Seventy-five percent of the surface of the Earth is covered with water, but more than ninety-seven percent of it is salt water that makes up the oceans. Another two percent is frozen in glaciers and the polar ice caps, leaving only one percent of all Earthly water available in usable form for life outside of the oceans.
WATER’S JOURNEY FROM MOUNTAINTOP TO THE SEA
The availability of water throughout the year will ultimately determine both the quality of life in a community and thereby the value of real estate. Consequently, our nation’s supply of quality water is precious beyond compare. In fact, water is the most valuable commodity from our nation’s forests and those of the world—all of them, public and private. But then, is water really a commodity in the sense of economic markets or is access to water part of the global commons—the birth-right of every individual?
Is water to become the ultimate economic/environmental club with which we bludgeon one another? This question is appropriate because we are running out of available supplies of quality, potable water.
Most water used by communities comes first in the form of snow and ice (aboveground water storage) either at high elevations or northern latitudes, where it melts and subsequently feeds the streams and rivers that eventually reach distant communities and cities—rivers, such as the Columbia in United States, the Amazon in South America, the Ganges in India, Yangtze River in China, the Volga in Russia, and the Rhine in Europe.
Lang Tang (27,000 = 8,230 meters) from an elevation 11,500 feet (3,505 meters) on Phulung Ghyang, Newakot District, Nepal, in May 1967, and a fifteen-foot (4.5-meter) snowpac in the high Cascade Mountains of Oregon in March 1958.
The Greater Himalayas, for example, hold the largest mass of ice outside the Polar Regions and are the source of the ten largest rivers in Asia, and the glaciers are melting rapidly. The cascading effects of rising temperatures and dwindling amounts of ice and snow in the region are affecting such things as availability of water (amounts, seasonality), biodiversity (endemic species, predator-prey relations), shifts in the boundaries of ecosystems (upward movement in tree-line and other changes in high-elevation ecosystems), and global feedback loops (shifts in the monsoons and loss of soil carbon). Climate change will also increase the uncertainty in water supplies and likely reduce agricultural production for human populations across Asia.2
Snowpack in the Alps near Melchsee, Switzerland, on the 24th of May, 1985.
Aside from glacial ice, the annual accumulation of snow (snowpack) can, under good conditions, last as snowbanks late into the summer or even early autumn. How much water the annual snowpack has and how long the snowpack lasts depends on six things: (1) the timing, duration, and persistence of the snowfall in any given year; (2) how much snow accumulates during a given winter; (3) the moisture content of the snow—wet snow holds more moisture than dry snow; (4) where the snowfall accumulates in relation to shade and cool temperatures in spring and summer, e.g., under the cover of trees and on north-facing slopes versus in the open and south-facing slopes with no protective shade; (5) when the snow begins melting and the speed at which it melts—the later in the year it begins melting and the slower it melts, the longer into the summer its moisture is stored above and below ground; and (6) the health of the overall water catchment.
Although the first five points seem self-evident, the last one requires some explanation. In dealing with the health of water catchments, one must consider those of both high and low elevation. How we treat our high-elevation forests (and those at more northerly latitudes) is how we treat a major portion of the most important sources of our supply of potentially available water—the purity and longevity of the snow and ice.
Snow being protected in late June and early July under the canopy of a high-elevation, ancient forest.
Snow disappears in two ways: sublimation and melting. Sublimation means that snow, accumulating in such places as the upper surfaces of coniferous boughs above the ground, evaporates and re-crystallizes without melting into water. When snow sublimates, it bypasses any role in our supply of available water. Melting snow, on the other hand, is a different story.
With the advent of late spring and early summer, snow begins to melt, and gradually infiltrates the soil as water until every minute nook and cranny is filled to capacity with this precious liquid, which all the while is obeying the unrelenting dictates of gravity as it journeys along ancient geological pathways toward the streams and rivers of the land on its way to the sea from whence it came. As gravity pulls the water downward through the soil, the slowly melting snow continually fills the void left by the departing liquid.
Snow and ice melting under the summer sun as the water slowly sinks into the soil, there to commence its long journey to the sea.
Thus, the amount and quality of water available for human use is largely the result of climate, topography, and the ecological integrity of the water catchments. In turn, water is stored in four ways: (1) in the form of snowpack and glaciers aboveground; (2) in the form of water penetrating deep into the soil, where it flows slowly belowground; (3) in belowground aquifers and lakes; and (4) in aboveground lakes and reservoirs.
There are, however, extenuating circumstances when it comes to cities built in such arid environments as deserts, for example: Las Vegas, Nevada, in the United States; Cairo in Egypt; and Lima in Peru. Cities like Lima, which get their water strictly from distant glaciers, are particularly prone to encountering significant problems with their long-term supply of water because alternatives are either severely limited or nonexistent.
The South American mountain range known as the Andes is the source of many Peruvian rivers. In fact, Peru has the largest number of tropical glaciers anywhere in the world, and the continual, slow release from this aboveground water storage is crucial because western Peru desperately needs the water all year round—particularly in the six or seven months of the dry season. Even though this coastal portion of the country generally has an abundance of water, its accessibility is unequal because of how the rivers are distributed across the landscape and because of the season variability of the high and low flows. Both circumstances are exacerbated because western Peru, with its large cities, is located on the Pacific-Ocean side of the Andes. Whereas coastal Peru is largely desert with less than 2 percent of the country’s water, that part of the country on the Atlantic side of the Andes has 98 percent of the water, but only around a quarter of the population.
Lima is a particularly poignant example of city that is not only situated in a desert with hardly any rainfall but also has to rely on the receding glaciers for its water. Nevertheless, Lima, which already has eight million people, swells by thousands of new arrivals every year—even as its supply of water is shrinking annually.
A team of Peruvian and international scientists estimate that Peru and Bolivia together account for more than 90 percent of the world’s tropical glaciers. However, the glaciers have lost about a third of their surface area between the 1970s and 2006. And this loss includes glaciers on Huascaran, Peru’s largest mountain, which reaches an elevation of 22,200 feet (6,768 meters). Moreover, the changing climate is melting the glaciers faster than in decades past and making the flow of rivers increasingly irregular, which is leading to more droughts and floods.
On the economic side, the dwindling supply of water affects every Peruvian household, to say nothing of the 80 percent of the country’s power, which is hydroelectric, as well as its agricultural exports and mining, both of which absorb huge volumes of this precious liquid.3
In contrast, most low-elevation water catchments, which may or may not be forested, must be much larger in area than a high-elevation catchment to collect and store the same amount of water. Although snow may not be as important for the storage of water in low elevations, the ability of water to infiltrate deep into the soil is equally important. The storage of water at low-elevation, non-forested areas is often in wetlands, subterranean aquifers and lakes, as well as in aboveground lakes and reservoirs.
Water stored in a mountain lake.
WATER–A CAPTIVE OF GRAVITY
In the end, water must reach human communities like Wallgau in Bavaria, West Germany—with the Alps in the background.
Unless otherwise noted, Text and Photos © by Chris Maser, 2009. All rights reserved. Opening photograph by and courtesy of Sue Johnston.