فهرست مطالب

Desert
Volume:17 Issue: 2, Summer - Autumn 2013

  • supplement
  • تاریخ انتشار: 1392/06/28
  • تعداد عناوین: 12
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  • H. Ahmadi, H. Azarnivand, M.R. Ekhtesasei, M. Tazeh Pages 211-214
    There have been different indices identified for desertification. Among these is technogenic desertification index which seems much more efficient. In this study, some of technogenic desertification indices were studied and evaluated. First land use maps of the region were taken from IRS-PAN satellite image and aerial photos analysis. After evaluating the area of different uses, lands that had productions (like agricultural and horticultural lands) were taken apart. The ration of production per surface unit was also calculated. The region roads map was also derived from satellite image. Finally per capita production, road and mine density and per capita green space indices were used. The per capita production index 9.1, population pressure with 59, road and mine density with 3.6 km/km2 and green space with 18.2 m2 for each person were the other indices calculated. According to the proposed table on these indices, per capita production and per capita green space in the region show very high level of desertification but road and mine density identifies lower level.
    Keywords: Land use map, Desertification indices, Technogenic desertification, Per capita production, Road, mine density, Green space
  • Gh.R. Zehtabian, H. Mohammad Asgari, M. Tahmoures Pages 215-224
    Our main objective in the present study was to assess the spatial variation of chemical and physical water properties. Prior to the design of groundwater quality monitoring networks, it is essential to investigate the spatial structure of the groundwater quality variables. A case study is presented which used ground water quality observations from groundwater domestic wells in the Dameghan, Iran. The anslyses of the spatial structure used the following variables: Electrical Conductivity (EC), PH, SAR, TDS, Sodium (Na), Calcium (Ca), Magnesium (Mg). For all these variables the spatial structure is described by means of geostatistical simulation, used to yield a series of stochastic images characterized by equally probable spatial distributions of the chemical and physical water properties across the area. The data set including 5 years of annual observations. At first normality and homogeneity of data are examined. Then variographic analysisusing two techniques including kriging, Weighted Moving Average (WMA) were applied for presenting spatial variation of water properties. Finally comparison of the results using statistical techniques showed that for more groundwater quality variables (e.g. TDS, EC, Cation, Na, Ca) kriging technique performed better than WMA-2 technique in characterizing the spatial variability. WMA-2 technique only for some groundwater quality variables like SAR and Mg has better result than kriging to simulate groundwater quality variables.
    Keywords: Water properties, Interpolation, Geostatistics, Spatial variation, Dameghan, Iran
  • H. Ahmadi, M.A. Saremi Naeini, M. Yadegari Pages 225-231
    In order to recognize the wind erosion situation of a region, the survey of its windiness is not sufficient and the physical characteristics of earth are of importance too. In fact, the outbreak of dust storms in a region is due to the sensitivity of earth and domination of wind in that region. In this investigation we have tried to find a way for determining the regions in which a dust storm is generated. In addition to wind rose that determines the windiness of a region, we have used another graph with the name of storm rose. With this new graph we have tried to find a relationship between the earth surface situations (threshold erosion velocity) and windiness of a region, so that we can reach a more suitable analysis for wind erosion. Studies made in the region show that where the threshold velocity less than 8 m/s (16 knots) is, the land is susceptible for erosion and thus has an important role in generationof dust storms. With the Storm roses drawn, it was also distinguished that most of the dust storms evolved in the region have the directions between west and northwest. So if we want to lessen the damages of flying dust and particles on Yazd city, we should stabilize the dust in the above-mentioned direction and bring them under control.
    Keywords: Wind rose, Wind storm, Wind erosion, Threshold velocity, Facies, Dust storm, Yazd, Ardakan plain, Pediment
  • Gh. Chamanpira, Gh.R. Zehtabian, Ahmadi H., M. Ekhtesasi Pages 233-240
    In recent years, the topic of desertification has been discussed in different ways in scientific areas. This event occurred globally, regionally and nationally and many steps were taken to stop it. Desertification is challenged universally and its destructive effects are unavoidable and its consequences do endanger the life of inhabitants. The identification of sensitive regions and prevention and avoidance from damages resulted desertification is the first step. Then various methods are used to preparation of plans and maps as well as to recognize the zones. Among these, ICD method was chosen for the area. Finally the plan of the present status of desertification was provided. In this plan anthropogenic causes as well as environmental cause, the kind of process, the determining criterion and subcriterion, the class and the severity of desertification were indicated. The results show the fact that desertification phenomena with average severity took place in the area and it is extending.
    Keywords: Desertification, Anthropogenic causes, Environmental causes, Desertification map, Kouhdasht basin
  • M.J. Nematolahi, S.K. Alavipanah, Gh.R. Zehtabian, M. Jafari, E. Janfaza, H.R. Matinfar Pages 241-248
    In order to assess the satellite data for soil investigation, ASTER digital data 20 June 2006, field study and phisiochemical properties of soil, were analyzed. All landcover classes including soils are classified based on morphological and physico-chemical characteristics. Images were geocorrected and photomorphic units were selected based upon visual interpretation and sampling in study area. The images was classified using maximum likelihood algorithm; with eight approaches. The classified image was compared with the ground truth map. The lowest classification accuracy was achieved by optimum index factor (OIF) approaches and hence application of OIF for discrimination of soils was not effective way. The results showed that best index is not only efficient and other information such as DEM (digital elevation model) with the spectral combination increase the accuracy of classification and Kappa coefficient. Salinity Indexes (SI) and Normalized Soil Index (NDSI) and Brightness Index (BI) were useful for discrimination of the soils in the study area. Typic Haplocambids showed the maximum reflection due to bright color. In addition, the minimum value was related to the Typic Torriorthents class, because of dark gravels. The result showed ASTER data can differentiate Typic Haplocambids from Typic Torriorthents, Typic Haplosalids and Typic Haplogypsids in arid lands.
    Keywords: ASTER, Soil, Maximum likelihood, Arid lands, Damghan, Iran
  • E. Zandi Esfahan, H. Azarnivand Pages 249-253
    Physiological effect of six levels of water stress (0, -0.1, -.03, -0.6, -0.9 and -1.2 MP) was studied on seed germination and plumule as well as radicule growth length in three species namely: Agropyron elongatum, Agropyron desertourm and Secale montanum. Polyethylene glycol (PEG) was used to provide appropriate water potentials. A total of 100 seeds in four replications (Petri dishes) were sown from each species. Experimental design was a factorial one of complete randomized design. Maximum germination rate was obtained at 0 MP. Germination rate and plumule and radicule growth declined with water potential level. The most resistance species to water stress are Secale montanum, Agropyron elongatum and Agropyron desertorum respectively.
    Keywords: Water stress, Polyethylene glycol, Germination, Plumule, Radicule
  • A. Kouhpeima, S. Feiznia, H. Ahmadi, S.A. Asghar Hashemi, H. Ghadimi Pages 255-264
    This contribution determines suitable fingerprinting properties for sediment source discrimination within the Amrovan and Atary catchments in Semnan Province, Iran. These catchments are representative of a range of geology formations and should therefore provide a meaningful basis for a general assessment of the degree of sediment source discrimination afforded by a range of fingerprint properties. By field investigation, 10 representative samples were collected from each sediment sources per catchments. Geological formation map was selected as the base of grouping samples. For the case of Amrovan catchment Hezar Dareh, Upper Red and Quaterrnary formations as well as gully walls were selected as the origin of sediments whereas in Atary Catchment karaj, Qum, Upper Red, Hezar Dareh and Quaternary formations were selected as the origin of sediments. The 15 properties selected as a tracer, comprised five groups of fingerprinting properties, including Organic constituents (C, N, P), base cations (Na, K, Ca, Mg), acidextractable metals (Cr, Co), clay minerals (Smectite, Colorite, Illite, Kaolinite) and magnetic properties consisting of Low Frequency Magnetic Susceptibility (XLF) and Frequency Dependent Magnetic Susceptibility (XFD). Several statistical methods were applied to the data including the Kruskal-Wallis, discrimination function analysis (DFA) and multivariate stepwise selection algorithm. Results indicate that the most powerful individual fingerprint property is organic constituent C, which successfully classifies 70% and 66% of samples in Amrovan and Atary catchmentsrespectively. Composite fingerprints incorporating constituents selected from several groups of properties using astepwise statistical selection procedure consistently provide the most robust discrimination of potential sediment sources. Results show also that organic constituents group of properties is extremely useful for sediment source discrimination in this catchments.
    Keywords: Composite fingerprinting, Sediment source discrimination, Catchment, Iran
  • K. Nosrati, H. Ahmadi, F. Sharifi, M. Mahdavi, M.R. Sarvati Pages 265-275
    Uncertainty associated with mixing models is often substantial, but has not yet been fully incorporated in models. The objective of this study is to develop and apply a Bayesian-mixing model that estimates probability distributions of source contributions to a mixture associated with multiple sources for assessing the uncertainty estimation in sediment fingerprinting in Zidasht catchment, Iran. In view of this, 31 geochemical tracers were measured in 35 different sampling sites of three sediment sources (rangelands, crop fields and stream banks) and 14 sediment samples from stream bed deposition. Based upon statistical analysis, the best 20 composition subsets of tracers (e. g. 2, 3, 4 …21) were then selected. Sediment source fingerprinting was used to explore the uncertainty in the contributions of sediment from the three sources. The results showed that the main source of uncertainty was the number of tracers included in the model andthe higher number of tracer in the model the lower deviation in uncertainty. However, differences between the ranges ofuncertainty values from subset 5 to subset 21 of tracers are not statistically significant. In the study area, mean of relative contributions associated with uncertainty from rangeland, crop field and stream bank sources (mean of subset 5 to 21) were 0.526, 0.059, and 0.411 respectively. These results can be useful as a scientific basis of sediment management and selecting the soil erosion control methods for decision makers of natural resources.
    Keywords: Sediment source, Discriminat analysis, Uncertainty, Bayesian, mixing model, Zidasht catchment
  • M. Shirazi, Gh.R. Zehtabian, H.R. Matinfar, S.K. Alavipanah Pages 277-289
    Soil Salinity has been a large problem in arid and semi arid regions. Preparation of such maps is useful for Natural resource managers. Old methods of preparing such maps require a lot of time and cost. Multi-spectral remotely sensed dates due to the broad vision and repeating of these imageries is suitable for provide saline soil maps. This investigation is conducted to provide saline soil maps with sensor LISS-III of IRS-P6 satellite data, in Najmabad of Savojbolagh. Satellite images belonging to 25 June 2006. For enhancement of images, salt Indices, Digital Elevation Model (DEM), False Color Composite imageries (FCC) and Principal Component Analysis (PCA), were used. Supervised classification method includes Box classifier, Minimum Distance, Minimum Mahalanobis Distance and Maximum Likelihood classifier, DEM, PCA1, PCA4 and Saline Indices (SI) were used. After classification, the class map salinity S0, S1, S2, S3 S4, were prepared. The results shows highest overall accuracy and kappa coefficient for the maximum Likelihood classifier estimate, respectively 99% and 97% and the lowest overall accuracy and kappa coefficient for PCA1 estimate, respectively 1% and 0% were obtained. Using Digital Elevation Model (DEM) also due to the difference in height position to the separation of saline lands is usefully. Most spectral interference relatedto non-saline soils and low saline soil. From among indices INT2 and PVI greatest ability to segregate is salty soils(especially classes S0 and S1).
    Keywords: LISS, III Sensor, Saline soil maps, Classification, Salt indices, DEM, PCA
  • M. Karimpour Reihan, S. Feiznia, A. Salehpour Jam, M.K. Kianian Pages 291-298
    Investigation of desertification trend needs understanding of phenomena creating changes singly or action and reaction together in the manner that these changes were ended up in land degradation. In investigation of pedological criterion onland degradation in Quaternary rock units, first, a part of the Rude-Shoor watershed area was selected. After distinguishing target area, maps of slope classes, land use and geology were created, and then map of units was foundedby overlaying and crossing these maps. In this research three indices of erodibility, salinity and permeability of soil were considered that finally each of them was shown in the shape of classified map. Then by overlaying and cross of these three maps, a new map was created that is an expression of research area zonation from the viewpoint of indices that formerly,were explained. As determining and distinguishing of desertification intensity of potential of created units from crossing of indices was not possible with using of pure mathematical or statistical relations, so were exploited principles and concepts of fuzzy logic and statistics for achieving to main result and were used functions of fuzzy algebraic sum, fuzzy algebraic product and fuzzy gamma after determining weight or value fuzzy gamma after determining weight or value of factors. Obtained results from a comparison of gained maps from different operators with an evidence map expresses thisactual that the most appropriate of fuzzy function for zoning desertification intensity or potential in research area and similar area with that is function of 0.8 from fuzzy gamma model (gamma = 0.8). After classification of obtained mapfrom function of 0.8 from fuzzy gamma model, by overlaying the desertification potential zonation map with land use map, kinds of soil zones were characterized on the base of their desertification effect. This research determined two classes of desertification qualitative potential (high 43.08% and moderate 56.92%).
    Keywords: Desertification, Range Land, Fuzzy Logic, Pedological Criterion, Erodibility, Salinity, Permeability
  • A. Mohebby, M. Jafari, A. Tavili, S.A. Javadi, E. Zandi Esfahan, M. Ramezani Pages 299-303
    It has often been stated or implied that grazing is an important factor in the land degradation process, a suggestion supported by various research projects, and this study investigated the effect of livestock grazing on stem height, crowncover, production, basal diameter, stem biomass, litter, leaf-stem index (leaf to stem weight), root diameter and weight and seed production per individual of the even-aged Atriplex canescens, by comparing two sites (grazed and non-grazed) across Zarand, Shahreiar rangelands located in the southwestern of Tehran, Iran. For this purpose, by using systematicrandom sampling method, four 300 m long transects were set up in each sampling area and ten quadrats were randomly assigned per transect [8] to measure the stem height as well as the crown cover, production, basal diameter, stem biomass, litter, leaf-stem index, seed production per individual and root biomass and diameter were measured at 3 soil depth (0-30, 30-70, >70 cm) with 4 replications within each of the two studied sites, results indicated that, grazing had no significantinfluence on stem height and leaf-stem index but crown cover, production, basal diameter, stem biomass, litter, seed production per individual, root weight and diameter of the even -aged Atriplex canescens were significantly greater than those of the un-grazed site.
    Keywords: Atriplex canescens, Enclosure, Grazing, Quantitative, qualitative properties
  • H. Joneidi Jafari, H. Azarnivand, A. Sadeghipour, A. Malekian Pages 305-307
    Salinity is one of the environmental factors that have a critical influence on the germination of seeds and plant establishment. Salinity affects imbibition, germination and root elongation. In this study, the germination characteristics of Matricaria comomilla and Thymus deanensis were studied. The purpose of this study was to investigate the effect of salinity on germination of these species. Seeds were treated with 0, 100, 200, 300 and 400mmol of NaCl. Daily and final germination percentages were recorded. The results showed that high salinity caused decrease in final germination percentage and Higher concentration of NaCl was germination inhibitor. Finally, results suggest that Thymus deanensis was more tolerant to salinity.
    Keywords: Thymus deanensis, Matricaria comomilla, Salinity, Germination