A bottom-up approach of stochastic demand allocation in a hydraulic network model: a sensitivity study of model parameters

“An ‘‘all pipes’’ hydraulic model of a drinking water distribution system was constructed with a
bottom-up approach of demand allocation. This means that each individual home is represented
by one demand node with its own stochastic water demand pattern. These water demand
patterns were constructed with the end-use model SIMDEUM. A sensitivity test with respect to
the resulting residence times was performed for several model parameters: time step, spatial
aggregation, spatial correlation, demand pattern and number of simulation runs. The bottom-up
approach of demand allocation was also compared to the conventional top-down approach,
i.e. a single demand multiplier pattern is allocated to all demand nodes with the base
demand to account for the average water demand on that node. The models were compared
to measured flows and residence times in a small network. The study showed that the
bottom-up approach leads to realistic water demand patterns and residence times, without
the need for any flow measurements. The stochastic approach of hydraulic modelling,
with a 15 minute time step, some spatial aggregation and 10 simulation runs, gives insight
into the variability of residence times as an added feature beyond the conventional way
of modelling.”

(Citaat: Blokker, E.J.M., Beverloo, H., etal. – A bottom-up approach of stochastic demand allocation in a hydraulic network model: a sensitivity study of model parameters – Journal of Hydroinformatics 13(2011)4, p.714-728 – Open Access)