Chapter 3 Decision Support Model (IUWS-DSM) - Tubdok

24 New Conception and Decision Support Model for IUWS
In storm water systems, the storage has the functions of limiting flooding and reducing
the amount of polluted storm flow discharged into a watercourse (Butler and Davies 2000).
The storm water storage can be in many different forms, such as on-site storage, i.e. storm
water is retained locally in buried tanks or surface ponds (Butler and Davies 2000), and
larger scale urban watercourse storage (Hall et al. 1993).
Valves and gates. In water distribution systems, valves fulfil three main tasks: regulating
flow and/or pressure, excluding the parts of the networks in the emergency or maintenance
situations, and protecting reservoirs and pumps (Trifunovic 2006). In sewerage systems, the
flow is controlled by different devices, such as orifice plate, penstock, vortex regulator,
throttle pipe and flap valve. As the important and costly apparatuses, they are included.
In addition, the vehicles can also be the suitable transport method, especially for solid
substances and liquid materials having small volume but with high substance contents, such
as the solids and sludge after treatment, the digested blackwater and the pure urine.
2.1.4.4 water fixtures
Water fixtures are the terminals connecting water and end uses. Improving the efficiency
of water fixtures is one of the most efficient and simple ways to save water. Typical example
is the toilet flushing devices. The new models consume water about 4 to 6 litres per flushing,
where the old type can reach 15 litres each flushing (NCDENR 1998). Meanwhile, the
modern toilet flushing devices have two buttons as one is for urinating and another is for
defecating, so that even less water is consumed for urinating. Thus, using water saving
fixtures shall be always considered and performed in the first place. In this conception, water
fixtures are not direct manifested, but the effects can be involved by managing the water
usage of water end-users.
All above mentioned facilities and structures (except for water fixtures) are taken into
account in IUWS, and their cost and energy consumption are calculated.
2.2 Subsystems
As discussed in § 2.1.2, the urban water systems consist of five subsystems that have
their individual system options and planning processes. Figure 11 is the general view of
structure and processes for determining each subsystem. The planning steps in Figure 11
have two tasks, i.e. information management, and infrastructure calculation. The information
refers to the essential planning data that are used to determine and optimise the water usage
and system scales. The task of infrastructure calculation is to determine the water system
options and calculate the system cost and energy consumption. All processes for each
subsystem work independently and are integrated together and applied to IUWS in the
hierarchy later on.
The subsystem of used water consists of two streams, i.e. water and matter, where the
stream of matter is particularly set up for the blackwater. As the solid substance, also as the
hygienic dangerous material, the human beings excrement should be isolated from the water
cycle. Hence, the blackwater system is designed as an independent system. The subsystem