Water Supply Siting and Management

Water is a critical resource for the health of ecosystems and the reproduction of society. Water siting refers to the process of transformation of this basic component of the biosphere into a resource able to satisfy human needs. Siting includes, therefore, both the places where water is captured for human activities and the technologies and institutional arrangements that make this transformation possible. Water management refers to the institutional, legal, and technological arrangements by which water is allocated temporally and spatially to the different users (agriculture, industry, urban, environmental flows).

Surface water and groundwater are the two main conventional sources of freshwater, and their use entails different technologies of capture and also different institutions to regulate its use. Surface water of rivers and lakes can be directly captured from the source by means of ditches, especially for agricultural use. However, for thousands of years, dams, reservoirs, and channels have been developed to guarantee water availability where and when needed. Interbasin water transfers are justified on the ground that they contribute to redress the balance between “surplus” and “deficit” basins. Dams, reservoirs, and water transfers are important human interventions to mobilize and transform nature and have important consequences on the environment and society. While these interventions allow population and crop growth where water is scarce, they also modify the physical environment and affect the living condition of local populations and environments.

Aquifers are underground geological formations formed by layers of porous and permeable materials containing water. By means of wells or pumps, water can be brought to the surface. In this case, the use and consumption of water tends to be more local. Overextraction of water from aquifers can cause depletion and pollution, often irreversibly damaging the source.

Other nonconventional sources of water supply may be also relevant in some contexts. Desalinization technologies involve several methods to [Page 3077]turn seawater or brackish water into freshwater. Currently, the most efficient of such methods is called reverse osmosis. However, large amounts of energy are consumed in the process, with subsequent emissions of carbon dioxide (if the primary energy sources are fossil fuels). In turn, this process is reflected in the economic costs and subsequently limits such technology to urban (including tourist related) and industrial uses in the developed world.

Aerial view of the spillway at Broken Bow Dam on Broken Bow Reservoir on the Mountain Fork River in McCurtain County, Oklahoma. This photograph shows only the spillway. The U.S. Army Corps of Engineers constructed the dams in 1968 for flood control, water supply, and hydroelectric power generation.

Source: U.S. Army Corps of Engineers.

Water harvesting is another technology traditionally practiced in the developing countries. It consists of the capture and storage of rainwater and has the advantage of not requiring a large infrastructure. Its usefulness at the local scale makes it an interesting resource that is being rediscovered in Western societies. Equally, the treatment and reutilization of wastewater (gray water) by means of small-scale or centralized utilities can be a resource for agriculture, industry, and even household outdoor uses. This practice is common in California.

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