Sedimentology
Sh. Erfan; K. Rezaei; R. Lak; S. M. Ale Ali
Abstract
Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, ...
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Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, is the main subject for current study. For mineralogical and sedimentological investigations 18 sediment cores were collected from the east and west of Urmia lake. 96 samples from 18 sediment cores in transect to the center of lake were collected and studied by X-ray diffraction (XRD) technique. The clay minerals include Kaolinite, Illite and Montmorillonite. Kaolinite and Illite are the most important clay minerals in the Coastal plain of urmia lake. Origins of clay minerals in the Coastal plain of urmia lake are generally detrital, occurred by physical weathering and indicate composition of bed rock. The study of surface sediments indicates that amount of clay minerals from margin to center of the lake such as another detrital mineral (Quartz) is decreased. In addition, amount of them towards depth is increased. Therefore, it shows the presence of a high water level and cold - humid climate in the past (late Pleistocene).
Geological Environment and Engineering
alireza arabameri; khalil rezaei; mojtaba yamani
Abstract
at first, a gully erosion inventory map was prepared using extensive field surveys and interpretation of aerial photographs, of which 172 gully erosion, 70% (121 gully) are used for modeling and 30% (51 gully) are used for validation purposes. In the next step, for the selection of parameters, after ...
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at first, a gully erosion inventory map was prepared using extensive field surveys and interpretation of aerial photographs, of which 172 gully erosion, 70% (121 gully) are used for modeling and 30% (51 gully) are used for validation purposes. In the next step, for the selection of parameters, after their initial identification, the multicollinearity analysis test was performed using coefficients of tolerance and variance inflation factor and the parameters with multicollinearity were deleted due to the reduced accuracy of the modeling, , Finally, 12 parameters were selected for modeling. The results of determining the significance of the criteria by entropy index method showed that elevation, lithology and NDVI parameters had the greatest effect on the occurrence of gully. In order to validate the model, the prediction rate and success rate as well as the SCAI index were used. The validation results showed that the combined model with a prediction rate of 956.0 (95.6%) and a success rate of 92.33 (92.3%) had excellent predictive accuracy and compared with the entropy index and evidential belief function with prediction rates of 0.932 and 0.917, and the success rates of 0.911 and 0.901, have higher accuracy. According to the results of the SCAI, class differentiation was appropriate in the combined model. According to the results, 28.95 percentage of the study area is located in high and very high susceptibility classes. The results of this research can be used by landuse planners to expansion development activities.
