پهنه‌بندی و تحلیل تغییرات زمانی و مکانی فرسایش خندقی و تاثیر آن بر روستاهای حوضه آبریز مند طی سالهای 1379 و 1403

تحلیل تغییرات کاربری اراضی و ارزیابی خطر فرسایش خندقی از جمله مسائل مهم در مدیریت منابع طبیعی و توسعه پایدار در حوضه‌های آبریز است. این تحقیق باهدف ارزیابی تغییرات کاربری اراضی و پهنه‌بندی خطر فرسایش خندقی در حوضه آبریز مند در سال‌های 1379 و 1403 انجام شده است. روش‌شناسی تحقیق شامل استفاده از داده‌های سنجش‌ازدور، پردازش تصاویر ماهواره‌ای لندست 5 (1379) و لندست 8 (1403) در google earth engine و تحلیل‌های gis می‌باشد. در ابتدا، تصاویر ماهواره‌ای پس از تصحیح اتمسفری به‌کمک الگوریتم random forest به پنج کلاس کاربری اراضی (اراضی کشاورزی، مراتع، جنگل‌ها، اراضی بایر و مناطق شهری) طبقه‌بندی شدند. سپس، لایه‌های شیب، ارتفاع، بارش و کاربری اراضی به‌منظور پهنه‌بندی خطر فرسایش خندقی با استفاده از تحلیل چندمعیاره (mce) تلفیق شدند. نتایج نشان داد که در سال 1403، تغییرات قابل توجهی در کاربری اراضی و افزایش خطر فرسایش خندقی در برخی مناطق حوضه آبریز مند مشاهده می‌شود. این تغییرات، به‌ویژه در مناطقی که دارای کاربری‌های کشاورزی و مناطق شهری بوده‌اند، اثرات منفی زیادی بر محیط زیست و پایداری روستاها داشته است. در نهایت، شناسایی مناطق پرخطر و ارائه راهکارهای مدیریتی جهت کاهش خطر فرسایش خندقی در این مناطق پیشنهاد می‌شود. 

zoning and analysis of temporal and spatial changes in gully erosion and its impact on the villages of the mond watershed during the years 2000 to 2024

1-introductionsustainable land management and adopting preventive strategies to control gully erosion are crucial for mitigating its negative impacts on communities and the environment. gully erosion, especially in arid and semi-arid regions, can lead to severe consequences such as agricultural land degradation, reduced land productivity, and environmental risks. the mond watershed in southern iran, with its unique geographical and climatic characteristics, has become increasingly susceptible to gully erosion due to climate change, population growth, and land use changes. villages within this watershed, as essential components of local communities, are directly affected by this process. temporal and spatial changes in gully erosion zonation from 2000 to 2024 have not only influenced the environmental conditions of the region but also affected residents’ livelihoods and rural development sustainability. identifying and analyzing spatial patterns of these changes can contribute to better natural resource management and more effective planning to mitigate adverse impacts.2-methodologythis applied research aims to assess land use changes and gully erosion risk zonation in the mond watershed during the years 2000 and 2024. the methodology is based on spatial and temporal analysis of remote sensing data and the application of geographic information systems (gis) combined with satellite image processing. data collection involved landsat 5 (2000) and landsat 8 (2024) satellite imagery, which were acquired and processed via google earth engine. elevation data from digital elevation models (dems) and climatic information such as temperature and precipitation were extracted from reputable global databases.for data analysis, atmospheric corrections were applied to the satellite images, and land use maps were classified using the random forest algorithm into five main classes (agricultural land, rangeland, forest, barren land, and urban areas). subsequently, slope, elevation, precipitation, and temperature layers were prepared in gis and integrated with land use layers. these datasets were used to produce gully erosion risk maps.3-results in 2000, areas with higher precipitation were concentrated in the northern and central parts of the watershed. by 2024, precipitation in these regions had decreased, potentially reducing gully erosion risk in some areas. however, the cumulative effects of past erosion remain evident in the region. changes in slope and geological formations have also influenced erosion trends. areas with steep slopes and marly or shale formations are more prone to gully erosion due to the high sensitivity of their soils to rainfall and surface runoff.many villages are located near areas with a high risk of gully erosion, particularly in regions with weak vegetation cover or limited surface water resources. high-risk areas in 2024 account for 1% more of the watershed’s area compared to 2000. this increase is likely due to vegetation degradation, new construction, or climatic changes exacerbating erosion. between 2000 and 2024, low-risk areas have slightly increased, but the percentage of villages within these areas has decreased. conversely, moderate-risk areas, despite a slight decrease in area, now host a larger proportion of villages, intensifying pressure on these zones. while high-risk areas have expanded, the number of villages exposed to these risks has not changed, but the spread of gullies and associated threats must be taken seriously. implementing management and protective measures can mitigate risks and ensure the safety of rural settlements.in 2000, high-risk areas covered 9% of the watershed, increasing to 10% in 2024. this rise is concerning as it indicates intensifying erosion in some regions4-discussion & conclusionsoverall, data analysis reveals that the risk of gully erosion in the mond watershed is increasing due to reduced rainfall, changes in slope and soil formations, and land use alterations. areas with steep slopes, weak vegetation cover, and erosion-prone formations are the most vulnerable. management measures such as vegetation restoration, runoff control, and changes in land use policies are necessary to prevent further degradation.a key finding is that many villages are located near high-risk areas prone to gully erosion. these villages, particularly in the southern and central parts of the watershed, face threats such as infrastructure damage, soil fertility loss, and reduced arable land. land use changes, especially the expansion of barren and residential areas, have increased erosion risks and heightened rural vulnerability to natural hazards. reduced rainfall in recent years, coupled with changes in vegetation cover and land slope, has significantly influenced the intensity and spread of gully erosion. while precipitation has declined in some areas, sandy and clay soils near steep slopes remain highly susceptible to erosion.