The effect of land use changes on the potential for landslide risk in Meshkinshahr County.

Introduction

Landslides are one of the most destructive geomorphological hazard processes of the range, which not only cause huge losses to human society and economic development but also pose a serious threat to the environment. In recent years, successive changes in land use, due to the necessity of meeting the various needs of the growing world population, represent an important part of global changes in the environment, and often unprincipled changes in land use as a dynamic factor related to human activities, also lead to an increase in the potential for landslides. Meshkinshahr County (located in Ardabil Province), due to environmental characteristics including; topographic conditions, loose and unstable surface materials on resistant formations, and climatic conditions, has a high potential for landslide hazards. However, in recent years, due to the growing population and unprincipled land use changes, the potential for this hazard to occur at the county level has increased. Accordingly, the present study seeks to evaluate the effect of land use changes on the potential for landslide hazard in this county.



Methodology

In this study, to investigate land use changes, first, Landsat satellite images from OLI-TM sensors for the years 2002 and 2024 were obtained from the US Geological Survey. Then, to prepare the images, geometric and atmospheric corrections were made on the images using Envi5.3 software. In the next stage, using the object-oriented classification method and the nearest neighbor algorithm using Ecognition software, land use maps were extracted in the two years under study. In the next stage, by identifying the effective factors involved in landslides in the region (including; Dem, slope, aspect, lithology, distance from fault, land use, precipitation, distance from communication road, and distance from river) and preparing information layers for each criterion in GIS, the evaluation and standardization of the layers were performed using the fuzzy membership function and weighting of the criteria, using the critic method. Finally; Final analysis and modeling were performed using the weighted linear combination multi-criteria analysis method.



Results and Discussion

Based on the results of the analysis of land use changes, in both years of study, poor pastures and dryland agriculture cover the largest area of the county. In contrast, irrigated areas and snow-covered lands have occupied the smallest amount of the total area of the county in both years 2000 and 2024. According to the results of the study, during the years of study; irrigated agriculture, dryland agriculture, residential areas, and irrigated areas have increased, and on the contrary, the area of gardens and forests, good pastures and poor pastures and snow-covered lands has decreased. In addition; considering the analysis of the method of land use conversion, it is observed that the largest land use change in the county was the conversion of poor pastures to dryland agriculture, and in 2024, compared to 2002, about 452.02 square kilometers of the area of poor pastures in the county was converted to dryland agriculture.

According to the results, in 2002, the slope, land use, and lithology criteria had the highest weight coefficient, respectively, and in 2024, the land use, slope, and lithology criteria had the highest weight coefficient. According to the landslide hazard zoning map, in 2002, the area of the very high-risk and high-risk categories was 457.606 and 994.776 square kilometers, which increased to 483.444 and 1103.104 square kilometers, respectively, in 2024. In terms of land use, in the landslide map in both 2000 and 2024, the areas with the very high-risk and high-risk categories were mainly located in agricultural uses (especially rainfed agriculture), pastures, and residential areas.



Conclusion

Considering the landslide zoning map in 2002 and 2024 and the large area of very high-risk and high-risk zones, it can be concluded that, in general, given the environmental conditions prevailing in the area, including the dominance of slopes with medium to steep slopes (15 to 80), altitudes of 1000 to 4000 meters, susceptible geological formations, rainfall and abundance of the waterway network and the under scouring of the slope support by flowing waters, fault structures and slope directions, trenching and removal of the slopes' toes following road construction and development activities, Meshkinshahr County has a high potential for the formation of landslide movements. However, with the changes in land use that have occurred in the county, such as an increase in the area of agricultural lands and residential areas, and a decrease in the area of pastures, gardens, and forest cover, the area of very high-risk and high-risk categories has increased by 25.835 and 158.328 square kilometers, respectively, in 2024 compared to 2000. Given the large area of landslide-prone areas in Meshkinshahr County and how land is being converted and changed, expert protection, watershed management, and management measures must be taken. Finally, it can be acknowledged that the results of this research have a practical aspect and it is expected that the use of the land use change map and landslide hazard zoning map obtained in the present study will be made available to stakeholders and organizations related to environmental hazard issues as a more powerful tool for understanding the effects of land use change on landslides and risk management and reducing losses and losses caused by the environmental hazard of landslides.