جستجوی مقالات مرتبط با کلیدواژه « topography » در نشریات گروه « منابع طبیعی »

The severe and widespread droughts in Ardakan, especially in recent years, have added to the livelihoods of farmers and villagers and have caused irreparable damage to the economy of the city. The present study was conducted to investigate the drought vulnerability or zoning in order to implement and implement comprehensive drought management in Ardakan. In this study, the effective factors that affect the drought vulnerability of the study area were transformed into information layers and then the relevant classifications were made. Then, the layers created in terms of importance in agricultural drought vulnerability were prepared using the Analytical Hierarchy Process (GIS) and weighted maps (GIS) maps of each layer of information in the Model (AHP) Was. Finally, the aforementioned environmental maps (GIS) are integrated and finally, the areas of the study area are classified into five classes of agricultural drought vulnerability (very severe, severe, moderate, low, very low) as the final damage map. Agricultural drought susceptibility of Ardakan city was classified. The results showed that the garden lands with an area of ​​1485.63 hectares were located in high drought class and less area in other drought classes. Most of the agricultural land with an area of ​​4558.59 ha was also in high drought class. Also, in terms of topography status, less than 1% of the lands and agricultural lands occupy the highest area of ​​29.62 square kilometers in the most vulnerable class. Also the area located on slopes of 1 to 2 and 2 to 5% in the next rank (13.68 and 2.17 sq km) are in high drought class. The results showed that the most agricultural drought vulnerability was related to central part of Ardakan and parts of Kharanagh. Ardakan, Ahmadabad and Torkabad village in the central part of the country are in the class of agricultural vulnerability. The village of Chah Afzal is also in a very vulnerable agricultural class. The villages of Aghda are divided into low and very low clusters. The results also indicate the importance of the topography of the region, especially the slope parameter in the impact of drought.

The present study aims to improve the assessment, soil salinity accuracy, using of OLI Landsat satellite image dated to 26 May 2015 and topographic parameters in the eastern region of Isfahan. Ground data were collected in date second half May by using the random sampling method from 29 sampling sites from the depth of 0-30cm. Spectrum indexes include OLI sensor bands, salinity indexes SI1, SI2 and SI3, soil indexes SBI and SCI, and vegetation indexes NDVI and RVI were obtained from processing referenced ground images. Also, topographic feature including slope percent, orientation of slope and elevation from sea level were extracted from Digital Elevation Model (DEM), then to estimate the salinity linear regression the stepwise method model was used. From analysis, regression indicated that on 99% statistical level, there is a meaningful correlation between EC of topsoil samples, elevation from sea level and band 4 (R2=0.68). The salinity map acquired from the regression model indicates the salinity is very high in the region so that more than 70% of the area has a salt concentration of more than 60 ds/m. Finally, the reliability of the model was evaluated using 20 percent of the samples. Results indicated that the model can estimate soil salinity by an RMSE=6.54 ds/m. According to the research results, Conclusion They are using elevation from sea level parameter with satellite data is Beneficial in the soil salinity research and causes improve the accuracy of the assessment.

In case of to the high costs of road construction at forest; it is necessary to create a road network which cover more area with low length and least destruction. This research for planning the best network by considering the silviculture aims, used the topographic map, slope map, hydrographic, geology, soil, land stability, silviculture condition and..., but because of low density and inaccessibility to some high quality forest area, it could not respond to the expected aims, therefore taking cate of all effective factors, the predicted main roads network which ratified by forests organization and proposed network which suggested by this research were assessed and considered. The access roads included both networks ,the characteristics of the predicted network and proposed network respectively are: length 45.448 & 42.840 Km, length density 16.64 & 15.68 m/ha , network cover 65.36% & 69.73%, by comparison of two network and identify high lighted main points such as density, cover percent, slope, percent of the roads which pass of the stable area and other factors, the proposed network by this research selected and suggested because of less density, high percent of network cover, better communication and passing of more stable area, reduction of secondary paths, decrease the costs of wood harvesting, transportations, road construct and maintenance, technical structures.

Accordance with the importance of air pollutants and their effects on human health، assessment of air pollutant emission model''s accuracy is significant. One of the models that widely used is AERMOD which is a permanent prediction model. The purpose of this research was evaluated the accuracy of AERMOD model، with and without application of topography. To achieve this goal، model ran with 24 hour meteorological data from Yazd synoptic station as input data and EAF stack monitoring data of I. A. S. Co. as the on-site data. Also، Global maper software version 13 was used for creating model''s requirements for DEM format with different resolutions of 30، 50 and 90 meters. After that، model ran on both situations، flat and non-flat area (with applying topography)، and then results compared together. The results indicated that the average concentration of pollutant in condition using topography is 0. 036 µg/m3 higher than condition without usage topography. Also، the results showed the maximum concentration of pollutant in the case without using AERMAP، is 1 µg/m3 in opposite direction to the prevailing wind، in stack western direction and with using AERMAP، the maximum concentration is equal to 17. 5 in prevailing wind direction in stack eastern and south eastern direction. Furthermore، by usage DEM with different resolutions، little difference was found in the mean concentrations predicted by the model. The result is that without implementation of AERMAP، the prediction was not sufficiently accurate. Furthermore، AERMAP could also be run with DEM 90 m and finally model could run.