نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری، استادیار گروه خاکشناسی دانشگاه تربیت مدرس
2 استادیار گروه خاکشناسی دانشگاه تربیت مدرس
3 استادیار پژوهش مرکز تحقیقات حفاظت خاک و آبخیزداری
4 عضو هیئت علمی دانشگاه لرستان
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Soil erosion can be considered as one of the most important obstacles in the way of sustainable development of agriculture and natural resources. The sediment from the erosion of watersheds, in addition to soil loss and decline in soil fertility, causes the reduction of water quality and endangers the effective life of reservoirs because of sedimentation. The Nojian watershed, located in Lorestan province, has physiographic and topographic features with specific geological formations that have a basic role in soil erosion and sediment yield pProcesses. Thus, to assess the results of empirical models, this watershed was selected as research area. In this investigation, the erosion and sediment yield of watershed was evaluated qualitatively and quantitatively by using MPSIAC (modified Pacific Southwest Inter-Agency Committee), EPM (Erosion Potential Method) and Hydrophysical models in the program of GIS. To run the selected model, after introducing the information layers into the GIS program and combining the layers in MPSIAC and EPM models, the given catchments were divided into 527 and 278 homogeneous units, respectively. Then, erosion rate and sediment yield were estimated in these homogeneous units. The amounts of sediment yield were estimated to be 1465348.1 and 489372.2 t/y by using MPSIAC and EPM models. For estimating sediment yield by Hydrophysical model, Nojian watershed was divided into 6 hydrological units based on method and amount of sediment that were estimated in these units. The amount of sediment estimated by using Hydrophysical model was 862470.1 t/y. For comparison of the models results, a figure of 81240 t/y, or the amount of sediment measured in hydrometric station was considered as the control level. The outcome of the research showed that estimating sediment by using EPM and MPSIAC models were 1.8 and 0.6 times those of measured amounts, respectively. On the other hand, estimating sediment yield by Hydrophysical model was more accurate as it was only 1.06 times the measured amounts. The results of the assessment on observed differences show that calibration of the empirical models is needed first to resolve the limitation of the models with regard to the existing conditions of the watersheds. Otherwise, the use of the models cannot yield accurate results.
کلیدواژه‌ها [English]
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