مجله مخاطرات محیط طبیعی
پیاپی 33 (پاییز 1401)

Legal issues have special importance in flood management. The present study has investigated the most important legal issues related to floods through descriptive survey research. The study population included employees with expert positions in legal offices and heads of county natural resources offices in all counties of Golestan province who were surveyed by census method. The data collection tool was a researcher-made questionnaire whose validity was confirmed by the legal experts. SPSS18 software was used for data analysis. Descriptive statistics and also Sign and Wilcoxon tests were used. The results showed the effectiveness of the current legal system in preventing floods, the influence of legal sentences regarding river and stream privacy, the power of legal units to litigate violations on the floodplain of rivers and streams, as well as the effectiveness of the current structure of the legal units of the natural resources offices to deal with the causes of floods, are at a moderate level. The most important legal weakness in flood management is related to monitoring the implementation of laws. According to the respondents, non-compliance with the rules and regulations of natural resources has played a strong role in the recent floods. Respondents also believed that the degree of overlap of duties between the custodians of rivers and streams and also disagreement among the custodians regarding the floodplain area of rivers and streams is considerable. The most important solutions to reform the legal system to improve flood management include imposing severe penalties for encroaching on the floodplain area of rivers and streams and giving priority to litigation of natural resource cases. According to the results, practical suggestions and recommendations have been presented to improve flood management.

The Siberian high-pressure system is one of the components of atmospheric circulation affecting the climate of Iran, especially in the cold season of the year. In this research, the place of the initial formation of this system and its synoptic features have been investigated. For this purpose, the lower tropospheric levels of atmospheric data for the three months December to February data from NCEP / NCAR were received for 22 years. Systems with thermal characteristics were isolated. Then, the central core of this system was determined daily for all months and their geographical coordinates were calculated. The results show that in the vast majority of the months from December to February, the main Siberian high-pressure core is located in the lower atmosphere of the Altai Mountains. The study also found that more than half of the days of Siberian high-pressure had two central nuclei. Thus, contrary to popular belief, the Siberian high-pressure core forms not on the low Siberian plains but the high altitudes of the Altai and Sayan Mountains. Adaptation of isothermal, isobaric, and height maps also showed that the core of the cold in the cold three months was generally on the north or northeast of the Siberian desert. However, the high-pressure core was located on these two high mountains for almost a day. Therefore, in addition to cold, the topographic factor (northwest-southeast extension) plays a very important role in the formation of the high-pressure core. According to the general results of research, this high pressure, directly or indirectly, is the cause of colds and cold waves in the cold period of the year, as well as early and late waves in the country.

Surface water resources are limited in many regions in Iran, so groundwater resources are considered the most suitable resources for supplying water. The excessive use of chemical pests and fertilizers has resulted in groundwater pollution. Therefore, it is necessary to determine the vulnerable areas to preserve these vital resources. In this study, the DRASTIC model was used to analyze the vulnerability of groundwater in Khaled-Abad- Bardood plain. Seven factors including the nutrition of pure water, groundwater depth, unsaturated area, soil texture, Hydraulic conductivity, aquifer media, and topography were used in the model. After the preparation of 7 layers, appropriate weight was assigned to these factors. Finally, by mapping these layers and applying their weight to them in ArcGIS 10.5, the vulnerability maps of the groundwater were generated. To validate the model, sampling and measuring the amount of nitrate for 13 wells located in the Khaled-Abad-Bardood plain were conducted. The results indicated that 22% of the plain was vulnerable based on the DRASTIC model, which was located in the vicinity of Bardood city and its eastern areas. The results also showed that the correlation of the DRASTIC vulnerability map with the measured nitrate was found to be 74 %.

Biodiversity faces various challenges which make its management difficult. This research aimed to investigate the challenges of biodiversity management in the Sorkhabad Protected Area of the Zanjan Province. The research was conducted using a qualitative approach through the grounded theory methodology. A sample of participants consisting of 15 experts from the Environmental Protection Administration and the Natural Resources and Watershed Management Administration in the Zanjan Province were selected through a theoretical and snowball sampling and the data were collected by semi-structured interviews. Using the Nvivo10 software, the data on biodiversity management challenges were analyzed through open coding, axial coding, and selective coding, which led to exploring 92 concepts, 38 initial categories, 22 principal categories, and 9 core categories. Then, the relationship among the core categories was identified. It was identified that biodiversity loss is interconnected with other natural hazards and environmental crises. Moreover, the threat and loss of biodiversity and other natural resources are directly and indirectly influenced by various factors consisting of weak national strategies and policies on biodiversity management; the weakness of allocating human, financial and physical resources of organizations responsible for biodiversity protection; poor knowledge, attitude and value system of rural communities about biodiversity management; unsustainable agriculture and natural resources use by rural communities; unsustainable use and intervention of people outside rural communities; unsustainable actions of external organizations; and lack of integrated and participatory management in biodiversity management.

The sand dunes of the study area are located downstream of Routack watershed, 40 km west of Saravan city (Baluchestan province, Iran) and in the northern margin of the agricultural lands of the region. Wind velocity data (direction and speed) of Saravan, Khash and Iranshahr stations (2006-2012) were used to study the dynamics of the dunes. The geometry of barkhan dunes were analyzed using the stereographic approach and their spatial and temporal mobility by Freiberger and Dean (1979) method. The results showed that the direction of Barkhan`s migration was varied temporally and spatially; from W and NW to E and SE. While the prevailing winds in terms of frequency of occurrence were mainly blown from NE (wind-rose), but in most cases the sand dunes direction did not correspond to the prevailing wind direction. The RDD were 28.9% from the NW, 17.8% from the SW, NW and no-migration, 10.7% from the SE, and 3.5% from the W and S. The results of the stereographic approach showed the instantaneous dynamics of barchans were mainly consistent with the Fryberger and Dean (1979) methods; so that the rate of sand transport was between 17 to 20 m3/yr.m and the wind intensity classified as low energy. The sands are also transported when the velocity threshold is greater than 6.78 m/s or at least equal to it. This conclusion is important due to windbreak networks design. This means that to stabilize the dunes; windbreaks must be installed perpendicular to the wind`s direction (west to the northwest) and the wind velocity should not exceed 6.78 m/s, between the windbreak rows.

Fault slip rate is the amount of displacement of one wall relative to another fault wall over a period of time. The duration of this shift can be measured using the luminescence dating method.  To determine the age by luminescence dating method, two dose parameters equivalent to normal dose and annual dose are needed. By dividing the dose equivalent to the natural dose by the annual dose rate, the age value is determined per structural unit.  To determine the dose equivalent to the normal dose, a protocol for measuring luminescence signals (data) and a program for analyzing the data are required. Data analysis was performed using R software. Because the usual international program to do this is analytics software. Data were also analyzed with analyst software.  The results of these two softwares and their effect in determining the slip rate of Rafsanjan fault were compared.  The amount of displacement measured on the Rafsanjan fault is 48 ± 4 meters.  The age was estimated to be 97-118thousand years using R software and 101-129 thousand years by analyst software.  Slip rates were obtained by R software and analysts, 0.41 to 0.53 and 0.36 to 0.48 mm / year, respectively.  Slip rates were obtained by R software and analysts, 0.41 to 0.53 and 0.36 to 0.48 mm / year, respectively.

This study provides an applied method to estimate the land sensitivity of wind erosion in the Hamoun-e Baringak Sistan, as an ephemeral lake. Due to the wide extent of the sources of dust and sand production in Sistan, finding areas that are prone to wind erosion is of paramount importance in prioritizing stabilization. For this purpose, indices of transport rate (erodibility), soil shear strength, and SAVI were conducted.  To investigate the land erodibility to aeolian transport, 74 graduated pins were embedded randomly in the ephemeral Baringak Lake bed and the aeolian transport rates were measured for the total study period. The shear strength of the soil surface was measured using Torvane. The vegetation canopy density was extracted from digital images using the SAVI index. The results showed that there is a very significant relationship (1%) between soil shear strength and SAVI indices with transport rates. It means that this proposed method may be also applied to estimate land sensitivity in environments instead of threshold friction velocity of wind erosion in the field. Comparison of the results of regression model estimation with transport rates in the field were significant.

The purpose of this research was carried out to assessing the vulnerability of drought beneficiaries and investigating and analyzing the components of drought crisis management in Sistan and Baluchestan province from expert’s viewpoints of the Jihad-Agricultural Organization. The method used in this research is descriptive-non-experimental. All experts of the Agricultural Extension and Education Unit of the Jihad Agricultural Organization of the province formed the statistical population of this study, a sample of which was selected and studied based on Morgan table and simple random sampling method (n = 72). The list of primary indicators (10 main indicators) in the research was determined by Delphi method (consensus of regional experts). Me-Bar & Valdez formula and SPSS software were used to assess the vulnerability and explain the components of drought crisis management. Findings showed that among the studied vulnerability indicators, economic, social and technical indicators were introduced as the most important vulnerability indicators in the drought period, which in general, the highest total vulnerability in drought conditions was related to technical vulnerability indicators. Findings showed that among the studied vulnerability indicators, economic, social and technical indicators were introduced as the most important vulnerability indicators in the drought period, which in general, the highest total vulnerability in drought conditions was related to technical vulnerability indicators. Also in the field of exploratory factor analysis indicated that the most important drought proponent components from viewpoint of agricultural experts are the components of agricultural management, ordering of augury system and communion, infrastructures development, water resources management, financial support, status of manual (integral policy), patronage of local convention and training and extension. These factors could explain 55.03% of the variation in drought management.

To investigate the flood effect on changing the Zarrin-Gol water quality parameters, water was sampled from five stations on the river in three periods before, during, and after a flood and then some physicochemical parameters were determined. F-test was used to compare and determine the statistical difference between the qualitative parameters. Then, the hydrogeochemical changes of the river, effective factors in controlling the chemical composition as well as the dominant processes of the river water were determined. Finally, saturation indices were used to predict the possibility of precipitation/dissolution of some carbonate and evaporative minerals in all three periods. Results revealed that during the flood, chloride, and sodium ions were predominant ions in water and the most changes at different times were related to these two ions. The predominant water type in the periods before and after the flood was Mg-HCO3. Based on the Piper and Durov diagrams, most pre- and post-flood samples have facies of recharge areas. While, during the flood, with the abundance of chloride and sulfate ions in the water, composite facies prevail, and TDS at this time is almost three times before it occurs. Based on the accumulation, distribution, and orientation of the samples on the Gibbs diagram, the main factor controlling the water chemistry of the Zarringol river in all three periods is the chemical weathering of the minerals that form the basin rocks. Also, based on the results of ionic ratios, some evaporative minerals dissolution such as gypsum simultaneously with the phenomenon of cation exchange is one of the dominant hydrogeochemical processes during floods. While in most samples before and after the flood, the reverse ion exchange process is predominant. According to the results of bivariate diagrams, the main source of salinity of the Zarringol river is the dissolution of evaporative minerals (such as halite) belonging to the Mubarak Formation.

Using different methods in landslide risk zoning and achieving the best results can lead to planning and managing potential hazards. The main objective of this study is to assess and determine the potential risk of landslide in Fereydoon Shahr city, west of Isfahan province, to provide a general framework for analyzing the probable landslide hazard in the study area. In this study, the accuracy of statistical and expert analysis (GIS-based) methods was analyzed using the Sentinel-1 radar interferometry method. This analysis leads to the presentation of the landslide hazard zoning map, susceptible areas, and determination of the factors affecting the landslide occurrence. Initially, for risk assessment and zonation, the causative factors including slope, elevation, gradient direction, curvature, distance to fault, distance to waterway, lithology, and vegetation were studied. And statistical correlation was created between each of the causative factors and past landslides in the GIS environment to assess the relative share of classes related to each factor. In the expert analysis method, the study area was analyzed based on expert opinion based on studies conducted on 70 landslides. The results, in addition to the Fereydoon Shahr sensitive and hazardous area map, showed about 67% overlap of very-high and high-risk areas in the risk zoning maps with pixels from the surface displacement map obtained from Sentinel radar images with the highest displacement. Which can indicate the possibility of landslides or landslide risk in these areas. Therefore, the use of radar images and the study of changes in land displacement can be a useful tool in monitoring and accuracy of the landslide risk zoning methods for planning in sensitive areas.

Among all the natural hazards in the country, according to recorded statistics and observations, floods have been the most destructive, and it has the highest frequency of occurrence. Floods are one of the known natural disasters that cause a lot of financial and human losses. This phenomenon can be controlled by identifying flood-prone areas and proper management. In the current era, due to human encroachment on rivers and land-use change or destruction of vegetation, flood damage has increased. These factors cause, in addition to increasing human and financial losses, damages such as soil erosion upstream and sedimentation downstream. In this research, using agent-based modeling in the NetLogo simulation environment, flood-prone areas in Shush city have been identified. The most important input was topography (digital elevation model) and then dynamic and temporal simulation was done by performing tessellation on the area and considering the rainfall in each cell as an agent. Using spatial analysis in ArcGIS software and comparing the simulation results with the location of the city and land use maps of the region, the possible causes of floods in this region have been investigated. Agent-based models with the incorporation of geospatial information systems (GIS) can be used as a new solution to solve spatial problems such as natural crises, destructive environmental impacts, and so on. Finally, preventive measures to prevent floods in this area are proposed.

In this research pollution of soil samples from the southern slopes of the Taftan volcano, SE Iran, and the Khash Plain to the south of the volcano is studied. The concentrations of Arsenic and Sulfur in the soil samples are 6-14 ppm and 0.03-0.51 wt.%, respectively, both more than the quality standard values of USEPA. Pollution zoning maps indicate that samples from Khash Plain to the south are, generally, more polluted in comparison with the samples from Taftan slopes to the north of the area. This phenomenon is associated with an increase in the fine-grained portion (silt-clay), and the pH of the soil samples. It is inferred from the comparison of the AS and S contents of the Khash Plain aquifer (0.005-0.1 and 72-528 mg/L, respectively) and the groundwater pollution zoning maps that water-soil ion-exchange reactions have played important role in the soil pollution processes. Some significant arsenic anomalies in the soil sample, despite the lack of the same in the groundwater, are attributed to arsenic mineralization due to Taftan hydrothermal activities. The mineralization is related to mercury-gold generation in the area which is usually accompanied by arsenic sulfide minerals realgar, AsS and orpiment, As2S3. Therefore, hydrothermal activities of the Taftan volcano produce a particular effect on arsenic and sulfur soil pollution.