Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis. In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis.
Tide stage, specific conductance, water temperature, and freshwater inflow at selected Hudson River (New York) gages updated every 4-hours to measure the effects of freshwater withdrawals and upstream movement of the salt front.
Landscapes of interwoven wetlands and uplands offer a rich set of ecosystem goods and services. Changes in climate and land use can affect the value of those services. We study these areas to understand how they may be changing.
Explanation of the Earth's gravitational field, emphasizing how USGS scientists measure gravity and portray these measurements on maps. Explains terminology of gravity anomaly maps and their relationship to the rock types and other geologic features.
Macroinvertebrate data collected by USGS or USFS from 73 sites from 2000 to 2007 and algal data collected from up to 26 sites between 2000 and 2001 in the Eagle River watershed, with emphasis on methods of sample collection and data processing.
Description of studies conducted to evaluate the surface water, ground water, water interactions, and water quality of Methow River Basin in Washington. With links to related science topics, datasets, maps, project summaries, and news.
Description of the North Dakota stream-gaging program using a Missouri River streamflow-gaging station in Bismarck, North Dakota as an example explaining how and why the USGS collects stream data with photos and directions for visiting the station.