Water Tale

Spinning a globe on its axis, or viewing satellite images of the earth, the immense surface area of water is deceiving. Most of the earth is covered by water. But two-dimensions belies the three-dimensional truth.

Consider two spheres:

Earth Sphere
The earth is a sphere slightly flattened at the poles. If it was possible to drill a core through the earth, it would be 7,918 miles long. The earth's diameter is about 7,918 miles across. 

Water Sphere
If every water molecule on earth was contained by a sphere, the sphere would be much smaller than the earth sphere. Visualized as a sphere, earth's water would be 860 miles across.

Volume of all earth's water as compared to the earth's volume.
US Geological Survey

Water as a sphere	Earth as a sphere
860 mile diameter	7,918 mile diameter

The tiny blue sphere located east of the much larger total water sphere represents all of the fresh water found in the ground, lakes, swamps, and rivers. The fresh water sphere is 169.5 miles in diameter.

You could not step twice into the same rivers; for other waters are ever flowing on to you.
― Heraclitus of Ephesus

REFERENCES

• The USGS Water Science School

Estuary Meditation

Estuaries are places where rivers meet the ocean ― bays, harbors, lagoons, salt marshes, tidal inlets, barrier islands, and sounds.

The estuary is a transition ecosystem between rivers and ocean ― a zone influenced by marine phenomena like tides, waves, and the influx of salt water and riverine phenomena like fresh water flows and sediment transport.

Conceptual Diagram of an Estuary.
Source: Louisiana Universities Marine Consortium (LUMCON)

Blue Crab

Estuaries are among the most productive micro-environments on earth with more organic matter created annually than comparably-sized forests, grasslands, or cultivated land.

Sheltered estuarine waters support thriving communities of plants and animals especially adapted for this ecosystem.

To stand at the edge of the sea, to sense the ebb and flow of the tides, to feel the breath of a mist moving over a great salt marsh, to watch the flight of shore birds that have swept up and down the surf lines of the continents for untold thousands of year, to see the running of the old eels and the young shad to the sea, is to have knowledge of things that are as nearly eternal as any earthly life can be.
― Rachel Carson

Estuary of Klamath River in Redwood National Park.

The nutrient cycle, the water cycle, and the cycle of life are the primary physical and biological phenomena found in estuaries:

• Nutrient Cycle - Many elements are recycled in estuaries providing sustenance to living organisms. The health of an estuary depends on a balance of these elements.
• Water Cycle - Evaporation occurs in estuaries and fresh water recharges ground water reserves.
• Cycle of Life - Estuaries provide food, shelter, and nurseries for animals. Decomposing animals provide nutrients for other organisms.

We need the tonic of wildness, to wade sometimes in marshes where the bittern and the meadow-hen lurk, and hear the booming of the snipe; to smell the whispering sedge where only some wilder and more solitary fowl builds her nest, and the mink crawls with its belly close to the ground.
― Henry David Thoreau

National Estuaries Day is an annual observation in the US held on the last Saturday of September.