Résumé
Countries near the southern borders of the Mediterranean have to pace with an imbalance between supply and demand of water: they face high population growth and thus continued growth in water demand. Further amplifying the problem, is that expanding the availability of water resources is not guaranteed (insufficient renewable water resources, unequally distributed resources even within territories, shared resources between several countries, inaccessible water resources). This situation has resulted so far mainly by mobilizing additional water: renewable resources are overexploited, non-renewable resources are depleted, and some countries are resorting to seawater. This water supply management can be expensive, due to the technology required and also in the long term when a nonrenewable resource is not optimally exploited. It must therefore be accompanied by water demand management, while making allowance for poverty level when the objective is to ensure a water access for all. The aim of this communication is to review the state of water demand and tool available to manage it. Water demand in the sub-region is characterized by a rate of drinking water often comprehensive in urban areas and a coverage rate for sanitation often disparate: in Egypt, Israel, Lebanon and Turkey, access to drinking water is almost universal in both urban and rural areas and sanitation coverage is greater than 90%; in Jordan, Tunisia and Morocco, drinking water access is almost universal in urban areas but less developed in rural areas; for 3 Algeria, the Palestinian Territories and Syria (situation prior to the Civil War) water and sanitation coverage are not universal but between 80 and 90%. The most recently observed monthly water consumption range from 7 to 14 m³ per household for all countries (end of 1990’s, 2000’s). In Tunisia, Morocco and Algeria, several studies report a fall in unit consumption of households connected to the water supply network. Expressed in terms of daily consumption per capita, consumptions in Morocco and Tunisia appear among the lowest values in the sub-region, those in Israel are the highest (where the standard of living is also the highest), as well as in Lebanon and Egypt, where tariff policy give very few incentive to save water. Different water demand management policies are implemented and the oldest one is pricing policy. The review of pricing policies in the sub-region produced the following observations: There is a great heterogeneity in tariff structures applied. The bill is mostly calculated according to metered water, and, most often, sanitation is integrated with the water bill. The most common rate base is binomial (a fixed part and a variable part). Jerusalem is currently applying the most incentive to water saving tariff grid with a very high initial price (3,07 US$/m³ for 10 m³). It is followed by Istanbul’s tariff grid for which the application of a high initial price (1,09 US$/m³ for 10 m³) is combined with a high tariff escalation. The least incentive pricing is that of Lebanon with an annual packaged fixed price. The tariff grid in force in Tunisia is among the least incentive: high tariff escalation does not compensate for the low level of initial price (0,38 US$/m³ for 10 m³) compared to other countries. Morocco is meanwhile in the average of regional practices (from 0,75 up to 0,91 US$/m³ for 10m³). One indicator of the impact of tariff policy on water consumption is given by the price elasticity measuring the change in demand due to a change in price. A dozen studies about water demand in the sub-region, giving data from 1980 to 2008, report price elasticity values ranging from -0.2 to -0.8 (with some outliers). They are slightly higher than those observed in developing countries, which in most cases range between -0.3 and -0.6 for private connections - data from a meta-analysis conducted by Nauges & Whittington (2009). The heterogeneity of tariff structures, even the novelty in comparison with the countries of the northern shore of the Mediterranean, are contrasted with the slow evolution of pricing policies in each country. This inertia is probably due to the sensitivity of water price, from a social and political point of view, since water is an essential commodity. Thus, given the significant issues in the region, other tools could be used to encourage water conservation: they may be technical (counting and network performance improvement), or institutional and regulatory (awareness campaigns, rationing, reuse of treated wastewater for irrigation).