Water is an essential component of the earth. Whether it is living beings or non-living beings, everybody needs water. Water on earth is present in various forms such as jet streams, lakes, oceans, and glaciers and subsequently stored in the form of groundwater. The water table is an underground boundary that is present in between the soil surface and the spaces where groundwater saturates.
At this boundary, the water pressure and the ground pressure are equal. Underneath this water, the table is a zone known as the saturated zone, where water fills all spaces between the sediments.
What is a Water Table?
It is an underground water boundary between the soil surfaces and the area where the groundwater saturates. The unsaturated zone is the area of the soil surface that is present above the water table. It is a space where oxygen and water fill the area between the sediments. Another name for an unsaturated zone is the zone of aeration. Underneath this water table is a saturated zone where water fills spaces between the deposits.
Water Tables Around Us
Water tables are present almost everywhere in the world, but the amount of water on these tables varies. The levels of water tables can also drop significantly if the water extraction is not well-sustained.
This non-sustainable practice has shown that large water reservoirs are getting depleted worldwide. The largest affected areas are India, the USA, and China, where they are almost depleted to a point where nature can’t restore them.
Shape and Height of Water Table
The water table is influenced by the land surface that lies above a water table. When it curves under hills, it is called a tall water table; when it drops under valleys, it is called a small water table. The source of the water table is precipitation. When a water table naturally meets the land surface, it makes springs.
Variations in the Water Table
The water table levels can vary in different areas and even within the same places. These are caused by the changes in precipitation between the seasons and years. It is cold outside in the winter and spring seasons, so the water level is high. Hence the water table rises, making the best water table.
However, there is a gap when the saturated zone is infiltrated by precipitation. The reason is that water takes time to trickle through the spaces in the sediments to reach the saturated zone. The irrigation process is also helpful in raising the water table as excess water comes from the ground. But during the summer, when the temperature is hot and humid outside, the water table levels deplete.
Additionally, during this time, the plants take up more water from the ground, and a lot of water is wasted in the process of transpiration. Humans are also responsible for lowering the water table levels by our practice of extracting the groundwater and not using it efficiently. The levels of depth can be measured, which are further used in determining the effects of season, climates, or human impact on groundwater.
Uses of the Water Table
Water is an essential part of every living being on this earth. Consequently, it also holds great importance and is very useful. Some of the uses are listed below.
- Water tables help measure aquifers that are saturated areas beneath them. These aquifers are used to extract water for plants and human beings.
- You can use the water from it for bathing and cleaning.
- It is used to water plants. Consequently, some water goes back to the ground and can be used repeatedly.
- But more and more extraction of this water for daily purposes is causing the water level to deplete.
- This depletion of water is also known as aquifer depletion.
- The water from water tables is primarily used in irrigation, drinking, industries, and hygiene.
- People in the areas where they have a good amount of water often put them on sale, known as water table sales.
The most enormous water table in the world
The Oglala aquifer in North America is one of the most extensive water tables in the world. It stretches over of450,000 square kilometers of the area distributed through the parts of Texas, New Mexico, South Dakota, Wyoming, Nebraska, and Oklahoma. More than 3000 cubic kilometers of groundwater is present in it.
Reduction in water tables levels
The ground cover of that area chiefly governs the water level. The spongy areas with absorbent vegetation have a more extensive amount of water in the water table since the water gets easily absorbed by the ground.
However, in urban areas, everything is covered with solid pavements; whether it’s parking slots or ground, we have a hard covering of marbles, making it difficult for water to reach the water table. Consequently, their levels decrease significantly.
Different Types of Water Tables
Fossil Water Tables
Water that has been stored in aquifers for thousands of years is called fossil water. Primarily, fossil water is considered a non-renewable resource because it cannot get replenished by precipitation. Extracting fossil water lowers an area’s water table permanently.
The tides determine some oceanic islands’ water tables. On these islands, freshwater seeps down and intersects with pockets of seawater that collect in porous soil.
Consequently, the denser seawater stays beneath the freshwater, causing the water levels to rise and fall with the tides.
Well, Well, Well
Water wells are simply holes that are dug below the water table. Wells can be explored by hand if the water table is relatively close to the surface. However, if it is hundreds of meters deep, you will require heavy machinery. You can either pull out water from the well using a bucket on a chain or rope or use more high-tech equipment like pumps.
How is The Water Table Used
Do you know that wells and irrigation are the two primary uses for groundwater ? As fresh water is necessary not only for drinking but for agriculture as well.
Wells and irrigation help extract water from the ground. Farmers can drill wells drilled into an aquifer located just below the water table. It is crucial to determine the depth of the water table. It is necessary in order to determine how deep the drilling of the well should be. In addition, they should also maintain access to it.
Therefore, farmers should drill wells enough to account for the seasonal fluctuation of the ground water levels. USGS estimates that nearly one-third of the United States population (almost 130 million people) relies solely on groundwater below the water table for drinking water.
Fluctuations in the Water Table
It is true that there are seasonal fluctuations in the water table, but it generally remains within a set range. Note that the level of water does not stay constant all year round. But instead, it fluctuates up and down seasonally.
The water level will generally be at its highest, especially in late winter and early spring. The reason being higher precipitation levels often recharge the aquifers.
This annual fluctuation in water level depth usually follows a pattern. The pattern ranges between standard high and low points. However, unusual or extreme weather conditions like a drought or flood could affect the water level stability. It may cause numerous issues for the surrounding area.
Causes of Fluctuations
Among the primary causes of water level fluctuations are the cycles of rain and dry weather that a location might experience. As you know, more water seeps into the ground during the rainy season. It raises the water level. In contrast, there is less water to recharge the aquifer during dry weather conditions. Therefore, the water table recedes.
These seasonal cycles often result in normal fluctuations in the water level. However, more significant and abnormal changes might be affected by extreme weather conditions like drought and flood.
Also, note that an extended period of limited rainfall may cause the level to drop below typical levels. It may cause long-term changes in the local vegetation and soil. Lastly, water level fluctuations might also be caused when farmers overuse and deplete the groundwater through drilled wells.
Hazards of Water Table Changes
The level of water changes could have several hazards, including the risk of wells running dry. As a result, farmers cannot sufficiently water their crops, which may also leave their livestock dehydrated.
Moreover, the risk of a drop in the water level may push farmers to abandon their shallow wells in search of deeper ones. It is necessary in order to prevent the death of their crops and livestock due to dehydration.
The water level, local soil conditions, and drainage can impact homes and their foundations. It may not be problematic if the soil drains efficiently and there is a relatively low water table. However, if the soil is absorbent and dense coupled with a high the water table, the ground around a home may swell and become saturated. Consequently, it can exert significant pressure on the foundation walls, cause water damage, and mold rehabilitation company.