کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4532907 1325156 2010 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The erosion rates of cohesive sediments in Venice lagoon, Italy
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
The erosion rates of cohesive sediments in Venice lagoon, Italy
چکیده انگلیسی

The stability of cohesive sediments from Venice lagoon has been measured in situ using the benthic flume Sea Carousel. Twenty four stations were occupied during summertime, and a sub-set of 13 stations was re-occupied during the following winter. Erosion thresholds and first-order erosion rates were estimated and showed a distinct difference between inter-tidal and sub-tidal stations. The higher values for inter-tidal stations are the result of exposure that influences consolidation, density, and organic adhesion. The thresholds for each state of sediment motion are well established. However, the rate of erosion once the erosion threshold has been exceeded has been poorly treated. This is because normally a time-series of sediment concentration (C) and bed shear stress (τ0(t)) is used to define threshold stress or cohesion (τcrit,z) and erosion rate (E). Whilst solution of the onset of erosion, τcrit,0, is often reported, the evaluation of the erosion threshold variation through the process of erosion (eroded depth) is usually omitted or not estimated. This usually leads to assumptions on the strength profile of the bed which invariably has no credibility within the topmost mm of the bed where most erosion takes place. It is possible to extract this information from a time-series through the addition of a step in data processing. This paper describes how this is done, and the impact of this on the accuracy of estimates of the excess stress (τ0(t)–τcrit,z) on E.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Continental Shelf Research - Volume 30, Issue 8, 15 May 2010, Pages 859–870
نویسندگان
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