Abstract:
One-Dimensional Transport With Inflow and Storage (OTIS) is a mathematical
simulation model used to characterize the fate and transport of water-borne
solutes in streams and rivers. The governing equation underlying the model is
the advection-dispersion equation with additional terms to account for
transient storage, lateral inflow, first-order decay and sorption. This
equation and the associated
... equations describing transient storage and sorption
are solved using a Crank-Nicolson finite difference solution.
OTIS may be used in conjunction with data from field-scale tracer experiments
to quantify the hydrologic parameters affecting solute transport. This
application typically involves a trial-and-error approach wherein parameter
estimates are adjusted to obtain an acceptable match between simulated and
measured tracer concentrations. Additional applications include analyses of
nonconservative solutes that are subject to sorption processes and/or
first-order decay.
A modified version of OTIS, OTIS-P, couples the solution of the governing
equation with a nonlinear regression package. OTIS-P determines an 'optimal'
set of parameter estimates that minimize the squared differences between the
simulated and measured concentrations, thereby automating the parameter
estimation process.
The OTIS solute transport model and related materials (data and documentation)
are made available by the U.S. Geological Survey (USGS) to be used in the
public interest and the advancement of science. You may, without any fee or
cost, use, copy, modify, or distribute this software, and any derivative works
thereof, and its supporting documentation, subject to the USGS software User's
Rights Notice.
Funding for software development was provided by the USGS Toxic Substances
Hydrology Program and the USGS Office of Water Quality.
[Summary provided by the USGS.] 
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