Groundwater management and nuclear applications for the northeast: how they can improve life quality in urban environment?

The groundwater has earned more importance in the last decades, due to growing demands, contamination, wasteful use and depletion of superficial sources. In Brazil, one of the regions with more intensive use of groundwater for urban populations supply is the North-eastern Coast. The hydrogeological province of Northeast Coast is formed by three aquifer systems located in sedimentary basins: Potiguar-Recife, Alagoas- Sergipe and Jatoba-Tucano-Reconcavo. Coastal aquifers are usually very sensitive to changes in hydraulic head and fluxes. The over exploitation, above the levels of natural recharge, cause risk of aquifer salinization by marine intrusion. Several wells have showed increasing values of dissolved salts along the last few years, and in some cases they were closed. In that context, some nuclear techniques have been used with great success. Like mentioned above, the use of isotopes (e.g. 2H, 3H, 3He, 18O, 13C, 14C, 15N, 34S, 36Cl, 222Rn, 234U) allow to determine recharge and discharge rates, the ionic strength flux and map the salinization path, giving valuable information for water use management. Other contribution from nuclear technology to coastal urban centres is the seawater desalination. The contracted capacity of nuclear desalination plants has increased steadily since 1965 and is now about 32.4 million m3/d worldwide. In Brazil, the nuclear desalination has begun to be evaluated by studies leaded by government companies and agencies. So, these nuclear applications together with a public system for water management can contribute to solve the main problems of the region, i.e. costly water supply, energy lack and environmental degradation. (author)