Spatial-Temporal Behavior Analysis of the Chaserka Babol Landslide by Combining Field Data and Remote Sensing

Introduction and Goal
Landslides, as one of the most destructive geomorphological phenomena, cause huge loss of life and property every year in different regions of Iran. Landslides are a type of slope movement is mostly influenced by natural factors such as earthquakes, heavy rainfall, and erosion, but is exacerbated by human interventions such as substandard construction, road construction, and changes in runoff patterns. The mountainous regions and steep slopes of the country, especially the northern regions, are the main focus of this phenomenon due to sensitive lithological and geological conditions. The consequences of landslides are not limited to the destruction of homes and vital arteries, but also lead to the blockage of transportation routes, damage to agricultural lands, and human casualties. By combining remote sensing methods and field studies, it is possible to provide 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 that inhibit this phenomenon is a fundamental step in risk reduction and crisis management. For this reason, this study aimed to assess the spatio-temporal behavior of the landslide mass in Chaserka, Babol.
Materials and Methods
In the first stage, to examine the history and identify the Chaserka landslide mass, historical images from Google Earth were used between 1981 and 2004, and five years, 2010, 2013, 2016, 2020, and 2025, were selected as samples. In this study, landslide behavior measurement networks with four reference points and 22 displacement monitoring points were designed and created. In addition, orthorectified aerial photographs were examined in different periods and their change trends were compared. For data processing and landslide monitoring geodetic network calculations, Leica Geo Office version 7 commercial software was used, and the model accuracy and overall accuracy were evaluated.
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) were the factors that caused the occurrence of landslides, but human interventions, especially the destruction of forest cover, non-engineering constructions, and land cover changes in previous decades, were the main factors in the instability of slope and the intensification of the risk of landslide. The highest incidence of landslides was observed in the northeast, east, and northwest directions on slopes of 25 to 45 percent and in areas with soil depths less than 50 cm. 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 hydrogeochemical balance of slopes and increased the risk of landslides. Therefore, the results of geodetic monitoring indicate gradual and continuous changes in the movement of the landslide masses. The changes recorded in five observational stages indicate that 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) were highly consistent with the dominant direction of landslides in the region, and this finding indicates the occurrence of gradual changes in the soil shear strength that ultimately cause slope failure. Overall, the results of this study emphasize the importance of comprehensive analysis of climatic, geomorphological, and human changes in landslide risk management. Based on the results of this research, to prevent landslides, appropriate planning should be carried out 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, based on the results of this study, it is recommended to establish a permanent monitoring system based on remote sensing data and accurate measurement of displacements to develop a landslide early warning system. In addition, considering the role and importance of vegetation in modulating the hydrological and structural conditions of the slope, targeted vegetation restoration using native species is suggested as a complementary solution in managing landslide stability. Also, considering the characteristics of extreme precipitation (type and intensity) due to climate change in northern Iran, continued long-term monitoring is recommended to analyze landslide mass behavior in response to hydro-climatic stimuli in other similar watersheds in the country.