Publications

A numerical model application was developed for the coastal area inland of the Ten Thousand Islands (TTI) in southwestern Florida using the Flow and Transport in a Linked Overland/Aquifer Density-Dependent System (FTLOADDS) model. This model couples a two-dimensional dynamic surface-water model with a three-dimensional groundwater model, and has been applied to several locations in...

Source water, defined as groundwater collected from a community water system well prior to water treatment, was sampled from 221 wells during October 2002 to July 2005 and analyzed for 258 anthropogenic organic compounds. Most of these compounds are unregulated in drinking water and include pesticides and pesticide degradates, gasoline hydrocarbons, personal-care and domestic-use...

Computer models of groundwater systems simulate the flow of groundwater, including water levels, and the transport of chemical constituents and thermal energy. Groundwater models afford hydrologists a framework on which to organize their knowledge and understanding of groundwater systems, and they provide insights water-resources managers need to plan effectively for future water demands...

Groundwater quality in the approximately 1,180-square-mile Northern Sacramento Valley study unit (REDSAC) was investigated in October 2007 through January 2008 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001, and is being...

Reliable estimates of the magnitude and frequency of floods are required for the economical and safe design of transportation and water-conveyance structures. A multistate approach was used to update methods for estimating the magnitude and frequency of floods in rural, ungaged basins in North Carolina, South Carolina, and Georgia that are not substantially affected by regulation, tidal

This report provides results of a rapid assessment of biological carbon stocks and forest biomass carbon sequestration capacity in the conterminous United States. Maps available from the U.S. Department of Agriculture are used to calculate estimates of current organic carbon storage in soils (73 petagrams of carbon, or PgC) and forest biomass (17 PgC). Of these totals, 3.5 PgC of soil...

Understanding the relation between dam release characteristics and downstream water quality in the lower Roanoke River, North Carolina, is important for natural-resource management and ecosystem protection. Data from four raingages, four water-quality monitoring sites, and one streamflow-measurement site were used to identify statistical relations and discernible quantitative or...

This report describes the Groundwater-Management (GWM) Process for MODFLOW-2005, the 2005 version of the U.S. Geological Survey modular three-dimensional groundwater model. GWM can solve a broad range of groundwater-management problems by combined use of simulation- and optimization-modeling techniques. These problems include limiting groundwater-level declines or streamflow depletions...

The glacial sediments that underlie the Plymouth-Carver-Kingston-Duxbury area of southeastern Massachusetts compose an important aquifer system that is the primary source of water for a region undergoing rapid development. Population increases and land-use changes in this area has led to two primary environmental effects that relate directly to groundwater resources: (1) increases in...

During 2005, the U.S. Geological Survey (USGS) developed, calibrated, and validated a multidimensional flow model for simulating streamflow in the white sturgeon spawning habitat of the Kootenai River in Idaho. The model was developed as a tool to aid understanding of the physical factors affecting quality and quantity of spawning and rearing habitat used by the endangered white sturgeon

The Wilcox Group of Eocene and Paleocene age is located throughout most of southern and eastern Arkansas. The Wilcox Group in southern Arkansas is undifferentiated, while in northeastern Arkansas, the Wilcox Group is subdivided into three units: Flour Island, Fort Pillow Sand, and Old Breastworks Formation. The Wilcox Group crops out in southwestern Arkansas in discontinuous, 1 to 3 mi...

Abstract.—Lampreys are among the least studied group of fishes in California. At least seven species inhabit freshwater habitats within the state, including the Kern brook lamprey Lampetra hubbsi, a California endemic. Four species are micropredators on fish, Pacific lamprey Entosphenus tridentatus (formerly L. tridentata), river lamprey L. ayresii, Klamath lamprey E. similis (formerly L...