In steady-state mass balance analysis, the reservoir can be modeled as having
inflows from the canals, Q,,, and outflow, Qout, which are aggregates of the daily inflows,
and outflows, and precipitation, P. A parameter of concern is assumed to enter at a
constant concentration for each inflow, C,,, and from precipitation, Cp. The pollutant is
removed as a function of detention time, td, initial concentration, C,,, and reaction rate,
kv. The pollutant exits the reactor to the surrounding system in the outflow at a
calculated concentration, Cout. The conceptual view of the mass balance (Figure 4-1) and
mathematical equation (Eqn. 4-1) also uses the concentration in each plug of water in the
reactor (C), the depth (D), and the area (A).
P
CP
10~ Reactor D
Qm A Qout
Cn Cout
Figure 4-1. Block Mass-Flow Diagram of Modeled EAASR
Q,,, C,, =Vxk, x C +Q,,, xC,, P x Cp (4-1)
Water Quantity Characterization
The water quantity characterization of the model is based on a volume balance of
the system. The volume balance of the system is represented by the total inflows minus
the total outflows equaling the change in storage (AS/At). From the reservoir alternatives
data provided by the IMC, the total inflows and outflows of the system are represented as
rainfall (P), inflows (Q,,), groundwater inflows and outflow (GWI and GWo), ET, and
outflows (Qout) (Eqn. 4-2). The change in storage per unit time, AS/At, is documented in
the SFWMM by the stage or depth of the reservoir.