Quantitative Properties of Delta Channel Networks
IBM THOMAS J WATSON RESEARCH CENTER YORKTOWN HEIGHTS NY
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Some simple procedures are developed for studying the topologic and geometric properties of delta distributary systems. A delta channel network has three kinds of vertices forks, junctions, and outlets and six kinds of links, each corresponding to one of the six possible combinations of upstream and downstream vertices. Various functions of the vertex and link numbers may be used to specify the topologic properties of the network. A particularly useful function is the recombination factor, or ratio of number of junctions to number of forks. This ratio varies from zero from networks with no recombination to unify for braided streams. A detailed topologic study of the networks of five natural deltas Colville, Irrawaddy, Yukon, Niger, and Parana shows recombination factors ranging from 0.5 to 0.85. The frequency of different kinds of links can be explained reasonably well be a simple model that assumes random connection of vertices. The link lengths for a given network appear to belong to a common distribution and to depend relatively little on location with respect to the coast. The results on the Parana suggest that it should be considered as two deltas in tandem, each with its characteristic recombination factor.
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