Of all freshwater found on Earth, about 69% resides in polar regions in ice caps and glaciers, about 30% can be found underground, and less than 1% is located in lakes, rivers, and swamps, the atmosphere, and in living things.
Freshwater on Earth
Ice, Snow, and Glaciers (almost 70%) - Even though the amount of water locked up in glaciers and ice caps is a small percentage of all water on (and in) the Earth, it represents a large percentage of the world's total freshwater.
Stored water as part of the water cycle
The water cycle describes how water moves above, on, and through the Earth. But, in fact, much more water is "in storage" at any one time than is actually moving through the cycle. By storage, we mean water that is locked up in its present state for a relatively long period of time. Short-term storage might be days or weeks for water in a lake, but it could be thousands of years for deep groundwater storage or even longer for water at the bottom of an ice cap, such as in Greenland. In the grand scheme of things, this water is still part of the water cycle.
Glaciers and icecaps: Storehouses of freshwater
Even though you've maybe never seen a glacier, they are a big item when we talk about the world's water supply. Almost 10 percent of the world's land mass is currently covered with glaciers, mostly in places like Greenland and Antarctica. Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff in areas where they occur.
In a way, glaciers are just frozen rivers of ice flowing downhill. Glaciers begin life as snowflakes. When the snowfall in an area far exceeds the melting that occurs during summer, glaciers start to form. The weight of the accumulated snow compresses the fallen snow into ice. These "rivers" of ice are tremendously heavy, and if they are on land that has a downhill slope the whole ice patch starts to slowly grind its way downhill. These glaciers can vary greatly in size, from a football-field sized patch to a river a hundred miles long.
Freshwater on Earth
Ice, Snow, and Glaciers (almost 70%) - Even though the amount of water locked up in glaciers and ice caps is a small percentage of all water on (and in) the Earth, it represents a large percentage of the world's total freshwater.
Stored water as part of the water cycle
The water cycle describes how water moves above, on, and through the Earth. But, in fact, much more water is "in storage" at any one time than is actually moving through the cycle. By storage, we mean water that is locked up in its present state for a relatively long period of time. Short-term storage might be days or weeks for water in a lake, but it could be thousands of years for deep groundwater storage or even longer for water at the bottom of an ice cap, such as in Greenland. In the grand scheme of things, this water is still part of the water cycle.
Glaciers and icecaps: Storehouses of freshwater
Even though you've maybe never seen a glacier, they are a big item when we talk about the world's water supply. Almost 10 percent of the world's land mass is currently covered with glaciers, mostly in places like Greenland and Antarctica. Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff in areas where they occur.
In a way, glaciers are just frozen rivers of ice flowing downhill. Glaciers begin life as snowflakes. When the snowfall in an area far exceeds the melting that occurs during summer, glaciers start to form. The weight of the accumulated snow compresses the fallen snow into ice. These "rivers" of ice are tremendously heavy, and if they are on land that has a downhill slope the whole ice patch starts to slowly grind its way downhill. These glaciers can vary greatly in size, from a football-field sized patch to a river a hundred miles long.
Bering Glacier is the largest glacier in North America
Bering Glacier is in Vitus Lake south of Alaska's Wrangell-St. Elias National Park, about 10 kilometersfrom the Gulf of Alaska. Combined with the Bagley Icefield, where the snow that feeds the glacier accumulates, the Bering is the largest glacier in North America. Warmer temperatures and changes in precipitation over the past century have thinned the Bering Glacier by several hundred meters. Since 1900 the terminus has retreated as much as 12 km. Most of the glaciers along the Alaskan coast are retreating along with the Bering Glacier.
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Groundwater (about 30%) - You see water all around you every day as lakes, rivers, ice, rain and snow. There are also vast amounts of water that are unseen—water existing in the ground. And even though groundwater is unseen, it is moving below your feet right now.
Groundwater flows underground
As part of the water cycle, groundwater is a major contributor to flow in many streams and rivers and has a strong influence on river and wetland habitats for plants and animals. People have been using groundwater for thousands of years and continue to use it today, largely for drinking water and irrigation. Life on Earth depends on groundwater just as it does on surface water.
There are rivers flowing below our feet ... a myth?
Have you ever heard that there are rivers of water flowing underground? Do you think it is true? Actually, it is pretty much a myth. Even though there are some caverns, lava and ice tubes, and horizontal springs that can carry water, the vast majority of underground water occupies the spaces between rocks and rock particles as water underground is more like water in a sponge. At a certain depth below the land surface, the spaces between the soil and rock particles can be totally filled with water, resulting in an aquifer from which groundwater can be pumped and used by people.
Groundwater flows underground
As part of the water cycle, groundwater is a major contributor to flow in many streams and rivers and has a strong influence on river and wetland habitats for plants and animals. People have been using groundwater for thousands of years and continue to use it today, largely for drinking water and irrigation. Life on Earth depends on groundwater just as it does on surface water.
There are rivers flowing below our feet ... a myth?
Have you ever heard that there are rivers of water flowing underground? Do you think it is true? Actually, it is pretty much a myth. Even though there are some caverns, lava and ice tubes, and horizontal springs that can carry water, the vast majority of underground water occupies the spaces between rocks and rock particles as water underground is more like water in a sponge. At a certain depth below the land surface, the spaces between the soil and rock particles can be totally filled with water, resulting in an aquifer from which groundwater can be pumped and used by people.
Some of the precipitation that falls onto the land infiltrates into the ground to become groundwater. If the water meets the water table (below which the soil is saturated), it can move both vertically and horizontally. Water moving downward can also meet more dense and water-resistant non-porous rock and soil, which causes it to flow in a more horizontal fashion, generally towards streams, the ocean, or deeper into the ground.
Surface Water (less than 1%) - Lakes, rivers, and streams
If people had to pick their favorite water body, they might choose a crystal-clear lake nestled in the mountains. Not all lakes are clear or are near mountains, though. The world is full of lakes of all types and sizes. A lake really is just another component of Earth's surface water. A lake is where surface-water runoff (and maybe some groundwater seepage) have accumulated in a low spot, relative to the surrounding countryside. It's not that the water that forms lakes get trapped, but that the water entering a lake comes in faster than it can escape, either via outflow in a river, seepage into the ground, or by evaporation. And if humans live nearby, then water levels can be affected by water withdrawals for human needs.
Rivers? Streams? Creeks? They are all names for water flowing on the Earth's surface. As far as this site is concerned, they are pretty much interchangeable. I tend to think of creeks as the smallest of the three, with streams being in the middle, and rivers being the largest.
Most of the water you see flowing in rivers comes from precipitation runoff from the land surface alongside the river. Of course, not all runoff ends up in rivers. Some of it evaporates on the journey down slope, can be diverted and used by people for their uses, and can even be lapped up by thirsty animals. Rivers flow through valleys in the landscape with ridges of higher land separating the valleys. The area of land between ridges that collects precipitation is a watershed or drainage basin. Most, but not all, precipitation that falls in a watershed runs off directly into rivers - part of it soaks into the ground to recharge groundwater aquifers, some of which can then seep back into riverbeds.
If people had to pick their favorite water body, they might choose a crystal-clear lake nestled in the mountains. Not all lakes are clear or are near mountains, though. The world is full of lakes of all types and sizes. A lake really is just another component of Earth's surface water. A lake is where surface-water runoff (and maybe some groundwater seepage) have accumulated in a low spot, relative to the surrounding countryside. It's not that the water that forms lakes get trapped, but that the water entering a lake comes in faster than it can escape, either via outflow in a river, seepage into the ground, or by evaporation. And if humans live nearby, then water levels can be affected by water withdrawals for human needs.
Rivers? Streams? Creeks? They are all names for water flowing on the Earth's surface. As far as this site is concerned, they are pretty much interchangeable. I tend to think of creeks as the smallest of the three, with streams being in the middle, and rivers being the largest.
Most of the water you see flowing in rivers comes from precipitation runoff from the land surface alongside the river. Of course, not all runoff ends up in rivers. Some of it evaporates on the journey down slope, can be diverted and used by people for their uses, and can even be lapped up by thirsty animals. Rivers flow through valleys in the landscape with ridges of higher land separating the valleys. The area of land between ridges that collects precipitation is a watershed or drainage basin. Most, but not all, precipitation that falls in a watershed runs off directly into rivers - part of it soaks into the ground to recharge groundwater aquifers, some of which can then seep back into riverbeds.
The Atmosphere - The atmosphere is full of water
The water cycle is all about storing water and moving water on, in, and above the Earth. Although the atmosphere may not be a great storehouse of water, it is the superhighway used to move water around the globe. Evaporation and transpiration change liquid water into vapor, which ascends into the atmosphere due to rising air currents. Cooler temperatures aloft allow the vapor to condense into clouds and strong winds move the clouds around the world until the water falls as precipitation to replenish the earthbound parts of the water cycle. About 90 percent of water in the atmosphere is produced by evaporation from water bodies, while the other 10 percent comes from transpiration from plants.
There is always water in the atmosphere. Clouds are, of course, the most visible manifestation of atmospheric water, but even clear air contains water—water in particles that are too small to be seen. One estimate of the volume of water in the atmosphere at any one time is about 3,100 cubic miles or 12,900 cubic kilometers. That may sound like a lot, but it is only about 0.001 percent of the total Earth's water volume of about 332,500,000, as shown in the table below. If all of the water in the atmosphere rained down at once, it would only cover the globe to a depth of 2.5 centimeters, about 1 inch.
The water cycle is all about storing water and moving water on, in, and above the Earth. Although the atmosphere may not be a great storehouse of water, it is the superhighway used to move water around the globe. Evaporation and transpiration change liquid water into vapor, which ascends into the atmosphere due to rising air currents. Cooler temperatures aloft allow the vapor to condense into clouds and strong winds move the clouds around the world until the water falls as precipitation to replenish the earthbound parts of the water cycle. About 90 percent of water in the atmosphere is produced by evaporation from water bodies, while the other 10 percent comes from transpiration from plants.
There is always water in the atmosphere. Clouds are, of course, the most visible manifestation of atmospheric water, but even clear air contains water—water in particles that are too small to be seen. One estimate of the volume of water in the atmosphere at any one time is about 3,100 cubic miles or 12,900 cubic kilometers. That may sound like a lot, but it is only about 0.001 percent of the total Earth's water volume of about 332,500,000, as shown in the table below. If all of the water in the atmosphere rained down at once, it would only cover the globe to a depth of 2.5 centimeters, about 1 inch.