مجله مخاطرات محیط طبیعی
پیاپی 28 (تابستان 1400)

Ganjnameh area is considered an important historical-cultural and touristic place in the west of Iran, seriously threatened by rockfall problems. Attractions of this area yearly attract several thousand visitors from all over the world. Several rockfall events have occurred in the area in the past. Rockfalls occurrences will threaten the life safety of visitors during visiting and surveying of the place. The primary purpose of this research was a preliminary analysis of rockfall potential for the cultural heritage site. For this purpose, an investigation based on three phases was done, which are included: site investigation, laboratory testing, and rockfall simulation. Unstable blocks size, the geometry of slopes, weathering conditions, joint study, and sampling were measured and done during the site investigation phase. Physico-mechanical properties of granite were determined in the laboratory. Total kinetic energy, bounce height, and translational velocity of fallen blocks were determined as rockfall simulation outputs. Based on the obtained result, different mechanisms were found on the left side and right side of the study area. The rockfall problems on the right side could be related to jointing and freezing-thawing action, whereas on the left side, steep slope, weathering, and saturating are the main controlling factors. The results indicated that the footpath between Ganjnameh inscriptions and waterfall, which has a dense concentration of visitors, is subjected to severe problems of rockfall occurrences from both sides, especially the left side. Eventually, for the reduction of rockfall potential and its risk, remedial works are suggested.

Flood is defined as “streamflow with high discharge which spreads temporary on the lands nearby the main river” and consequently there will be some risks. Due to proper conditions, most of the economic and social activities take place in these areas. Therefore, it is important to determine flood zonation due to flood discharge with different return periods in these areas. In this regard, the Cheshmehkileh River located in Tonekabon Township has vast river boundary zones and most of the economic and social activities are carried out in its neighborhood, which is susceptible to flood hazard according to flood conditions and occurred floods. The cross sections were derived using the digital elevation model (DEM) with scale of 1:1000 in Arc/GIS environment and HEC-GeoRAS extension and the obtained outputs were entered into HEC-RAS hydraulic software. Manning roughness coefficients and flood discharge with five return periods of 2, 5, 10, 25, 50 and 100-year were entered into HEC-RAS model and water surface profile was computed  in flow path and flood zonation for different return periods was derived using the HEC-RAS output information through geographical information system. The obtained results showed that the longer the return period, the wider the surface affected by flood. Also, the highest flood area is related to agricultural land use with an area of 6.24 ha and after residential land uses with an area of 3.94 ha, forest with an area of 2.9 ha and orchard of an area of 0.8 ha were located at the following ranks.

The study of tectonic structures of volcanic areas is very effective in controlling the hazards caused by their reactivation. In this study, while introducing the different types of Sahand volcanic products and how they are deposited in the areas around the volcano, stratigraphy, lithology and how these deposits are deposited in different Sahand valleys using field and laboratory studies are discussed. According to field evidence, the Sahand volcanic complex is formed in a continental environment with shallow and calm local lakes with an area of 7200 square kilometers with a maximum altitude of 3595 meters above sea level in northwestern Iran between Tabriz and Maragheh. The activity of this volcanic mass began in the mid-Miocene and continues until the late Pleistocene. The study area is located in the West Alborz-Azerbaijan zone and is an important part of the Arab-Eurasian plate collision area. After the closure of Neotetis in the late Cretaceous and the continuation of plate convergence and its intensification in the Pliocene, significant shortening, thickening and elevation occurred in the crust of northwestern Iran and eastern Turkey, and at the same time, extensive Plio-Quaternary volcanic activity formed. Due to uplift, numerous fractures and faults occurred in the area between the broken areas and due to the dominance of tensile forces and movement along the faults, especially the faults along with the slip and stretched basins, the intersection of faults, and fold axes. Estimated values of quality coefficient in the study area show that most of the areas in the study area are active areas in terms of tectonic location and tectonic seismicity. According to the results obtained in this study, the Sahand volcano and its surrounding regions are characterized by relatively low and a high gradient of can be observed in the region. The relationship between quality coefficient for North Tabriz fault and surrounding areas including Sahand volcano Qc = 49.00 ƒ 132 is estimated to have a much greater reduction than other areas, which indicates high heterogeneity and high meat heat flow in the active and seismic zone of the northern Tabriz fault and the surrounding areas.

Flood is the most common natural hazard in the world that affects many people every year. This study aimed to assess the probability of flood hazard in Gamasiab River of Kermanshah using Multi Criteria Decision Making Approach (MCDA). So, four factors such as height, slope, distance from river, and land use were prepared and each factor was subdivided into 9 classes in the form of descending valuation. Then Normalized Weight Index (NWI) was calculated according to the effect of each factor on the probability of flood and Weighted Linear Combination (WLC) method was used to provide the final map of the flood hazard risk zonation. The results of flood risk zonation showed that about 61 square kilometers (12%) on both sides of the Gamasiab River had high and very high vulnerability. The Bistoon City and the lower reaches of the Gamasiab River have the high and very high-risk probability due to the decreasing of slope and height downstream of the Gamasiab basin. According to the results, Multi Criteria Decision Making Approach is a powerful, fast and low cost method in basins without hydrometric information for preparing flood risk maps.

The humanitarian relief supply chain and rescue in disasters is critical crisis management to save lives, take injured bodies to emergency facilities, remove homeless people and their belongings from destroyed areas supply necessities of people in calamities. The purpose of this research is to present a model to identify associations between logistic components of relief and rescue in crisis upon happening a likely earthquake in Tehran. Initially upon the literature review and evaluation of theoretical foundations, we identified the dimensions and logistic parameters of relief rescue following the opinion of experts and adopting fuzzy screening method. The statistical population consisted of twenty relief rescue logistics experts and professors predominant in these topics. Fuzzy pairwise comparison questionnaires were distributed among experts once dimensions and logistic parameters of relief and rescue were identified. The face validity and reliability of questionnaire were evaluated and confirmed respectively by opinion of experts and use of Gogoous-Boucher method. Dimensional investigation by analysis of fuzzy decision making trial and evaluation laboratory revealed that water and food supply, and providing medical services have greatest influence, whilst removing and sheltering homeless people Incident comes with the highest susceptibility. In the study of indicators, strengthening of residential, office, educational and medical buildings, emergency housing, provision of quality drinking water and the use of modern logistics and relief technologies (rescue set; robots; dogs Rescue ...), the most effective and resilience of power plants, refineries, power transmission lines, oil, gas and sewage arteries, search and rescue of the missing, providing quality food and arrival Relief aid is most effective in the shortest possible time.  The results can give a full mentality of crisis management to understand the logistic components of relief and rescue.

The aim of the current study is spatiotemporal analysis of changes in minimum, maximum and mean air temperature over Iran based on Representative Concentration Pathway (RCP) of the fifth report of IPCC. To do this, three datasets have been used: 1) Daily maximum, minimum and mean air temperature data for 42 synoptic stations during 1/1/1979 to 31/12/2005, 2) National Center for Environmental Prediction (NCEP) and National Center for Atmospheric Research (NCAR) data for 26 variables, and 3) Representative Concentration Pathway (RCP) scenarios data during 1/1/2006 to 31/12/2100. The model was calibrated using predictors from the NCEP/NCAR reanalysis datasets over the base period 1979–2005. The selected downscaling model structure has been done by a recommended method by Mahmood and Babel (2013) which is a combination of the correlation matrix, partial correlation, and P-value was used. Due to the bias, downscaled temperature data forced by CanESM2 model was corrected using a bias correction technique for each station.  Finally, changes in the characteristics of temperature were estimated for the future period (2006–2100) based on the future scenarios RCP2.6, RCP4.5 and RCP8 compared to the base period (1979–2005). The projected changes were assessed with the nonparametric modified Mann-Kendal trend test and Sen Slope estimator at 95% confidence level. The results showed great reliability of SDSM downscaled model structure and screening of variables. The findings illustrated that minimum, maximum and mean air temperature were projected to increase. The projected increases was larger in semi western part of country. Minimum air temperature projected to increase 0.35, 0.6 and over 1 ℃ based on the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Maximum air temperature increases rapidly after 2070 decade and projected to increase more than 1℃ rather than base period (1979-2005). The projected changes showed that warming of Iran’s air temperature more over 0.5 ℃ after 2040 and reached to 1.5 ℃ by the end of twenty first century.

Bazman volcano, in the South East of Iran, northwest of the city of Iranshahr and is located in the north of the city Bazman. The aim of this study was active tectonic basinemanating from the Bazman volcano (with a focus over the city Bazman) and its environment as well as the level of tectonic activity in the region is the relative. In this regard has been paid to the study of morphometric indices The morphometric indices which include over Drainage Basin Asymmetry (Af), Sinuosity Front Mountain (Smf), Longitudinal slope gradient of River (SL), Floor width to valley Height (Vf), Hypsometric Integral (Hi), Mean axial tilt channel (MASC), the shape of the basin (Bs) for the study of tectonic activity in the area has been used. These indicators have been studied to evaluate the relative tectonic activity (IAT) of the basins and sub-basins of the region. The results of geomorphic analyzes are expressed as a relative index of tectonic activities (IAT). This index shows the tectonic activities of a region in four categories of low, medium, high and very high activity. on the Base of studies, the classification of tectonic activity is as follows: Area with very high relative tectonic activity in the northwestern and northeastern parts of the study area, These basins are located in the north-northeastern and eastern parts of the region, which is mainly affected by lithology (especially around the volcano), the young vertical movement of faults and active tectonic structures in these basins. The zone with moderate relative tectonic activity is located in the middle and southern parts of the region and the zone with low relative tectonic activity is located in the basins of the central, western and southwestern parts of this zone. The results of the analysis of indicators indicate tectonic activity in the area of Bazman volcano and its surroundings. Due to the located of Bazman city and population centers in the vicinity of the volcano, especially its southeastern part, the possibility of geological hazards in the future is inevitable.

Paveh Township has long been affected by landslides due to specific geological and geomorphologic features and anthropic activities. This study aimed to map landslide risk and its relationship with factors affecting their occurrence and compare the ANN model with (OWA) method to assess landslide risk in Paveh Township. Therefore, landslides in the area were first identified using extensive field surveys. Maps of factors affecting landslide occurrence (lithology, slope, slope direction, elevation, precipitation, land use, distance from the waterway, distance from the road, distance from the fault, soil) in GIS software then extract the relevant layers Was done. To perform the OWA model, weighting was performed by the fuzzy method using the Critical and Evaluation and Standardization of benchmark maps and to perform an artificial neural network (MATLAB) software. Each neural network parameter was determined by trial and error method. Then with the final structure of the network with 8 neurons in the input layer, 13 neurons in the hidden layer, and 1 neuron in the output layer. According to the results of the study of slope factors, land use, lithology, and soil, respectively, by weight factor; 0.156, 0.143, 0.139, and 0.131, received the most importance. Which according to the model output (OWA) was 15.53 and 26.64%, respectively, in two very high and high-risk classes, respectively. Due to the output of the neural network 19.88% and 29.82% of the area is located on the high-risk floor. Very high-risk and high-risk areas are mainly located in 15-30% slope, agricultural use, unbearable and weak quaternary structures, and in soils with a high percentage of clay, silt, and marl. The two models were compared and the OWA model had higher accuracy.

Landslide is one of the natural hazards in which monitoring the displacements and changes requires the use of special techniques due to its slow, continuous and gradual movements. In this regard, the PSI technique with extensive terrestrial coverage as well as high temporal and spatial resolution, is one of the most accurate and low-cost remote sensing techniques to identify and display displacements. Since the village of Mashayekh in the city of Mamasani in Fars has been facing the problem of landslides for several years, and this phenomenon has caused the gradual destruction of the houses and farms of the villagers, so, this research tries to evaluate and monitor the displacement of the landslide mass using the mentioned technique. For this purpose, 75 radar images of Sentinel 1 were selected during 3 periods from 2014 to 2019 and were processed by PSI method. Based on the obtained results, the maximum displacement rate at the landslide mass from October 2, 2014 to May 31, 2016 at the rate of 1.5 cm per year, during the period of July 18, 2016 to December 28, 2017 at the rate of 5.3 cm per year. And during the period from January 9, 2018 to July 27, 2019, it has reached 5.7 centimeters per year. In addition, the area of landslide mass has been expanded from 3.5 Km2 to 4 Km2. The results of the research indicate a continuous and progressive displacement in this mass in the study area.

The study was performed aimed to determine the root causes of the destruction of rangelands using a descriptive-analytical method in Sistan region. For this purpose, 81 components were identified firstly by field method, literature reviews, and brainstorming in four sections: 1) the political-managerial, 2) the social, cultural and educational, 3) the economic and 4) the ecological. The interaction matrix was formed with the identified components in the form of a questionnaire and was completed by 36 respondents from specialists, experts, and stockholders. Identified components were screened using structural analysis to obtain influential components with high influence and low dependency. The state of dispersion of components in the dependence and influence axes showed that the system is stable in direct and indirect methods, as well as the potential direct and indirect effects methods of structural analysis. Based on the results, nine components identified as the most important components that can control the future, and for any program and action to rehabilitate rangelands, we must improve the state of these components, firstly. Eight of these components are in the political and managerial section and one in the social, cultural and educational part. Among these three components, the unselecting of competent officials, the dominance of relations over the rules, and the irresponsibility of members of parliaments in all methods were identified as the most influential components. Lack of proper protection of basic and genetic resources, lack of proper use of natural and cultural goods and services, border problems identified as the most dependence components, and as indicators of rangeland status that monitoring their status recommended to measure the success of the management. The results of this study showed that the crisis in the rangeland state in Sistan is mostly a managerial-political crisis at the highest levels of government and not ecology at the local low levels.