desalination | US Geological survey (2023)

Faculty of Water Sciences HOMEwater use issueswater quality issues

(Video) Lesson 8 - U.S. Geological Survey Topographic Maps

Thirsty? How about a refreshing glass of seawater?

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No, don't take us literally! Humans cannot drink salt water. But salt water can be transformed intofresh water, which is what this portable, inflatable solar still is all about (it even converts to a small package). The process is called desalination, and it is used increasingly around the world to provide people with drinking water. Most of the United States has, or can have access to, ample supplies of drinking water. But, fresh water can be in short supply in many parts of the country and the world. And as the population continues to grow, freshwater shortages will occur more frequently, if only in certain places. In some areas,saltwater(ofOcean, for example) is being transformed into drinking water.

The "simple" hurdle that must be overcome to convert seawater to freshwater is to remove the dissolved salt in the seawater. This may seem as easy as boiling some seawater in a pot, capturing the steam, and condensing it back into water (distillation). Other methods are available, but these current technological processes must be done on a large scale to be useful for large populations, and current processes are expensive, energy-intensive, and involve large-scale facilities.

What makes water saline?

What do we mean by "salt water"? Saline water contains significant amounts (referred to as "concentrations") of dissolved salts. In this case, the concentration is the amount (by weight) of salt in the water, expressed in "parts per million" (ppm). If the water has a concentration of 10,000 ppm dissolved salts, then one percent of the water's weight is dissolved salts.

These are our parameters for salt water:

(Video) The US Geological Survey Has Just Found Something Terrifying In The Middle Of The Rocky Mountains

  • Fresh water: less than 1000 ppm
  • Slightly saline water - From 1,000 ppm to 3,000 ppm
  • Moderately saline water - From 3,000 ppm to 10,000 ppm
  • Very saline water - From 10,000 ppm to 35,000 ppm

By the way, ocean water contains about 35,000 ppm of salt.

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The world's need for fresh water

The scarcity of freshwater resources and the need for additional water supplies are already critical in many arid regions of the world and will become increasingly important in the future. Many arid areas simply lack freshwater resources in the form of surface water, such as rivers and lakes. They may have only limitedunderground water resources, some of which are becoming more brackish as the extraction of water from aquifers continues. Evaporation from solar desalination is used by nature to producerain, which is the main source of fresh water on Earth.

According to the International Desalination Association, globally, more than 300 million people receive water from desalination plants. The largest desalination plant in North America, the Claude "Bud" Lewis Carlsbad Desalination Plant, is located near San Diego, California. It generates about 10 percent of the fresh water used by about 3.1 million people in the region and costs about twice as much as other water sources. There are currently 11 desalination plants in California and 10 more plants have been proposed. The largest desalination plant in the world, the Sorek Desalination Plant is located south of Tel Aviv, Israel and produces more than 137 million gallons of fresh water per day. In contrast, the Carlsbad plant produces approximately 50 million gallons of water per day.

As of 2015, in the US, in some states, public water sources include desalinated seawater or brackish groundwater that has been treated to reduce dissolved solids. A combined 7.21 million gallons per day of saline surface water withdrawal for utility use was reported in the US Virgin Islands, Texas, Florida, and Massachusetts. A combined 263 million gallons per day of saline groundwater abstraction for public use was identified in Florida, California, Texas, Virginia, Kansas, and Utah. (Deiter et al., 2018).

(Video) U.S. Geological Survey (USGS)

Other Method: Reverse Osmosis

Another way that salt water is desalinated is through the "reverse osmosis" process. In the simplest terms, water, containing dissolved salt molecules, is forced through a semi-permeable membrane (essentially a filter), in which larger salt molecules do not pass through the holes in the membrane, but the smallest water molecules do.

Reverse osmosis is an effective way to desalinate salt water, but it is more expensive than other methods. As prices drop in the future, the use of reverse osmosis plants to desalinate large amounts of salt water should become more common.

Desalination is not modern science

Desalination by distillation is one of humanity's earliest forms of water treatment and remains a popular treatment solution around the world today. In ancient times, many civilizations used this process on their ships to turn seawater into drinking water. Today, desalination plants are used to convert seawater into drinking water on ships and in many arid regions of the world, and to treat water in other areas polluted by natural and unnatural contaminants. Distillation is perhaps the only water treatment technology that most completely reduces the widest range of contaminants in drinking water.

In nature, this basic process is responsible forwater cycle (hydrological). The sun provides energy that causes water to evaporate from surface sources such as lakes, oceans, and streams. Hewater steamit eventually comes into contact with cooler air, where it condenses again to form dew or rain. This process can be artificially mimicked and faster than in nature by using alternative sources of heating and cooling.

Why don't we see more desalination plants if fresh water is so scarce?

The main reason we don't see more desalination plants is because of the cost of running these plants. Salt dissolves easily in water and requires a lot of energy to break chemical bonds. Energy consumption adds to the cost of running a plant, and the cost of the technology to desalinate water also takes its toll.

Sometimes, environmental protection is a factor that can prevent the construction of desalination plants. In 2022, following a 20-year plan to build a desalination plant in Huntington Beach, California, the California Coastal Commission rejected the bid to build the plant due to concerns about higher water rates, loss of marine life, and impacts on poor families. who already lived nearby. Industrial Areas. Area residents did not like the fact that the plant took in 100 million gallons of seawater per day, desalinated half of it, and discharged the other half as saltier brine.

(Video) Finding geological materials through the U.S. Geological Survey

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Your own personal desalination plant

Do you remember seeing the photo at the top of this page of a floating solar still? The same process that drives this device can also be applied if you are in the desert and need a glass of water.

The low-tech approach to accomplishing this is to build a "solar still" that uses the sun's heat to run a distillation process to cause dew to form on something like a plastic sheet. The diagram to the right illustrates this. The use of seawater or plant material in the body of the still creates moist air which, due to the enclosure created by the plastic sheet, is heated by the sun. Moist air condenses water droplets on the underside of the plastic sheet and, due to thesurface tension, the drops of water adhere to the sheet and fall into a drinker, from where they can be consumed.

Some facts about desalination

  • It is estimated that about 30% of the world's irrigated areas suffer from salinity problems and remediation is considered too expensive.
  • According to the International Desalination Association, as of June 2015, 18,426 desalination plants were in operation worldwide, producing 86.8 million cubic meters per day and providing water to 300 million people. This number increased from 78.4 million cubic meters in 2013, an increase of 10.71% in 2 years.
  • The largest users of desalinated water are in the Middle East (mainly Saudi Arabia, Kuwait, the United Arab Emirates, Qatar and Bahrain), which uses about 70% of the world's capacity; and in North Africa (mainly Libya and Algeria), which uses about 6% of the world's capacity.
  • Among industrialized countries, the United States is one of the largest users of desalinated water, especially in California and parts of Florida. The cost of desalination has prevented desalination from being used more frequently.

To learn more about desalination/desalination plants, visit the links below.

(Video) US Geological Survey: Culture and Change

*Some of this information comes from the Educational Water Foundation and the Corpus Christi Public Administration TAMU-CC.


What does a geological survey show? ›

The U.S. Geological Survey is the nation's largest water, earth, and biological science and civilian mapping agency. It collects, monitors, analyzes, and provides scientific understanding of natural resource conditions, issues, and problems.

What is desalination in geography? ›

Desalination is the removal of salt from seawater. This produces clean drinking water and is particularly useful in countries that have coastlines but no readily available fresh water sources, such as rivers and streams.

Is USGS part of DOI? ›

The USGS (United States Geological Survey) is a science bureau within the United States Department of the Interior.

Why are geological surveys performed? ›

The surveys contribute important data to the USGS and other federal agencies to compile assessments of minerals, energy, alternative energy, water, natural hazards, and other resources and information that are important to our nation.

How is a geological survey done? ›

Geological surveying employs techniques from the traditional walk-over survey, studying outcrops and landforms, to intrusive methods, such as hand augering and machine-driven boreholes, to the use of geophysical techniques and remote sensing methods, such as aerial photography and satellite imagery.

What is the difference between geological survey and Geographical survey? ›

Geography describes the way in which human culture influences the natural environment and also the way in which various regions have an impact on the people living there. As against, Geology talks about the composition, structure, material and processes of the Earth and the changes that took place over time.

What is the biggest problem with desalination? ›

Energy costs aside, one of the biggest concerns regarding desalination in the United States is brine waste. After ocean and brackish waters are stripped of salt and minerals to produce freshwater, the resulting byproduct contains very high salinity levels.

Why is desalination a problem? ›

Desalination has the potential to increase fossil fuel dependence, increase greenhouse gas emissions, and exacerbate climate change if renewable energy sources are not used for freshwater production. Desalination surface water intakes are a huge threat to marine life.

What are the 3 cons to desalination? ›

List of Disadvantages of Desalination Plants
  • They require high costs to construct and operate. ...
  • They require huge amounts of energy. ...
  • They create a harmful impact on the environment.
Sep 19, 2016

What does a geotechnical survey include? ›

A full geotechnical examination includes surface and subsurface exploration, soil and groundwater sampling, and laboratory analysis. This type of due diligence helps to see how the soil will respond to proposed changes. It is also often required to obtain a building permit for a construction project.

What type of data does the United States Geological Survey not collect? ›

The USGS Organic Act specifically authorized the examination of the geological structure and mineral resources of the nation, but did not specifically address water resources, ecosystem resources, natural hazards, and climate change, all of which are current mission areas in the USGS.

Why do still need geological data after construction? ›

Engineering geology helps ensure a safe and cost-effective design for construction projects. Gathering geological information for a project site is important in the planning, design, and construction phase of an engineering project.

Is USGS credible? ›

The USGS serves the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.

Who funds USGS? ›

Congress appropriates funds for the agency through the annual Interior, Environment, and Related Agencies appropriations acts. Through P.L. 116-260, Congress appropriated $1.316 billion to the USGS for FY2021 under Division G, the Department of the Interior, Environment, and Related Agencies Appropriations Act, 2021.

What branch of government is DOI? ›

The U.S. Department of the Interior is a Cabinet-level agency that manages America's vast natural and cultural resources. Our department employs some 70,000 people, including expert scientists and resource-management professionals, in eleven technical bureaus: Bureau of Indian Affairs.

What are the 7 geological processes? ›

Geologic Processes

These include: diagenesis, Earthquakes, erosion, glaciation, hydrothermal processes, isostacy, land subsidence, liquefaction, metamorphism, sediment transport, sedimentation, tectonic processes, volcanic activity, Earth tides, deformation, soil formation, magnetic storms, and mass wasting.

What are the 4 main things studied by geologists? ›

Geologists study the materials, processes, products, physical nature, and history of the Earth.

What are the 3 types of surveying? ›

Exploratory, descriptive, and causal are the three main types used in survey research. It helps to familiarize yourself with these types before designing your survey research.

What are the four types of surveying? ›

Branches of Surveying:
  • Geodetic surveys.
  • Topographic surveys.
  • Hydrographic surveys.
  • Cadastral surveys.
  • Engineering surveys.

What is the main purpose of a geological map? ›

A geologic map displays the placement, distribution, characteristics, and age relationships of rock units and formation, along with structural features, on a two-dimensional base map.

What types of information do geologic maps show? ›

A geologic map shows the distribution of materials at or near the Earth's surface. Rock types or unconsolidated materials are generally grouped into map units and depicted using different colors. Geologic maps show information collected manually in the field by walking Vermont's landscape.

What are examples of geological evidence? ›

Some common examples include fossils, patterns of soil, kinds of rock, shape of glaciers, and structure of landforms.

How do you do geological mapping? ›

The steps of geological mapping activity are:
  1. Make outcrop observation, and make a description of it.
  2. Measure the position of rocks (strike and dip), geological structure elements, and other geological elements.
  3. Make a record observations in a field notebook.
  4. Determine the outcrop location by using GPS.
Mar 19, 2019

What are the 3 main ideas of geology? ›

1.5 Three Big Ideas: Geological Time, Uniformitarianism, and Plate Tectonics. In geology there are three big ideas that are fundamental to the way we think about how Earth works.

What types of tools do geologists use to gather data? ›

Geologists use a lot of tools to aid their studies. Some of the most common tools used are compasses, rock hammers, hand lenses, and field books.
Geology Tools List:
  • Rock Hammer.
  • Hand Lens.
  • Field Notebooks.
  • Handheld GPS.
  • Compass.
  • Field Vest.
  • Mineral Hardness Kit.
  • Acid Bottle.

Why is geological map analysis important? ›

Geologic mapping is a highly interpretive, scientific process that can produce a range of map products for many different uses, including assessing ground-water quality and contamination risks; predicting earthquake, volcano, and landslide hazards; characterizing energy and mineral resources and their extraction costs; ...

How is a geologic map used to locate oil or gas? ›

By drilling several cores miles apart, geologists can correlate the rock units and create an image of what exists and where below the surface. Combining this information with rocks exposed at the surface, which can give clues about rock orientations below, can be a powerful tool in locating oil and gas.

What are the 7 types of map information? ›

Some of the most commonly used maps are the physical, political, weather, economic, resource, population, and world maps.

What is the oldest geological evidence? ›

Researchers at UCLA and the University of Wisconsin-Madison have confirmed that microscopic fossils discovered in a nearly 3.5 billion-year-old piece of rock in Western Australia are the oldest fossils ever found and indeed the earliest direct evidence of life on Earth.

What are the 2 main evidences that geologist use? ›

Geologists have used two main types of evidence to learn about Earth's interior: Direct evidence from rock samples Indirect evidence from seismic waves.

What is a geologist salary? ›

Which country is best for geologist? ›

Best countries to study geology
  • Geology in USA.
  • Geology in UK.
  • Geology in Canada.
  • Geology in Lebanon.
  • Geology in Australia.

What are the 5 Principles of geology? ›

The Principles of Geology
  • Uniformitarianism.
  • Original horizontality.
  • Superposition.
  • Cross-cutting relationships.
  • Walther's Law.


1. U.S. Geological Survey in Menlo Park
2. The US Geological Survey Has Just Found Something Worrying In The Middle Of The Rocky Mountains
(Unexplained Mysteries)
3. The Geological Survey of Canada: An overview
(Simply Science)
4. US Geological Survey Bathymetry
(St Petersburg Science Festival)
5. Nature Connects: Dr. Sasha Reed, U.S. Geological Survey Biogeochemist
(The Nature Conservancy)
6. Winter Water Quality Monitoring with the U.S. Geological Survey
(Northern Water)


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