In This Chapter
Contemplating the uneven distribution of a precious resource
Navigating the ups and downs of sea level
Considering water rights (and water wrongs)
Drinking water: Sometimes it’s not a good idea
T he sound of the Earth is ker-ploosh. Nearly 70 percent of our planet’s surface is covered by water, and the vast majority of that water is ocean. In addition, water is in the air you breathe and mixed in with the soil underfoot. Then you have lakes and rivers and icecaps. So, it really isn’t a stretch to say, “Water, water everywhere.”
The geography of water is vital to our lives. It has an impact on where people live, the shape of our world, fisheries and agriculture, trade and commerce, and, of course, satisfaction of our thirst. Once you’ve thought seriously about the geography of water, you may never look at a glass of water in the same way!
Many geography books don’t include a chapter on water. Instead, the authors opt to sprinkle the subject throughout their books. Obviously, I’ve decided to go against the flow and put it all here in one big puddle, with one exception: I’m going to hold off discussing ocean currents, which have a major influence on climate, until the next chapter.
Taking the Plunge: Global Water Supply
Although water is everywhere, it’s very unevenly distributed. The oceans account for 97.25 percent of the global water supply. Ice caps account for another 2.05 percent, and together that makes 99.3 percent. Of the 0.7 percent that remains, 0.68 percent is groundwater. Most of that is mixed in with soil, but a small portion is potentially available to humans as well water. And that leaves 0.02 percent, which comprises all the world’s lakes, all the world’s rivers, and all the vapor in the atmosphere.
What these data tell us is that the vast majority of the Earth’s water is unavailable for human use. In some countries, there are “desalinization” plants that — as the name implies — remove the salt from seawater and produce potable fresh water. The process is rather expensive, however, and helps satisfy the needs of only a few localities — coastal cities, mainly. As a meaningful solution to the global water crunch, it’s simply not feasible given the current level of technology. And if the amount of potable water isn’t worrisome enough, the geography of supply is often way out of whack with the geography of need. Fresh water is often abundant in areas where human need for it is scarce. And fresh water is often scarce where human need is abundant. The following sections show you just how the global water supply is broken down.
Where did all that water come from?
Actually, all that water isn’t all that much considering Earth as a whole. Water may cover 70 percent of Earth’s surface, but it accounts for only about 0.5 percent of the planet’s weight. Oceans, on average, are about 2 to 3 miles deep, but the average distance from Earth’s surface to its center is 3,960 miles. So the deepest of the deep blue seas is but a shallow veneer of surface material.
Apparently, all that water was here from the beginning. When Earth was a newborn fireball, its water was mixed together with other planetary matter. Indeed, probably much, much more water was on the inside of the planet than on the outside. Any substance that can exist as a solid, liquid, or gas is rather amazing. That’s water. Because early-Earth was so hot everywhere, water was then in a gaseous state instead of liquid. Gases are lighter than solid matter, so they want to rise. In time, the gaseous water inside the Earth migrated (rose) to the outside and into the primordial atmosphere. This migration continued until the crust cooled (blocking the migration of additional internal water vapor to the surface), although subsequent volcanic activity may be thought of as planetary “burps” that spew additional water into the atmosphere, along with a lot of other stuff.
Eventually the water vapor in the atmosphere condensed and formed rain. Some scientists believe that downpours began very early on. Others believe that didn’t happen until eons later, after the crust cooled. But most agree that the vast majority of Earth’s surface waters originated in rain that fell from the sky over a very, very long period of time.
Those ice caps are really cool!
Earth’s “ice caps” are actually continental glaciers, whose origins are described in Chapter 7. Cool? They sure are. Ice caps account for about 2 percent of Earth’s water. That may not seem like much, but as a portion of all the water that exists on this planet, 2 percent turns out to be a lot of wet stuff — or actually hard stuff, because it’s water in a solid state.
You want data? Antarctica’s ice cap is as deep as 15,760 feet. If you stood at that spot, you would not literally be on top of Antarctica. Instead, you would be on top of a 3-mile-thick piece of ice that is on Antarctica (see Figure 8-1). Indeed, the total volume of that ice cap is estimated to be about 30 million cubic kilometers. That’s a lot of margaritas.
Want more? Well, there’s Greenland, which is one of the great misnomers in the history of real estate. It really ought to be named Whiteland, because close to 99 percent of it is covered by ice cap. Actually, Greenland’s ice cap is only about 10,000 feet deep at its thickest, so it’s practically minor league compared to Antarctica.
Getting out: Oceans, seas, gulfs, and bays
Most of earth’s water is oceans, including seas, gulfs, and bays. The difference between these terms is basically a matter of size and location. Ocean comes from the Okeanos of Greek mythology, which was a river thought to encircle the Earth. And indeed, the ocean is a continuous body of water that encircles the land, but it also consists of a handful of divisions that are also referred to as oceans — Atlantic Ocean, Pacific Ocean, Indian Ocean, and Arctic Ocean. So ocean is the big enchilada.
Seas, gulfs, and bays are parts of the ocean that adjoin land bodies. Generally, seas are ranked second (after oceans) with respect to size. They may be relatively enclosed by land, as is the Mediterranean Sea, or they may be “open” to the ocean, as is the Arabian Sea. A gulf is a part of an ocean or sea that extends into the land. Dictionaries suggest that gulfs are smaller than seas but bigger than bays. A bay may be defined as an inlet of a sea or gulf. For example, Tampa Bay is an inlet of the Gulf of Mexico.
That’s by the book, of course. In reality, things aren’t so neat and tidy. Con-sidering the Indian Ocean and parts thereof (see Figure 8-2), for example, you can see that the Bay of Bengal is bigger than the Andaman Sea and the Gulf of Oman. When it comes to these place-names, it’s kind of like being told “size matters” and then finding out it doesn’t. Basically, what happened is that, way back when, some explorer or mapmaker simply labeled a water body and the name stuck. Maybe that person didn’t appreciate the true size of the feature being named or didn’t appreciate the nuances of vocabulary. Whatever the case, the result is a dictionary that suggests a definite rank order with respect to size of seas, gulfs, and bays, and a world map that says it ain’t necessarily so.
Why are the oceans salty?
Dissolved mineral salt is the key. As water flows to the seas, it comes into contact with lots of rock and rock particles. These contain mineral salts, minute quantities of which are dissolved and carried along by running water. It’s probably in the stuff you drink, but because the salt content is so low, you don’t notice anything peculiar.
Ultimately, that water with its low salt content joins the sea. The sun continually evaporates sea water, producing vapor that becomes future rainfall. But here’s the punchline: It’s the ocean water that gets evaporated and not its salt content. So during evaporation, the salt gets left behind, only to have “new salt” added to it as freshwater eternally runs to the sea. Give this process a couple million years (which it did), and the result is an ocean of water too salty for human consumption.
How about de-salting the waters? That certainly is possible. Desalination (distilling sea water to remove the salt) is a fairly simple process, and goodness knows the oceans contain more water than humans will ever need. But de- salting seawater in the copious quantities that cities require is very, very expensive. Few can afford it, so desalination is not a particularly viable option.
Coming inland: Lakes
A similar brand of confusion reigns with respect to inland bodies of water. A lake is a body of water completely surrounded by land. But when you open an atlas and browse the lakes, you find some are called seas. For example, the Caspian Sea and Aral Sea are in Asia. The Salton Sea is in California, and the Dead Sea is between Israel and Jordan. Logic would suggest that a “sea” should be bigger than a “lake.” In reality, every one of the Great Lakes is larger than the Dead Sea, and so are a bunch of not-so-great lakes.
The explanation is that the previously-named seas (which are really lakes) are salty. Each occupies a basin — a depression in the landscape. Fresh water flows in, but nothing flows out. So you end up having an ocean in miniature. That is, the rivers bring minute quantities of dissolved salts to the lake/sea, which is essentially a dead-end repository. When the sun evaporates the surface waters, the salt gets left behind. Keep this up for many, many years, and what you have is a lake whose waters are not only salty, but are even saltier than your average ocean water. That’s the way it is with the Great Salt Lake, which apparently has every right to be called a sea but is not. Again, somebody way back when gave a name to a water body, and the label stuck regardless of the logic.
Shaping Our World: Oceans
Because they contain more than 97 percent of Earth’s water, oceans deserve to be considered in some depth. And when you get to the bottom of things you find that oceans are home to important resources. That in turn leads to the question “Who owns the oceans?” If that isn’t enough, there’s the business of sea level change, which literally shapes and re-shapes our world.
Going where the action is: The continental shelves
Off the coasts of continents are relatively flat expanses of ocean bottom that average about 300 feet in depth — shallow by oceanic standards. Such a feature is called a continental shelf (see Figure 8-3). The distances that the shelves extend from the shore vary. While the continental shelf off California extends 2 to 3 miles, the one off Newfoundland extends seaward some 200 miles.
Altogether, the continental shelves define what is arguably the most economically important part of the ocean. A growing human population translates into a need for more food (especially stuff that is high in protein) and more mineral resources. Increasingly, oceans are being looked to as sources of supply. And in that regard, the continental shelf is where the action is.
Something very fishy going on
If you were a fish and lived in the ocean, then chances are you would hang out over the continental shelf, just like almost every other fish. Schools are in session there for good reason — lots of food is available. Here’s how the food gets there:
Plant life: Because shelf water is shallow (compared to mid-ocean depths), some sunshine hits bottom and gives rise to plant life that serves as food for small fish that serve as food for bigger fish, and so forth.
River flow: Rivers empty onto the continental shelves. Their flow typically contains a lot of organic matter (especially dead, decaying, or dissolved plant parts), which adds to the abundance of fish food.
Vertical mixing: Wave action and turbulence produce a considerable amount of vertical mixing over the continental shelves. As a result, organic matter gets distributed over the depths, making for a very robust feeding environment.
Fuel for thought
Petroleum and natural gas underlie some areas of the ocean bottom, just as they are located under some areas of dry land. In the oceanic setting, these resources are found exclusively under continental shelves because they alone in the marine environment are composed of the geological features in which oil and gas are found. So when you see photos of offshore oil rigs, you are looking at an important economic activity that coincides with a continental shelf. Again, that’s where the action is.
Claiming ocean ownership
The existence of all the marine goodies leads to the rather important issue of ocean ownership. That is, who owns them? How far offshore does a nation’s sovereign territory extend — if at all? For countries that have coastlines — and for ships at sea — having an answer is important for the following reasons.
National security: Countries have the right to defend themselves from attack or intrusion. It’s crucial to be able to determine, therefore, the point at which a ship “crosses the line.”
Police power: Criminal activities can take place on water as well as land. Drug smuggling is a key example. Legally, however, the police and Coast Guard can only board vessels at sea within their jurisdictions. Thus, it is of some importance to clearly define how far out to sea those jurisdictions extend.
Trade and commerce: Thousands of freighters and tankers ply the ocean. The captains and navigators who set ships’ courses need to know where they can “sail as they please” and where they need permission by virtue of having entered a foreign country’s territorial waters. Only by defining the extent of ocean ownership can that be determined.
Resource ownership: Disagreement between countries concerning ownership of or access to resources can lead to conflict. “Marine goodies” mentioned earlier are potential sources of contention. Therefore, clear definition of the extent of ocean ownership may prevent conflict over oceanic resources.
Dire straits: The oceans contain several straits — narrow waterways that separate land bodies. About a dozen of them are major bottlenecks as far as international shipping is concerned. It is important to determine whether these are international waterways through which ships of all nations may freely pass, or if they belong to the countries that border them — and which would therefore have the right to deny passage or charge tolls.
So a tragedy occurs. And indeed it is a double tragedy, because it didn’t have to happen. If one or more coastal countries had had jurisdiction over the fishery — the commons — then, ideally, they would have enacted and en-forced resource management rules designed to keep fish populations and fish harvests in balance. And in the end, all concerned would have benefited — the fishermen, the consumers, and most importantly, the fish.
For decades the United Nations (and the League of Nations before it) sponsored conferences on “The Law of the Sea” to determine the nature and extent of offshore jurisdiction as well as other issues related to ocean use. In 1982, those efforts resulted in a draft treaty entitled the United Nations Convention on the Law of the Sea (UNCLOS), which became international law in 1994. The jurisdictional provisions are depicted in Figure 8-3. If you think of yourself as the coastal country in that diagram, then the following list details what the different zones mean to you.
Territorial Sea: Adjoining your coastline is a zone known as territorial sea that extends 12 nautical miles (nm). (A nautical mile equals 1.15 “regular” miles.) This area is all yours to do with as you please. Vessels that might engage in fishing or mineral extraction in this area may do so only with your permission. Vessels that just want to pass through have the right of innocent passage, meaning they are free to travel provided they don’t threaten your security or violate your laws. Warships of other countries have the right to be here, but in normal times that is considered unnecessarily provocative.
Contiguous Zone: The Contiguous Zone extends another 12 nautical miles past the border of the territorial sea. You don’t own this area in all respects, but you can enforce your customs, immigration, and sanitation laws within this area. Hot pursuit, chasing and boarding vessels suspected of involvement in illegal acts, is also allowed.
Exclusive Economic Zone: Exclusive Economic Zone (EEZ) extends as far as 200 nautical miles from the coast. All fishing and mineral exploration in this area is under your control. The presumption, of course, is that you exercise this power wisely for the management of marine resources. Also, it’s no accident that the dimension of EEZ places almost all of the world’s continental shelf under somebody’s official jurisdiction.
The High Seas (International Waters): The High Seas (also known as International Waters) extends beyond the EEZ. They are open to vessels of all nations for whatever purpose. Thus, everybody enjoys the right of innocent passage in this area. In theory, mineral resources that lie on or under high seas ocean bottom are for the benefit of all the peoples of the world. In reality, the minerals down there are at the disposal of a handful of countries that possess the technological wherewithal to go get them.
The various offshore zones may appear straightforward, but in the real world they often don’t work. Consider the United States and Cuba, two countries that aren’t exactly bosom buddies. Each country is theoretically entitled to what is shown on Figure 8-3. But Key West, Florida, is only about 90 miles from Cuba. Adjustments had to be made, therefore, beginning with a zone of High Seas in between to guarantee the right of innocent passage to ships of all countries. After that, the U.S. and Cuba were each allotted equal, but reduced, amounts of the other zones shown on the diagram.
When you give the world map a major look-see, you find virtually dozens upon dozens of other watery expanses where the diagram “doesn’t work.” Each was reconciled on a case-by-base basis. Straits were given special attention to guarantee the right of innocent passage.
Getting a rise out of oceans
Sea levels are rising. The ice caps on Greenland and Antarctica, plus a majority of the world’s glaciers, are slowly shrinking. The shrinking is a by-product of global warming (also called the greenhouse effect), which you can read about in Chapter 18. As the glaciers slowly recede, their melt water returns to the oceans, which rise. Perhaps the most important word there is “slowly.” Unless you live very close to sea level, you have no cause to have a nightmare about the ocean rising around your ankles. I would caution you, though, to think very carefully about beachfront real estate as a long-term investment.
How high the oceans will rise is open to debate because nobody knows for certain the future course and severity of global warming. But consider the past as a portent of possibilities. About 18,000 years ago, at the peak of the last Ice Age, sea levels were about 475-500 feet lower than they are today — because so much water was “locked up” on land in the great glaciers. About 400 years ago, the English founded Jamestown, Virginia, and built a wharf. Today, that wharf is about 12 feet under water, a victim of rising sea level.
Geographically, rising sea level is very important. Perhaps the most basic element of geography is the familiar outline of the continents and other major land bodies that you see on a world map. For the last 18,000 or so years, the world map has been changing, with the ocean on the up-and-up. And this trend will continue for the foreseeable future. Thus, you may legitimately think of today’s world map as a single frame of a very long movie. You know the plot: Oceans are rising. As for the ending . . . well, several outcomes are possible. All involve higher sea levels. Even if the change is slight, the impact will be significant. A rise of just a couple of feet in the next century will affect millions of people. The highest elevations of several island republics (The Maldives in the Indian Ocean, for example) are “just a couple of feet” above sea level. Much of the Bahamas is “just a couple of feet” above sea level, and so too are large areas of Bangladesh — one of the most densely populated countries in the world. And literally dozens of populous port cities around the world have millions of people and trillions of dollars of infrastructure “just a couple of feet” above sea level. Significant change is on way. The map will look different. The world’s geography will be different.
Getting Fresh with Water
Water, water everywhere. While the oceans may be the biggest water bodies out there, they’re not necessarily the most important — it’s time to talk about some drops you can actually drink. And that entails the water cycle (or hydrological cycle), which, as far as physical processes are concerned, is a doozy. See Figure 8-4 for a look at the water cycle. You simply cannot live without it, and neither could any other living thing that requires fresh water because the water cycle is the world’s one and only producer of fresh water — no water cycle, no fresh water — it’s as simple as that.
In addition to the stages described in the next section, the water cycle has two overriding characteristics that are good to keep in mind. Here they are:
It really is a cycle. The water really does go round and round just like the diagram suggests. “Cycle,” therefore, very appropriately describes what’s going on.
The cycle is a closed system. By closed system, I mean that nothing gets added to it or subtracted from it. For all intents and purposes, the amount of water on Earth is fixed — closed to change. Thus, if a lake or reservoir dries up, the water is not really “gone.” Instead, it has relocated elsewhere within the system.
The stages of the water cycle
Here are the principal components of the water cycle:
Solar energy: Technically, sunshine isn’t part of the water cycle for the simple reason that sunlight isn’t water. But it’s the sun that sets the cycle in motion. The sun is the pump that gets things moving.
Evapotranspiration: Whew! That’s a mouthful. And it’s a combination of two words: evaporation and transpiration. With regards to the first word, some water evaporates when it receives solar energy. That is, it changes from a liquid state to a gaseous state: vapor. With salty sea-water, only the water evaporates, and not the salt. So salty seawater becomes freshwater vapor in the atmosphere.
With regards to the second word, transpiration, you perspire, plants transpire. Plants give off moisture when the sun heats them up — only it’s called transpiration. Plant sweat is a key input into the vapor in the atmosphere, especially in lush, tropical areas.
Condensation: Water vapor is so small that it’s invisible. But when lots of individual bits of vapor cluster and combine, they become visible miniature droplets of water. This is condensation, and if it happens by the gazillions, you get a cloud. As to exactly what happens to produce condensation, well, I’m holding that until Chapter 9.
Precipitation: If condensation continues, then the droplets continue to get bigger and put on weight until they are too heavy to remain suspended in the atmosphere. They then fall to Earth as precipitation. This phenomenon may take various forms, including snow, sleet, hail, and most commonly, of course, rain.
No, I didn’t forget to write something. Instead, each deserves a separate heading because, no matter where you live, one or both is responsible for your water supply.
Run-off: Going with the flow
Some of the water that falls to earth collects on the surface and begins a down-slope journey to the sea — there to complete the water cycle. Trickles join to form babbling brooks (why do brooks babble, anyway?), which join to form rivers. Basically, it’s fresh water on the move, and every last drop of it is potentially available to people.
Rivers have long served as water supply systems for cities and towns. But rivers that bring drinkable water can also take away sewage and waste. That’s great unless you happen to live downstream — there to discover your drinking water is no longer drinkable thanks to your upstream neighbors. And most people live down stream from somebody else, so problems afloat.
To solve the problem, many towns and municipalities have gotten into the business of capturing drinkable run-off by building dams that create reservoirs that store water that can be transferred to where people need it. These public works tend to get located in not-yet-contaminated headwaters. Some-times, however, these headwaters are far from the people who will consume them, and therefore require construction of aqueducts to resolve the geographic difference between supply and demand. Some of the water that supplies New York City, for example, comes from a reservoir more than a hundred miles away.
Infiltration: Out of sight, not out of mind
Some of the water that falls to earth infiltrates the soil. That is, it seeps into the ground. Because nature has been at this for a long, long time, some lands are underlain by substantial aquifers — subterranean accumulations of water. Better to think of these not as underground lakes but as areas of super-saturated soil or porous rock (yes, rock!) with a high water content. If your water supply comes from a well, then you live on water that has infiltrated. Well water can be suitable to drink as is, or it may require minimal treatment. But infiltrated water has two potential problems — contamination and depletion.
Along with rainwater, chemical fertilizers and industrial wastes can seep into the soil and contaminate aquifers. One of the more horrific potential results is a cancer cluster — an area whose residents have a disproportionately high incidence of some kind of cancer. These areas may occur because a factory dumped carcinogenic wastes that seeped into an aquifer and eventually mixed with people’s water supply.
Quite often, people consume water from aquifers much faster than nature replaces it. Nature was putting water in aquifers long before people came along. But the amount of water in the bank can diminish quickly when people start drawing from that watery account in quantity.
Consider, for example, the Ogallala Aquifer, which underlies a considerable portion of the American High Plains (see Figure 8-5). If you reside in the U.S., then that aquifer is vitally important to you even if you live nowhere near it because a host of crops that feed people and fatten livestock are grown in great quantities in the High Plains with the use of irrigation water from the Ogallala Aquifer. And the water within it is being consumed much faster than is being replenished. Wells must be dug deeper and deeper. Theoretically, one day, they may all dry up.
Doom and gloom? Not necessarily. Advances in agriculture are making it possible to produce good harvests with less water. Greater conservation also is possible, as is greater use of regional rivers for irrigation. And if worse comes to worse, well, portions of the High Plains could revert to something akin to the lush natural grazing lands (the prairies) that were done away with to make way for farms.
Applied Geography: Drip irrigation
In arid and semi-arid lands, water for irrigation has long been applied to fields by means of open-air ditches between rows of crops. Although this method has helped satisfy the food needs of unknown numbers of people over the millennia, it has three significant drawbacks. First, a substantial volume of water may evaporate before it reaches the plants. Second, the amount of water that seeps into the soil is usually far more than the plants actually need. Third, the mineral salts that build up in the soil as a consequence of evaporation may ultimately undermine the usefulness of the farmland and lead to its abandonment.
In some countries, however, these environ-mental effects have been largely nullified by introduction of drip irrigation. In this technique, water reaches the fields and is distributed up and down crop rows by means of thin plastic tubing that is perforated by tiny holes every few inches. Water is forced through the tubing at very low pressure; so instead of squirting out of the holes like so many tiny fountains, the water slowly drips out. Because of the tubing, very little water is lost to evaporation. Moreover, drop by drop application results in little water wasted and minimal salt accumulation. All in all, therefore, drip irrigation is proving to be an effective and fairly low cost means of making maximum use of a scarce arid-land resource.
Good to the very last drop
The bottom line with respect to run-off and infiltration is that you can’t take more water out of the system than nature puts into it. Reservoirs and aquifers can dry up. In that event, water will still be everywhere, albeit in forms that are not readily accessible (such as vapor in the air or veneer surrounding soil particles) or in amounts that satisfy local needs. Humans number six billion and counting. More people mean more direct consumption, more irrigation, and more industrial use. How these needs will be met remains to be seen, but they will clearly reflect the geography of a precious resource.