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At least 811 records · Page 45Linked to original sources
USGS2003

Effects of hydrology on red mangrove recruits

Coastal wetlands along the Gulf of Mexico have been experiencing significant shifts in hydrology and salinity levels over the past century as a result of changes in sea level and freshwater drainage patterns. Local land management in coastal zones has also impacted the hydrologic regimes of salt marshes and mangrove areas. Parks and refuges in south Florida that contain mangrove forests have, in some cases, been ditched or impounded to control mosquito outbreaks and to foster wildlife use. And while mangroves dominate the subtropical coastlines of Florida and thrive in saltwater environments, little is known about how they respond to changes in hydrology under managed or variable tidal conditions. USGS researchers designed a study to evaluate the basic hydrological requirements of mangroves so that their health and survival may be more effectively managed in controlled impoundments and restored wetlands. Mangroves are commonly found in the intertidal zone (between low and high tides) in a rather broad spectrum of hydrologic settings. Because they thrive at the interface of land and sea, mangroves are subject to changes in freshwater flow (flow rate, nutrients, pollutants) and to marine influences (sea-level rise, salinity). Salinity has long been recognized as a controlling factor that determines the health and distribution of mangrove forests. Field and experimental observations indicate that most mangrove species achieve their highest growth potential under brackish conditions (modest salinity) between 10 and 20 parts per thousand (ppt). Yet, if provided with available propagules, successful regeneration, and limited competition from other plants, then mangroves can survive and thrive in freshwater systems as well. Because little is known about the growthand survival patterns of mangrove species relative to changing hydrology, USGS scientists conducted greenhouse and field experiments to determine how flooded or drained patterns of hydrology would influence growth of the red mangrove, Rhizophora mangle (fig. 1). Red mangrove propagules (recruits) of select sizes and genotypes (i.e., genetically similar groups) were planted both in greenhouses and in the field. Seedling growth was monitored in both studies on a quarterly basis for over a year; measurements included shoot growth, seedling height, and a final harvest of plant biomass.

Fact Sheet↗
USGS1994

National Water-Quality Assessment Program: The Sacramento River Basin

In 1991, the U.S. Geological Survey (USGS) began to implement a full-scale National Water-Quality Assessment (NAWQA) program. The long-term goals of the NAWQA program are to describe the status of and trends in the quality of a large, representative part of the Nation's surface- and ground-water resources and to identify the major natural and human factors that affect the quality of those resources. In addressing these goals, the program will provide a wealth of water- quality information that will be useful to policy makers and managers at the national, State, and local levels. A major asset of the NAWQA program is that it will allow for the integration of water-quality information collected at several scales. A major component of the program is the study-unit investigation-the foundation of national- level assessment. The 60 study units of the NAWQA program are hydrologic systems that include parts of most major river basins and aquifer systems of the conterminous United States. These study units cover areas of 1,000 to more than 60,000 square miles and represent 60 to 70 percent of the Nation's water use and population served by public water supplies. Investigations of the first 20 study units began in 1991. In 1994, the Sacramento River Basin was among the second set of 20 NAWQA study units selected for investigation.

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USGS1998

U.S. Geological Survey Real-Time River Data Applications

Real-time river data provided by the USGS originate from streamflow-gaging stations. The USGS operates and maintains a network of more than 7,000 such stations across the nation (Mason and Wieger, 1995). These gaging stations, used to produce records of stage and streamflow data, are operated in cooperation with local, state, and other federal agencies. The USGS office in Indianapolis operates a statewide network of more than 170 gaging stations. The instrumentation at USGS gaging stations monitors and records river information, primarily river stage (fig. 1). As technological advances are made, many USGS gaging stations are being retrofitted with electronic instrumentation to monitor and record river data. Electronic instrumentation facilitates transmission of real-time or near real-time river data for use by government agencies in such flood-related tasks as operating flood-control structures and ordering evacuations.

Fact Sheet↗
USGS1999

Nevada

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Fact Sheet↗
USGS2000

Magnitude and distribution of flows into northeastern Florida Bay

Changes in water-management practices have been made to accommodate a large and rapidly growing urban population along the Atlantic Coast and to meet the demand for intensive agricultural activities. These changes have resulted in a highly managed hydrologic system consisting of numerous canals, levees, control structures, and pumping stations that have altered the hydrology of the Everglades and Florida Bay ecosystems. Over the past decade, Florida Bay has experienced sea-grass die-off and algal blooms, which are indicators of ecological change attributed primarily to the increase in salinity and nutrient content of bay waters. Because plans are to restore sheetflow in the Everglades wetlands to its natural state, water managers anticipate a change in the magnitude and timing of freshwater exiting the mainland through the creeks that cut through the embankment or as sheetflow into Florida Bay.

Florida↗
USGS2001

Did you feel it? Community-made earthquake shaking maps

Since the early 1990's, the magnitude and location of an earthquake have been available within minutes on the Internet. Now, as a result of work by the U.S. Geological Survey (USGS) and with the cooperation of various regional seismic networks, people who experience an earthquake can go online and share information about its effects to help create a map of shaking intensities and damage. Such 'Community Internet Intensity Maps' (CIIM's) contribute greatly in quickly assessing the scope of an earthquake emergency, even in areas lacking seismic instruments.

California, Washington↗
USGS2003

Predicting future mangrove forest migration in the Everglades under rising sea level

Mangroves are highly productive ecosystems that provide valued habitat for fish and shorebirds. Mangrove forests are universally composed of relatively few tree species and a single overstory strata. Three species of true mangroves are common to intertidal zones of the Caribbean and Gulf of Mexico Coast, namely, black mangrove (Avicennia germinans), white mangrove (Laguncularia racemosa), and red mangrove (Rhizophora mangle). Mangrove forests occupy intertidal settings of the coastal margin of the Everglades along the southwest tip of the Florida peninsula (fig. 1).

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USGS1994

National Water-Quality Assessment (NAWQA) Program, Long Island-New Jersey (LINJ) Coastal Drainages Study Unit : Scope of the Long Island-New Jersey Coastal Drainages Study-Unit investigation

Scope of the Long Island-New Jersey Coastal Drainages Study-Unit Investigation In 1991, the U.S. Geological Survey (USGS) began a National Water-Quality Assessment (NAWQA) Program to document the status of and trends in quality of a large representative part of the Nation's water resources and to provide a sound scientific understanding of the primary natural and human factors that affect the quality of these resources. The program is designed to produce long-term, consistent water-quality information that will be useful to policymakers and managers at national, State, and local levels. Investigations of 60 hydrologic systems (study units), which include parts of most major river basins and aquifer systems in the United States, are the building blocks of NAWQA. A framework has been established to ensure nationwide consistency in the approach to each study--in field and laboratory methods, in water-quality measurements, and in the supporting data requirements. Twenty studies were started in 1991, 20 more have begun in 1994, and 20 are scheduled to begin in 1997. A major design feature of the program that will facilitate integration of water-quality information at national, regional, and local scales is coordination between the individual study-unit teams and the national synthesis effort at all stages of the investigations. Thus, results that relate to various topics addressed in the study-unit investigations will be integrated smoothly into NAWQA's national synthesis component. Teams have been developed to address the following topics of national importance: pesticides, nutrients, and volatile organic compounds. These teams are investigating the specific issues by means of comparative studies of a large set of hydrologic systems distributed over a wide range of environmental settings found in the 60 study-units. The information below summarizes the goals and scope of the NAWQA Program and the Long Island-New Jersey Coastal Drainages study, which began in 1994.

New Jersey↗
USGS1997

Volcanic ash - danger to aircraft in the north Pacific

The world's busy air traffic corridors pass over hundreds of volcanoes capable of sudden, explosive eruptions. In the United States alone, aircraft carry many thousands of passengers and millions of dollars of cargo over volcanoes each day. Volcanic ash can be a serious hazard to aviation even thousands of miles from an eruption. Airborne ash can diminish visibility, damage flight control systems, and cause jet engines to fail. USGS and other scientists with the Alaska Volcano Observatory are playing a leading role in the international effort to reduce the risk posed to aircraft by volcanic eruptions.

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USGS1999

New Hampshire

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Fact Sheet↗