The St. Lawrence and the World’s Major Rivers
Excerpt from a talk given by Jean Burton, an Environment Canada biologist, at a conference organized jointly by the Association des biologistes du Québec and St. Lawrence Plan partners in June 1998.
Situating the St. Lawrence on the broad spectrum of the world’s major rivers is far from easy. The problems facing all riverside populations of the world’s major rivers are huge and we, the shoreline inhabitants of the St. Lawrence, are among the most fortunate in the world.
1- Introduction
To start, three concepts need to be defined: “major river,” “watershed” and “river ecosystem.” We’ll begin with the concept of “major river”, a label that is both useful and misleading. The term is useful in that it allows us to classify river systems according to their physical dimensions. However, this concept is also misleading, because physical dimensions alone are poor indicators of a river’s importance to the human communities that live along its shores and depend on its resources. For examples of this, we need look no further than most of Europe’s rivers, which are major rivers in the historic and cultural sense, but not in terms of their physical dimensions.
The concept of “watershed” must also draw our attention. We are in the habit of talking about the St. Lawrence as though it springs from the clay of the Montreal Plain. The St. Lawrence also includes the Great Lakes upstream and the international stretch between Kingston and Cornwall in Ontario. We can, of course, focus our attention on the reach located in Quebec territory. However, many of the issues that will be discussed over the course of this symposium are based in the upstream part of this river system.
Finally, the concept of “integrated river ecosystem management” was broadened considerably during the 1990s and can be defined as follows: “Informed decision makers taking into account all of a watershed’s uses and resources in an ecosystem approach. It aims to ensure the sustainability of the human communities that depend on that watershed, through the development of harmonious relations among the users themselves and between humankind and the river. At the local level, this management requires user involvement, at the appropriate level; at the national level and especially the regional level, it must reflect political and legal considerations.” This definition comes from the workshop on international cooperation that I facilitated during the symposium on rivers and the planet in October 1992. You will surely have noticed that this definition applies the principles of sustainable development to river ecosystems.
2 - The uniqueness of the St. Lawrence
The St. Lawrence is 3260 km long, with a watershed measuring 1.6 million km2 and an average annual flow of 13 000 m3/sec. Globally, it ranks nineteenth in length, fifteenth in watershed surface area, and thirteenth for average annual flow. The St. Lawrence is similar in length to the Danube (Hungary), the Volga (Russia) and the Murray (Australia). Its watershed area is similar to that of the Volga and the Murray, while flow is akin to that of the Ganges (India) and the Mississippi (United States).
The St. Lawrence is a small river compared with the Zaire (Africa), the Yangtze (China) or the Amazon (Brazil). However, it is larger than Europe’s rivers in terms of flow and watershed area. In North America, the St. Lawrence has the greatest average annual flow and ranks third in length and watershed surface area, after the Mississippi and the Mackenzie (CSL 1993).
However, it is as a river system that the St. Lawrence is unique. You will remember that the concept of “river system” also includes human aspects.
We can, for example, compare the St. Lawrence on the basis of size of demand, using population density per square kilometre of watershed to illustrate this aspect. We can also calculate pressures on this resource using the relationship between population and average annual flow. On both counts, the St. Lawrence ranks very high. The availability of water is another meaningful indicator, measured in m3/sec per capita. The St. Lawrence’s situation again appears very advantageous.
In political terms, the situation of the Great Lakes/St. Lawrence ecosystem is relatively simple, with a bi-national context in the upstream part; in contrast, some watersheds spread through as many as 15 countries. It should be noted that the forced sharing of a common resource provides examples of both ongoing collaboration and armed conflict. Regional watershed organizations have existed for several decades, having the equitable sharing of water resources as their basic tenet. However, real or feared conflicts between riverside nations sharing the same river also exist: the Nile, the Tigris and the Euphrates all illustrate the importance that water will play in the very near future.
In industrialized countries, the legacy of human activity is strongly felt through the artificialization of shores and even of the main stem of the river, wetland loss, flow and level control. All these phenomena impact the integrity and functioning of a river system. The legacy is also weighty in terms of chemical pollution of all sorts. Europe’s rivers have been domesticated since ancient times and put to humanity’s use; today, they still support a large part of the economy activity of these countries, representing the major routes for regional transportation (the Rhine and the Danube, for example). The issues involve both water quality and water quantity.
In developing countries, the impact of human activity is more often masked by the continued imposition of Nature’s rules: severe flooding in monsoon climates or repeated droughts in Sahelian areas. The impact of natural disasters is devastating for these essentially agricultural economies. Here, the quantity of water is the main issue, whereas its quality is primarily associated with waterborne diseases.
What puts the St. Lawrence in a class all its own is all of these factors combined: nature, its physical and biological aspects, and the relatively recent impact of human activity. The fact remains that the river and its shoreline inhabitants are in a very advantageous situation; simply recall that the Great Lakes constitute a 23 000 km3-reservoir, representing nearly one fifth of the world’s freshwater resources.
3 - Similiraties
The St. Lawrence shares some common characteristics with other major river ecosystems. By virtue of their sheer size, river basins cross several climate zones. The St. Lawrence is no exception (different ecozones: boreal forest, mixed forest, Atlantic/maritime). Rivers run either in a north-south direction, like the Nile, or share a cordillera and flow into the sea below, like the Amazon, the Mekong or the Senegal. In all cases, a major river cuts through a broad range of ecological zones.
The spectre of climate change does not spare rivers. In England, with a drought that has lasted for two years, a third of households have had to reduce their water consumption and there are thoughts of importing French water through the Eurotunnel (Hydroplus 1996). Along the St. Lawrence, watering restrictions have already been introduced in some municipalities. In a future yet to be determined, reduced flows and dropping levels, along with an increase in drought frequency (especially in the Lake Erie basin) will very likely affect us (Environment Canada 1996). The probable rise in sea level, associated with reduced average annual flows, would lead to a rise in the saltwater intrusion beyond its current limit, upstream from île-aux-Coudres. The Mackenzie Basin is already experiencing some effects of climate change: an average temperature rise of 1.7% since 1885 has been reported, with early snow melt. This situation is already very common in several rivers, where a drop in rainfall and resource retention in upstream reservoirs have resulted in the accelerated salinization of the deltas; the Nile and the Mekong are very good examples of this.
All major rivers are facing a rapid increase in demand. Worldwide, the demand for water has increased by a factor of ten since the beginning of the century. Today, most of the renewable and easily accessible water resources have already been developed. Agriculture is the main user, although in a single century its share has dropped from 90.5% to 62.6% on average. However, in Africa, 88% of the water still goes to agriculture, most of which is used for irrigation. Over the same period, the share used by industry rose from 6.4% to 24.7%, the main industrial use being cooling water for thermal and nuclear power plants.
Over the course of this century, cities will increase their consumption from 2.8% to 8.5% (WWO-UNESCO 1991). It is also in cities that the situation is of the greatest concern. Even though, during Water for Life Decade, an additional 360 million city dwellers were provided with access to safe drinking water, the urban population grew by 400 million over the same period (UNCHS 1992). For example, despite the fact that the City of Las Vegas was built right in the Mohave Desert, with barely 100 mm of annual precipitation, it not only holds the water consumption record for the United States at 720 l/resident/day, but also takes in 1000 new residents every week. In Senegal, during the same time period, the average consumption in the cities was 29 l/resident/day.
The impact of human activity on the biodiversity of the major river ecosystems is also being felt. For example, the Niger now has only 10% of the number of wildlife species it had in 1960 (Niger 1996). As another example, the Rhine, also invaded by the zebra mussel, now takes in North American species of amphipods and decapods in the Netherlands reach (The Netherlands 1993). Our country is not the only one to receive exotic species through marine transport.
As for water quality issues, they are varied, and include pathogens, organic pollution, eutrophying pollution and salinization. The major rivers receive their share of discharges of all sorts. The greater the flow, the greater the assumed receiving capacity of the river ecosystem.
However, what sets the major rivers apart is their fundamental role in supporting human communities and their activities. It is interesting to note how many cities started and grew on the shores of rivers: Budapest (Danube), Kanpur (Ganges) and Cairo (Nile), to name a few.
It is easy to understand why when you see the range of activities that depend on water and its uses. This diversity of uses does not come without a certain amount of conflict. It is necessary to reconcile competing demands for the same resource that is also limited in quantity and quality. How are priorities to be set? That is the question that plagues all managers.
Therefore, we can state that, despite its advantageous situation, the St. Lawrence shares some of the same challenges as the world’s other rivers.
References
St. Lawrence Centre. 1991. L’évaluation comparative des grands fleuves. Speech by Michel Lamontagne, Quatrièmes Entretiens Jacques-Cartier. Lyon, December 4, 1991.
St. Lawrence Centre. 1993. Info-flash on the state of the St. Lawrence. Environment Canada, Conservation Directorate. Montréal.
UNCHS. 1992. International Conference on Water and the Environment. Background Paper: Water and Sustainable Urban Development. Dublin, January 26–31, 1992.
Environment Canada. 1996. National State of the Environment Report. Chapter 6; Great Lakes and the St. Lawrence. Ottawa.
Hydroplus. 1996. Great Britain: drought threatens again. 63:10.
Niger. 1996. Gestion intégrée des usages et des ressources liées au fleuve Niger en territoire nigérien. Ministry of Hydrology and the Environment. Niamey.
The Netherlands. 1993. Ecological rehabilitation of the River Rhine. The Netherlands’ research summary report (1988–1992). Amsterdam.
WHO-UNESCO. 1992. Water Resources Assessment. International Conference on Water and the Environment. Dublin, January 26-31, 1992.
Jean Burton, a retired biologist, worked at Environment Canada’s St. Lawrence Centre.
Date modified: 2008/05/01 – Important Notices
