|The Water Planet|
Wednesday, April 2, 2014
Map makers tell us that oceans cover 70% of the Earth. Given the great depths of the oceans, geologists conclude that 97% of the Earth's water is salt water. Only 3% of the Earth's water is fresh water, and 2/3 of that is locked up in ice caps and glaciers (at least for the time being). If you are doing the math, you've already concluded that only 1% of the Earth's water is available to maintain us and all other fresh water organisms in the manner of living to which we've become accustomed.
Of that 1%, only 30% is surface water (including atmospheric water that may – or in England WILL – precipitate) and 70% is underground. Of the surface water, 87% is in lakes, 11% in swamps, and 2% in rivers. I am not making this up.
I may not be very good at math, but even I can calculate that the 2% of surface water's 30% of fresh water's 1% of all the Earth's water that comprises rivers amounts to only .00006, or 6/100,000 of the Earth's water. In other words, rivers hold less than 1/100th of 1% of all the Earth's water. This is small consolation to those who have been experiencing floods, but the numbers don’t lie.
I’ve lived most of my life near rivers. Not the wide, calm, navigable rivers typically associated with shipping – but the raging and foaming rivers tumbling from the Sierra Nevada over iconic waterfalls, and the violent rivers of Arizona and Utah, endlessly carving magnificent canyons through the desert landscape. For all their power, the rivers of the American southwest carry very little water – only a small fraction of that carried by the Mississippi. Yet the economic importance of those rivers is demonstrated by how very little of their waters actually reach the sea – most being diverted to irrigate crops and satisfy domestic needs like flushing toilets and filling swimming pools. When you think about it, rivers are essential to our way of life.
Yet to a boy reading maps, a river can be more a curiosity than a necessity. Maps typically depict a river by a squiggly blue line with one end terminating at a lake or ocean. But the other end just starts – sometimes at a lake or at a glacier, but often where there is no noticeable geological feature. Is that what rivers do – do they just start, like a line on paper? Even a ten-year-old boy can conceive tiny drops of rain coalescing into a flash flood, but a flash flood isn’t a river. A river has a continual flow. So, where does a river's water actually start its continual flow? When my teachers couldn’t satisfactorily answer what I thought to be a simple question, I knew I would need to explore a river myself to find out. I didn't expect it to be easy, but it had to be easier than exploring terra incognita.
First I had to choose a river to explore. No ten-year-old boy could resist the allure of the Amazon or the Congo. Yet somehow I intuitively knew that my mother wouldn't allow me to enter jungles infested by mosquitoes and pythons, so I didn't even bother to ask. Movies depicting killer mummies inhabiting Egyptian pyramids probably disqualified the Nile also. I hadn’t heard of any monsters inhabiting the Mississippi though, and I convinced myself that no mother would deny her son the opportunity to re-live the adventures of Tom Sawyer and Huck Finn. So as a ten-year-old boy I resolved to follow the Mississippi to its source, wherever that may be. I just had to wait for the right time to ask permission.
Somehow, more than half a century of life sidetracked my resolve. Then one day a few years ago, while Janet and I were touring London, I stumbled upon a footpath sign marking something called the Thames Path, and a long-dormant idea slowly stirred from the recesses of my mind. The words “I wonder if...” had barely passed my lips, when Janet rolled her eyes in mock disbelief – but she knew what was coming next. I immediately dragged her off to Covent Garden and into Stanfords Book Store, where I picked up a guidebook and a handful of OS maps.
The book and maps confirmed my hunch. I didn't need to follow the Mississippi – the English had actually made it easy for me to follow a river to its source. No mosquitoes, no pythons, no mummies – rather, an easy 180-mile footpath lined with dozens of hotels offering hot showers and soft beds; scores of pubs serving hot meals and cool drinks; and legions of Brits yearning to explain to a ten-year-old boy what exactly it is that England does with more than its share of fresh water.
So if my body can hold itself together for a few more months, and if England’s winter floods will drain as the contour lines on my maps show they are supposed to, I’ll attempt to follow the River Thames to its source. Then, to be sure I don’t reach any premature conclusions based on flimsy evidence, I’ll actually search out the source of as many other rivers as I can. Huck Finn would be envious.