Heavy mineral transportation downstream in a gravel bed meandering river

Abstract

This research is an attempt to get a better understanding of density sorting in a gravel-bed meandering river. The study area is 4.3km long reach of Coledale Beck in the English Lake District. Coledale Beck is a upland mountain stream that flows straight through a mining area where baryte and other heavy minerals were mined for. These heavy minerals flow downstream and the baryte is analysed in this research. The river was sampled and samples were density separated by a heavy liquid. Then the sediment was then analysed in ImageJ software. The result shows not only a downstream decrease in heavy minerals concentration but also a downstream fining trend in grain size. The baryte minerals also show a change in shape from elongated grains at the head of the river to more spherical grains downstream. However there are no further signs of abrasion and this research concludes that selective sorting is the mechanism behind the downstream fining trend. Its not concluded that sorting by density is the only influence however the effect of density is a major factor in the selective sorting, and density is an important factor of sorting by entrainment, transport and settling and the main reason for the rapid downstream fining trend.

Date of Award	1 Aug 2013
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Merren Jones (Supervisor) & Stephen Covey-Crump (Supervisor)