SANZ Eugenio ( ) Departamento de Ingeniería y Morfología del Terreno. Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos. Madrid. Spain. U.P.M. Ciudad Universitaria, s/n. 28040-Madrid. email@example.com
INTRODUCTION AND PURPOSE: According to the figures presented by Achttiemble (1987), Spain is one of the countries in Europe that makes least use of groundwater for town supply; only about 30% of the population is supplied from this source. A simplistic view might underestimate the importance of groundwater in Spain, apart from the special value of this resource in the island and Mediterranean regions. Groundwater is seen, however, as the best water resource for town supply. Aquifers in Spain extend over about 35% of the country and it is estimated that 25% of them could supply large exploitations (ITGE, 1989). The recent years of drought have shown the instability of a large number of surface supplies in comparison with the more regular groundwater flow, less susceptible to climatic changes. Some of these supply systems have been able to avoid water restrictions by emergency drilling of wells or because they had a complementary supply from groundwater. A good proportion of these aquifers provide water of high quality as is shown by the use that is made by the thousands of wells and springs throughout the country. Here we examine the importance of groundwater for small towns and villages in Spain. Spanish statistics for the use of water have not been drawn up systematically by any official department; available estimates made and published sporadically, have been made either by individual investigators or by the government, so there are no reliable official figures since those available are based on extrapolations which are still clearly inadequate. The recent study made by the Ministry of Public Administration , CEDEX (2001) and A.E.A.A.S. of use of water supplies to towns with populations of over 50,000 and those with fewer than 20,000 should be extended to cover the use of water in industry and in agriculture. The following organisations and authors have published reports on this subject: Organización Sindical Española (1975), Llamas et al (1976), IGME (1981), Llamas (1983), Iglesias López (1985), Sánchez Guzmán (1983), and Sanz (1995) A.E.A.A.S. (1987, 1990, 2002) CEDEX (2001). An inquiry was made by the Ministry of Public Administration in 1995 into the level of infrastructure and equipment in use in a wide rural zone, defined as the group of townships with a population below 20,000. From this wide survey, data can be taken on withdrawal and supply for comparison with similar data collected by the Spanish Association of Water Supply and Sewage (AEAAS) (1987, 1990, 2002) and covering the 283 towns whose population is over The results are considered in three sections: the first examines the nation-wide figures and the different types of withdrawal (Fig. 1) (CEDEX, 2001); the other two consider the differences among communities of different sizes and among the hydrographic basins (Figs. 2, 3). The differences between the autonomous regions are studied by Sanz (1995). In the classification by population size the uses of the water are not recorded.