Summary This article characterizes the societal metabolism of the Colombian economy, identifying the main factors of natural resources use, overuse, or exhaustion. The environmental sustainability of a country depends to a large extent on the size of the economy compared to the available resource base. Material flow indicators provide an assessment of size or scale of economies. Direct material flow indicators are used to analyze the ecological dimension of economic activity in the period 1970–2007. Some resource extraction conflicts are briefly described in the light of material flow analysis. Foreign and domestic demand promotes increasing extraction and export of domestic natural resources. This is sometimes related to an irreversible deterioration of the local environment. The concept of “ecologically unequal exchange” with the rest of the world is analyzed in this context. Colombia has a large and growing negative physical trade balance, whereas per capita use of materials is still about half of the industrial countries’ average.

The current model of water resources management in Brazil is decentralized, participative and integrated, and adopted the river basin as a planning unit. It is based on the performance of watershed committees; each committee has its own composition and rules of procedure, governed by its statute. The basic principles of this management have been established by the Brazilian Constitution of 1988 and detailed by the National Water Resources Policy in 1997. At the State level, São Paulo enacted its water resources policy in 1991. This paper examined the participatory process in basin committees of the São Paulo State and its implications in the implementation of the instruments of water management, based in a case study of the Tiete - Jacaré Watershed Committee, using questionnaires filled by the Committee’s members (2009 - 2011). Engagement and integration among the stakeholders was observed. Still, the interviews’ results have shown that the Committee’s statute should be reviewed due to differences between the Federal and the State legislation, mainly regarding the participating sectors and representatives. It also showed a need for more information about water resource issues in this basin and in the State of São Paulo, as a whole. At the same time, it is recommended that representativeness of the institutions within the water council management be improved and that the work produced by the technical chambers be recognised at the committee decision-making level

The pisciculture sector in Colombia, has grown 13% annually between 1988 and 2013, and it is the sixth major water user. Considering the influence that pisciculture has over the water resources, the water footprint of pisciculture was studied as a sustainability indicator, a method was developed to estimate the water footprint of the sector, which include not only the direct and indirect components, but also the green, blue and grey water footprint. The method was applied to the three most produced species in the country: tilapia (Oreochromis mossambicus), cachama (Piaractus brachypomus) and trout (Oncorhynchus mykiss), to corresponding case studies in Valle del Cauca, Colombia. It was found that the water footprint of tilapia culture is 5,486 m 3 /Ton, cachama culture is 6,193 m 3 /Ton, and trout culture is 19,854 m 3 /Ton. The highest total water footprint for tilapia was that of the concentrated feed, followed by the blue water footprint, associated with the amount of water that remains stored in the ponds, whereas for the cachama and trout, the highest water footprint was grey, due to the high concentrations of solids and nutrients present in fish excretions and unconsumed feed.Keywords: Method, pisciculture, sustainability, water footprint, water resources. ResumenEl sector piscícola en Colombia creció en promedio 13% anual de 1988 a 2013 y es el sexto mayor usuario de agua en el país. Considerando la presión que ejerce la producción piscícola sobre las fuentes de agua, se estudió la huella hídrica (HH) de la piscicultura como un indicador de sostenibilidad. Para ello se desarrolló una metodología que mide la HH en el sector, que incluye sus componentes directos e indirectos, así como las huellas hídricas verde, azul y gris. La metodología se aplicó a las tres especies piscícolas más producidas en el país: tilapia (Oreochromis mossambicus), cachama (Piaractus brachypomus) y trucha (Oncorhynchus mykiss), para sendos casos de estudio en el Valle del Cauca, Colombia. Se encontró que la HH total del cultivo de tilapia es de 5,486 m 3 /Ton, la del cultivo de cachama de 6,193 m 3 /Ton y la del cultivo de trucha de 19,854 m 3 /Ton. La huella hídrica total más alta para la tilapia fue la del alimento concentrado, seguida por la huella hídrica azul, asociada a la cantidad de agua que permanece almacenada en los estanques; en la cachama y trucha la mayor huella hídrica total fue la gris, relacionada con las altas concentraciones de sólidos y nutrientes, presentes en las excretas de los peces y en el alimento concentrado no consumido.

Brazil and Colombia are rich in terms of water supply, ranking as world leaders in the supply of water resources. Despite this, both countries have problems of relative scarcity of this vital liquid in highly populated areas with much economic activity. Establishing policies and legal environmental standards has long tradition in both countries. However, although there are provisions and instruments for water management at the water basin level, these do not necessarily follow the conceptual development of integrated water resources management (IWRM). As a result, the two countries have partially implemented IWRM elements but with different characteristics both in its structure and instrumentality. In Colombia the State Government, through the Regional Environmental Corporations, implements IWRM (concessions, fee for water use, pollution rate, basin plans, etc), with no formal involvement of civil society management. In Brazil, however, IWRM management structure and tools are decentralized and participatory, as are the Water Basin Committees, entities where the State Government, municipalities and users participate, those with the greatest weight in water management. In Brazil, however, this model is not yet implemented in all watersheds. Thus, the aim of this paper is to compare the institutional and legal aspects of water management models in Brazil and Colombia with regard to the integrated water management concept. For the latter, we worked with a case study for each country regarding Nima River watershed (Colombia) and Tietê Jacaré (Brazil)

Este texto tiene como propósito desarrollar una discusión conceptual sobre el tema del desarrollo sostenible desde las perspectivas de la sostenibili- dad débil y la sostenibilidad fuerte, que permita hacer recomendaciones para la operacionalización de este concepto en Colombia. El ensayo parte de una revisión histórica de las relaciones entre desarrollo y ambiente en el siglo XX; posteriormente se aborda el tema central del ensayo que corresponde a la discusión entre sostenibilidad débil y fuerte. Con base en este punto, se plantea una propuesta concep- tual para operacionalizar este concepto en el país. Finalmente se entregan las conclusiones del deba- te en términos de recomendaciones de política.