تغییرات مکانی خطر فرسایش خاک در حوزه آبخیز بریموند استان کرمانشاه

فرسایش خاک یکی از تهدیدهای مهم برای حفاظت از منابع آب‌وخاک به شمار می‌رود. حال آن‎که تاکنون مولفه‌های مختلف آن ازجمله تغییرات مکانی موردتوجه لازم قرار نگرفته است. هدف اصلی این پژوهش تعیین خطر فرسایش بالقوه و بالفعل حوزه آبخیز بریموند استان کرمانشاه با استفاده از مدل corine و در سامانه اطلاعات جغرافیایی بوده است. اطلاعات موردنیاز مربوط به عوامل اصلی فرسایش خاک شامل فرسایش‌پذیری و فرسایندگی خاک ازجمله شیب، پوشش گیاهی، عمق، بافت، درصد سنگریزه تهیه و در محیط arcgis تلفیق و طبقه‌بندی شد. درنهایت نقشه‌ پتانسیل فرسایش‌پذیری خاک به ترتیب از تلفیق نقشه‌های فرسایش‌پذیری، فرسایندگی و شیب تهیه شد. سپس نقشه فرسایش واقعی خاک از تلفیق نقشه‌ پتانسیل فرسایش‌پذیری خاک و پوشش گیاهی به دست آمد. مطابق نتایج مربوط به پراکنش پوشش گیاهی مختلف در منطقه، مجموع کاربری دیم و بایر با مساحت 65.48 درصد بیش‌ترین مساحت را به خود اختصاص داده است. علاوه بر آن، پوشش‌های مرتع و جنگل نیز با گستره سطحی 29.65 و 4.87 درصد، به ترتیب دومین و سومین مساحت از پوشش گیاهی در منطقه را داشتند. مطابق نقشه پتانسیل فرسایش‌پذیری خاک مشخص شد که به ترتیب حدود 65.57، 23.62 و 10.81 درصد از وسعت منطقه در محدوده پتانسیل فرسایش متوسط، کم ‌و زیاد قرارگرفته است. هم‌چنین فرسایش واقعی خاک به ترتیب 53.83، 15.53، 30.64 درصد در محدوده کم، متوسط و زیاد قرار دارد. بر همین اساس و در راستای مهار فرسایش و جلوگیری از اثرات منفی و توسعه آن در حوزه آبخیز بریموند، استفاده از اراضی متناسب با توانایی و استعداد آن‌ها، حفظ وضعیت پوشش فعلی و انجام طرح‌های مدیریتی باهدف احیا پوشش گیاهی پیشنهاد می شود.

spatial soil erosion risk at the brimvand watershed in kermanshah province, iran

introductionsoil erosion is considered as one of the critical threats to the conservation of water and soil resources. however, until now, its various components, including its spatial changes, have yet to be given due attention. in order to implement soil erosion control and conservation programs in the watershed, it is essential to have basic information leading to know and accurately identify the factors affecting the degradation of soil and water resources. meanwhile, the corine model has been considered as one of the practical models for estimating soil erosion and displaying the spatial distribution of soil erosion with easy and accessible inputs. the corine model developed based on the universal soil loss equation (usle) was therefore employed in the present study in the gis environment to determine the potential and actual erosion risks of the brimvand watershed in kermanshah province, iran. materials and methodsthe main associated factors of soil erosion, viz. soil erodibility and erosivity, such as slope, vegetation, depth, texture, and percentage of gravel, were collected, compiled, and ultimately classified in the arcgis software. the fournier index (fi) and fao-unep drought index (di) were used to prepare the input maps. the fournier index reflects the performance of the soil erosive agent. in other words, it shows the role of rainfall on soil erosion. the fao-unep drought index shows the simultaneous performance of evaporation and precipitation on soil erosion of a region. the potential soil erosion risk was obtained by combining slope, erodibility, and erosivity layers. in addition, the actual soil erosion risk map was determined by combining the vegetation map and potential soil erosion risk. results and discussionbased on the results of the vegetation distribution in the region, the use of rainfed and abandoned lands had the largest area in the watershed, with an occupation percentage of 65.48%. furthermore, the rangeland and forest areas, with respective coverage of 29.65 and 4.87%, stood in the second and third priority from the viewpoint of the area. the region has varying slopes, but more importantly, it has a low slope. soil texture, depth, and gravel content significantly affect the area’s erosion. the soil depth in a large part of the watershed, especiallywith a slope of less than 4% is more than 65 cm where it is mainly covered by abandoned and rainfed lands. in the studied area, the depth of the soil decreases with height increase, which indicates that the high slopes of the area are dominantly outcrops. most of the area has gravel contents between 10 and 40%. the erosion potential of the region is not that much high because of the desired features of the affecting factors. according to the potential soil erosion risk, it was determined that about 65.57, 23.62, and 10.81% of the area were classified as intermediate, low, and high erosion potential, respectively. further, the actual soil erosion risk was categorized as low, intermediate, and high with respective areal coverage of 53.83, 15.53, and 30.64%. it is therefore implied that the amount of erosion and sediment transfer will increase if the land cover in the watershed is declined.  this indicates that the erosion rate was highest in hilly areas due to lack of vegetation and soil with loamy texture. accordingly, to curb soil erosion and prevent its associated adverse effects in the brimvand watershed, it is strongly suggested to use lands based on their capability and potential, maintain the present cover status, and carry out management plans to restore vegetation. conclusionsoil erosion remains one of the most critical challenges in watersheds, and its neglect can lead to various problems for the beneficiaries. in light of this, the present study aimed to address this issue by employing the corine model to assess potential and actual soil erosion in the brimvand watershed of kermanshah province, iran. the research findings reveal the pivotal role of vegetation in mitigating soil erosion. notably, areas with gentle slopes, which are inherently susceptible to erosion, benefit significantly from vegetation cover, leading to a noticeable reduction in erosion. however, the loss of this protective cover can trigger a rapid increase in soil erosion and subsequent loss of valuable soil resources. by shedding light on the spatial distribution of soil erosion, this study emphasizes the importance of preserving and promoting vegetation in the watershed to ensure its long-term sustainability and safeguard the well-being of those who depend on it. therefore, land utilization should be planned based on capacity and potential of the land to curb erosion and avoid its detrimental impacts in the brimvand watershed. in addition, not only the current cover situation has to be maintained but also the vegetation conditions have to be improved through the implementation of managerial and reclamation plans leading to managing soil erosion.