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The model was developed to simulate self-purification mechanisms that occur in
a small stream heavely polluted by an organic load. As the main detritical
processes that occur in small streams take place in the sediment, the model
was applied to simulate the dynamics of both dissolved organic matter and
benthic microorganisms. The physical part of the model included a
hydrodynamical component derived from Saint-Venant`s equations, coupled to a
transport model based on a convection-dispersion equation under uniform,
unsteady flow conditions. The simulation of the biodegradation machanisms was
based on biofilm kinetics. The linkage between hydrophysical and benthic
mechanisms affords a dynamic description of the system. Transport modeling
provides a picture in space and time of the evelution of organic carbon
concentration in water. This evolution makes it possible to predict the fate
of the benthic biological component. The main characteristics of the model
STATE VARIABLES: cross sectional area, discharge, organic substrate in the flow, biofilm, organic substrate, microbial biofilm biomass.
FORCING FUNCTION: temperature, tributary inputs.
MAIN PARAMETERS: disperson coefficient, transfer velocity at the interface, biofilm shearing rate, maximum growth rate, bacterial decay rate, half saturation coefficient, biofilm cellular density.
INPUTS: Stream length, geometric description of the stream, time series of the discharge at the point x=0, time series of the organic load at x=0.
The purpose of the model was twofold: (i) to simulate the self-purification mechanisms in a lotic ecosystem and more generally, organic matter decomposition processes; (ii) to couple the two approaches which are commonly used in aquatic modeling, the transport oriented and the ecology oriented approaches.
Source of the Abstract:
Joergensen S.E., B. Halling-Soerensen and S.N Nielsen (Edts.) 1996: Handbook of Environmental and Ecological Modelling. CRC Press Boca Raton et al. 672 pp.