Did you know that 99% of the useable freshwater on Earth is groundwater? Did you also know that in north and central Orange County we are sitting on a vast groundwater basin that supplies 77% of our drinking water? National Groundwater Awareness Week in the U.S. is March 8-14, so this is a great time to call attention to the importance of this natural resource.

First, let’s go over five national and state facts about groundwater, according to the National Ground Water Association:

1. The amount of available groundwater is 20 to 30 times larger than all U.S. lakes, streams, and rivers combined.

2. 44% of the U.S. population depends on groundwater for its drinking water supply.

3. 53.5 billion gallons of groundwater are used for agricultural irrigation each day. In 1990 that number was only 2.2 billion.

4. The largest U.S. aquifer is called the Ogallala Aquifer, which underlies 250,000 square miles stretching from Texas to South Dakota.

5. California pumps 10.7 billion gallons of groundwater each day, a third more than the second-highest state, Texas.

The Orange County Water District (OCWD) manages the Orange County Groundwater Basin to ensure that there is ample water for the 2.5 million people that live in the north and central parts of the county, and the water is of the highest quality for drinking. Here are five additional interesting facts about your local groundwater basin:

1. Since its inception as a California special district in 1933, OCWD has safely tripled the basin yield, which has supported the growth in the region.

2. Our groundwater basin holds 13 trillion gallons of water, but only a tiny fraction of this can be utilized without causing physical damage and seawater contamination from the adjacent Pacific Ocean.

3. Groundwater is annually pumped from over 200 wells operated by 19 cities, including Fullerton, and water agencies within OCWD.

4. OCWD annually puts back 115 billion gallons of water in the basin and uses Santa Ana River water, natural rain water and stormwater, imported water and Groundwater Replenishment System advanced purified water to do this.

5. The Groundwater Replenishment System, which came online in 2008, provides 100 million gallons per day of advanced purified water and is the primary source to refill the basin. When its final expansion is completed in 2023, it will provide 130 million gallons per day. That will be enough water to fulfill the water needs of 1 million people.

It would be impossible for Orange County to continue thriving without groundwater. That is why OCWD does everything it can to ensure that high quality groundwater is always available. Groundwater is a precious resource that we all share and should protect for generations to come.

Most of the drinking water in Orange County is groundwater, pumped from over 200 drinking water wells operated by 19 cities and water agencies within the Orange County Water District

We already know that there are lots of people who utilize well water or groundwater to fulfill their daily needs. Truly, the groundwater possesses a significant role to maintain the availability of residence and industrial sources, and also maintain the balance of the sources, in general, there are several utilizations of water in human life.

What is the definition of groundwater? According to some experts, groundwater is water that found beneath the ground that can be collected by using a well, tunnel or drainage system, even by using a pumping system. Groundwater also can be called a stream that naturally flows into the ground surface through a jet of water or seepage. In addition, groundwater can be classified into shallow groundwater and deep groundwater.

The presence of groundwater due to rainwater, which most of it flows into river, lake, or swamp. Some of the rainwater will permeate into the ground and if this continuously takes place to the saturated zone, then the water will become groundwater. The ability of water to permeate into the ground through some small cracks is one of the properties of water. The position of groundwater can reach several tens or even hundreds of meters beneath the Earth’s surface. Here are 10 advantages and disadvantages of groundwater use in daily life.

Advantages of Groundwater

1. For Life Necessities

Inside the human body, most of it contains water. Our life can’t be separated from the water. Human can survive for a certain period of time without eating any food, however, human can’t survive any longer without water. Groundwater can be used for drinking water, bath, cooking, washing, and other activities. Generally, each house is equipped with the ground well with 5 to 15 meters depth, which is adjusted according to the area or ground condition where the house belongs to.

2. For Irigation

Irigation system must be supported by sufficient availability of water and one of the solutions of the water supply for irigation purpose is the presence of groundwater. Irigation is the important factor for agriculture. In example, farmer can create an artesian well and then pump the groundwater from the well up to surface then distribute the water to the farm. The existence of groundwater will support the farmer if the rainfall is at the lowest point or in the dry season.

3. As clean water supply

One of the advantages of the groundwater is as the natural clean water supply. The groundwater that covered beneath the ground has been through natural filtration so the hygiene of the groundwater is more assurred. One of the good signs of the groundwater is purity, doesn’t have taste and color, has neutral pH and doesn’t contain any harmful bacteria such as E. coli. The groundwater is better than surface water, which the surface water tends to contaminated because there is no cover of the surface water.

4. For electricity generation

As we know, the hydropower plants use surface water such as dam, river or lake. However, the groundwater also can be used to generate electricity. In example, in the area of South Gombong, the area isn’t supplied by any electricity companies, so the inhabitants of South Gombong took the initiative to create power plant by using flow of underground river. They dam up the flow and then the water was pumped up to the surface. Then, the water was distributed to power generation unit to drive the turbine and generator will generate electricity.

5. As nature laboratory

The existence of grounwater inside a cave can be used by researcers as nature laboratory. Due to its open location, the water source in a cave is easy to study. There are many things that can be studied about groundwater in a cave, because there are many unique organisms that live in the groundwater and it’s so in enticing for further research.

6. As industrial water source

Industrial sectors also need water as their raw material. One of the industries that needs water as raw material is bottled water industry. Besides that, batik industry also requires water for production process of batik fabric by using groundwater.

Disadvantages of Groundwater

1. Overused

Indeed groundwater is classified as renewable natural resource, however, the groundwater is exploited rapidly. Continuous usage of groundwater causes the decreasing of groundwater volume, this will causes several problems for farmers or residences that only depend on the usage of groundwater during the dry season and will find out that the water supply is wear off or decreasing.

2. Causing landslide

The decreasing of groundwater can cause depression of surface ground, if this continues to happen, there will be a degradation of the ground. Aside from causing empty space beneath the ground that cause the ground sinks in, the decreasing of the groundwater will cause degradation of plain land that cause area located around coastline or lowland tends to get flood or submerged in sea water. Groundwater is one of the causes of underwater landslides.

3. Water contamination

There are many researches show some areas in Indonesia have poor quality of groundwater. The contamination in groundwater cannot be vanish only by cooking the groundwater because the cooking process only relieve the existence of bacteria and not the contamination in the groundwater. The contaminated groundwater can cause some health problems such as indigestion, hypertension, mental development disorder, physical development of baby, and many other problems, if the contaminated groundwater is used or drank. Therefore, there are some water pollutions sources, including industrial waste that contaminates water sources.

4. Time and cost losses

Indeed the utilization of groundwater will require more manpower and time to do the digging and extraction process of the groundwater and then distribute it to the required place. The cost required for these processes isn’t cheap because aside from buying the required equipments, we also need to spend expenses to buy water supply if there are any problems or the groundwater supply is depleted.

Well, those are 10 advantages and disadvantages of groundwater use in daily life. As stated before, there are many advantages of groundwater for daily life, but also there are several disadvantages. In conclusion, we must protect the environment related to groundwater in order to preserve the availability and quality of the groundwater.

The two most important forces controlling water movement in rock are gravity and molecular attraction.  Gravity causes water to infiltrate until it reaches impermeable zones where it is diverted laterally.  Gravity generates the flow of springs, rivers, and wells.  If the pores in rocks and sediments are connected, gravity allows the water to move slowly through them.  However, the smaller the opening, the harder it is for gravity to cause water movement.  The second force, molecular attraction, slows the flow of water through small pores.  Water is attracted to the surface of every particle with which it comes in contact.  The force results from the attraction of the molecules of two substances for each other.

The molecular attraction of water in rocks

The attraction between water and soil or rock particles is termed adhesion.  It is effective only over short distances.  Thus, only a thin film of water is locked to the outside of each grain resisting the flow downward in response to gravity. It is this adhesion that helps hold water in the soil for plants.  If gravity were the only force involved, all water would drain through the soil to some depth.  In fine-grained sediments such as silt and clay, the aggregate surface area which can attract water molecules is very great.  Fine-grained materials hold more water over a longer period of time than the same volume of coarse-grained materials such as sand or gravel.

Surface tension and capillarity

The attraction of water molecules for each other is termed cohesion.  It can be demonstrated by immersing a pencil in water and noting the drop that remains at the base of the pencil, seemingly held there by the water above it. This attraction is due to the surface tension characteristic of water, caused by cohesion.  Water will also rise in a small tube if it is immersed.  This phenomenon is called capillary action or capillarity.  The smaller the tube, the higher the water will rise.  In The Occurrence of Ground Water in the U.S. with a Discussion of Principles, USGS Water-Supply Paper 489 (1923), Oscar E. Meinzer states the reason for this attraction of the water for the walls of the tube as follows: “The water in a capillary tube is held up not only by the attraction of the walls of the tube for the water but by this attraction acting through the cohesion of the water, whereby the influence of the attraction of the water was extended far beyond the range of molecular forces.”  Capillary action is important in rocks and sediments because pores immediately above the saturated zone are filled with capillary water.  The more fine-grained the sediment or rock, the higher the water is pulled.  The diameter of the pore opening and the degree of connection with the saturated zone is very important.  So much water is drawn into the pores above the water table that this zone is given a special term, the capillary fringe.

Permeability of rocks

Permeability is the capacity of a rock to transmit water under pressure.  If no pressure exists, a static equilibrium is present and there is no tendency for water to move.  This condition is very rare in nature.  Most water can be thought to be in a dynamic state or moving in response to a pressure gradient.

Meinzer defines permeability as follows: “The permeability of a rock is measured by the rate at which it will transmit water through a given cross-section under a given difference of pressure per unit of distance.”  In a sequence of sedimentary rock with varying permeability, it commonly can be shown that horizontal permeability or permeability that is parallel to the bedding of rocks such as sandstone and conglomerate is greater than permeability at right angles to bedding.  This is because some beds in the sequence have such low permeability that vertical infiltration is slow whereas lateral permeability in units below confining beds is good.

No rocks near the surface of the earth are impermeable if enough pressure is applied in forcing the water through the natural openings in the rock.  However, the forces generated by nature are insufficient in some cases to produce detectable permeability and rocks with such characteristics are said to be relatively impermeable.  Examples of such rocks are found in shales that contain clays that swell on wetting and thus close off natural openings that may exist when the rock is dry.  On the other hand, coarse, clean gravel contains such large openings that it readily transmits water.  Ordinarily, such deposits function as the best aquifers where they can be easily recharged.  Dirty or clay-rich gravels have much less permeability because the fine silt and clay between the larger particles effectively slow down or block completely the flow of water through some of the pores between the sand grains.

Coefficient of permeability

The coefficient of permeability (P) used by the USGS may be expressed as the number of gallons of water a day, at 60 °F, that is conducted laterally through each square foot of water-bearing material (measured at right angles to the direction of flow), under a hydraulic gradient of 1 foot per foot.  It has the units of gallons per day per square foot (gpd per sq. ft.).

For analyzing field tests involving flow through the entire thickness of aquifers, it is generally more convenient to use the coefficient of transmissivity (T) of C.V. Theis (1935, The relation between lowering of the piezometric surface and rate and duration of discharge of a well using groundwater storage, Transactions of the American Geophysical Union 16, 519-524).  Theis expressed as “T = coefficient of transmissiblity of aquifer, in gallons a day, through each 1-foot strip extending the height of the aquifer, under a unit gradient—this is the average coefficient of permeability (Meinzer) multiplied by the thickness of the aquifer.” It is expressed in gallons per day per foot (gpd per ft.).  Both definitions are based upon Darcy’s law.*

Darcy’s law

Darcy’s law states that the rate of movement of water through porous media is proportional to the hydraulic gradient:

q = k × dh/dl

in which q = velocity of movement; k = constant of proportionality, which is the hydraulic conductivity; and dh/dl = hydraulic gradient, expressed as a change in head (dh) over a given change in flow length (dl).

For review, hydraulic gradient is the change in static head per unit of distance in a given direction, usually the direction of maximum decrease.  Hydraulic gradient may be expressed in ft. per ft. or cm, per meter, etc., in the same way slope may be written.

*Groundwater hydrology began as a quantitative science when Henry Philibert Gaspard Darcy (1803-1858), a French hydraulic engineer, published a report on the water supply of Dijon, France. Darcy’s law is a foundation stone for several fields of study including groundwater hydrology, soil physics, and petroleum engineering.  

Much of the water we use comes from the ground. Learn more about the importance of groundwater, the threats to its safety, and how to protect its sources during Groundwater Awareness Week.

Water is one of the world’s most precious resources. People use water every day for many activities, such as drinking, bathing, recreation, agriculture, cooling, manufacturing, and medical uses. Although water plays an essential role in everyday life, many people don’t realize that much of their water comes from the ground.

Groundwater is water found below the earth’s surface in spaces between rock and soil. Surface water is water that collects above the earth’s surface, such as streams, rivers, lakes, or oceans. Thirty percent of all the fresh water on Earth is groundwater, while the other 70% is surface water. Groundwater supplies water to wells and springs and is an important source of water for public water systems and private wells in the United States.

An estimated 145 million Americans get their tap water from a groundwater source.

Groundwater Contamination

All groundwater sources should be protected from contamination (germs and harmful chemicals).

Protecting the safety of groundwater is an important priority for countries throughout the world, including the United States. Most of the time, U.S. groundwater is safe to use. However, groundwater sources can become contaminated with germs, such as bacteria, viruses, and parasites, and chemicals, such as those used in fertilizers and pesticides. Contaminated groundwater can make people sick.

Water infrastructure requires regular maintenance.

Groundwater sometimes contains naturally present germs and harmful chemicals from the environment, such as arsenic and radon. More often, however, human activities contaminate ground water. These human causes can include incorrect use of fertilizers and pesticides; poorly situated, constructed, or maintained septic systems; improper removal or storage of wastes; mining and construction; and chemical spills at work sites.

Contamination of groundwater systems can lead to outbreaks of disease. Previous outbreaks have occurred either because the groundwater was untreated or because of problems with water treatment. The most common germs identified in groundwater outbreaks include:

• Shigella
• Hepatitis A
• Norovirus
• Giardia
• Campylobacter
• SalmonellaOther germs that cause outbreaks from groundwater include Cryptosporidium (a parasite), E. coli (a bacterium), and assorted viruses. From 2009 to 2017, 96 outbreaks linked to groundwater systems were reported to CDC.

  You can learn more about some of the most common environmental chemicals that may be found in community water supplies by visiting CDC’s Environmental Public Health Tracking Network.

  The presence of germs and harmful chemicals in our groundwater can lead to health problems, including diarrhea, reproductive problems, and nervous system disorders. Infants, young children, pregnant women, the elderly, and people whose immune systems are weakened because of HIV/AIDS, chemotherapy, or transplant medicines may be more likely to get sick from certain germs and chemicals.

• Is Your Water From a Groundwater Source?

  Public Water Systems

  

  Private well owners should have their water tested annually.

  One-third of Americans — more than 102 million people — get their drinking water from public water systems that use groundwater. The EPA regulates drinking water quality in public water systems. You can find out more about your local drinking water quality and possible contaminants by viewing your Consumer Confidence Report (CCR), which most utility companies are required to provide to customers.

  Private Wells

  An estimated 43 million Americans get their water from private groundwater wells, which are not subject to EPA regulations. Private groundwater wells can provide safe, clean water. However, contamination that can cause sickness also can occur in well water. If you have a well, you should take steps to protect it and have the water tested annually to make sure your water is safe from harmful germs and chemicals. State and local health departments provide information to help well users protect their drinking water.