What is freshwater storage

Surface water includes the lakes, reservoirs human-made lakes , ponds, streams of all sizes, from large rivers to small creeks , canals human-made lakes and streams , and freshwater wetlands. The definition of freshwater is water containing less than 1, milligrams per liter of dissolved solids, most often salt. As a part of the water cycle, Earth's surface-water bodies are generally thought of as renewable resources, although they are very dependent on other parts of the water cycle.

The amount of water in rivers and lakes is always changing due to inflows and outflows. Inflows to these water bodies will be from precipitation , overland runoff , groundwater seepage, and tributary inflows. Outflows from lakes and rivers include evaporation , movement of water into groundwater, and withdrawals by people.

Humans get into the act also, as people make great use of surface water for their needs. So, the amount and location of surface water changes over time and space, whether naturally or with human help. Certainly during the last ice age when glaciers and snowpacks covered much more land surface than today, life on Earth had to adapt to different hydrologic conditions than those which took place both before and after.

And the layout of the landscape certainly was different before and after the last ice age, which influenced the topographical layout of many surface-water bodies today. Glaciers are what made the Great Lakes not only "great, " but also such a huge storehouse of freshwater. Nile Valley in Egypt—Water makes the desert bloom. If you ever wondered if the expression "Water makes the desert bloom" was true, there is no better proof than this satellite picture of the Nile Valley in Egypt.

Credit: NASA. As this picture of the Nile Delta in Egypt shows, life can even bloom in the desert if there is a supply of surface water or groundwater available.

Water on the land surface really does sustain life, and this is as true today as it was millions of years ago. I'm sure dinosaurs held their meetings at the local watering hole million years ago, just as antelopes in Africa do today. And, since groundwater is supplied by the downward percolation of surface water, even aquifers are happy for water on the Earth's surface.

You might think that fish living in the saline oceans aren't affected by freshwater, but, without freshwater to replenish the oceans they would eventually evaporate and become too saline for even the fish to survive. As we said, everybody and every living thing congregates and lives where they can gain access to water, especially freshwater. Just ask the 6 billion people living on Earth! Here's a satellite picture of the world at night.

The most obvious thing you can see is that people live near the coasts, which, of course, is where water, albeit saline, is located. But the interesting thing in this picture are the lights following the Nile River and Nile Delta in Egypt the circled area. In this dry part of the world, surface-water supplies are essential for human communities. And if you check the price of lakefront property in your part of the world, it probably sells for much more than other land.

View the full image from NASA. To many people, streams and lakes are the most visible part of the water cycle. Not only do they supply the human population, animals, and plants with the freshwater they need to survive, but they are great places for people to have fun. Water storage locations are commonly referred to as reservoirs. Each stage of the hydrologic cycle involves the storage of water Figure 1. Water can be stored in the atmosphere, on the surface of the Earth, or underground.

Natural reservoirs include oceans, glaciers and ice sheets, groundwater, lakes, soil moisture, wetlands, living organisms, the atmosphere, and rivers. Collectively, all water storage areas make up the hydrosphere. Most water on earth is found in the oceans and seas, followed by glaciers and groundwater. Water from the ocean evaporates into the atmosphere, then falls back to Earth's surface as precipitation.

Most precipitation falls back into the ocean but some precipitation falls onto land. Water moves from reservoir to reservoir through different hydrologic fluxes such as evaporation , condensation , the flow of rivers, precipitation , and anthropogenic diversion. Oceans, rivers, ice caps, the atmosphere, aquifers, and lakes are all examples of reservoirs with varying residence times.

The residence time describes how long the water stays in a reservoir before leaving. Water in aquifers below the oceans is generally saline, while the water below the land surfaces where freshwater, which fell as precipitation, infiltrates into the ground is generally freshwater.

There is a stable transition zone that separates saline water and freshwater below ground. It is fortunate for us that the relatively shallow aquifers that people tap with wells contain freshwater, since if we tried to irrigate corn fields with saline water I suspect the stalks would refuse to grow. Source: Gleick, P.

In Encyclopedia of Climate and Weather, ed. Do you think you know about groundwater? Quiz icon made by mynamepong from www. Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth.

Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years. The air is full of water, even if you can't see it. Higher in the sky where it is colder than at the land surface, invisible water vapor condenses into tiny liquid water droplets—clouds.

When the cloud droplets combine to form heavier cloud drops which can no longer "float" in the surrounding air, it can start to rain, snow, and hail What is streamflow? How do streams get their water? To learn about streamflow and its role in the water cycle, continue reading. Perhaps you've never seen snow. Or, perhaps you built a snowman this very afternoon and perhaps you saw your snowman begin to melt. Regardless of your experience with snow and associated snowmelt, runoff from snowmelt is a major component of the global movement of water, possibly even if you live where it never snows.

For the water cycle to work, water has to get from the Earth's surface back up into the skies so it can rain back down and ruin your parade or water your crops or yard. It is the invisible process of evaporation that changes liquid and frozen water into water-vapor gas, which then floats up into the skies to become clouds.

The atmosphere is the superhighway in the sky that moves water everywhere over the Earth. Water at the Earth's surface evaporates into water vapor which rises up into the sky to become part of a cloud which will float off with the winds, eventually releasing water back to Earth as precipitation. The air is full of water, as water vapor, even if you can't see it.

Condensation is the process of water vapor turning back into liquid water, with the best example being those big, fluffy clouds floating over your head. And when the water droplets in clouds combine, they become heavy enough to form raindrops to rain down onto your head. You can't see it, but a large portion of the world's freshwater lies underground.

It may all start as precipitation, but through infiltration and seepage, water soaks into the ground in vast amounts. Geophysical Research Letters, 31, doi Journal of Geophysical Research, , — Environmental Working Group, Joint U.

Snow and Ice Data Center. Boulder, CO. Journal of Geophysical Research, submitted. Geophysical Research Letters, 32, doi Griffiths RW Gravity currents in rotating systems.

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