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Newsletter and Technical Publications

Lakes and Reservoirs vol. 2

The Watershed: Water from the Mountains into the Sea

How Can We Manage and Use Our Frewshwater Resources in an Environmentally-Sustainable Manner?

As noted in the previous chapters, fresh water passes over and through a myriad of natural landscapes in its journey to the sea. It also reacts to a range of natural and human- induced activities and obstacles in its journey, many of which can fundamentally change both its flow, volume and character. Thus, in concluding this discussion of the movement of water from the time it falls as precipitation and snowfall onto the land surface, and through the various water systems and water-bodies it may encounter on its journey back to the sea, the central question is: how we can effectively manage and use this precious resource in a manner that insures us a continuing supply in the future. It is of particular interest to consider its sustainable supply and use within the context of its role as a basic component and driving force for socioeconomic development.

As previously noted, liquid freshwater resources comprise only about 2%of the world’s total water volume. All life as we know it depends on this relatively small fraction. Nevertheless, even this quantity is thought to be adequate to meet our current and foreseeable water needs, if it were managed and used in a sustainable manner. At the same time, we must also not forget the fundamental water needs of nature. Terrestrial and aquatic ecosystems, for example, require a minimum inflow of water to maintain their structure and function (i. e., a wetland cannot remain a wetland if it does not receive a certain minimum inflow of water). Flowing water also moves minerals, nutrients and other materials through ecosystems, and drives many biogeochemical cycles. Unfortunately, however, as we allocate our available water resource between competing human users, we seldom consider the water requirements of natural ecosystems, even though many are vital for our own existence.

The organizations of the United Nations, together with Governments and non- governmental organizations met in Rio de Janeiro, Brazil, in 1992 at the United Nations Conference on Environment and Development (UNCED). This international conference, also referred to by some as the World Summit and the Rio Conference, gave birth to what is known as Agenda 21, which recognizes and provides a framework and guidance for addressing human and ecosystem water needs in a rationale and sustainable manner. Agenda 21 promulgated the view that sustainable use of scarce water resources requires humans to consider water and its related environmental linkages in an integrated manner (“integration ” refers to the process of making a whole from the parts), and within the context of an entire watershed or groundwater aquifer.

Previous chapters of this document described the various components of the natural landscape through which water passes on its journey to the sea. If the goal is to insure sustainable water resources, other important factors that must be considered include the quantity of available water and its condition, the geology, type of soil and character of the landscape over which it flows, the types of vegetation in the watershed, the watershed flora and fauna, the numbers, types and locations of pollution sources, the population centers and the extent of agricultural production, where the water is located in the watershed and where and how it is used, etc. These largely scientific and technical concerns define the quantity, location and condition of our existing water resources, as well as providing us with a picture of human and ecosystem demands on these resources.

Just as important, however, are socioeconomic issues, which are as diverse as the scientific and technical components. They include such components as the institutional structures that exist within a country and/or watershed, the existing laws and legal frame- work, the population patterns, the economic development characteristics and trends, the educational status of the watershed inhabitants, the existing social and cultural structures and beliefs, the state of public awareness, economic capabilities and political realities. Sustainable water management also involves integrating users and stakeholder interests in a participatory manner when allocating available water resources among competing uses and users (including ecosystem water needs). To this end, the watershed appears to be the fundamental water planning and management unit. In fact, experience suggests that these various social and economic elements are as important as the scientific and technical factors in addressing sustainable water resources, primarily because they fundamentally define how humans manage and use (and abuse) their available water resources (Photo 49).

Photo 49: Over exploitation of groundwater during irrigation.

Accordingly, and although not an exhaustive listing, an integrated and environmentally-sustainable management plan for freshwater resources should ideally incorporate the elements identified in Table 2.

Table 2: Relevant elements of an integrated environmentally sustainable freshwater management plan. detail

Water systems that cross international boundaries bring an additional dimension into the equation. It is estimated, for example, that there are more than 300 international river basins, most with considerable potential for fueling economic development. An undetermined, but equally important, number of groundwater aquifers is shared and used by more than one country. Because aquifers are the subterranean equivalent to watersheds, many of the same principles described above in regard to surface watersheds are equally applicable to groundwater systems. Unfortunately, because they are often viewed as politically-sensitive issues, many Governments and international organizations have shied away from resolution of international surface and groundwater problems. As a result, international water systems have not received the management attention they need, with predictions of future “water wars ” being heard in some circles.

Photo 50: Tiete River, a highly polluted river crossing in Sao Paulo, Brazil. As a concluding observation, it might be said that many of the observations contained in this report are simply commonsense to most individuals. Indeed, most have been reiterated in some form in many regional and international water-related fora during the last decade. Nevertheless, the unfortunate reality is that humans generally continue to treat freshwater resources as a cheap, abundant and perpetually available resource. As a result, we continue to accord these resources a relatively low priority in our national and international political arenas. Accordingly, many already- serious environmental issues continue to worsen around the globe, with the supply and quality of water resources being especially sensitive to such problems. Increasing population growth and urbanization (photo 50), particularly in the developing world, and the resulting increased poverty and competition for limited natural resources, including fresh water, are paramount among the causative factors for environmental degradation. Escalating costs, lack of investment funds, increasing technical complexities and lack of understanding of fundamental water issues also work to impede development and implementation of necessary remedial programs and projects for addressing the issue of sustainable supplies of clean, safe freshwater resources. Nevertheless, human recognition that water is precious, finite and irreplaceable will hopefully provide humanity with the impetus for a proactive approach to insuring its sustainable management and use on a watershed scale, both within and between countries.

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