نوع مقاله : پژوهشی
نویسندگان
1 دانشجوی دکتری گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ایران
2 دانشیار فقید گروه علوم و مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری
3 استادیار فقید گروه علوم و مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری.
4 گروه مهندسی آبخیزداری-دانشکده منابع طبیعی-دانشگاه علوم کشاورزی و منابع طبیعی ساری
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goal
Landslides, as one of the most destructive geomorphological phenomena, can cause huge human and financial losses to different regions of Iran every year. Landslides, as a type of slope movement, are mainly affected by natural factors such as earthquakes, heavy rainfall, and river erosion, but this phenomenon can be exacerbated by human interventions such as unprincipled construction, road cuts, and changes in runoff patterns. The mountainous regions and steep slopes of the country, especially the northern regions of the country, are the main focus of this phenomenon due to their susceptible lithological and tectonic conditions. The consequences of landslides are not limited to the destruction of homes and vital arteries, and often lead to the blockage of transportation routes, damage to agricultural lands, and human casualties. The integration of remote sensing methods and field studies allows for more accurate monitoring and assessment of landslides. Geotechnical and geomorphological analyses play a significant role in identifying susceptible areas and managing the risk of this natural hazard. Therefore, studying and identifying unstable zones and analyzing the factors controlling this phenomenon is a fundamental step in risk reduction and crisis management. For this reason, the present study was conducted to assess the spatiotemporal behavior of the landslide mass in Chaserka, Babol.
Materials and Methods
The Chaserka landslide is located southeast of Galugah city and 35 km south of Babol city. This area is located in the Sajjad Rood watershed and has an area of about 72 hectares. In the first stage, landslide points were identified using the evaluation of previous studies, initial visits, and familiarization with the area. Then, using public information, the landslide mass boundary was determined on the ground using a handheld GPS device, and the landslide area boundary was determined using topographic maps and satellite images. For this purpose, a combination of remote sensing data (23 Landsat and Spot satellite images), a digital elevation model (DEM) with an accuracy of 10×10 meters, and 50 field data points (23 landslide points and 27 non-slip points) was used. In order to control the displacement caused by landslides, a network with 20 control points was created in sensitive areas of the landslide area according to the location of joints, cracks and masses suspected of sliding on the ground. Subsequently, land-use change trends were identified and the geodetic network for landslide monitoring was processed and calculated. Finally, the confusion matrix was used to evaluate the accuracy of the model and calculate the overall accuracy.
Results and Discussion
The results of this study indicate the combined role of natural factors and human interventions in the occurrence of landslides in the Chaserka region. The analyses indicate that natural factors such as slope, direction of the slope, and geological features (marl, shale, and Neogene clays) have been the cause of the occurrence of landslides, but human interventions, especially the destruction of forest cover, non-engineering constructions, and land cover changes in recent decades, are the main driving factors of slope instability and the intensification of landslide risk.The highest incidence of landslides has been observed in the northeast, east, and northwest directions with slopes of 25 to 45 percent and in areas with soil depths less than 50 centimeters. Changes in land cover in the last 40 years from virgin forests to roads and agricultural lands, in addition to reducing vegetation cover, have disrupted the hydrogeomechanical balance of slopes and increased the risk of landslides.The results of geodetic monitoring indicate gradual and continuous changes in the movement of the landslide masses. These changes, recorded in five observational stages, indicate that the landslides in Chaserka are gradual and dynamic processes that ultimately lead to sudden failure. The analyses showed that significant displacements at some points (such as R2 and R3) are closely aligned with the dominant direction of landslides in the region, indicating the occurrence of gradual changes in the soil shear strength that ultimately cause the failure of the slopes.Overall, the results of this study emphasize the importance of comprehensive analysis of climatic, geomorphological, and human changes in landslide risk management and show that to prevent these phenomena, it is necessary to make appropriate plans to control land cover changes and preserve vegetation in sensitive areas.
Conclusion and Suggestions
The findings of the monitoring and behavior analysis of the Chaserka landslide mass indicate that gradual deformations before sudden rupture are the main factor in the instability of this mass. Therefore, the establishment of a permanent monitoring system based on remote sensing data and accurate measurement of displacements can be the basis for the development of a landslide early warning system. In addition, considering the role and importance of vegetation in modulating the hydrological and mechanical conditions of the slope, targeted vegetation restoration using native species can be recommended as a complementary strategy in managing the stability of the landslide mass. Also, considering the changing type and intensity of extreme precipitation due to climate change in northern Iran, continued long-term monitoring is necessary to analyze the behavior of the landslide mass in response to hydro-climatic stimuli in other similar watersheds of the country.
کلیدواژهها [English]
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