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In the current study, the risk of landslides in the Zamkan Watershed, located in Kermanshah Province, was evaluated. Two machine learning models, Support Vector Machine (SVM), and Logistic Regression, were used to prepare a landslide susceptibility map. Toward this, 13 informational layers including elevation, slope, aspect, Melton ruggedness number, terrain convexity, stream length, valley depth, topographic wetness index, precipitation, geological formations, distance from rivers, distance from roads, and vegetation cover were utilized as independent variables. Approximately 70% of the watershed's landslide pixels were used for model training, and 30% for model validation. Model validation was performed using ROC curves. The results indicated the higher performance and accuracy of the radial basis function (RBF) kernel of the SVM model for generating landslide hazard maps in the study area. The area under the curve (AUC) for the RBF kernel was approximately 0.951 for model training and 0.944 for model testing. The results suggest that slope with a coefficient of 0.28, precipitation with a coefficient of 0.27, lithology with a coefficient of 0.26, and elevation with a coefficient of 0.22 are the main controlling factors for landslides occurrence in the Zamkan Watershed. Both the SVM model and logistic regression confirmed the deterministic effects of selected factors on landslides. About 35% of the study area as classified as highly susceptible to landslides, primarily in the eastern half of the watershed. Factors such as high elevation, steep slopes, heavy precipitation, and the Kazhdomi Formation's composition were identified as key contributors to this susceptibility. [ABSTRACT FROM AUTHOR]

Determining the extent of riverbank erosion and displaying it as a map in a GIS environment is effective in the optimal management of water and soil resources. The aim of the current research is to delineate the riverbank erosion zone from aerial photographs, perform regression modeling, and identify factors influencing the development of riverbank erosion using various spatial data including physiographic, hydrological, geological, and environmental data in different sections of the Balikhlouchai River in Ardabil Province. Initially, influential parameters in riverbank erosion in the region, including topographic, soil and land factors, hydrology, and land use changes, were calculated. Accordingly, the variables under study were obtained for four time periods: 1955 using aerial photographs, 1980 using TM satellite images, and years 2010 and 2013 using Google Earth images, and the effective extent of riverbank erosion was compared. Subsequently, multivariate regression analysis was performed using independent variables (including topographic, hydrological, soil erodibility, and land factors) and the effective extent of riverbank erosion as the dependent variable, using SPSS software, and suitable models were developed to estimate the amount of different riverbank erosion. Based on the results of regression analysis, environmental parameters such as slope of the river reaches, peak discharge, area under irrigated agriculture, concentration time, pasture coverage, and residential areas played a more significant role in exacerbating riverbank erosion. [ABSTRACT FROM AUTHOR]

The growing population and expansion of rural activities, along with changing climatic patterns and the need for water during drought periods, have led to a rise in the water demand worldwide. As a result, the construction of water storage structures such as dams has increased in recent years to meet the water needs. However, dam construction can bring significant alterations to the natural flow regime of rivers, and it is therefore essential to understand the potential effects of human structures on the hydrological regime of rivers to reduce their destructive impacts. This study analyzes the hydrological changes in the Shahrchai River in response to the Shahrchai Dam construction in Urmia, Iran. The study period was from 1950 to 2017 at the Urmia Band station. The Indicators of Hydrological Alteration (IHA) were used to analyze the hydrological changes before and after regulating, accounting for land use changes and climatic factors. The results revealed the adverse effects of the Shahrchai Dam on the hydrological indices. The analysis showed an increase in the average flow rate during the summer season and a decrease in other seasons. However, the combined effects of water transferring for drinking purposes, a decrease in permanent snow cover upstream of the dam, and an increase in water use for irrigation and agricultural purposes resulted in a decrease in the released river flow. Furthermore, the minimum and maximum daily flow rates decreased by approximately 85% and 65%, respectively, after the construction of the Shahrchai Dam. Additionally, the number of days with maximum flow rates increased from 117 days in the pre-dam period to 181 days in the post-dam period. As a concluding remark, the construction of the Shahrchai Dam, land use/cover changes, and a decrease in permanent snow cover had unfavorable effects on the hydrological regime of the river. Therefore, the hydrological indicators should be adjusted to an acceptable level compared to the natural state to preserve the river ecosystem. The findings of this study are expected to guide water resource managers in regulating the sustainable flow regime of permanent rivers. [ABSTRACT FROM AUTHOR]

This study aims to investigate the impact of forest exploitation methods on monthly discharge and hydrological indices of river flow using graphical methods in a forested watershed in North Iran. To achieve this, 10 hydrological index changes related to river flow regime influenced by the Shelterwood/clear cutting, Femel cutting, and the Near Nature approach forest cutting methods were assessed. According to the results, it can be stated that the Shelterwood/clear cutting method influenced monthly flow indices by increasing the coefficient of variations and intensifying runoff production, while the Femel cutting and the Near Nature approach methods contributed to regulating the flow regime and sustaining river flow. The influence of various tree-cutting techniques on river flow values and fluctuations is more evident during the wettest months compared to low-water months. The period of Shelterwood/clear cutting disrupted the natural correlation between precipitation and runoff production. Furthermore, the shift from Shelterwood/clear cutting to Femel cutting and the Near Nature approach progressively diminished the slope of the curve, indicating a reduction in monthly runoff at both measurement stations. In conclusion, opting for an appropriate method, such as the Near Nature approach, is preferable from both ecological and hydrological perspectives when managing forest areas in the study region and similar conditions involving comparable topography, climate, soil, and forest stands. The index-based coupled with graphical methodology employed appropriately demonstrates the influence of logging techniques on monthly flow patterns, which provides valuable insights into evaluating the repercussions of alternative management interventions on river flow dynamics. [ABSTRACT FROM AUTHOR]

The increasing human needs and changes in climate patterns have led to the construction of water storage structures to meet the water demand in many regions worldwide, including Iran. Consequently, the hydrological regimes of rivers in various parts of Iran, due to human activities such as dam construction, have undergone alterations in recent decades. Understanding the effects of dams on river hydrological regimes is essential for river flow management and the preservation of river ecosystems. In this regard, the present study assesses the changes in the health of the Urmia's Shahrchai River flow during three periods: pre-dam construction, dam construction, and dam operation, from 1951 to 2017, through calculating different flow health related indices. The results indicate that the deviation of all hydrological health sub-indices in the post-dam construction period is higher than the pre-dam construction period. Moreover, the deviation of flow regime sub-indicators was predominantly low to moderate until 1998 and varied from low to very high after 1998. Additionally, the highest deviation of studied flow health-related indices occurred during the reference and dam operation periods for flood occurrence and minimum monthly flow, respectively, while during the dam construction period, it pertained to minimum monthly flow. Furthermore, the findings suggest that the hydrologic health of Shahrchai River flow decreased by approximately 16% and 45% during the dam construction/operation periods, respectively, compared to the reference period. The results of this study can be utilized in the understanding of flow alteration and the sustainable regulation of the Shahrchai River flow regime. [ABSTRACT FROM AUTHOR]

Rivers are very important in terms of human uses and ecological functions. In the present research, the environmental flow components of the Khiavchai River have been determined. Therefore, changes in the EFCs were determined using IHA software. According to the results, the values of low flows were high in the first period (1988 to 2017), but decreased in recent periods. Also, the decrease in the discharge values of the maximum flow indicators and the increase in the number of days with zero discharge to the number of 174 days were also caused by the change of the river regime. The amount of peak rate and decline rate components has increased in recent periods. The values of low flow duration indicators and low flow frequency have increased. Based on the change of flow dispersion index, the occurrence of strong or very low flows in the river has been intensified. According to the FDCs, in the early periods of the river flow regime, river flow was higher than 0.01cms during the year, while in recent periods it has decreased to less than 0.001cms. Based on the changes in the duration of the flow in recent periods, the duration of the river has changed to 50-60% of the days of the year with a very low discharge. Overuse of river flow changes in the flow regime, and successive droughts have increased the severity of the change in the flow regime and the deviation of the river conditions from the normal state. [ABSTRACT FROM AUTHOR]

Fractal dimension is a powerful and important index that reflects the physical and morphological characteristics of rivers and has a close relationship with geometric features of rivers. The fractal pattern was used to investigate the sinuosity of the Gharehsou River in Ardabil Province, using the box-counting method. The results show that the fractal dimension of the Gharehsou River varies between 2.068 and 2.186. The minimum fractal dimension is in the first category of meanders with lower areas of tangent circle, and the maximum number of circles falls into the eighth category (having high areas of tangent circle). Based on the correlation between the number and area of tangent circles (0.71 to 0.84), it can be said that the river reaches studied follow a fractal and self-similar pattern. The fractal dimension values in the Anzab village-Taleb Qeshlaqi village reach were calculated to be 2.23, indicating a higher level of selfsimilarity, which is related with the naturalness of this river reach, which is located within a plain area, and the river has undergone more evolution. On the other hand, in the Taleb Qeshlaqi village-Sabalān Dam reach, the fractal dimension value was found to be 1.85, which may be related to the river traversing steeper paths, limiting its meander development and making the fractal pattern less observable. Human interventions in the river's course, as well as the river's passage through agricultural lands in some cases, have led to changes in the width and depth of the river and restrictions on meander expansion. [ABSTRACT FROM AUTHOR]

Background: Assessing the changes in public attitudes toward pandemics is crucial in adapting public health strategies to changing circumstances. This study aims to assess the community's attitude toward the COVID-19 pandemic using the Social Profile Ratio (SPR) method among different occupational groups in Ardabil province. Methods: Employing a cross-sectional survey design, this research assessed the attitudes of 230 respondents toward the COVID-19 pandemic in June 2020. Then, the standard SPR method, along with the Index of Resolution (IR), was utilized to analyze the SPR scores, considering different aspects (prevention, control, treatment, and impacts) of the pandemic. Results: According to the SPR values, the occupational groups had different points of view. The highest life expectancy (30 years) was attributed to employees, students, collegians, and instructors. Notably, employees and university professors had the highest SPR and IR values (9.343 and 1) for the prevention indicator. Regarding the control indicator, the unemployed and university professors had SPR and IR values of 5.36 and 0.733, respectively. The highest SPR value of 44.11 in terms of treatment was attributed to employees, while students had the highest SPR value of 10.03 in terms of impact indicator. Conclusion: The study identified employees, university professors, and the unemployed as the most effective groups across prevention, control, treatment, and impact indicators. [ABSTRACT FROM AUTHOR]