I recently came across Robert Szucs’s beautiful maps of the world’s drainage basins. Studying the maps got me thinking: what’s the largest country entirely contained within the drainage basin of a single river? Unfortunately, Szucs doesn’t provide maps for every country, and I think that none of the country maps he does provide shows a single drainage basin (though many of the state maps do).
I’m going to go with the DRC.
Bet as I can tell, the entire Democratic Republic of the Congo is located in the Congo River basin
Magnificent.
Love the notion the notion that somebody has plotted the drainage basin of the Atacama Plateau.
Or the hydrology of Lake Phibbs, SA whose primary source is theoretically an overflow from Lake Eyre. Just nobody has ever seen water in it.
I’ll agree with the DRC. Although to be really correct you have to say single “significant” drainage basis or something like this, to exclude the tiny watersheds practically any country with a seacoast has that are drained by small streams and rivers near the coast which flow directly into the ocean.
The DRC’s coastline is 27 miles. A large chunk of that is the Congo mouth and the associated mangroves, and then some lagoons. I consider those coastal, not really watershed drainage.
It looks like at the DRC extreme east side there is drainage to the Nile, at Lake Albert. Still, I think DRC is the best example of what the OP is looking for.
Another question would be: List all the countries that exist within a single drainage basin. I would think the list would be pretty small.
An interesting drainage basin factoid: Triple Divide Peak in Montana is where drainage to the Pacific, Atlantic, and Arctic oceans meet. The only place in the world where drainage to 3 oceans exists.
It’s not really the best example if it doesn’t fit the criteria of the question, is it? If it’s confirmed that some of the DRC drains into the Nile, then we need to find a different country.
Yeah, go on, let’s make such a list.
I did a cursory search and came up with the following countries that appear to be entirely in one drainage basin:
Hungary - Danube
Romania - Danube
Liechtenstein - Rhine
Bhutan - Brahmaputra
Lesotho - Orange
None are very big, but Romania is the largest of these at 92,000 square miles.
Are there any others?
Here’s an interesting drainage basin factoid: Snow Dome on the Alberta and British Columbia border is where drainage to the Pacific, Atlantic, and Arctic oceans meet. The only place in the world where drainage to 3 oceans exists*.
*Depending on definitions as with Triple Divide Peak
The DRC has a shoreline on both Lake Edward and Lake Albert, so portions of it must drain into the Nile by definition.
Likewise I don’t think Romania would count, because it has a shoreline on the Black Sea, so some short streams in the southeast of the country drain directly into the Black Sea rather than into the Danube.
Hungary looks like probably being the winner, albeit that it has separate drainage basins which join up outside the borders of the country (for example the Danube itself, and the Tisa, which joins the Danube in Serbia).
I’m not sure how to treat dry areas that don’t support permanent streams leading to the sea. It’s not usually easy to tell from online maps whether these areas are separate closed watersheds with no outlet to the sea (like the Great Basin), or simply parts of the main river basin too dry to support permanent streams. I don’t have access to detailed topographical maps that would answer the question.
For example, almost all of Iraq (168,754 square miles) is drained by the Shatt al-Arab system which includes the Tigris and Euphrates. But there are small areas around the periphery of the country that are questionable as to whether they’re part of the same basin.
Likewise it looks to me like all the water that drains to the ocean from Paraguay (157,048 square miles) does so by the Paraná River system. However, there are dry areas in the north and west and I can’t tell if that’s part of the river’s basin.
The Wikipedia article on endorheic basins lists two lakes with no outflow in or on the border of Hungary.
So, are we counting endorheic basins as drainage basins for the purpose of the OP?
Say it with me: “endorheic”. Beware the little furry guys.
Perhaps, but I was making the point concerning all candidates, not just the DRC. If you don’t exclude stuff like the watershed I happen to live in, which drains 20 square miles of area into the SF Bay, there are simply not a lot of examples.
Similarly, the map of South Africa makes it look like the Molopo River has a major flow into the Orange. In reality, the flow is almost theoretical: in all but the most extreme flood conditions the Molopo dries up in the sands of the Kalahari desert.
It’s pronounce endo-rheic, not Endor-eic
He asked you to say it with him.
To truly fit the definition, a country would have to be landlocked, because otherwise some water will drain directly into the sea rather than into the river basin (as in the example of Romania above).
It looks as if Lesotho would definitely count. Paraguay seems to fit the bill too - I think all of the Gran Chaco does drain to the south. This map shows the whole of Paraguay being in the Rio de la Plata basin, and Paraguay is of course larger than Lesotho.
Just as well, seeing as the main road appears to have been built in the river!
The eastern part of the Lesotho border is actually legally defined as the watershed of the Orange River, so it definitely counts.
Easiest way to put a road through the endless sand dunes - build it in the dry riverbed. If it floods once every century, well, ehhh. :shrug:
DRC is interesting though, as the country was initially defined as encompassing the whole Congo river drainage basin. Henry Stanley was trying to prove the Nile was part of the same water system so that Egypt magically became part of Congo. Apparently he failed but claimed to find Livingstone. King Leopold’s Ghost is a fascinating read, although Heart of Darkness is shorter.