Millions of cubic miles of water exists in the ground. You can't see it, but not only is it there, it is always moving around -- mostly downward, but also horizontally. Moving groundwater helps keep rivers full of water and allows for people to draw out water via wells. Moving groundwater is an important part of the water cycle.
• Water Science School HOME • Groundwater topics •
Groundwater Flows Underground
Credit: Howard Perlman, USGS
A neighbor's driveway with some water on it... not very exciting, but it is an excellent example of how groundwater flows underground and can seep back to the land surface. This simple process demonstrates one of the basic aspects of the water cycle.
This picture really demonstrates why there is water in many streams even after long periods of no rainfall. You have to "look below the surface" (pun intended) of what you see here. The water on the driveway is not runoff from the surface, but is seepage out of the ground after a downpour the day before.
During the rainstorm water soaked into the ground in the hill above the driveway. As happens with water below ground, it started moving along underground layers of soil and rock that are porous enough to allow water to move through it. After a storm, water doesn't move straight down into the ground, but, rather, it moves both downward and horizontally along permeable layers. The water is moving downhill ("down-gradient") toward a creek at the bottom of the hill.
Normally, the water would just flow underground to the bottom of the hill and seep out of the stream banks into the creek. But here the driveway was dug deep enough into the ground so that it cut into the permeable layer of soil that carries the underground water downhill. Thus, you can see groundwater seepage coming to the surface.
By the way, it is seepage such as this that helps keep water flowing in many creeks and streams during periods of drought.
Want to learn more about how groundwater flows underground? Follow me to the Groundwater Basics website!
Below are other science topics associated with groundwater.
Groundwater Information by Topic
Infiltration and the Water Cycle
Groundwater True/False Quiz
Groundwater Storage and the Water Cycle
How the U.S. Geological Survey Monitors Water
- Overview
Millions of cubic miles of water exists in the ground. You can't see it, but not only is it there, it is always moving around -- mostly downward, but also horizontally. Moving groundwater helps keep rivers full of water and allows for people to draw out water via wells. Moving groundwater is an important part of the water cycle.
• Water Science School HOME • Groundwater topics •
Groundwater Flows Underground
Sources/Usage: Public Domain.Groundwater seeping back to the land surface a day after a heavy rain.
Credit: Howard Perlman, USGSA neighbor's driveway with some water on it... not very exciting, but it is an excellent example of how groundwater flows underground and can seep back to the land surface. This simple process demonstrates one of the basic aspects of the water cycle.
This picture really demonstrates why there is water in many streams even after long periods of no rainfall. You have to "look below the surface" (pun intended) of what you see here. The water on the driveway is not runoff from the surface, but is seepage out of the ground after a downpour the day before.
During the rainstorm water soaked into the ground in the hill above the driveway. As happens with water below ground, it started moving along underground layers of soil and rock that are porous enough to allow water to move through it. After a storm, water doesn't move straight down into the ground, but, rather, it moves both downward and horizontally along permeable layers. The water is moving downhill ("down-gradient") toward a creek at the bottom of the hill.
Normally, the water would just flow underground to the bottom of the hill and seep out of the stream banks into the creek. But here the driveway was dug deep enough into the ground so that it cut into the permeable layer of soil that carries the underground water downhill. Thus, you can see groundwater seepage coming to the surface.
By the way, it is seepage such as this that helps keep water flowing in many creeks and streams during periods of drought.
Sources/Usage: Public Domain.Groundwater moves underground. Of course, the source of all water is precipitation, the downward arrows coming down from the top in the diagram. Some of the water hitting the landscape runs downhill and into the stream (purple arrow)—this is runoff. The tan area is the unsaturated zone, which is the top layer of the ground which gets saturated during a heavy rainfall, stays wet but not saturated, after a rainfall, and can become quite dry during times when no precipitation falls. This zone is the area that plants put down roots in, and thus draw water from. The green arrow shows that water moves up from the unsaturated zone into the plants and then out of the plants as evapotranspiration.
Sources/Usage: Public Domain.Want to learn more about how groundwater flows underground? Follow me to the Groundwater Basics website!
- Science
Below are other science topics associated with groundwater.
Groundwater Information by Topic
Groundwater is one of our most valuable resources—even though you probably never see it or even realize it is there. There is water somewhere beneath your feet no matter where on Earth you live. Groundwater starts as precipitation, just as surface water does, and once water penetrates the ground, it continues moving, sometimes quickly and sometimes very slowly. Eventually groundwater emerges back...Infiltration and the Water Cycle
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. Water in the ground keeps all plant life alive and serves peoples' needs, too.Groundwater True/False Quiz
How much do you know about the water below your feet? Take our Groundwater True/False Quiz and find out.Groundwater Storage and the Water Cycle
The ground stores huge amounts of water and it exists to some degree no matter where on Earth you are. Lucky for people, in many places the water exists in quantities and at depths that wells can be drilled into the water-bearing aquifers and withdrawn to server the many needs people have.How the U.S. Geological Survey Monitors Water
There are many pieces of equipment, both mechanical and electronic, that are installed at stream-monitoring sites all around the world to measure, record, and transmit both water-quantity and water-quality information. The U.S. Geological Survey (USGS) monitors "real-time" streamflow and water-quality conditions for thousands of streams nationwide. - Publications