ارزیابی اثرات عملیات حفاظت خاک و آب بر ویژگی‌های خاک، فرسایش و رسوب در حوزه‌ آبخیز ریمله استان لرستان

ارزیابی اثربخشی انواع اقدامات حفاظت خاک و آب بر ویژگی‌های خاک، فرسایش و رسوب از اهمیت بالایی در برنامه‌ریزی و مدیریت خاک برخوردار است و از اقدام‌های حرکت به‌سوی توسعه‌ پایدار محسوب می‌شود. بر این اساس این پژوهش با هدف ارزیابی اثرات اقدامات حفاظت خاک و آب از نظر فرسایش و رسوب و ویژگی‌های خاک در حوزه‌ آبخیز ریمله استان لرستان اجرا شد. جهت پیش‌بینی فرسایش قبل و بعد از اجرای اقدامات حفاظت خاک و آب، از مدل epm استفاده شد. به‌منظور بررسی ویژگی‌های خاک، عوامل جرم مخصوص ظاهری، بافت خاک، اسیدیته، هدایت الکتریکی و نفوذپذیری خاک در دو عمق صفر تا30 و 30 تا60 سانتی‌متری خاک ارزیابی شد. نتایج مقایسه‌ خصوصیات فیزیکی و شیمیایی خاک در دو عرصه‌ تحت عملیات حفاظت خاک و آب و منطقه‌ شاهد با یک‌دیگر، نشان داد که با اقدامات حفاظت خاک و آب، مقدار جرم مخصوص ظاهری، تغییر بافت خاک، اسیدیته و هدایت الکتریکی خاک سطحی افزایش معنادار نیافته است. مقایسه‌ داده‌های نفوذپذیری در مناطق شاهد و مناطق حفاظت ‌شده نشان داد که اجرای عملیات حفاظت خاک و آب بر نفوذپذیری خاک اثر مثبتی داشته است. به‌طوری‌که مقدار نفوذپذیری در عمق 30 تا60 سانتی‌متری خاک از 69/0 در منطقه‌ شاهد به 38/0 در منطقه‌ عملیات اصلاحی کاهش ‌یافته است. هم‌چنین، مقدار فرسایش و رسوب کل سالانه در شرایط کنونی نسبت به قبل از اجرای اقدامات حفاظت خاک و آب به‌ترتیب به‌طور متوسط حدود 6793 مترمکعب و 5712 تن کاهش‌یافته‌اند. نتایج آزمون t زوجی نشان داد که اقدامات حفاظتی خاک و آب انجام‌ شده در حوزه‌ آبخیز ریمله توانسته است اختلاف معنا‌داری را در کاهش فرسایش و رسوب ایجاد کند. با توجه به یافته‌های پژوهش می‌توان بیان کرد که اقدامات حفاظت خاک و آب در کاهش فرسایش و رسوب اثر مثبت معنا‌داری داشته است ولی تاثیر آن بر بالا بردن کیفیت خاک مطلق نیست.

evaluating the effects of soil and water conservation measures on soil characteristics, erosion, and sedimentation in the rimeleh watershed of lorestan province

introductionhealthy soils contribute to climate change mitigation by sequestering carbon and reducing greenhouse gas emissions. moreover, water resources are crucial in addressing climate change impacts, especially as they are increasingly affected by shifting weather patterns. conservation efforts can enhance resilience to the effects of climate change. water and soil conservation play a significant role in economic stability. sustainable management of these resources can enhance agricultural productivity, leading to food security and increased income for farmers. additionally, protecting watersheds can help reduce costs related to erosion control, water purification, and disaster recovery from floods and droughts. today, the role of soil and water conservation management measures in increasing vegetation cover is of particular importance due to their effects on soil stabilization. vegetation cover can act as a barrier between the ground surface and raindrops, and by preventing raindrops from directly impacting the soil surface, it prevents soil particles from disintegrating. evaluating the effectiveness of different water and soil conservation measures on soil properties, erosion, and sedimentation is crucial in soil planning and management. it is considered one of the steps towards achieving sustainable development. therefore, this study evaluated the effects of water and soil conservation measures on erosion, sedimentation, and soil characteristics in the rimeleh watershed of lorestan province.materials and methodsthe rimeleh watershed area is about 7319 ha. the minimum and maximum elevations are 1500 and 2783 masl, respectively, and the average slope of the watershed is about 28 percent, with an average rainfall of 499 mm per year. its average annual temperature is 11.2 c. in this study, the normalized difference vegetation index (ndvi) was used to prepare the land use layer using landsat satellite images and ilwis software. in addition, the land use of the 1990s was prepared using existing aerial photographs and compared with the current land use map. first, the data were checked for heterogeneity, including the presence of outliers. to test the null hypothesis that the means of the studied variables were equal to zero, a one-way analysis of variance (anova) was used, and to compare the means between treatments, duncan's test was used at a 5 % significant level. the erosion potential model (epm) was used to predict erosion before and after the implementation of water and soil conservation measures. to investigate the soil characteristics, bulk density, soil texture, acidity, electrical conductivity, and soil permeability were evaluated at depths of 0-30 and 30-60 cm. results and discussioncomparing the soil physical and chemical properties in the two areas under conservation measures and the control area showed that the bulk density, soil texture, acidity, and electrical conductivity of surface soil did not significantly increase with water and soil conservation measures. a comparison of permeability data showed that conservation measures had a positive effect. in addition, the amount of total annual erosion and sedimentation under the current conditions have decreased by an average of 6793 m3 and 5712 tons, respectively, compared to before the implementation of conservation measures. the results of the paired t-test showed that the water and soil conservation measures were able to reduce erosion and sedimentation significantly. in general, no significant effect of measures on soil acidity was found. the results indicate that in both the first and second soil depths, a significant difference in electrical conductivity was evident between the conserved areas and control areas. the study of soil bulk density for both surface and deep depths showed that there was no significant difference. the soil bulk density value in the protected area was lower than in the unprotected areas, which could be due to the higher organic matter content in the protected areas. conclusionthe implementation of soil and water conservation measures such as engineering and bioengineering measures (drywall, check dam, turkinst, gabion and earth dam), terracing, pond construction, and gardening development in the rimeleh watershed could significantly increase the physical and chemical properties of the soil. the results also showed that the amount of total sediment output after project implementation has significantly decreased. finally, it can be concluded that soil and water conservation measures have had a significant positive effect on reducing erosion and sedimentation, but the effect of soil and water conservation measures on improving soil quality is not absolute, and their effectiveness is highly dependent on the different climatic and geological conditions.