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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Freshwater Last Updated on 2014-09-06 18:32:23 The definition of freshwater is water containing less than 1000 milligrams per liter of dissolved solids, most often salt. The global distribution of freshwater resources varies greatly from region to region (see Figure 1). An 'inventory' of Earth's waters shows that approximately 97% of the global water supply is found in the oceans, which are saline. A very small amount of salty water is also located in saline lakes (e.g., the Caspian Sea). The remaining water inventory (3%) is 'freshwater'. Permanent ice (e.g., continental and mountain glaciers) is the largest freshwater storage on Earth, accounting for about 2% of the total global supply - or nearly 69% of the total freshwater supply. Freshwater is also found beneath the Earth's surface as groundwater (approximately 30% of the total freshwater supply) and in surface water storages such as lakes, streams,... More »
Ecoregions of Wisconsin (EPA) Last Updated on 2014-06-26 16:34:28 Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources; they are designed to serve as a spatial framework for the research, assessment, monitoring, and management of ecosystems and ecosystem components. Special purpose maps of characteristics such as plant communities, water quality, soils, and fish distributions are necessary and have long been used for dealing with specific research and management problems. Ecoregions, on the other hand, portray areas within which there is similarity in the mosaic of all biotic and abiotic components of both terrestrial and aquatic ecosystems. Recognition, identification, and delineation of these multipurpose regions are critical for structuring and implementing integrated management strategies across federal, state, tribal, and local governmental agencies that are responsible for... More »
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 »