مجله مخاطرات محیط طبیعی
پیاپی 26 (زمستان 1399)

The phenomenon of the subsidence of the Earth is called the downward movement of the Earth's surface, which is not easily identifiable and quantifiable due to its slow evolution. The most appropriate method is to use radar data and differential interferometry techniques. Since physical compression and pressure drop are the main causes of subsidence in the places where water is extracted, D-InSAR's integrated zoning and its simultaneous investigation with subsurface factors reflect the anomalous deformation pattern created by subsurface factors. It shows well and demonstrates that the use of D-InSAR has been helpful in subsidence navigation. For this purpose, D InSAR radar data interferometry method was applied to ENVISAT and PALSAR radar satellite data from ASAR and ALOS sensors in 2006-2008, respectively. Ambient drought moderated the effect of phase change caused by atmospheric compounds, and the lack of challenge vegetation minimized the coherence of the phase radar images and made it possible to measure changes in the C and L band radar data annually. The maximum displacement was estimated by the C band of 0.14 m and by the L band of 0.12 m. Finally, we modeled the statistical results of the groundwater of the region and the amount of subsidence estimated by the mentioned radar images by linear regression method. There is groundwater, in relation to ASAR image per meter change in groundwater level we will have 0.025 meter change in ground level elevation and PALSAR (HH) image per meter change in groundwater level, 0.021 meter change in height we will have.

Considering the ability for spatial quantification of various hydrological components, the distributed modeling of rainfall-runoff processes across the watersheds plays a key role in terms of water resources management, river engineering, flood control, and storage facilities as well as simulation of different watershed management scenarios. To this end, the Kinematic Runoff and erosion model, KINEROS2, has been used to assess the spatial distribution of rainfall-runoff processes components for the identification of surface runoff and flood generation hotspots across the Ramian’s Goorchay watershed with an area of about 254 km2 in the east of the Golestan Province. For evaluation of the model performance, 6 recorded rainfall-runoff events in the watershed were selected and divided into two sets of 3 events. The first set was used to run and calibrate the model and the second set was used to validate the model results. The mainland use types of the watershed are the Hyrcanian lush forest and rainfed agriculture on sloping lands. The rainfall-runoff simulations were carried out on an hourly basis.  The results of the performance evaluation of the model indicated that the KINEROS2 model is good enough at simulating the hydrological components of peak discharge and time to peak of flood hydrographs. However, it rarely performs well at simulating flood volume. The spatially distributed simulated map of surface runoff depth shows that various locations of the watershed have different flood generation potential. Whereas, the middle section of the watershed, where extensive land use change from forest to agriculture has occurred, shows high flood generation hazard potential, while the upstream section of the watershed displays lower flood generation potential despite having steep slopes.

Floods and droughts are two Extreme phenomena that will always happen in most parts of the world with different frequencies. The occurrence of extreme climate phenomena has been one of the major challenges in the world. Karkheh River is one of the western rivers of Iran that in times of flooding causes huge human and infrastructure damages. The purpose of the present study is to investigate the trend of floods in the Karkheh basin to identify their increase or decrease trend. Detection and analysis of flood trends in Karkheh basin during the period of 1966 -2019 was performed on the precipitation data of 48 stations and daily discharge data of the Mazhin station by parametric (regression line) and nonparametric methods (Man -Kendall test). Drought analysis of the basin showed that this basin had a severe drought with a period of 10 years (2005 – 2015) which has had a great impact on reducing the discharge and occurrence of floods in the region. Besides, the results of the repeatability of precipitation with the Markov Chain Model showed that the occurrence of droughts in the Karkheh basin is always more likely than other events. Although annual rainfall has a declining trend, maximum daily rainfall at most of the basin has an increasing trend. Analysis of the floods trend showed that the frequency of floods has two different periods. Most occurrences of floods (22 cases in 1969 and 15 cases in 1972) in the period (1966-1991) and is the lowest occurrence of floods Related to the course (1992-2019) But what is important Floods events with greater magnitude for the first time in the second course. So that floods with an instantaneous discharge of more than 5000 and 9000 m3 occurred in the second period. Another result of this research is the time displacement of flood events So that until 1992 Of the 64 floods, 53 occurred in April, But after 1992 floods occurred one month earlier in March(The decade 1992 – 2001), in February(The decade 2001 – 2011) and the third decade in January.

The Iranian plateau is a vast area of pressure throughout the alpine-Himalayan orogenic belt, that with the continuous movement of the plates in this area, we encounter the seismic activity in most parts of Iran. In this research, investigation of the tectonic earthquake and earthquake hazard analysis has been considered using a deterministic method and study of the active fault lines in Boroujerd city in the north of Lorestan province. The main objective of the study is to confront the risk of earthquakes by identifying the maximum magnitude and maximum horizontal acceleration of the earth for the active faults lines of the area and also analyzing and zoning the environmental hazards associated with this phenomenon. For this purpose, the main faults lines of the area were identified by using the satellite imagery, the geological map and field studies and then, the earthquake with the most probability was determined by using the definitive method of the earthquake plan, and using the existing empirical relationships among the earthquake characteristics. Based on the calculations, the magnitude of the earthquakes caused by the main faults in this area ranged between 6.17 to 7.07 Gal and the peak ground acceleration (PGA) based on the Donovan and Campbell methods were 0.308 and 0.321 Gal. Studies showed that the two phenomena of liquefaction and landslide are the most important environmental hazards after the earthquake occurrence in Boroujerd area. In this research, liquefaction hazard zoning and landslide hazard maps are provided based on seismic-geotechnical hazards zoning guidelines and fuzzy logic methods. Then, by integrating liquefaction and landslide hazard maps, the map of environmental hazards has been prepared. Based on the results, 12.9, 25.6, 24.8, 17.6, and 19.1 percent of the area are in very low, moderate, high and very high-risk classes, respectively.

Urban passageways, as one of the important physical elements of the city, have a significant role in the vulnerability, so that if blocked, they may increase the damage and damage many times before and after the earthquake; Issues and disruptions have led to disaster management as an approach to reduce the vulnerability to natural hazards, especially earthquakes in cities, so it is important to examine the network because of its close relationship with other land uses. The purpose of this study was to analyze the spatial network vulnerability of passages to reduce its vulnerability to earthquakes in the central part of Zanjan city. In this regard, the present study, using the descriptive-analytical method, using statistical blocks data set of 2016, detailed plan of 2015 and referees' views, compiled comprehensive indicators and analyzed for AHP model in ArcGIS environment and finally by combining criteria and Fuzzy Logic Generation Layers has analyzed the vulnerability of an urban road network to earthquakes. The findings show that the high burnout of the buildings in the passage walls, high population density, and a high degree of confinement has made the central part of Zanjan city highly vulnerable to possible earthquakes. The total area of the study area was 82 hectares, 9.2 hectares of high vulnerability, 20.4 hectares of high vulnerability, 25.4 hectares of moderate vulnerability, and 11.5 hectares of low vulnerability and 15.5 hectares of 29 hectares. They are very vulnerable and very vulnerable. Finally, it can be stated that the most important factors of the passage network in the central part of Zanjan are: exhaustion of passage wall texture, high density of passage-related population, and a high degree of blockage of passages.

The public transport system, such as Metro, has been created for the rapid and easy movement of passengers due to population growth in recent decades. Tabriz is one of Iran's cities with a subway system as well. The existence of Tabriz's fault in the north of Tabriz as the biggest threat fault in northwestern Iran and as a result of severe flooding in many of the country's cities this year, it seems necessary to assess the risks on the subway routes and stations in Tabriz. Combined flood and earthquake risk maps were prepared using FUZZY-AHP to have a comprehensive overview of the status of hazards. The purpose of this study was to identify flood and earthquake risk using 10 flood risk criteria and 14 earthquake risk criteria in the study area metro lines and stations. According to the final results of the flood risk zoning, there is no station in the very low-risk class, but there are 203,621 meters of low-risk subway lines, 5 stations and 6013,768 meters of high-risk subway lines. It also has 2 stations and 2454,91 meters of low-risk subway lines and 2 stations and 722,898 meters of high-risk subway lines, which make it necessary to identify and link stations with a potential risk of occurrence.

Heavy metals (Mercury, Arsenic, Lead, Zinc, Copper, Nickel, and Cobalt) of groundwater in Amanabad plain on the 12 drinking wells were compared in the years of 1997 and 2016 downstream of Arak Landfill. A comparison of heavy metal concentrations of wells with drinking standards indicates that water is not contaminated with Mercury, Zinc, Copper, Nickel, and Cobalt in the two years. The waters showed contamination with Arsenic in 2016 and Pb in 1997 and 2016 respectively. The index of Arsenic and Lead metal contamination in wells in 2016 was more than ten times that of 1997. Fifty-eight percent of drinking water wells, which had a moderate level of pollution in the 1997 year, but, were high polluted in the 2016 year. Examination of Arsenic and Lead concentrations in leachate and soil of Arak landfill showed that they are more than 50 times the standard water and even drinking water of Amanabad plain. The study showed that Arsenic and Lead in the wells of the area were caused by landfill leachate. Lead has also been derived from atmospheric dust in nearby industries and traffic in the area. Therefore, measures should be taken to reduce Arsenic and Lead in the Arak municipal solid waste landfill as well as industries and urban transport.

Rivers provide water and energy for nature and humans. Thus, water supply is the most important economic role of rivers. Process of erosion sediment transportation is one of the most important hydrodynamic processes which affect a lot of hydraulic systems such as basins, rivers, coasts and harbors, dams, bridges, farms, and construction facilities. Taleghan River is a major river located in the south hillside of Alborz. The river has dynamic behavior affected by various factors including geology, gradient, land use, hydraulic flow condition, and morphological behavior. Analyzing the stability of Taleghan river bank using mathematical and statistical models and comparing its results with field observations is the aim of this research. Therefore, to achieve this aim BEHI model and statistical one-way analysis of variance (ANOVA) is used and then compared with field and visual observations. The results concerning scoring show moderate to high danger of riverbank erosion in upstream sections and high to very high danger of riverbank erosion in downstream sections. According to the results of one-way analysis of variance (ANOVA), the effects of gradient and discharge have been more than the other parameters. In this analysis, the meaningful parameters consist of mean depth; bank full, riverbank high, discharge, and gradient. According to the results, erodible edges were identified.

Due to the low spatial resolution and simplification of atmosphere general circulation models compared to regional and short-term models, the outputs of these models cannot represent an accurate approximation of climatic conditions of the study area. Due to time-consuming and lack of economic efficiency in the use of dynamic models, there has been increased public attention to the use of statistical downscaling methods. One of the most useful and common methods in statistical downscaling is SDSM. For this purpose, the first, the atmospheric parameters in the region over the past 32 years (1984-2015) was investigated by the Mann-Kendall test. The results showed that changes in temperature and rainfall data have a significant trend. Then, by down-scaling, the data using SDSM software, the daily parameters of maximum, minimum, average temperature and rainfall of Haraz river basin in Mazandaran province were simulated according to RCP2.6 (optimistic) and RCP8.5 (pessimistic) scenarios and CanESM2 Climatic Model from the new CMIP5 series in three periods of twenty years from 2020 to 2079. Finally, under the RCP8.5 critical scenario, until the end of the prediction period, the maximum, minimum and average temperature of the basin will be increased 0.91, 1.13 and 0.96o C, respectively and precipitation decreased 15.1% (7.4 mm) compared to the base period.

In this study, we have tried to investigate the interaction between groundwater resources of the Urmia domain and Urmia Lake through numerical modeling. The conceptual model of the Urmia aquifer has been prepared using available information and results of geophysical studies. Modeling of flow and soluble transport in the coastal part of Urmia aquifer has been done using the GMS software package. In this case, groundwater flow is first modeled using the MODFLOW module and then the solute transport (in this study, chloride concentration) is performed using the MT3DMS code. After modeling the flow and soluble transport, the outputs are used in the SEAWAT code. The calibration of aquifer hydraulic parameters was performed using the PEST code and manual method. In running the model in unsteady state and using calibrated parameters, the values of ME, MAE and RMSE of the model reached 0.11, 1.14 and 1.41, respectively. The results of flow modeling, solute transport, and mixing of saline and freshwater in the Urmia aquifer show that in the present situation, the relationship between the Urmia aquifer and Urmia Lake is as low as possible and the salinity of the aquifer is very low. Besides, the analysis of the water resources behavior in the coastal parts of this aquifer in two scenarios, including the 50% reduction in discharge of four main rivers and the 50% increase in groundwater extraction, shows that no significant change was made in the results of this model. Since solute transport is a function of flow dynamics in the region, a one-way flow of groundwater towards Urmia Lake, low permeability sediments (due to particle size and formation of salt layers) prevents the invasion of the Urmia Lake saltwater into the aquifer environment.

In recent years, Dust haze has been a major health threat in southern and southwestern provinces of Iran, and Children suffer the most from Dust haze. Therefore, it is necessary to design educational centers to prevent the negative effects of walnut Dust haze. Exterior walls and windows are the most important routes for Dust haze to enter the classroom. Therefore, initially using simulation software, in addition to maintaining natural ventilation conditions, architectural elements reduce the amount of Dust haze penetration into the interior. The most important variables in this study are the distance between the walls and the amount of surface area. results show that increasing the distance between the two crusts results in a decrease in the wind flow velocity in this space and the Dust haze particle saturation. Slowing down will only work up to a distance of 200 cm, and then no change in wind speed will occur. Besides, the use of louvers in the inlet wind direction by directing the wind flow to the underside of the space between the two shells and reducing the level of air inlet leads to reduced wind velocity and particle saturation. Examination of the use of variable-angle louvers shows that the proper condition for creating natural ventilation conditions and reducing the penetration of indoor particles occurs when the louvers are angled relative to the 50-degree horizon.