فهرست مطالب

  • Volume:8 Issue: 1, Winter 2010
  • تاریخ انتشار: 1389/05/09
  • تعداد عناوین: 11
  • V. Gholami, M. Mohseni Saravi, H. Ahmadi Page 1
    Urbanization is a pervasive global trend. The development of residential areas and road network in Hajighoshan watershed (northern Iran) has been observed in the recent several decades. The objective of this study is the quantitative investigation of the effects of impervious surfaces development and urban development on runoff generation and flood hazard. The study of urban area development was carried out using aerial photos, topographic maps and satellite images. Also a rainfall-runoff model was presentedusing GIS (HEC-GeoHMS extension) and HEC-HMS model. Then, the model was optimized with initial lossand SCS-Lag parameters. The optimized model was evaluated using the other 4 events of flood. In the nextstage, the development of impervious surfaces was included in the validated hydrologic model and theireffects on intensifying runoff generation and flood hazard was investigated quantitatively during the recentforty years. The results showed that the runoff generation potential has increased in Hajighoshan watershedbecause of urban development during forty years ago.
  • A. Najafi, A. Solgi, S.H. Sadeghi Page 13
    The effects of traffic frequency and skid trail slope on dry bulk density, litter mass and rutting are examined.Treatments included a combination of four different traffic frequencies (3, 7, 14, and 20 passes of a rubberskidder) and three levels of slope (<10%, 10%-20% and > 20%.) The results showed that dry bulk density,rut depth and soil displacement increased with the increase of traffic frequency and slope, but floorcoverage decreased. Within each traffic treatment soil compaction raised with the increase of skid trail slope,so that significant differences in dry bulk density were observed between slope of < 20% and those one>20%. Bulk density has become quite close to the critical value after 14 cycles. With increase of the skiddercycles from 14 to 20, bulk density remained approximately constant. We observed soil displacement on thetreatments with 7 cycles: rutting on the treatments started with 7 cycles and slope of >20%. Soil disturbanceincreased significantly on slopes with > 20 % inclination with a dry bulk density of 1100 kg m-3 after 3 cyclescompared to 830 kg m-3 on slopes < 10 %. In addition the forest floor mass on the treatments with 7 cyclesand slopes of >20% (437.6 kg/ha) was significantly (p<0.05) lower than treatments with 14 cycles and slopesof <10% (841.4 kg/ha.) Data suggest that disturbance increased earlier in the steep treatments than in lesssloping conditions. The dramatic increase of soil disturbance on treatments with slopes of >20% may beassociated with increasing load on the rear axle combined with slipping on steep slope trail.
  • M. Ghasemnezhad, M. A. Shiri, M. Sanavi Page 25
    In this study, the effectiveness of chitosan coating treatment to control weight loss and maintaining fruit quality of apricot was investigated. Fruits were coated with 0.25%, 0.5% and 0.75% chitosan as well as distilled water (control). Following treatments, fruits were stored at 0°C and 80 ± 2% relative humidity for 25 days. The weight loss, total soluble solids (TSS), titratable acidity (TA), TSS/TA, pH, vitamin C, total phenolics and antioxidant activity (DPPHsc%) were followed at an interval of 5 days up to 25 days. Weight loss from all treated and untreated fruits increased over storage time. The weight loss of chitosan coatedfruits was increased in comparison to untreated samples. There was no significant difference for total soluble solids (TSS), titratable acidity (TA), TSS/TA, pH, vitamin C in coated and uncoated fruits storage. Chitosan coatings significantly increased the content of total phenolics and antioxidant activity, as 0.5% chitosan showed maximum total phenolics (82.65 mg GAE/100g) and antioxidant activity (23.77 DPPHsc%). The chitosan coatings proved to induce the antioxidant capacity and also to sustain the total phenolic content.
  • A. Mahdavi Page 35
    In land use planning, mapping the present land use / land cover situation is a necessary tool for determining the current condition and for identifying land use trends. In this study, in order to provide a land use/ land cover map for Ilam watershed, the IRS-1C image data from 25th April 2006 were used. Initial qualitative evaluation on data showed no significant radiometric error. Ortho-rectification of imagery was accomplished using ephemeris data, digital maps of topography and 45 ground control points with RMSe less than 0.7 pixels. Different suitable spectral transformations such as rationing, PCA, Tasseled Cap transformation were performed on the images in ILWIS software to enhance and produce new artificial images. Image classification was done using supervised classification maximum likelihood and minimum distance classifier utilizing original and synthetic bands resulted from diverse spectral transformation. Unsupervised classification was used to determine strata for ground truth. The results were assessed using a sample ground truth map through systematic random sampling and samples were designed in circle form and 1000m² area. Finally, nine main classes of land use / land cover (Rangeland, Forest (dense, semi-dense, sparse, very sparse), Agriculture, gardens, settlements and bare lands) could be determined. For representing accuracy, the rate was used from some criteria of accuracy such as overall accuracy and Kappa coefficient with 83% overall accuracy and 0.78 kappa coefficient.
  • R. Akhavan, Gh. Zahedi Amiri, M. Zobeiri Page 43
    Estimating the amount of variation due to spatial dependence at different scales provides a basis for designing effective experiments. Accurate knowledge of spatial structures is needed to inform silvicultural guidelines and management decisions for long term sustainability of forests. Furthermore, geostatistics is a useful tool to describe and draw map the spatial variability and estimation of forest variables. Therefore, this research was conducted to investigate on spatial variability and to estimate forest stock variables using geostatistical approach in a mixed hardwood forest, located in the Caspian region of Iran. Field sampling was performed based on a 150m by 200m systematic rectangular grid of 3 clustered plots (50m away). Each sample plot consisted of two concentric circles. Overall, 434 sample plots were measured in 502 hectares. Experimental variograms for forest basal area, volume and tree density were calculated and plotted using the geo- referenced inventory plots. All the variograms showed weak spatial auto- correlations between samples, even in short distances. Estimations were made using fitted variogram models and ordinary block kriging. Cross- validation results showed that all the estimations are biased, because of the large variability and weak spatial structure in the forest stock variables. Therefore, kriging could not make accurate estimations because of high spatial variability of forest growing stock related variables in this heterogeneous and uneven-aged forest.
  • Zarkamir., Goethalsp., De Pauw, N Page 55
    Classification trees (J48) were induced to predict the habitat requirements of tench (Tinca tinca). 306 datasets were used for the given fish during 8 years in the river basins in Flanders (Belgium). The input variables consisted of the structural-habitat (width, depth, gradient slope and distance from the source) and physic chemical (pH, dissolved oxygen, water temperature and electric conductivity), and the output ones were the abundance and presence/absence of tench. To find the best performance model, a three-fold cross validation was applied on the entire dataset. In order to evaluate the model stability, the dataset were remixed in 5 times, obtaining in total 15 different model training and validation events. The effect of pruning on the reliability and model complexity was tested in each subset. The performance evaluation was based on a combination of the number of Correctly Classified Instances (CCI) and Kappa statistic. The results showed that the predictive performance evaluation was suitable, confirming the reliability of classification trees methods. The overall average of CCI and Kappa for the prediction of tench was obtained 75.8% and 0.53. When analyzing the ecological relevance of classification trees, it seemed that the structural-habitat variables were important predictors compared to physic chemical variables
  • Motamed, M. K., Golmohammadi, F Page 65
    Nowadays the growth of deserts is one the most important problems in Iran. This phenomenon has many reasons such as growth of population, global changes in the climates and many undesirable consequences such as the erosion of agricultural soils and immigration of rural people to urban regions mainly to the capital of Iran, Tehran. Isfahan province is one of the semi-arid and desert regions in the center of Iran. It is the first province in Iran that has made rural parks in its arid and semi-arid rural regions. As the successful experiences of developing and developed countries shows, the main instrument to achieve people\''s successful participation in rural development is efforts for planning and operating extension education projects. The purpose of this paper is to examine and study the role of extension education factors in persuading rural people to participate for establishing and maintaining rural parks in order to decrease desert generation, improve ecosystems and reduce immigration from rural regions in Isfahan province. The type of the research is mixed - qualitative and quantitative- methods. The findings of the research, reveals meaningful relationships between educational and demographic characteristics of extension education employees responsible in rural parks of Isfahan, and achievements in their works. There are also meaningful relationships among age, number of children, quantity of education, quality and distance of rural parks from villages and quantity and quality of using the villagers in establishing and maintaining rural parks. As a whole, the findings of the research prove that to take into account the extension education factors has a major role in establishing and maintaining rural parks and is essential in increasing the efficiency of the similar rural development projects in Iran.
  • Amirib., Assareh, M. H., Jafarim., Rasuolib., Arzanih., Jafari, A. A Page 79
    Salinity is one of the major environmental stresses that limit plant growth and productivity. Glasswort (Salicornia herbacea L.) is one of the native halophytic plants of Iran that widely spread in salt areas. The purpose of this study was to determine the physiological and growth responses of S. herbacea to salinity stress. Plastic pods (15 cm diameter, 20 cm height) with the Silica sand bed were used for the experiment. The solution used for the study consisted of 0 (control), 100, 200, 300, 400, 500 mM of NaCl and Na2SO4. S. herbacea seeds cultivated at five pots for each treatment in green house condition. Plants were irrigated with half strength Hoagland?s nutrient solution for 6 months. Salt treatments were applied for 45 days. Shoot and root dry weights, proline, glucose, ion concentration, Osmotic Potential (OP), Relative Water Capacity (RWC), Water Use Efficiency (WUE)? Net Assimilation Rate (NAR), Specific Leaf Area (SLA) and Leaf Area Ratio (LAR) were measured. Data analysis showed that Mg 2+, Ca+2 and K+ decreased when salinity increased but Na+ increased. CL- increased when NaCl increased but significantly inhibited at higher Na2SO4. Dry weight, WUE, SLA, NAR and LAR increased in up to 100 to 300 mM NaCl and Na2SO4 but decreased with a further increase in salinity. S. herbacea uptakes more ions in chloride soil than that of sulfate soil. WUE, NAR and dry weight are more at sulfate soil. It is also assumed that salt tolerance mechanism of S. herbacea changes at different salts. Measurement of osmotic potential showed that it did not significantly increased when salinity increased. In addition, glucose did not promote up to 400 mM. Therefore, S. herbacea L. is a high tolerant halophyte which grows well up to 500 mM of NaCl and Na2SO4 salt. Salinity enhances the growth of S. herbacea and its optimum growth occurs at 100? 300 mM. Proline, glucose and osmotic potential remain unchanged at moderate
  • Dadrash., Kardovani, P Page 89
    This resaerch was conducted in order to study the importance of economic, social and touristic to the Anzali wetland, north of Iran. Data was collected through \"field research\" and \"documentary research\". Nominal scales, Likert and Guttman scales were used for the compilation of questionnaires. Findings of the present research indicate that the variation of population growth rate in the peripheral villages of Anzali wetland underwent a decline throughout the period between 1997 and 2007, falling to 1.2% comparing to the existing 3.3%. The suitability of ecological conditions in the peripheral rural communities of Anzali wetland draws a number of tourists to the region in summer. From the viewpoint of tourists, July, August and September? scored 11, 10 and 8 respectively? are ecologically the most appropriate months to visit Anzali wetland and surf its peripheral natural landscapes elaborately. Scoring 29, summer has obtained the best rank of tourism among the four seasons of the year with respect to the ecological appropriateness of travelling to Anzali wetland. The ratio of summer\''s tourism rank to spring, autumn and winter would be 2.07, 3.63 and 7.25 respectively. In order to attract more tourists and utilize the regional potentialities in an effective manner, technically dependable, environmentally, socially, touristically and financially, sustainable planning with the integrated participation and education of the inhabitants would be necessary
  • Nasrollahzadeh, A Page 97
    Caspian Sea is the largest enclosed body of water on the earth. Since the collapse of Soviet Union in 1991 and discovering large oil and gas fields, some issues such as political, economic and environmental events, made the Caspian Sea important. The ecology of the Sea are being endangered due to several issues such as petroleum extraction, river and sea pollutions, water level rise, biological damages, decline of Caspian seals and lack of legal regime among the neighbors. Tremendous infrastructures have had serious impacts on the ecosystems around the Caspian Sea and have often imposed long term damages to the sea. Activities around the Caspian Sea endangered the balance of this very sensitive and fragile ecosystem. Large oil stains on the sea level and thousands of acres of soil contaminated by oil leaking from abandoned wells are some parts of the pollutions. Some people must endure to the Caspian borders. In addition, there are various pollution-related industries, especially chemical and mineral industries, large non-irrigated agricultural and also domestic wastes. These impurities in addition to the negative impact of oil have serious effects on human welfare and wildlife of the area. Ecological balance of the Caspian Sea is nearly going to be ruined (?fendieva & M. Dzhafarov 1993). The increase of pollutions in the area has made many problems. The negative effects of shipping activities, oil and gas extraction and oil transport through the sea, have always been problematic. Destruction of flora and fauna are of the consequences of pollution. Finally, exploitation of Caspian Sea oil and gas provide the new challenges about the ecosystem of the environment. The natural resources of environment are the source of potential wealth. So they can easily increase the conflict for example legal aspects between neighbors as well as the risk of security in the region.