Marina Herrera-Pantoja Queretaro Water Commission. Querétaro Av. 5 de Febrero No. 35, Col. Las Campanas CP 76010 México hpmarina@yahoo.com Abstract The Central and northern regions of Mexico receive less than 20% of Mexico’s precipitation, however they contain 77% of the population and generate 87% of the Gross Domestic Product (GDP) of the country (INEGI, 2005). […]