Hydrologists study all aspects of water and its relation to geography, geology, biology, and chemistry. Of greatest interest currently is how to keep our streams, lakes, reservoirs, and subsurface water supplies from being polluted, and how to clean up the water that has already been contaminated with a variety of inorganic and organic chemicals. As scientists, hydrologists are always interested in how water moves through the hydrologic cycle and where in the cycle water is most vulnerable to degradation. Hydrologists use many tools to do their work, from shovels to mass spectrometers, and new tools are being developed every day. Computers undoubtedly are the most used tool. A description of hydrology and what hydrologists do can be found at http://wwwdutslc.wr.usgs.gov/infores/hydrology.primer.html .
What kind of career opportunities exist for hydrologists, and what kind of education is required?
Many agencies (Federal, State, local, and private consulting firms) employ hydrologists, who do a wide variety of work. At the Federal level the U.S. Geological Survey and U.S. Environmental Protection Agency probably employ the greatest number of hydrologists, but land management and regulatory agengies such as the Department of Energy, Nuclear Regulatory Commission, Bureau of Land Management, Bureau of Reclamation, U.S. Forest Service, National Weather Bureau, Natural Resources Conservation Service, National Park Service, and U.S. Fish &Wildlife Service also employ people who require knowledge of hydrologic processes. Most States also employ hydrologists in their Department of Natural Resources or Department of Environmental Quality, and more and more counties are employing hydrologists to keep track of water distribution and water use in their districts. The annual salary of hydrologists depends upon experience and acedemic training. Most “hydrologists” hired before about 1990 were actually engineers, geologists, biologists, chemists, or physicists. Today, many universities and colleges offer undergraduate and graduate degrees in hydrology or environmental science. These disciplines require extensive course work in math and science (geology, chemistry, physics, biology, calculus, etc.), but of equal importantance is the ability to communicate your scientific results both orally and in writing.
If you are the U.S. Geological Survey, why do you study water and not rocks?
When the U.S. Geological Survey was first established in 1879, the main purpose was to map and study the land and its resources; in other words, to geologically survey the United States. The role of the USGS has grown along with the changing needs of the country, and the USGS has diversified to include not only a Geologic Division and a National Mapping Division, but also a Water Resources Division and a Biologic Resources Division. Of course there is some overlap among the divisions, which is why we all work together and are collectively known as the U.S. Geological Survey. Perhaps a more appropriate name would be "U.S. Earth Survey," however, the traditional name has remained throughout all reorganizations because of the USGS reputation for providing unbiased earth-science information. The USGS motto more accurately states our mission: Science for a changing world.
How often are USGS topographic maps updated?
Most USGS map products are produced out of central offices through the National Mapping Division of the USGS; there is no individual mapping office for each State. The National Mapping Division can be contacted by selecting "Mapping" at the top of the Utah District home page. Here in the Water Resources Division, the maps we produce are specific to the hydrologic projects that we are working on. Just like you, we depend upon the National Mapping Division for their most updated maps, which we use as base maps for our hydrologic information.
Is there water under the ground?
Yes. The main body of subsurface water is found in the saturated zone of aquifers. Aquifers can be only a few feet below the surface or more than a thousand feet deep. Aquifers are the primary source of drinking water in arid and semi-arid parts of the United States where the amount of surface water (water in streams, lakes, and reservoirs) is limited. There is also subsurface water in soils (which is mostly used by plants), and in the zone found between the soil zone and the saturated zone of aquifers. This zone is called the unsaturated zone. The unsaturated zone includes a layer directly above the aquifer called the capillary fringe where water in the saturated zone is drawn upward by capillary action.
How can you find out how deep the water table is in a specific location?
The depth to the water table can change (rise or fall) depending on the time of year. During the late winter and spring when accumulated snow starts to melt and spring rainfall is plentiful, water on the surface of the earth infiltrates into the ground and the water table rises. When water-loving plants start to grow again in the spring and precipitation gives way to hot, dry summers, the water table will fall because of evapotranspiration. The most reliable method of obtaining the depth to the water table at any given time is to measure the water level in a shallow well with a tape. If no wells are available, surface geophysical methods can sometimes be used, depending on surface accessibility for placing electric or acoustic probes. Data bases containing depth-to-water measurements made in the past are maintained by the USGS. The Utah State Division of Water Rights maintains a data base of drillers' logs that have water-levels recorded when a well was drilled, and hydrologic consultants often have reports that contain water-level data from shallow boreholes. Consulting any or all of these sources is a good first step in finding out the depth to the water table.
How much natural water is there?
The earth is estimated to hold about 1,460,000,000 cubic kilometers of water. The breakdown of where all that water resides is estimated as follows:
Oceans (saline) 1,419,120,000 cubic kilometers Ice caps and glaciers (fresh) 31,244,000 cubic kilometers Ground water (fresh and saline) 8,906,000 cubic kilometers Streams and lakes (fresh) 132,860 cubic kilometers Lakes (saline) 116,800 cubic kilometers Other--soil, atmosphere, biosphere (fresh) 480,340 cubic kilometers
Is there water in the air and do we lose water from the earth to outer space?
Yes, there is water in the air. At any given time about 0.001 percent of the earth's water is in the atmosphere above the earth. Little or none is ever lost to outer space.
There are many different kinds of treatments depending on what contaminant is in the water. Biological contamination is usually treated by heat (boiling) or by filtration. Inorganic contaminants dissolved in the water can be removed by distillation or chemical exchange. Organic contamination has been treated by biological and chemical remediation, and new treatment methods are being tried every day.
Water is recycled by using it over and over again. This sometimes requires removing contaminants that have been introduced by a particular use before putting the water back into the natural hydrologic cycle for eventual reuse. The type of reuse determines what clean-up treatment may be warranted.
What is the difference between water and ice?
Ice is cold, hard water, in solid form. Both water and ice consist of hydrogen and oxygen molecules. In general, pure water at sea level is in liquid form when its temperature is greater than 0 degrees Celsius (32 degrees Fahrenheit) and in solid form (ice) when its temperature drops below 0 degrees Celsius (32 degrees Fahrenheit). It turns to a gas, water vapor, when its temperature rises above 100 degrees Celsius (212 degrees Fahrenheit).
What would happen if the temperature in the world rose enough to melt all the snow and ice at the North and South Poles?
No one knows for sure what would happen if the snow and ice in the polar regions all melted. Sea level would rise, which would flood coastal regions. Climate would be affected worldwide. Isostatic rebound would occur where ice masses were removed from continents, causing the land surface there to rise. Many scientists are trying to predict the effects of climate changes such as a general warming trend by using computer climate models. Much more research needs to be done before we can confidently predict results.
How are data collected at USGS gaging stations tranferred automatically to the USGS website?
All the gaging stations that appear on the “Current Conditions” section of our website have satellite telemetry that basically works like this--An electronic data logger, using a 12-volt battery supply, monitors and records gage heights at selected intervals (usually 15 minutes). The data are periodically transmitted to a satellite in geo-stationary orbit over the equator. The transmitter is called a GOES radio transmitter, and USGS stations typically transmit data every 4 hours. The data are relayed via the satellite to a groundstation in Maryland, and then from Maryland via satellite to a USGS groundstation in Carson City, Nevada. From Nevada, the data are transmitted via landline to our computer system. USGS software decodes the data, which often (but not always) arrives in binary format, and puts it in a format that our hydrologic-data processing software (ADAPS) can recognize. The gage-height data are stored and manipulated to provide streamflow in cubic feet per second.USGS website software continuously accesses the various data files (site information, gage height, and discharge) and portrays the information graphically. Most of the data-logging systems use 12-volt power from a wet-cell battery with a solar panel recharging system. Data can also be transmitted via cellular and FM frequencies, but both require direct line of sight to a repeater.
What is “El Nino” and what are its effects?
El Nino is a natural phenomenon that recurs every few years during which the trade winds, which normally blow from east to west across the Pacific Ocean just north of the equator, lose their intensity. This allows the warm water that is typically around Indonesia to move east to the area just west of the coast of South America near Peru and Ecuador. The change in the typical Pacific Ocean water temperatures causes worldwide changes in normal weather patterns. In the United States, El Nino causes winter temperatures to be warmer than normal, and floods occur in California and in the southeastern states. Likewise, El Nino was responsible for the hot and dry summer of 1998 in Florida that caused the extensive wildfires. El Nino is so named because the effects of the warmer water off Peru is usually noticed near Christmas time. El Nino is Spanish for “Christ child.”
Several types of data can be collected to assist hydrologists predict when
and where floods might occur. The first and most important is monitoring the
amount of rainfall occurring on a realtime (actual) basis. Second, monitoring
the rate of change in river stage on a realtime basis can help indicate the
severity and immediacy of the threat. Third, knowledge about the type of storm
producing the moisture, such as duration, intensity, areal extent, etc., is
valuable for determining possible severity of the flooding. And fourth, knowledge
about the characteristics of a river's drainage basin, such as soil-moisture
conditions, ground temperature, snowpack, topography, vegetation cover, impermeable
land area, etc., can help to predict how extensive and damaging an impending
flood might become.
Floods are a dangerous hazard throughout the world. On average in the United
States, about 165 people are killed and about $2 billion of damage occurs each
year. Most people underestimate the power and destructiveness of flood waters.
There are two basic kinds of floods, flash floods and the more widespread river flooding. Flash floods generally cause greater loss of life and river floods generally cause greater loss of property. A flash flood occurs when runoff from excessive rainfall causes a rapid rise in the stage of a stream or normally dry channel. Flash floods are more common in areas with a dry climate and rocky terrain because lack of soil or vegetation allows torrential rains (typically from summer thunderstorms) to flow overland rather than infiltrate into the ground. River flooding is generally more common for larger rivers in areas with a wetter climate, when excessive runoff from longer-lasting rainstorms (such as from a cold front) and sometimes from melting snow causes a slower water-level rise, but over a larger area. Floods also can be caused by ice jams on a river, or high tides. Most floods can be linked to a storm of some kind. The National Weather Service collects and interprets rainfall data throughout the United States and issues flood watches and warnings as appropriate. The National Weather Service uses statistical models and flood histories to try to predict the results of expected storms. The USGS maintains a network of streamflow-gaging stations throughout the country for which the discharge and stage are monitored. Flood estimation maps are generally produced by estimating a flood with a certain recurrence interval or probability and simulating the inundation levels based on flood plain and channel characteristics. More information on floods is available from the USGS Hydrologic Information Center at http://www.nws.noaa.gov/oh/hic and from the USGS national home page at http://water.usgs.gov . For more information on real-time flood monitoring, please see USGS Fact Sheet FS-209-95, which is available on-line at http://water.usgs.gov/public/wid/FS_209-95/mason-weiger.html.
How is the salinity of Great Salt Lake measured?
The salinity of Great Salt Lake is measured by taking specific gravity and temperature measurements and comparing them to standardized values reported in a table. Specific gravity is measured in the field by testing a water sample with a device very similar to a battery or antifreeze tester.
How is the amount of ground water and precipitation that enters Great Salt Lake determined?
The USGS measures the inflow to the lake from each of the major rivers (the Bear, Weber, and Jordan) to determine surface-water inflow. A comptuter model is used to determine average inflow from ground-water sources. This model also uses precipitation and evapotranspiration data from weather stations around the lake.
How are the surface area and volume of Great Salt Lake determined?
The water-level elevation of Great Salt Lake is measured at three gages. The north part of the lake is measured at Saline, and the south part at Promontory Point and Saltair Boat Harbor. From these elevations, capacity and area tables are used to estimate the surface area and the volume of water in the lake.
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URL:http://ut.water.usgs.gov
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