Tag Archives: Lakes

How many lakes are there?

How many lakes are there? We don’t actually know. Lakes are often undercounted, or small lakes ignored, in larger scale geophysical surveys. It is hard to count the small lakes, or in some cases, even to define them. A recent study (published in Geophysical Research Letters) examines this question. We want to know how many lakes there are, and how much surface area they take up, in order to understand better the global Carbon cycle (and for other reasons). From the Abstract of this study:

An accurate description of the abundance and size distribution of lakes is critical to quantifying limnetic contributions to the global carbon cycle. However, estimates of global lake abundance are poorly constrained. We used high-resolution satellite imagery to produce a GLObal WAter BOdies database (GLOWABO), comprising all lakes greater than 0.002 km2. GLOWABO contains geographic and morphometric information for ~117 million lakes with a combined surface area of about 5 × 106 km2, which is 3.7% of the Earth’s nonglaciated land area. Large and intermediate-sized lakes dominate the total lake surface area. Overall, lakes are less abundant but cover a greater total surface area relative to previous estimates based on statistical extrapolations. The GLOWABO allows for the global-scale evaluation of fundamental limnological problems, providing a foundation for improved quantification of limnetic contributions to the biogeochemical processes at large scales.

So, there are fewer than thought but they take up more space than thought. Who would have thought?

Interestingly, there are more lakes at higher latitudes. Because of the uneven distribution of land surface in the Northern vs. Southern Hemispheres (more land in the north) this means more lakes in boreal regions, and more specifically, more lakes in previously glaciated regions. This makes sense because glaciation (and deglaciation, melting of the glaciers) produces lakes. The immature terrain produced by a glacier eventually matures with erosion joining streams and rivers to those lakes, making them disappear. If no glaciers return to a previously glaciated region, eventually all the lakes (or most of them) will disappear.

Look at the Congo, Amazon and Nile basins for examples of large inland regions in the tropics. There are very few lakes. Now look at North America north of the maximum extent of the recent (Wisconsin) glacier. Lots and lots of lakes.

Walking around the lakes

When I was a kid, I spent a lot of time at lakes, but the idea of walking around a lake hardly every occurred to me or anyone else. This might be because the lakes were either really big (like the Great Sacandaga Reservoir) or nestled into deep sided rock canyons carved out by glaciers, and thus, not walk-aroundable. Lakes were central places, termini of inland pathways, points along long distance hikes, not things you walked around.

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Where I grew up, lakes were important. We would spend considerable time driving to them, and once there, camp next to them for a couple of weeks. Every now and then we’d go and camp next to the really really big lake. The one with England on the other side, or so my brother would tell me. All the lakes had these big chairs along the swimming areas that lifeguards sat in. The really really big lake had extra tall chairs. I remember thinking that they could probably see England from up there!
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Distribution of Water on the Earth

This has come up a couple of times recently, so I thought I’d summarize the information here.

The distribution of water on Earth in cubic kilometers

Salt water: 1,318,062,462
Glaciers: 28,005,430
Groundwater: 12,270,210
Lakes: 106,396
Swamps: 13,452
Rivers: 2,446
Vapor: 13,000
Biological: 1,120

(Biological means like your spit and guts and all the juicy parts of worms and tree saps and water in bacteria and stuff.)


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The First Fishing Opener

His face wore a blank expression, but you could tell he was hiding disdain. He was looking down on us both figuratively and literally. He looked down because he sat on a swivel chair that rode atop a metal stem inserted in the tall open deck of his Lund fishing boat, the remote control for a small electric motor in one hand, and a casting rod rigged with an elaborate contraption of hooks, weights, jigs, and a tiny live minnow trying to swim as fast as possible through the air in which it was suspended. He wore a camouflage hat, and his enormous frame was covered by a camouflage jacket, a camouflage vest, and camouflage rain pants, offset with oversize but somehow stylish green rubber boots.
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