A GENERAL OVERVIEW OF SPANISH ARTIFICIAL RECHARGE OF GROUNDWATER EXPERIENCES. THE ROLE OF IGME, THE SPANISH GEOLOGICAL SURVEY, IN ARTIFICIAL RECHARGE IN SPAIN

INTRODUCTION.

Artificial recharge of groundwater has had a little development in Spain, for various reasons. The most significant of these is the priority given, for many years, to the construction of surface reservoirs and dams. Nevertheless, several promising recharge projects have been developed. In modern times, artificial recharge of aquifers was first carried out in the early 1950s, in Catalonia, by the Barcelona Water Company. Using wells and scarification of the riverbed, the mean annual water recharged was 7.7 Mm3. In the middle 1980s, the Spanish Geological Survey (IGME) put into operation projects in Guadix, in the Esgueva Valley, in the Oja Valley, and in Vergel (Alicante). For the future, more than 35 new artifical recharge projects have been planned by the Spanish water authorities all over the country, involving an amount of more than 300 Mm3/year of recharged water.

ARTIFICIAL RECHARGE IN ALLUVIAL AQUIFERS.

a) The flood plain of the Oja river (La Rioja). The artificial recharge plant consists of 3 ponds and 10 km of canals. Water recharged came from winter surplus of the Oja river. The volume of water infiltrated in the plant varied from 2.5-5 Mm3/year.

b) The rio Verde-Guadix plain (Granada). Artificial recharge plant consisted of six ponds with a total infiltration surface area of 11,500 m2. Water came from the drainage of a mine. The average volume infiltrated was 17,400 m3/day. The initial infiltration capacity was 3 m/day, although it decreased to 0.65 m/day over a 10-year period.

c) The alluvial aquifer of Girona river, Vergel (Alicante) Recharge is currently made through large diameter wells with deep-level horizontal galleries. Recharge water comes from Girona river surplus. The recharged volume is estimated in 1.55 Mm3 per year. Till now, clogging has not been a problem. New wells are planned to be put into operation next months in order to increase the rechaged volume and the aquifer's available water.

ARTIFICIAL RECHARGE IN LIMESTONE AQUIFERS.

Only a few experiences have been put into operation in this kind of aquifers. The Carmona calcarenitic aquifer (Seville) is recharged using an infiltration pond, a sedimentation pond, and also a well 9.5 m deep and 1.2 m diameter. Recharge water comes from suspluses of the Guadalquivir river. Other tests have been done in several limestone aquifers of Jaen province.