جستجوی مقالات مرتبط با کلیدواژه "گامای فازی" در نشریات گروه "جغرافیا"

Landslide risk zoning plays a significant role in the development of safe and sustainable infrastructure, urbanization, land use, and environmental planning. Identifying and determining sensitive and landslide-prone areas not only prevents damages but also provides a basis for the implementation of slope stabilization plans. Landslide risk zoning is done through different methods including statistical, expert evaluation and definitive methods. Choosing appropriate zoning method depends on the type of analysis, study area, experts’ skills and knowledge, and the type of geological and geomorphic parameters affecting landslide risk.  The main goal of this study were preparing a landslide distribution map, identifying the factors affecting landslides, and zoning its danger in Khorramabad-Arak Freeway (Khorramabad to Boroujerd). Using satellite images and field studies as well as frequency ratio (FR) model, a landslide distribution map was prepared, and the factors influencing landslides including slope, lithology, slope direction, elevation classes, land use, rainfall, distance from fault factors and the network of waterways were analyzed. Fuzzy gamma (0.9) was used for zoning the landslide risk. The landslide hazard map was divided into very low (18.55%), low (30.67%), medium (26.51%), high (18.15%) and very high category (6.12%) and finally validated by ROC curve. The results of ROC curve analysis for Fuzzy GAMMA showed that the landslide sensitivity map in the study area has excellent predictive power with area under the curve of AUC=0.94. Therefore, it is suggested to apply the obtained results for freeway security and regional planning.

The core of urban development planning theories is the respect and promotion of environmental issues and the move to sustainable and green cities. In this process, one of the strategies for realizing green cities is to frame the emergence and enhancement of green and natural areas in cities such as urban green space use. However, having adequate green spaces and their proper location can be very helpful in having healthy cities, given the necessity of the present study, which has been accomplished by the analytical-descriptive method. the purpose of this study is to analyze the spatial optimal deployment of urban green spaces in district 6 of Ahvaz city to achieve the purpose of the study of 13 urban land uses along with green space land use evaluation. Source for collecting, extracting and producing research data is Map 1: 25000 Land Use District 6 of Ahvaz Municipality. To analyze this information after fuzzing the layers using fuzzy functions in Arc GIS 10 software, Fuzzy Gamma Operator (Fuzzy Gamma) was used to evaluate the optimal locations of urban green space deployment in Zone 6 which was best achieved by Considering the current status of land uses in Area 6 to analyze the optimal placement of green space so that, according to the Fuzzy Gamma Analysis of 0.9, the central to northern parts of the region are the best locations for the establishment of green spaces in Ahvaz District .

The emergence of a city, more than anything else geographical conditions function is so that every size city developed, they deal with various unit’s topography and geomorphology and matters related to them is more. The impact of the changes that anatomical deformation and developing its shows space cities. Objective of the study comparing quantitative methods, math and examine how their performance in the process of finding the optimal development of a place in the Doroud city. For this purpose, methods of fuzzy logic and analytic hierarchy process fuzzy examined and compared to their according to the sources and available data from 10 indicators of land, the shape of the earth, highways, railways, the main and sub - rift, permanent rivers, mines, land, oil and gas lines, as well as the map of the city and surrounding villages in the form of software GIS arc environment has benefited. The results showed that with regard to field surveys taken model is based on fuzzy approach, the best path of development in the southeast and shows the land route to the development of appropriate almost to agriculture. End route to the south of the city and the quality of the other side is limited. gamma model is the best way to linear shape and development along the lines of transportation, shows (road connected to the city north west), and the results this issue is shown of the fuzzy gamma operator very accurate and in greater detail with regard to a situation selected variables in the areas of study.

The research methodology of "descriptive-analytic" with the aim of analyzing the indicators in the assessment of urban development in the catchment Ghaffar has been carried out in area. Indicators of urban development in the area according to available data resources include 12 factors of topography, vegetation, slope gradient, the land, soil conditions, altitude, power user, the communication area, the hydrology of the region, the economic and social area, region, land use and fault conditions which are classified. To form database and providing required layers of base map we used data on natural resources of Khuzestan. To achieve the status of urban development in Ghaffar catchment conversion layer and software were produced in Arc GIS 10. According to the fuzzy membership functions of the fuzzy map conversion and in order to analyze their situation and assess the model of urban development we offered Ghaffar catchment area a fuzzy gamma operator (Fuzzy Gama). Maps produced in the ArcGIS software and fuzzy process and analysis layers show that among selected indicators about 0.67 of the basin area is not suitable for urban development. Test threshold of 0.7, 0.8 and 0.9 for gamma analysis shows that, Gamma analysis phase with a threshold of 0.7 in accordance with the conditions of the region and consistent with than the limited parts of southeast and east bordering of the catchment areas of basin for urban development is not appropriate.

The land of Iran has significant vast areas of Karst landforms due to the relatively high carbonaceous rocks deposited during different geologic eras. Karst landforms are noteworthy from many aspects. The prime importance of these regions is the considerable amount of underground water stored in Karst formations which are favorable, both in quality and quantity, as human potable resource. In addition to studies performed to identify karstic regions of Iran, studying the geomorphologic aspect of karstic areas could be a noticeable help in studies related to underground water resources. In a total review, necessary and effective factors for karst formation and development are divided into chemical, physical and hydrological groups. Usually seven elements act together to form karstic landforms: precipitation, elevation, lithology, carbonate rock thickness, Carbon Dioxide pressure, temperature and Tectonics. Although all these elements would act as an independent factor, the dissolution of karst in the real world is mainly affected by two major factors: precipitation and temperature. It should be mentioned that when temperature is low, precipitation variation has little effect on karst dissolution rates, but, when temperature rises to 16–20°C, karst dissolution rates rise quickly as precipitation increases. Since the carbonate rocks are solvent to acids, and since the temperature and precipitation cause the formation of Carbonic Acid by solving CO2 into precipitation water, the two mentioned factors highly control the Karst Process. Also, the karst dissolution is a function of water and temperature, henceforth, any factor that could increase the contact between karstic lands and water- such as drainage network, faults, etc…- may also increase karst dissolution. Therefore, in this research, the authors have tried to zone the mentioned basin for karst dissolution using Fuzzy Gamma coefficient. A) Study area:The study area is Seif Abad -e- Laghar which is located between northern latitudes of 27ᵒ50’ and 28ᵒ06 and eastern longitudes of 52ᵒ51 and 53ᵒ16. Seif Abad is a sub-basin of the Mond great basin located in the Kazeroun County having an area of 1244.82 square kilometers and a perimeter of 192.2 kilometers. The average precipitation of the basin is 298.5 millimeters and the average temperature is 22.7 Celsius degrees. There are 12 wells to measure the quality and quantity of underground water in the study area.B) Materials: In order to perform the study, after reviewing former studies, 9 parameters were selected as final variables: precipitation, temperature, sinkhole density, distance from sinkholes, drainage network density, distance from streams, faults density, distance from faults, and slope. To achieve these variables, data were gathered from different sources: climatic data were obtained from Iran’s meteorology organization, hydrology data were obtained from Iran’s water company and Fars Province’s regional water firm. Physiological data were extracted from the digital elevation model (DEM) of the region. Then, data were entered into ArcGIS 9.3 to produce the variables using spatial analysis functions and ArcHydro tools. In order to combine the variables, the Fuzzy Gamma was employed. Based on Fuzzy sets theory, a fuzzy set is a set in which the amount of membership for each factor is between zero and one. The membership degree is determined using experts’ ideas. Then, the fuzzy combination functions are used. Five functions of fuzzy subscription, fuzzy community, fuzzy multiplication, and fuzzy sum are used to combine the factor sets. In this research, in order to zone the intensity of karst dissolution, various Gamma coefficients were used. To choose the most appropriate gamma coefficient for such mean, a correlation coefficient between each layer derived from gamma estimation and interpolated Calcium ion layer (as a factor of dissolved carbonate) was calculated. The coefficients showed that the highest correlation exists between gamma 0.4 and the calcium ion interpolated layer. Henceforth, the gamma 0.4 was employed to calculate the final zoning map. Results and After converting the layers into fuzzy layers, and applying the gamma 0.4 and combining the data, the final map was calculated and drawn. Then, the final map was divided into 5 classes of very low, low, moderate, high, and very high based on standard deviation. The results showed that the basin is averagely in a low dissolution rate. Also, the spatial distribution of karst dissolution is heterogeneous. According to the relative homogeneity of precipitation, temperature, drainage density and distance from streams in the basin, these factors do not seem to be as much effective as other factors. Elaborately, regions with high karst dissolution are mainly coincident on areas with high sinkhole and fault density, and low slope. Generally, the main direction of regions with high and low dissolution follows the general elevation and topography situation which is northwestern- southeastern. In a geological view, the area with maximum dissolution rate is located on the terrace deposits. A part of the second erosion area is also located on the terrace deposits and the other part is located on the Bangestan group. Studying the area of each dissolution class shows that more than 80 percent of the basin’s area is of very low and low classes and only 2.82 and 3.93 percent of the basin is in very high and high dissolution classes respectively. Therefore, it could be concluded that the basin has a low dissolution of carbonate rocks which might be due to the low precipitation rate over the basin. The dissolution of carbonate rocks seems to be significantly dependant to precipitation rate and temperature. However, it is also affected by some other variables such as the purity, thickness, and the age of the carbonate rocks, which are not studied in this paper. In this research, it was revealed that the gamma 0.4 coefficient works the best in predicting and interpolating the carbonate rocks dissolution rate. Also, the minimum and maximum dissolution areas are located respectively in north and southwest of the basin. Besides, the maximum dissolution in non-carbonaceous and carbonaceous rocks occurs in terrace deposits and Bangestan group respectively. Also, the minimum dissolution rate was estimated in Bakhtiari Conglomerate (non-carbonaceous) and Asmari and Jahrum Formations (carbonaceous).