Implementation plan for the National Water-Quality Assessment Program
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Open-File Report↗
Geology topics
D.S. Knopman
Publications and source records attributed to D.S. Knopman.
Factors related to the water-yielding potential of rocks in the Piedmont and Valley and Ridge provinces of Pennsylvania
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Water-Resources Investigations Report↗
Analytically-derived sensitivities in one-dimensional models of solute transport in porous media
Analytically-derived sensitivities are presented for parameters in one-dimensional models of solute transport in porous media. Sensitivities were derived by direct differentiation of closed form solutions for each of the odel, and by a time integral method for two of the models. Models are based on the advection-dispersion equation and include adsorption and first-order chemical decay. Boundary conditions considered are: a constant step input of solute, constant flux input of solute, and exponentially decaying input of solute at the upstream boundary. A zero flux is assumed at the downstream boundary. Initial conditions include a constant and spatially varying distribution of solute. One model simulates the mixing of solute in an observation well from individual layers in a multilayer aquifer system. Computer programs produce output files compatible with graphics software in which sensitivities are plotted as a function of either time or space. (USGS)
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