GEO-6 Regional Assessment for Latin America and the Caribbean
More than 80 per cent of freshwater available for downstream populations and ecosystems in the semi-arid tropics and sub-tropics originates in mountains (UNEP 2013b). Glaciers partly contribute to the water that travels down the western slope of the Andes, supplying coastal regions with water, mostly during the dry season (Chevallier et al. 2011). Therefore, reduction in glacier size will affect availability of water downstream (Vuille et al. 2008). For example, glacier retreat in the area surrounding the Shallap, Tararhua and Uruashraju glaciers along the Cordillera Blanca could lead to a 30 per cent decrease in average dry season discharge (Baraer et al. 2012). In Bolivia, glaciers of the southern Cordillera Real supply approximately 15 per cent of potable water for the urban areas of La Paz and El Alto and can increase to approximately 30 per cent during the dry season from May to August (World Bank 2014b). The hydropower industry will also feel the residual effects of melting glaciers such as reduced streamflow, which could result in decreased efficiency and energy output (UNEP 2013b).
Considerations on consumption and production patterns
The importance of water for productive activities and the availability of funds from foreign assistance, international financial institutions and increased national budgets, have driven many governments to develop ambitious plans to expand infrastructure, often forgetting basic requirements: demand management and efficient use of water.
According to IWA (2014) “while it is accepted that in some areas water resources are insufficient to provide the necessary supply, it is also evident in many areas that the problem is not the availability of water, but the fact that so much is lost through leakage”.
Losses can also be a function of an aging water network, constructed in the 20th century with no anticipation of population growth. Resources and local capacity to maintain and operate water distribution networks are limited in many
areas. This has led to water stress and scarcity11
in countries
like Antigua and Barbuda, Barbados, and Saint Kitts and Nevis (GWP 2014; UNEP 2008).
In a recent meeting of water utility agencies from Latin America (World Bank 2013) it was estimated that 45 per cent of water is lost before it reaches the customer. In some countries the figure can be as high as 67 per cent loss in urban water systems (ANAM 2014; Cashman 2014).
UNEP (2011b) estimated that “with no improvement in the efficiency of water use, water demand is projected to overshoot supply by 40 per cent in 20 years time” (globally). Water use efficiency is usually measured as the amount of water used to produce value (litres/USD); as the amount of water used to generate a product (litres/item) or the amount of water used per person (litres/capita). Thus, water use efficiency translates into water savings and increased productivity.
There are several approaches that can be applied to achieve water use efficiency at different levels. They include the adoption of technology (from household rainwater harvesting systems to advanced wastewater treatment) and production methods (e.g. closed loop systems and “cradle- to-cradle”
design), regulatory frameworks (water nexus, use
permits, economic incentives), natural resources planning (consideration of the water-energy-food
water/
11 Water stress versus water scarcity: Hydrologists typically assess scarcity by looking at the population- water equation. An area experiences water stress when annual water supplies drop below 1 700 cubic metres per person. When annual water supplies drop below 1 000 cubic metres per person, the population faces water scarcity, and below 500 cubic metres, absolute scarcity. Water scarcity is defined as the point at which the aggregate impact of all users impinges on the supply or quality of water under prevailing institutional arrangements to the extent that the demand from all sectors, including the environment, cannot be fully satisfied. Water scarcity is a relative concept and can occur at any level of supply or demand. Scarcity may be a social construct (a product of affluence, expectations and customary behaviour) or a consequence of altered supply patterns, for example stemming from climate change.
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