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ENHANCED STREAM WATER QUALITY MODEL (QUAL2EU)
Description:
The enhanced stream water quality model QUAL2E and QUAL2E-UNCAS (37) permits simulation of several water quality constituents in a branching stream system using a finite difference solution to the one-dimensional advective-dispersive mass transport and reaction equation. The conceptual representation of a stream used in the QUAL2E formulation is a stream reach that has been divided into a number of subreaches or computational elements equivalent to finite differences. For each computational element, a hydrologic balance in terms of flow (q), a heat balance in terms of temperature (t), and a materials balance in terms of concentration (c) is written. Both advective and dispersive transports are considered in the materials balance. Mass can be gained or lost from the element by transport processes, external sources and sinks (e.g., Waste discharges or withdrawals) or by internal sources and sinks (e.g., Benthic sources or biological transformations). The equation is solved for the steady flow, steady state condition in a classical implicit backward difference method. The specific equations and solution technique are described in detail in the QUAL2E computer program documentation.