Etudes de valeurs de référence pour l'indice linéaire de pertes dans le cas des services ruraux de distribution d'eau potable
| Autor: | Eddy Renaud, Bernard Brémond, Poulton, M. |
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| Přispěvatelé: | Réseaux épuration et qualité des eaux (UR REBX), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Irstea Publications, Migration |
| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | WATER LOSS 2007 Bucarest, ROM WATER LOSS 2007 Bucarest, ROM, 2007, pp.9 HAL |
| Popis: | In France, the main indicator used to quantify the evolution of leakage levels in water distribution systems is the Linear Losses Index (LLI), which has been defined and recommended by governmental environment agencies [1], thus (using IWA terminology [2]): LLI (m3/km/day) = distribution input (A11) metered consumption (A13 + A16) 365* Mains length (C6) In order to make a preliminary estimate of the potential for reducing leakage in a network, it is necessary to define reference values for LLI. Literature values tend to reflect the character of the network, either "rural" or "urban". However, it is evident that there will be disparities in the values, depending on the perception of whether a network is rural or urban and to what degree. The French Ministry of Agriculture provides access to decentralised services for the management of public water distribution systems in rural areas. The data gathered by these organisations are validated by means of a purpose-built computer system. An investigation was carried out by a collection of directorates from various Départements (French counties), with data from 2000 rural water suppliers being made available. The data covered different time periods with 2004 being the most recent year of available data. The main data collected were: Annual volume produced, imported and exported Annual volume consumed Number of consumers Network lengths In total, more than 15000 LLI values could be calculated. The study provided evidence of the unsuitability of IWA's reference values when used to determine unavoidable annual real losses in the case of rural networks [3]. It is shown that for services with a low consumer density that the linear loss index derived from the calculation of unavoidable annual real losses using the reference values is greater than the actual values. At the same time the different reference values used in France by the large water companies and institutes (water basin agencies) to judge the acceptable level of leakage have been studied. These references are on each occasion determined with consideration to the rural or urban nature of the network. The criterion used to determine the character is either the density of consumers (number per km) or the linear index of consummation (volume consumed per km per day). The comparison also shows a trend of overestimation for extensive networks when real data are compared to reference values. A practical application of the results obtained in the study has been realised in the Département of Gironde in the South West of France. The main water resource in this region is from deep groundwater resources. These are generally over-exploited and a general decrease in the piezometric head is observed. To counter this situation, the public agencies have implemented a scheme for managing the distribution cycle with the reduction of abstraction from theses deep resources being the primary objective. One of the important steps in water economy is the reduction of losses in water distribution systems. Investigations lead by Cemagref have progressed in quantifying potential reductions in water loss and to prioritise the battle against leaks in the hierarchy of water distribution management. |
| Databáze: | OpenAIRE |
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