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

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

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<strong>Chapter</strong> 3 · <strong>Decision</strong> <strong>Support</strong> <strong>Model</strong> (<strong>IUWS</strong>-<strong>DSM</strong>) 81<br />

Likewise, Figure 36 is an example showing the water usage of UD. Since the first option<br />

is almost the same as second one, it is skipped for simplifying the graph. The local sources<br />

(as loc.src.(UD)) are added into the third options because the reclaimed water anyway turns<br />

to the local water source through the indirect potable reuse. On the contrary, it is skipped in<br />

the fourth option of direct non-potable reuse in order to reduce the system complexity. As<br />

water reuse system can only be involved once, three options, i.e. directly reuse in WUU,<br />

indirect reuse in UD and direct reuse in UD, are mutually exclusive. In this example, the<br />

suface runoff utilisation is not considered in UD as it is utilised in CA.<br />

The graph already clearly shows different parts of water usage including demands, water<br />

source composition and discharged used water, as well as the relations in between. Thereby,<br />

the graph helps to make decision in the way of considering both water supply and used water<br />

management simultaneously.<br />

m 3 /d<br />

6000<br />

4000<br />

2000<br />

0<br />

-2000<br />

-4000<br />

WUU:<br />

ext.src.<br />

+rf.wa. +drct.<br />

reuse<br />

Water Usage of UD (as demonstration)<br />

+both WUU:<br />

ext.src.<br />

+rf.wa. WUU:<br />

ext.src.<br />

+rf.wa.<br />

UD: ext.src. (+loc.src.) UD: +indrct.reuse UD: +drct.reuse<br />

Scenario 1<br />

Figure 36: Water usage of UD (demonstration)<br />

drct.reuse (UD)<br />

indrct.reuse (UD)<br />

ext.src. (UD)<br />

loc.src. (UD)<br />

wa.demand (UD)<br />

used.wa.->disch.<br />

Up to CA, its water usage is the superimposition of its affiliated UDs and WUUs. In the<br />

same way, the required external source in UD is the water demand of CA (as wa.dmnd.(CA)<br />

in Figure 37. Meanwhile, for better revealing the relation between water demand and water<br />

sources, the water amounts of local sources of CA (as loc.src.(CA)) and surface runoff<br />

utilisation (as srfc.runoff(CA)) are presented in Figure 37. For representing the complicated<br />

situation, the local source of UD (as loc.src(UD)) is also involved and its covered water<br />

demand is correspondingly subtracted from CA. In actual projects, the situation is normally<br />

simpler than it in Figure 37.<br />

There are generally two situations in CA:<br />

1. combination of local source and indirect potable reuse; as CA: loc.src. + indrct.reuse<br />

2. combination of local source and external source. as CA: loc.src. + ext.src.<br />

Following the same rule, if water is indirect potable reused in CA, the reuse options in UD<br />

and WUU do not take place, whereby only two cases are in the first situation. If external<br />

sources (as ext.src.(CA)) is considered, all other options in UD and WUU can be involved

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