these projects. Irrigation efficiency (70%) was in the third rank among the options.
    Conclusion
    The remarkable thing in the ranking of scenarios is that the current account scenario (SC1) is lasted ranking that shows Sistan region's water status, according to the study criteria is not good
    Keywords: Fuzzy Multiple Attribute Decision Making, WEAP Model, Prioritize, Agriculture Development Project, Hirmand Catchment
  • E. Samari , M. Farzam , P. Abrishamchi* Pages 215-223
    Aims
    Drought and high temperatures are main environmental stresses for noxious plants in the arid environments. Responses of arid land plants to drought are complicated and include different adaptive mechanisms in terms of physiological, morphological, and phenological responses. This research aimed at investigating phenological and/or morphological responses of two globally important noxious plant species, Centaurea virgata Lam, and Scariola orientalis (Boiss.) Soják, during growth season of a dry year.
    Materials & Methods
    The present experimental research site was conducted in Noh-Dareh Mountains, Mashhad, Iran. Weekly field visits were done during the growth season (March to September) in 2011. Understory soil moisture and air temperature were recorded together with some morphological plant traits of both species. Daily air temperature and sporadic rainfalls were recorded and their possible effects on changes in plant phenology were investigated. The data were analyzed by SPSS 22 software, using t-test to examine differences in the selected parameters between the two species at each phenological stage.
    Findings: Both species produced temporal rosette leaves that favored the high soil moisture in early growth season (March) and led to rapid shoot (stems and cauline leaves) production in the late April. However, they showed contrasting growth strategies in response to rain pulses and summer drought.
    Conclusion
    C. virgata is a drought escaping and opportunistic plant that threats the native flora during spring of normal and wet years, whereas S. orientalis is a slow growing drought resistant species and can be a major treat both in dry and normal years
    Keywords: Centaurea virgate| Scariola orientalis| Morphology| Seasonal responses| Phenology
  • M. Arabkhedri*, M. Mahmoodabadi , Sh. Taghizadeh , A. Zoratipour Pages 225-233
    Aims
    Soil erosion has been known as the most important land degradation feature in the globe and is also identified as a serious environmental threat due to its onsite and offsite effects. The aims of this study were to evaluate temporal changes of sediment concentration in a soil with high clay content under erosion by rainfall and inflow as well as interpreting the reasons for their very high erosion rate.
    Materials & Methods
    This experimental study was done in the Rainfall and Erosion Simulation Laboratory of the Soil Conservation and Watershed Management Research Institute (SCWMRI). All experiments were performed at a 20% slope gradient under 55.9mm.h-1 rain intensity for 30 minutes. Four slope lengths (1, 6, 12 and 18m) were considered for erosion simulation. With regard to the 6m length of the flume, 1 and 6m lengths were simulated only under rainfall and the other two longer lengths by combining rainfall-inflow.
    Findings: Very high concentrations up to 80, 59, 40 and 9gr.l-1 were recorded in 18, 12, 6 and 1m slope lengths, respectively. Sediment concentration increased exponentially by increasing the length of the slope that could be explained by the influence of flow velocity increase on longer slopes. The high sediment concentration could be justified by the breakdown of the soil mass during rainfall and the formation of more than 65.0% of fine aggregates in the size of silt and very fine sand.
    Conclusion
    The erodibility of clayey soil can be explained by the secondary aggregate size distribution rather than texture properties
    Keywords: Marly soil Erosion simulation Slope length Tilting flume
  • M. Sinaei*, M. Bolouki , D. Mirshekar Pages 235-240
    Aims
    It has been shown that sea turtles have temperature-dependent sex determination. Therefore, their sex determination is useful in understanding their reproduction ecology and population status. The aims of the present study were to estimate the sex ratio and to study the effect of inundation on the sex ratio of the hatchling green sea turtle (Chelonia mydas).
    Materials & Methods
    This experimental study was carried out on the 300km of Chabahar Beach on the northern coast of the Sea of Oman in July to December, 2015. Five areas which have the highest densities of nesting green sea turtles were chosen. The temperature of three different depths of green sea turtle clutches laid (50cm; above the egg hole, 85cm; center of egg hole and 120cm; below the egg hole) were recorded using automated intra-nest recording devices. Linear Regression Analysis and Pearson correlation coefficient were used. Statistical analyses of the data were conducted by SPSS 20 and Microsoft Office Excel 2010.
    Findings: The statistical mean temperature in thermosensitive period (TSP) of the nests at three depths of 50cm, 85cm, and 120cm at the chabahar beaches were recorded between 26.1±1.1 to 30.6±1.0. The storm had decreased the mean temperature in thermosensitive period of the nests.
    Conclusions
    The storm decreases the mean temperature in thermosensitive period of the nests. The Nilofar storm stops the increasing feminization. It can be an important step in the implementation of conservation, rehabilitation, and reconstruction programmers
    Keywords: Chelonia mydas| Sea of Oman| sex ratio| feminization| male-biased
  • Y. Taghi Mollaei*, A. Karamshahi , S.Y. Erfanifard Pages 241-257
    Aims
    One of the most commonly used applications in forestry is the identification of single trees and tree species compassions using object-based image analysis (OBIA) and classification of satellite or aerial images. The aims of this study were the valuation of OBIA and decision tree (DT) classification methods in estimating the quantitative characteristics of single oak trees on WorldView-2 and unmanned aerial vehicle (UAV) images.
    Materials & Methods
    In this experimental study Haft-Barm forest, Shiraz, Iran, was considered as the study area in order to examine the potential of Worldview-2 satellite imagery. The estimation of forest parameters was evaluated by focusing on single tree extraction using OBIA and DT methods of classification with a complex matrix evaluation and area under operating characteristic curve (AUC) method with the help of the 4th UAV phantom bird image in two distinct regions. Data were analyzed by paired t-test, multivariate regression analysis, using SPSS 25, Excel 2016, eCognation v. 8.7, ENVI, 5, PCI Geomatica 16, and Google Earth 7.3 Software.
    Findings: The base object classification had the highest and best accuracy in estimating single-tree parameters. Basic object classification method was a very useful method for identifying Oak tree Zagros Mountains forest. With using WV-2 data, the parameters of single trees in the forest can extract.
    Conclusion
    The accuracy of OBIA is 83%. While UAV has the potential to provide flexible and feasible solutions for forest mapping, some issues related to image quality still need to be addressed in order to improve the classification performance
    Keywords: Separation of single trees| Canopy| Remote sensing| Classification| Haft-Barm of Shiraz
  • P. Zarei , A. Talebi*, M. Alaie Taleghani Pages 259-268
    Aims
    Evaluating the factors affecting the mass movement and recognizing the regions sensitive to landslide are vital for planning, performing the construction projects, and providing proper management solutions in sensitive regions. The aim of the present study was to investigate the stability of the hillslope using the Stability Index Mapping (SINMAP) model to recognize the most important factor in causing the landslide by one-time sensitivity analysis method.
    Materials & Methods
    In the experimental research, the studied area included several watersheds in Javanrud, Kermanshah Province, Iran. Sensitivity analysis was performed for slope angle, internal friction angle, depth of soil, hydraulic conductivity, saturated storage ratio and rainfall. Accordingly, each of the mentioned parameters was changed by 10% to 75% compared to their initial value, assuming that other parameters remain constant. Then, the safety factor (FS) for each variation and the ratio of safety factor variations to initial FS were calculated.
    Findings: The slope angle was the most important effective factor in causing the landslide in this region. The Second and the third factors were internal friction angle and saturated storage ratio, respectively.
    Conclusion
    The slope angle is the most important factor in causing the instability in all hillslopes, as where this factor is reduced by 20%, FS initial value increased by twice. After slope angle, soil internal friction angle has the highest importance, which shows a direct relationship with factor of safety. It means that, as this angle increase, stability of the hillslopes will also increase
    Keywords: Hillslope instability| Landslide| Sensitivity analysis| sinmap model
  • K. Heidary , A. Najafi Nejad*, L.W. Dekker , M. Ownegh , A. Mohammadian Behbahani Pages 269-284
    Introduction
    Soil water repellency was first reported in the first half of the 20th century for peat soils. Depending on the severity of water repellency, a water repellent soil will resist water penetration during seconds to hours or even days. This has detrimental effects on surface and subsurface flow processes such as increased runoff, erosion, and preferential flow. The present study was conducted with the aim of investigating the effects of Soil water repellency on hydrological and erosion processes in order to identify gaps in the existing investigations.
    Conclusion
    Major survey gaps remained, including the dissociation of the symptoms of water repellency on soil erosion such as the existence of a soil crust and little knowledge of the temporal patterns of water repellency and their hydrological outcomes. Understanding the mechanisms of water repellency is relevant to the separation of different causal chains as well as the adjust runoff coefficients in different water repellency areas. Soil water repellency can be caused by a variety of compounds and processes and generally occurs after a period of drying weather. Under such conditions, the soil can change from a wettable to a water-repellent state when dried below its critical soil water content. Soil water repellency is found to occur in different soils worldwide, ranging from coarse to fine-textured. Water repellency in soils can result in losses of plant-available water, reduced agricultural crop production, and deterioration of turf quality on sports fields
    Keywords: Hydrology Hydro morphology Runoff Soil erosion Soil water repellent layer