Sedimentology and hydrogeology of two braided stream deposits

Two approaches were used to quantify the spatial distribution of hydrofacies in braided stream deposits. One approach involved mapping a 50 by 60 by 3.3 m section of a proximal braided stream deposit. In a second study, we generated a 400 by 400 by 2.6 m section of a medial braided stream deposit using a computer model. In both cases we produced three-dimensional images showing connected hydrofacies with high permeabilities that form preferential flow paths. This information was input to a groundwater flow model and flow paths were analyzed by following the transport of imaginary particles. In both systems, particles that were uniformly distributed at the up-gradient end of the model clustered dong preferential flow paths during transport, showing that connection among high-permeability facies is a critical factor in hydrogeological investigations involving assessment of contaminant movement and remediation. (C) 1999 Elsevier Science B.V. All rights reserved.