Chapter 3 : Reservoir models - KU Leuven

3.3.3 Other features
The reservoir modelling system Remuli is a Fortran 90 coded software program,
which is compiled into an executable file. The interface for the input and output is
an Excel-sheet using macro’s in Visual Basic. The reservoir modelling system Remuli
has an online manual, which is a file in html-format. This manual is included in
appendix B.1. More details on the possibilities can be found in this manual.
Simulations can be performed with single storms, i.e. composite storms as well as user
defined rainfall series. More important are the long term simulations, which can be
performed for the Uccle rainfall with a time step of 10 minutes for the period
1967-1993. In the future this rainfall period can be extended. It is also possible to
select short rainfall series from this historical rainfall series with the reservoir
modelling system as will be described in paragraph 4.3.
Reservoirs can be connected in series and parallel, not only via the throughflow,
but also via the overflow. This means that off-line storage basins in treatment plants
and at overflows can be modelled. Also the modelling of return pumps is
implemented. Return pumps can be used to empty a reservoir after a storm or can also
represent the flow through a flap valve. This type of connection can be used if the flow
is not determined by the reservoir from which the water is pumped, but by the volume
V in the reservoir where the water is pumped into. This is incorporated in the
continuity equation of the receiving reservoir :
dV
dt
= Qin + Qp − Qthrough
(3.17)
Q
p
V
= Qpm
−
V
Q pm
(3.18)
m
The relationship for the pumped discharge Q p (Q pm is the maximum pump capacity)
can be piecewise linear, using the ranges of storage of the reservoir in which the water
is pumped. The pumped discharge has to decrease monotonously with increasing
storage in the receiving reservoir. For every time step it is checked if the volume
that can be pumped is available in the reservoir where the water is pumped from.
Using the possibilities on the modelling of reservoirs and return pumps even the
hydraulic behaviour of a treatment plant can be modelled as is shown in figure 3.30
for the sewer system and treatment plant of Dessel. The modelling of very complex
systems becomes possible, but it is rarely necessary to model it in such a detailed way.
The extremely simplified model in figure 3.27 for the same system already gives very
good results.
Chapter 3 : Reservoir models 3.33