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Hydrogeology involves using knowledge from both hydrology (the study of water occurrence, distribution, movement, and quality) and geology (the study of the solid earth and the processes that shape and change it) to understand how water interacts with geological systems.

  • Floods: The power of water Featured News Article Floods: The power of water Floods: The power of water

    The deadly and destructive power of water High resolution (Credit: NOAA) Did you know fast moving water just above your ankles can knock you off your feet? Most... More »

  • Groundwater assessment methodology Featured Article Groundwater assessment methodology Groundwater assessment methodology

    Groundwater assessment methodology is vital for understanding the relationship of aquifer dynamics to precipitation and to the characteristics of the land surface of the Earth.... More »

  • Current U.S. Flood Information Featured News Article Current U.S. Flood Information Current U.S. Flood Information

    When flooding happens, USGS field crews are among the first to respond. During and after storms and floods, USGS field crews measure the streamflow and height of rivers... More »

  • Limestone Featured Article Limestone Limestone

      Limestone  is a sedimentary rock whose chief mineral component is calcite (calcium carbonate: CaCO3). Limestone can be formed by precipitation of calcite... More »

  • Atmospheric River Storm: ARkStorm Featured Article Atmospheric River Storm: ARkStorm Atmospheric River Storm: ARkStorm

    ARkStorm Scenario The U.S. Geological Survey's (USGS) Multi Hazards Demonstration Project (MHDP) has prepared its second full scenario, called ARkStorm. The scenario... More »

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Calcium Last Updated on 2013-10-24 16:29:12 Calcium is the chemical element with atomic number 20; it has an atomic mass of 40.078 atomic mass units (amu). The chemical symbol for calcium is Ca. Calcium is a soft gray alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust; moreover, it is the fifth most abundant dissolved ion in seawater both in terms of number of atoms and mass, after sodium, chloride, magnesium, and sulfate.[1] Calcium an is essential nutrient for almost all living organisms, with vital roles in cellular metabolism, especially with regard to movement of the calcium ion Ca++ into and out of the cytoplasm functions as a signal for many cellular processes. As a chief component needed in mineralization of bones and shells, calcium is the most abundant metal by mass in a large number of faunal species, especially vertebrates, testudines and mollusca. Previous... More »
Less rainfall for drought-sensitive Southern Hemisphere regions? Last Updated on 2012-05-18 00:00:00 Increasing aridity could lead to major problems for societies and ecosystems in already-arid places. Dead Ahead: Less Rainfall for Drought-Sensitive Southern Hemisphere Regions? Warming climate may mean less rainfall for drought-sensitive regions of the Southern Hemisphere, according to results just published by an international research team. Geoscientist Curt Stager of Paul Smith's College in Paul Smiths, N.Y., and colleagues found that rainfall in South Africa during the last 1,400 years was affected by temperature--with more rain falling during cool periods and less during warm ones. The findings, published in the journal Climate of the Past, are supported by the National Science Foundation (NSF). "The link between climate change and rainfall in certain latitudes can have large effects on ecosystems," said Paul Filmer, program officer in NSF's... More »
Atmospheric science Last Updated on 2012-03-27 00:00:00 Atmospheric science is the umbrella term for the study of the atmosphere — the blanket of air covering the Earth. It is a relatively new discipline that is concerned with the composition, structure and evolution of the atmosphere as well as its processes and how those processes interrelate with other systems.[1][2 The adjacent image[4] depicts the various processes occurring in the atmosphere and how they relate to other Earth systems such as agriculture, land, sea and air transportation, other ecosystems, air pollutant emissions, the water cycle (evaporation and rainfall), forests and forest fires, deserts and desert dust, industry, etc. To the extent that atmospheric science focuses primarily on the Earth's atmosphere, it can be regarded as a subfield of the "Earth sciences" discipline, each of which is a particular synthesis of the fundamentals of... More »
Columbia River Last Updated on 2012-02-26 00:00:00 The Columbia River is the largest North American watercourse by volume that discharges to the Pacific Ocean. With headwaters at Columbia Lake, in Canadian British Columbia, the course of the river has a length of approximately 2000 kilometers and a drainage basin that includes most of the land area of Washington, Oregon and Idaho as well as parts of four other U.S. states and two Canadian provinces. Much of the higher elevation temperate coniferous forests within the Columbia Basin are ecologically intact; however, considerable destruction of basin grasslands has occurred over the last two centuries via overgrazing and conversion to cropland. Sizable damage has been sustained in the Columbia River over the last two centuries due to massive amounts of chemical runoff from agricultural uses, and also due to construction of dams and locks altering the natural river hydrology.... More »
Floods: The power of water Last Updated on 2011-09-08 00:00:00 The deadly and destructive power of water High resolution (Credit: NOAA) Did you know fast moving water just above your ankles can knock you off your feet? Most people do not!  That’s why each year, more deaths occur due to flooding than from any other thunderstorm related hazard. Many of the deaths occur in automobiles as they are swept downstream. Of these drownings, many are preventable, but too many people continue to drive around the barriers that warn you the road is flooded. You will not know the depth of the water nor will you know the condition of the road under the water.  Whether you are driving or walking, if you come to a flooded road, Turn Around Don't Drown! Most flash floods are caused by slow moving thunderstorms, thunderstorms that move repeatedly over the same area, or heavy rains from tropical storms and... More »