Title page for ETD etd-04222002-134815


Type of Document Dissertation
Author Almedeij, Jaber H.
URN etd-04222002-134815
Title bedload transport in gravel-bed streams under a wide range of Shields stresses
Degree PhD
Department Civil Engineering
Advisory Committee
Advisor Name Title
Diplas, Panayiotis Committee Chair
Dancey, Clinton L. Committee Member
Loganathan, G. V. Committee Member
Renardy, Yuriko Y. Committee Member
Schetz, Joseph A. Committee Member
Keywords
  • mode
  • pavement
  • rivers
  • flow
  • segregation
  • sediment entrainment
Date of Defense 2002-03-28
Availability unrestricted
Abstract
Bedload transport is a complicated phenomenon in gravel-bed streams. Several factors account for this complication, including the different hydrologic regime under which different stream types operate and the wide range of particle sizes of channel bed material. Based on the hydrologic regime, there are two common types of gravel-bed streams: perennial and ephemeral. In terms of channel bed material, a gravel bed may have either unimodal or bimodal sediment.

This study examines more closely some aspects of bedload transport in gravel-bed streams and proposes explanations based on fluvial mechanics. First, a comparison between perennial and ephemeral gravel-bed streams is conducted. This comparison demonstrates that under a wide range of Shields stresses, the trends exhibited by the bedload transport data of the two stream types collapse into one continuous curve, thus a unified approach is warranted. Second, an empirical bedload transport relation that accounts for the variation in the make-up of the surface material within a wide range of Shields stresses is developed. The accuracy of the relation is tested using available bedload transport data from streams with unimodal sediment. The relation is also compared against other formulae available in the literature that are commonly used for predicting bedload transport in gravel-bed streams. Third, an approach is proposed for transforming the bimodal sediment into two independent unimodal fractions, one for sand and another for gravel. This transformation makes it possible to carry out two separate computations of bedload transport rate using the bedload relation developed in this study for unimodal sediment. The total bedload transport rate is estimated by adding together the two contributions.

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