The term “bioregion” is attractive, but not often rigorously defined. It seems to be either a river valley (watershed) or a region with similar flora and fauna. These two definitions may often overlap to delineate the same region, but sometimes not; for example, if we are dealing with a very long river or one with many tributaries.

Even in the watershed definition used alone, there are ambiguities. There are many small and even tiny streams running straight into the sea rather than into a larger river, especially in regions where mountains are close to the seashore. These “micro-watersheds” are far too small and numerous for what is intended here, and yet must be somehow included if we are contemplating a system that would cover the Earth’s land areas completely and exhaustively. To avoid this over-fractalization, the micro-watersheds would have to be joined together or to adjacent macro-watersheds. Perhaps this would not be too difficult to do, if we use the watershed definition in a non-dogmatic way, only as a primary guide.

The tentative initial definition of a watershed bioregion would be the land area drained by a stream which runs into the sea or into a lake without an outlet, such as the Caspian or the Aral. The Great Lakes at the Canada-U.S. border would be part of the St. Lawrence River system.

The patchwork of river valleys so defined could not serve as the basis of a political division of the world. The political division should be either the existing nation state system (but this is not very stable, it keeps changing; and also the areas and populations are grossly unequal) or a scheme of equal-population voting districts, about 5 million people each (i.e. a total of 1,000 of them), as described in my paper by that name. But for an economic division of labour and for ecological supervision purposes, river valleys (watersheds) might be very suitable units.

Units for economic-ecological planning (eco-eco districts) do not have to coincide with political, cultural, or national/ethnic units. There can be a reasonable separation of functions here, creating patterns of overlap which could usefully knit the world together in two alternative ways. The two kinds of division would correspond approximately to physical and cultural geography, two branches of the overall science of geography, usually presented in atlases in two different sets of maps.

In the present nation-state system, rivers often coincide with national borders, which is an occasion for conflicts between the two neighbouring countries over their rights to use the water for irrigation, household use, power generation, and navigation, or over pollution prevention and clean-up. Wars have been fought over the Tigris-Euphrates system (between Iran and Iraq), the Jordan (between Israel and Syria and Israel and Jordan), and the Indus river (between India and Pakistan). There is a dispute over the Ganges-Brahmaputra between India, Bangladesh and Nepal, and over the Nile between Egypt, Sudan, and Ethiopia/Uganda. These river valleys are cradles of civilization, with long histories of human habitation. (Only the great rivers of China are all within one nation-state.) It would be more conducive to eco-eco cooperation if each river were in the middle of the region being managed, not at a border between two regions. In the proposed new system, the borders between regions would run along mountain chains, or at least the locally highest ground. We would still have “natural” borders, but of a different kind (the high places, not the low places) .

The dispute over the Nile is actually a bit different: not between states across the river from each other, but between downstream and upstream states. Such disputes are also quite common, since the upstream state is in an advantaged power position: it can cut off the water supply to its downstream neighbour, or threaten to do so. Not only can Ethiopia do this to Sudan, or Sudan to Egypt, but Turkey can do it to Iraq and Nepal to Bangladesh. This gives a new meaning to the expression of occupying the strategic “high ground”. Again, including the upper and lower river valley in the same region would help to moderate such conflicts.

Here then are some of the river valleys which would exist as single units in the proposed system (only the major ones are named):

• In North America: Mackenzie, Fraser, Columbia, Colorado, Rio Grande, Red river, Mississippi-Missouri, St. Lawrence.
• In South America: Orinoco, Amazon, Parana-La Plata.
• In Europe: Garonne-Dordogne, Loire, Seine, Rhone, Meuse-Moselle-Schelde, Rhine, Elbe, Oder, Vistula, Po, Arno, Tiber, Danube.
• In former Soviet Union: Dniester, Bug, Dnieper, Don, Volga, Amu-Darya (Oxus), Syr Darya, Irtysh-Ob, Yenisey, Lena.
• In the Middle East: Tigris-Euphrates, Jordan, Nile.
• In Africa: Niger, Volta, Congo (Zaire), Limpopo, Zambezi.
• In South and South-East Asia: Indus, Ganges-Brahmaputra, Irawadi, Mekong.
• In China: Yangtse, Yellow River.

This list of 48 rivers is a very incomplete list. In fact, the major watersheds do not cover the land surface very well. We left out the British Isles, the Iberian Peninsula, Scandinavia, most of the Balkans, Japan, Australia, New Zealand, the Philippines, Indonesia, and all the islands worldwide. Obviously we would need some scheme supplementary to the watershed scheme to get a good system of eco- districts. Perhaps the other part of the definition of a bioregion (distinctive flora and fauna) would have to be drawn on after all.

The whole scheme needs a lot of further study.