Dr Habibollah Fasihi, Dr Taher Parizadi, Mrs Nahid Noori,
Volume 0, Issue 0 (3-1921)
Abstract
Among the many kinds of natural hazards, earthquake is one of the rare events that human science has not yet been able to control or even predict. Physical structure conditions of human settlements play an important role in vulnerability to this natural disaster. The purpose of this article is to investigate natural and physical characteristics of Kuhdasht in terms of earthquake vulnerability. The city with a population of 90,000 and an area of about 540 ha, locates in the west of Lorestan province, Iran. The data are provided from GIS file of 2016 Iranian Public Census of Population and Housing, GIS files of Kuhdasht land use and GIS files of Iran faults and lithology. A few layers have been added to these files through observation. It is used Arc-Map 10-8 to combine layers and produce maps. Then we used Excel software to do statistical analysis on data tables. Findings showed that the site of study area locates in a middle risk zone of earthquakes, but its close distance to active faults can be a warning for occurring destructive earthquakes. High proportion of non-resistant buildings, high density of buildings in some parts of the city and the presence of two gas stations in the middle of residential buildings, are the most important components of Kuhdasht vulnerability. In contrast, plenty of open spaces, high proportion of non-apartment houses, low population density and permeability of passages are important strengths in this regard. The central part of the city from which the city originated, is more vulnerable than the other parts. Due to the existence of the trade centers here, it is necessary to pay more attention to in future plans.
Firooz Mojarad, Razieh Kheiri, Zahra Noorisameleh,
Volume 14, Issue 35 (3-2015)
Abstract
Iran's Potential for the occurrence of drought at various severities illuminates the need to examine this phenomenon with new indexes. The major deficiency of the current indexes is that they cannot monitor the droughts in daily scale. Effective Drought Index (EDI) overcomes this defect. The goal of this study is to analyze the frequency of daily droughts by EDI in 43 synoptic stations in a 30-year period. Accordingly, the frequency of daily droughts in the stations was calculated by EDI during the seasons and the year. Then the stations were divided into five groups using cluster analysis based on total frequency of mild to most severe droughts (categories 1 to 4), and frequency patterns in each group were examined. The results showed that the most severe droughts have not happened in the stations except for Gorgan, Zanjan and Torbat-Heydariyeh. In contrast, the frequencies of mild, moderate and severe droughts, all being equal, are much more than most severe droughts, and their frequencies are almost equal. In 56 percent of the days, a variety of droughts (mild to most severe) has occurred in the whole country. Based on the output maps, frequency distribution of droughts in the country does not follow a certain geographical pattern, so it could be cocluded that all types of droughts have happened in all regions of the country. However, maximum total frequency of daily droughts (mild to most severe) is observed in the east and center parts. The decrease in the EDI values over time shows the tendency of the most stations towards drought.
Miss Rana Norouzi, Mr Sayyd Morovat Eftekhari, Mr Ali Ahmadabadi, Miss Khadijeh Alinoori,
Volume 25, Issue 78 (9-2025)
Abstract
In recent decades, land subsidence has emerged as a geomorphological hazard and one of the environmental crises, causing irreparable damage to Iran's plains annually, with the most significant current cause being the water crisis. The Eshtehard plain, as one of the industrial and agricultural hubs of Alborz Province, is of great importance and has been declared a critical prohibited zone by the Ministry of Energy due to the sharp decline in groundwater levels. Therefore, assessing the rate of subsidence and addressing the causes and influencing factors for its risk management is of great importance.
In this study, the Differential Radar Interferometry (D-InSAR) technique was used to examine the subsidence of the Eshtehard plain, utilizing data from the Sentinel-1A satellite over the time period of 2017–2023. During this period, the region's subsidence ranged between -2.08 cm and -2.93 cm, with the highest subsidence occurring between 2019 and 2020, approximately -2.93 cm, and the lowest between 2022 and 2023, about -2.08 cm. The rate of subsidence increases from east to west and in the southern expanse. In fact, the maximum subsidence in all study periods is concentrated in the Eshtehard aquifer area, which contains a large portion of farms and villages, the city of Eshtehard, industrial towns (Kosar, Omid, and Eshtehard), agricultural lands, and the highest concentration of underground resources (wells). The results of hydrographs and interpolation using data from piezometric wells also show a drop in groundwater levels and an increase in depth in this area. At the same time, the results of examining the correlation between land subsidence and groundwater depth changes were significant at the 95% level, indicating that as groundwater depth increases, subsidence in the region also increases. Based on subsidence change profiles, the subsidence pattern in the study area is complex. These temporal and spatial variations indicate various influences, including human activities (such as the intensity and type of activity or excessive extraction of water from underground resources), environmental factors, geological characteristics (sediment composition, aquifer thickness, bedrock position, etc.), the rate of aquifer recharge and discharge, and so on.
