Water is essential for life. It maintains the functions of organisms and ecosystems, is the building block of living organisms, the means for transporting material in the environment and facilitates the flow of energy through oceanic and atmospheric circulations. It is also necessary for food production, personal hygiene and other needs of the human population, industrial production and fisheries. Rivers, lakes and ecosystems adjacent to water bodies also provide services including flood control, transport for people and goods, leisure, purification of municipal and industrial wastewater, power generation, and provide habitat for aquatic plants and animals (Jackson et al., 2001; Baron et al., 2002; UN-WWAP, 2006).
Water is considered a renewable resource that could be used without affecting its long-term availability (Gleick, 1998). However, several global organizations have pointed out that fresh water availability and access are critical issues to address in the coming years. Although water is abundant on our planet, only about 2.5 percent is freshwater; of this, nearly two-thirds is "trapped" in glaciers and permanent ice caps, making it inaccessible for use.
The challenges to face in this regard are related to health, supply to cities, environmental protection, food, industry and energy. The main challenge is to achieve a balance that preserves aquatic ecosystems and their valuable environmental services, while supplying good-quality water to both human populations and productive activities (WRI, 1999; Revenga et al., 2000; UN-WWAP, 2006; PNUMA, 2004).
Water policies and management are essential for sustainable development (Carabias and Landa in Painting and Osorno, 2006). For planning and management of water resources to be truly effective, information encompassing all aspects of the hydrological cycle and widely available to stakeholders is required (Gleick, 1998).
This chapter shows the indicators chosen for describing the situation of water resources, in terms of availability and quality. It is divided into two sections. The first one includes indicators that display the pressures on water availability for different uses, the state of these and actions taken to preserve this resource for the future. The second section deals with water quality issues, the quality-stressing factors, the condition of the country's water bodies and the actions taken to halt their deterioration and, eventually, to allow their recovery.
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Carabias, J. y R. Landa. Agua y Medio Ambiente. En: Pintado L. y G. Osorno (Eds.). Agua, usos, abusos, problemas, soluciones. Edit. Mapas. México, D.F. 2006.
Gleick, P. H. Water in Crisis: Paths to sustainable water use. Ecological Applications8: 571-579. 1998.
Jackson, R. B., S. R. Carpenter, C.N. Dahm, D. M. McKnight, R. J. Naiman, S. L. Postel y S. W. Running. 2001. Water in a Changing World. Issues in Ecology. No. 9. PNUMA. GEO. Anuario 2003. Nueva York. 2004.
Pintado L. y G. Osorno (Eds.). Agua, usos, abusos, problemas, soluciones. Edit. Mapas. México, D.F. 2006.
PNUMA. GEO. Anuario 2003. Nueva York. 2004.
Revenga, C., J. Brunner, N. Henninger, R. Payne, y K. Kassem. Pilot analysis of global ecosystems: Freshwater systems. WRI. Washington, D.C. 2000.
UN-WWAP. Water a shared responsibility. The United Nations World Water Development Report 2. UNESCO. 2006
WRI. Water: Critical shortages ahead? En WRI, UNEP, UNDP, and WB., World Resources 1998-99: Environmental change and human health. 1999. p.188-193. Disponible en: http://pubs.wri.org/pubs_content_text.cfm?ContentID=1030. Fecha de consulta: 30-10-2012.