کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6431811 1635399 2015 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dimensionless critical shear stress in gravel-bed rivers
ترجمه فارسی عنوان
استحکام برشی بحرانی بی اندازه در رودخانه های بستر ماسه
کلمات کلیدی
استرس برشی بحرانی، معیار سپر، استرس برش دانه، سرعت برش، رودخانه های گچبری، حوضه میوز،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی


- This paper first compiles critical shear stress values from 26 studies of gravel-bed rivers (GBRs) worldwide.
- We highlight values obtained primarily using tracers for 18 GBRs in the Meuse Basin.
- The values depend on the type of mobilization and the river size.

This paper first compiles critical shear stress values from 26 studies of gravel-bed rivers (GBRs) worldwide. The most frequently proposed value of the Shields criterion (θc) is 0.045, but three major groups with θc values ranging from < 0.030 to > 0.100 were identified.Second, dimensionless critical shear stresses (the Shields criterion) were evaluated for 14 GBRs (18 sites) with watershed areas ranging from 12 to 3000 km2. Different approaches were used to identify the initial movement of the bed material: painted and PIT-tag pebbles, sediment traps, and bedload samplers. The Shields criterion (θc) was estimated using the total shear stress (τ) and the grain shear stress (τ′). Several shear stresses were also estimated using shear velocities. For bedload transport, we obtained an average Shields criterion (θc) of 0.040. The values were higher in small rivers (> 0.050) than larger rivers (< 0.030) because of more significant bedform shear stresses. The Shields criterion (θ′c) was lower when the grain shear stress (τ′) was used and only reached 0.019. Different values are also proposed in relation to the type of mobilization: the θc value for partial transport was ~ 0.025 and exceeded 0.040 for full transport (usually reached in association with discharges with a 10-year return period). The values based on the results of sediment traps and a bedload sampler were greater than those obtained using tracers, but these differences are smaller than those usually reported in the literature.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geomorphology - Volume 250, 1 December 2015, Pages 308-320
نویسندگان
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