Editor’s Note: This is a column on the area’s watershed by Blyden Potts and guest columnists to help raise awareness of the area’s tributaries and the efforts of the area’s volunteers to keep them clean.
“We forget that the water cycle and the life cycle are one.” – Jacques Cousteau.
Cousteau did not simply mean these words in a spiritual or rhetorical sense. He meant it literally: The water cycle is physical, integral in us, and we are physical, integral in it.
At some point in life you learned about the hydrological cycle, but in case it doesn’t come back to you, allow me a quick refresher. The water cycle is the movement of water through our environment. The “cycle” consists in the fact that water from oceans and lakes evaporates, becomes atmospheric moisture and forms clouds and then falls back on earth as precipitation. In cold regions, snow or ice can accumulate, but rain falling on land either penetrates the groundwater or flows into waterways and flows back into the sea to complete the cycle.
Graphic representations of this cycle can be found in countless textbook illustrations and on the Internet.
When we focus on the cyclical aspect we tend to think of water in motion, but the water cycle encompasses all of the water on and in the planet. Most of the water is “stored” in relatively static locations. A water molecule can often remain in one of these “reservoirs” for millennia. Over 96.5 percent of the earth’s water is in our oceans. Another 3.4 percent is in ice caps, glaciers and groundwater. The proportion of active parts of the cycle is less than 0.1 percent at any point in time, including all streams, rivers and lakes in the world as well as the total moisture in the earth’s atmosphere.
Another thing that is overlooked is that living organisms are part of the water cycle. Water flows through every plant, every animal and every person. The proportion of plants and animals in the world’s fresh water on the earth’s surface is only in the range of 1 percent at any time, but the influence of life on the water cycle is greater because water circulates through plants and animals over time.
The transpiration of trees and other plants is a motor that brings moisture back into the air. In the Amazon and other tropical rainforests, the biomass of the vegetation and the transpiration rates are so great that rivers with atmospheric moisture develop, which shape the weather of our planet. Mankind also has considerable power to influence the world’s water cycle for better or for worse.
The water cycle would by and large still exist without life, but life as we know it would not exist without the water cycle. Most of the human body is made up of water. You can probably survive without food for a few weeks or more, but only a few days without fresh water. Water circulates through us as we live. In with food and drink, out with urine and sweat. Our food depends on water, because what we eat comes from plants and animals that mainly need and consist of water. Most food webs are ultimately maintained by photosynthesis, which requires water. For these reasons, among other things, the distribution and flow of water forms on which human populations live on the planet, as you can see on a map.
Any disruption, damage, or major change in the planet’s water cycle can disrupt, damage, or significantly change our way of life and even our viability. Therefore we should not forget that we are in the water cycle and the water cycle is within us; why we shouldn’t regard shore landscapes as something outside of our existence, but as our fellow members in a shared ecological context on which our lives depend.