ISSUE 6
OCT-DEC 2004

Reduction of Network Losses

The current estimated level of network losses in Paros is in the range of 25% of the total supply. The option that was explored was a gradual reduction of losses from 25% to 15%, through successive network replacements. The application of this intervention was made on the assumption that internal network replacement will be gradually implemented in the different municipalities. First priority was given to the larger municipalities, Paroikia, Naoussa and Marpissa and secondary to the minor ones, Agairia, Arhilohos, Kostos and Leykes. The assigned scheduling of network replacements was made on the basis of demand size, current network status and observed deficits.

The process of network replacement has been estimated to last approximately 3 years, with an even distribution of costs throughout this time. The total cost of the option is presented in Table 1. In the case of the traditional settlements of Paroikia and Naoussa, where the internal distribution network is particularly old, extended and in some cases even undocumented, replacement may last up to 4 years.

Table 1. Network Replacement Costs

Municipal Department	Total Network Replacement Cost (€)
Paroikia	450,000
Naoussa	202,000
Marpissa	94,500
Arhilohos	51,000
Agairia	61,500
Leykes	133,500
Kostos	50,100
Total	1,042,600

Option results

Figure 1 presents the new demand for each municipal department under the BAU – Normal Scenario. Network replacements for Paroikia and Naoussa occur during the period 2005-2008, for Marpissa from 2005 to 2007 and for the other municipal departments in 2006, 2009 and 2012.

Scheduling of replacements does not differ much for the other two examined scenarios. The implementation of the option can be delayed in the smaller municipal departments with the exception of Kostos, whose boreholes are used to supply the department of Paroikia.

Figure 1. Domestic demand per municipal department
under the network loss reduction option (BAU + Normal scenario)

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Effectiveness

Reduction of losses through distribution network replacements shows a significant improvement in terms of both domestic and irrigation demand coverage. The reduction of losses results in improved efficiency in the supply of water towards the domestic use (Figure 2 and Figure 3). As with all measures targeted to promote conservation, some improvement in irrigation demand coverage is observed; this is due to the decline in domestic groundwater abstractions resulting in higher water availability for agricultural purposes (Figure 4 and Figure 5). Since no additional supply sources are introduced in the system, the effect of the option for both domestic and irrigation water use, decreases as domestic demand becomes higher due to population growth. This is not of course the case for the LD+HW scenario where, after 2015 demand stabilises. (Figure 3).

Figure 2. Percent demand coverage effectiveness of Reduction of Network Losses
to Domestic use

Figure 3. Percent Improvement of deficit in Domestic use
with respect to the reference scenarios

Figure 4. Percent demand coverage effectiveness of Reduction of Network Losses
to Irrigation use

Figure 5. Percent Improvement of deficit in Irrigation use
with respect to the reference scenarios

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Direct and Environmental Costs

Figure 6 presents the direct cost (expressed as the present value over the period 2004-2030) between the three scenarios after the implementation of the scheduled network replacements. An average reduction of direct costs of about 4% is common between all three scenarios. Additionally, in all three cases direct costs are smaller than those of the respective reference scenario, since the volume of water delivered to domestic uses is significantly lower. This reduction of annual operational costs adequately covers the expenses of the network replacements. The effect of the option is less significant under a high dry frequency; however the relatively low cost makes the measure a candidate for further examination during the strategy development phase.

Figure 6. Total direct cost difference of the Reduction of Network Losses option
under the three scenarios (Present Value – Million €)

As the introduction of network improvements does not directly affect the level of abstraction, the environmental costs within each scenario show no significant variation, with the exception of the LD+HW scenario, where the preferential abstraction from less vulnerable aquifers (possible only under high availability conditions) means an improvement in overall environmental performance (Figure 7).

Figure 7. Total environmental cost difference of the Reduction of Network Losses option
under the three scenarios (Present Value – Million €)

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