Chapter 3 : Reservoir models - KU Leuven

1.2
throughflow (m 3 /s)
1
0.8
0.6
0.4
0.2
0
hydrodynamic model
dynamic reservoir model
0 1000 2000 3000 4000 5000 6000 7000
storage (m 3 )
Figure 3.16 : Storage/throughflow-relationship for the sewer system
of Dessel when the dynamic storage is included
for a composite storm that will just lead to an overflow event.
3.2.3.4 Extra storage during the overflow event
During the overflow event the water will rise above the crest level. In some cases this
increasing water level can lead to significant extra backwater effects, which results in
increased storage in the system. This storage above the crest level can be defined as
dynamic storage as is shown in figure 3.14, but it is difficult to link this dynamic
storage unambiguously to the inflow as proposed in paragraph 3.2.3.2. Therefore, it
is better to define an extra storage above the crest level as the storage between a
horizontal plane at the crest level and a horizontal plane at the maximum water
level above the crest of the overflow (figure 3.17). In that definition the dynamic
storage is only the part above the horizontal plane at the maximum water level
above the crest of the overflow. Again, this is an artificial division, but these three
components can be recognised in the system behaviour.
This extra (static) storage above the weir can be assumed to be a function of the
overflow discharge. For a free overflow the relationship between discharge Q and
water level h above the crest is a non-linear function [Berlamont, 1996] :
(3.1)
This relationship may be the case for a storage basin (figure 3.18).
Chapter 3 : Reservoir models 3.17