• groundwater
    Groundwater covers a low plain.

    Photograph by Kavin Ho, MyShot

    Drop in the Bucket
    Groundwater makes up about 20 percent of the world's fresh water, but its still less than one percent of all the water on Earth, including all ocean water and permanent ice on the planet.

    Groundwater is all the water found underneath the Earths surface. This water comes mostly from rain, melted snow, and other water that seeps through soil, sand, or the cracks in the sidewalk.

    Thanks to gravity, the water just keeps moving downward, underneath the Earths surface, until it cant go any farther. When the water hits a layer of rock or earth it cant get through, it just sits there and builds up. This tub of water underneath the surface is called an aquifer.

    Groundwater can eventually seep back up to the surface. Youll find it peeking out of the Earth in things like springs and wetlands. There, the surface of the Earth falls below the aquifer level.

    People use groundwater to water the fields that grow our fruits and vegetables. It can even come out of our tap at home. To get the groundwater out of the ground and up to our surface level, scientists and engineers use devicescalled wells.

    Scientists worry about problems that pop up when we take too much groundwater for our day-to-day living, including home, business, and agricultural use. One problem is that the groundwater is getting further and further away from the Earths surface. People are using groundwater faster than rain or snowmelt can replace it. That means people have to drill further and further down under the surface to get to the groundwater.

    It might not sound like a big deal, but when groundwater is that far down, the soil and clay that make up the surface of the Earth get stressed out and weak. Eventually, a weak surface area can sink. This is called a sinkhole. Sinkholes are problems in areas that have to drill deep for groundwater, including parts of the state of Texas and places in India.

    Scientists say the Earth might not be the only planet in our solar system to enjoy groundwater. It might have existed on the planet Mars long, long ago. Groundwater might even exist way out by Jupiter, on Europa, one of its moons.

    The Great Artesian Basin in central and eastern Australia has one of the largest aquifers in the world. It stretches for almost two million square kilometers (more than 772,000 square miles). The water in this aquifer is more than one million years old.

  • Term Part of Speech Definition Encyclopedic Entry
    aquifer Noun

    an underground layer of rock or earth which holds groundwater.

    Encyclopedic Entry: aquifer
    clay Noun

    type of sedimentary rock that is able to be shaped when wet.

    drill Verb

    to make a hole using a rotating digging tool.

    Earth Noun

    our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.

    Encyclopedic Entry: Earth
    engineer Noun

    person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

    Europa Noun

    moon of Jupiter.

    freshwater Noun

    water that is not salty.

    fruit Noun

    edible part of a plant that grows from a flower.

    gravity Noun

    physical force by which objects attract, or pull toward, each other.

    groundwater Noun

    water found in an aquifer.

    Encyclopedic Entry: groundwater
    ice Noun

    water in its solid form.

    Encyclopedic Entry: ice
    Jupiter Noun

    largest planet in the solar system, the fifth planet from the Sun.

    Mars Noun

    fourth planet from the sun, between Earth and Jupiter.

    planet Noun

    large, spherical celestial body that regularly rotates around a star.

    Encyclopedic Entry: planet
    rock Noun

    natural substance composed of solid mineral matter.

    sand Noun

    small, loose grains of disintegrated rocks.

    scientist Noun

    person who studies a specific type of knowledge using the scientific method.

    seep Verb

    to slowly flow through a border.

    sinkhole Noun

    hole formed in a rock or other solid material by the weight or movement of water.

    Encyclopedic Entry: sinkhole
    snow Noun

    precipitation made of ice crystals.

    snowmelt Noun

    water supplied by snow.

    soil Noun

    top layer of the Earth's surface where plants can grow.

    solar system Noun

    the sun and the planets, asteroids, comets, and other bodies that orbit around it.

    spring Noun

    small flow of water flowing naturally from an underground water source.

    vegetable Noun

    plant that is grown or harvested for food.

    wetland Noun

    area of land covered by shallow water or saturated by water.

    Encyclopedic Entry: wetland
Tell us what you think