- Amin Salehpour Jam, - Jamal Mosaffaie, - Mahmoudreza Tabatabaei,
Volume 6, Issue 3 (9-2019)
Abstract
Investigation of desertification trend needs an understanding phenomena creating changes singly or action and reaction together in the manner that these changes end up in land degradation and desertification. In the investigation of pedological criterion affecting on land degradation in alluvial fans, first, maps of slope classes, land use and geology were created, then a map of units was founded by overlaying and crossing these maps and grid layer created by extension of ET GeoWizards in ArcGIS 10.3 software. In this research three indices of erodibility, salinity and permeability of soil were considered, finally according to the seven level scales, each of them was shown as the classified map. In this research, nonparametric methods of Friedman and Kendalls' W rank tests were used to prioritize the options, in the manner that after defining crisp numbers in seven level scales, the rank means were calculated. The rank means obtained from Friedman and Kendalls' W rank tests alter from 7/00 to 17/33. Obtained results from the nonparametric methods showed that 74/18 % (4245/77 ha) and 25/82 % (1477/67 ha) of the area were classified into two classes of medium and very heigh desertification potential, respectively. The results also showed that the youngest and old gravel fans of the area have desertification potential of very high (798/75 ha) and low (152/23 ha), respectively.
Dr Sara Kiani, Dr Morad Kavyani, Dr Amirali Tavasoli,
Volume 10, Issue 4 (12-2023)
Abstract
The Namak Lake is situated between three provinces: Isfahan, Qom, and Semnan. However, the functioning of Namak Lake and its susceptibility to environmental, ecological, economic, and social influences not only affect the immediate surroundings but also impact other provinces. Naturally, a crisis in this lake can have negative effects on human communities and the residents of the surrounding areas in terms of environmental, economic, and social aspects. Therefore, the aim of this research is to identify the temporal-spatial changes in the salinity of Namak Lake and, subsequently, to investigate and analyze the effects of these changes on the environmental security of the surrounding regions. To achieve this goal, salt zones were identified using soil salinity indices, including the Normalized Difference Salinity Index (NDSI), Salinity Index 1 (SI1), Salinity Index 2 (SI2), and Brightness Index (BI), over a 30-year period (1992-2021) with five-year intervals. Then, using the maximum likelihood method, the salt zones were classified into four land cover types, including water zone, moist zone, salt zone, and other uses. The results of this study indicate that due to the reduction in water inflow into the lake as a result of dam construction in the upstream basin and the effects of climate change, the water zone, or seasonal lake, of Namak Lake has disappeared and the salt zone has expanded in this area. The most significant changes in the lake are related to the northwestern part of the lake, where major rivers such as Jajrood, Shur, Qarechai, and Qamaroud flow into this part of the lake, contributing to its drainage. Therefore, dam construction on these rivers has led to a downward trend in water flow into the lake. Furthermore, the results suggest that due to the absence of settlements and human communities near Namak Lake and the natural and climatic conditions of the region, it is not expected that environmental incidents that could have security and political implications will occur in the short term.
