Abstract

Surface profiles of a tailings delta and several modern prograding river deltas are described by the equation y = axb, where x and y are horizontal and vertical distances, respectively, from the edge of the delta lip. This relationship is used to determine the slope of a profile at any specified point and to determine the location of the transition point between foreset and bottomset beds. A dimensionless equation of the form Y = XB is used to compare the shapes of different deltas; the exponent B has an average value of about 0.5 and 0.9 for lake and ocean deltas, respectively. The depth of the water in the receiving basin is a key factor that influences the shape of the foreset beds. The shape of the profile for foreset beds of lake deltas can be closely predicted by y = Kx0.533, where K is a coefficient that correlates with the maximum depth of water, ymax, in the lake near the delta front. For ocean deltas, where ymax is undefined, K must be correlated with some other reference parameter such as y1, which locates the toe of the foreset bed.

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