the present water crisis has many components of an environmental, economic and social origin: overuses of water, pollution, changes in availability, and water mismanagement are some of the current problems. to cope with these problems and enhance strategies for long term management, the following programs and approaches are presented: a) a watershed approach, integrating research, monitoring, data base and management; b) an improved water governance system based on participation of stakeholders and the public and private sector; c) strategic studies considering water and the economy, water and metropolitan regions, water and energy; d) a framework for international cooperation on shared watersheds; e) an economic evaluation of water resources services (surface and underground, lakes, rivers and reservoirs). f) a capacity building program for managers, with an integrated, predictive and hydrographic basin approach.

Neste trabalho, discutem-se os problemas relacionados com os impactos na quantidade e qualidade de água e os principais avanços recentes referentes à organização institucional e à legislação no Brasil e no exterior, e apresentam-se idéias e realizações de projetos de longo alcance com repercussão futura na gestão das águas.

This paper describes and discusses the impacts of the passage of cold fronts on the vertical structure of the Carlos Botelho (Lobo-Broa) Reservoir as demonstrated by changes in physical, chemical, and biological variables. The data were obtained with a continuous system measuring 9 variables in vertical profiles in the deepest point of the reservoir (12 m) coupled with climatological information and satellite images, during a 32-day period in July and August, 2003. During periods of incidence of cold fronts the reservoir presented vertical mixing. After the dissipation of the cold fronts a period of stability followed with thermal, chemical, and biological (chlorophyll-a) stratification. Climatological data obtained during the cold front passage showed lower air temperature, higher wind speed and lower solar radiation. The response of this reservoir can exemplify a generalized process in all shallow reservoirs in the Southeast Brazil and could have several implications for management, particularly in relation to the phytoplankton population dynamics and development of cyanobacterial blooms. Using this as a basis, a predictive model will be developed with the aim of advancing management strategies specially for the drinking water reservoirs of the Metropolitan Region of São Paulo.

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