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At least 541 records · Page 30Linked to original sources
USGS2012

Groundwater quality and simulation of sources of water to wells in the Marsh Creek valley at the U.S. Geological Survey Northern Appalachian Research Laboratory, Tioga County, Pennsylvania

This report provides a November 2010 snapshot of groundwater quality and an analysis of the sources of water to wells at the U.S. Geological Survey (USGS) Northern Appalachian Research Laboratory (NARL) near Wellsboro, Pennsylvania. The laboratory, which conducts fisheries research, currently (2011) withdraws 1,000 gallons per minute of high-quality groundwater from three wells completed in the glacial sand and gravel aquifer beneath the Marsh Creek valley; a fourth well that taps the same aquifer provides the potable supply for the facility. The study was conducted to document the source areas and quality of the water supply for this Department of Interior facility, which is surrounded by the ongoing development of natural gas from the Marcellus Shale. Groundwater samples were collected from the four wells used by the NARL and from two nearby domestic-supply wells. The domestic-supply wells withdraw groundwater from bedrock of the Catskill Formation. Samples were analyzed for major ions, nutrients, trace metals, radiochemicals, dissolved gases, and stable isotopes of oxygen and hydrogen in water and carbon in dissolved carbonate to document groundwater quality. Organic constituents (other than hydrocarbon gases) associated with hydraulic fracturing and other human activities were not analyzed as part of this assessment. Results show low concentrations of all constituents. Only radon, which ranged from 980 to 1,310 picocuries per liter, was somewhat elevated. These findings are consistent with the pristine nature of the aquifer in the Marsh Creek valley, which is the reason the laboratory was sited at this location. The sources of water and areas contributing recharge to wells were identified by the use of a previously documented MODFLOW groundwater-flow model for the following conditions: (1) withdrawals of 1,000 to 3,000 gallons per minute from the NARL wells, (2) average or dry hydrologic conditions, and (3) withdrawals of 1,000 gallons per minute from a new well 3,500 feet to the southwest that was drilled to provide water for Marcellus gas-well operations. Results of simulations indicate that during average hydrologic conditions, infiltration from Straight Run, a tributary to Marsh Creek, provides nearly all the water to the NARL wells. During dry conditions, the areas contributing recharge expand such that Asaph Run contributes about half of the water to the NARL wells when withdrawals are 1,000 or 2,000 gallons per minute. The addition of a simulated withdrawal of 1,000 gallons per minute from the nearby new well does not substantially affect the sources of water captured by the NARL wells. These results are subject to some limitations. The water-quality samples represent a snapshot of groundwater chemistry for only one hydrologic condition; the concentrations of some constituents may change temporally. In addition, samples were collected and analyzed for hydrocarbon gases, but not organic constituents associated with hydraulic fracturing; additional sampling for these constituents would provide a more complete water-quality baseline. The sources contributing water to the NARL wells and the new well were simulated by use of a simplified one-layer model of the glacial sand and gravel aquifer for steady-state conditions that in reality are never achieved. Steady-state simulations of dry hydrologic conditions show that it is possible for the NARL wells to capture water from Asaph Run; however, maps of simulated groundwater time-of-travel indicate that a dry period of unusually long duration would be required. A better analysis could be done by recalibrating the groundwater-flow model with a finite-difference grid having multiple layers, cells smaller than the 200-foot by 200-foot cells used in this study, and transient stress periods.

Pennsylvania↗
USGS2024

National-scale remotely sensed lake trophic state from 1984 through 2020

Lake trophic state is a key ecosystem property that integrates a lake’s physical, chemical, and biological processes. Despite the importance of trophic state as a gauge of lake water quality, standardized and machine-readable observations are uncommon. Remote sensing presents an opportunity to detect and analyze lake trophic state with reproducible, robust methods across time and space. We used Landsat surface reflectance data to create the first compendium of annual lake trophic state for 55,662 lakes of at least 10 ha in area throughout the contiguous United States from 1984 through 2020. The dataset was constructed with FAIR data principles (Findable, Accessible, Interoperable, and Reproducible) in mind, where data are publicly available, relational keys from parent datasets are retained, and all data wrangling and modeling routines are scripted for future reuse. Together, this resource offers critical data to address basic and applied research questions about lake water quality at a suite of spatial and temporal scales.

Scientific Data↗
USGS2003

Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985–1999

High-elevation lakes in the western United States are sensitive to atmospheric deposition of sulfur and nitrogen due to fast hydrologic flushing rates, short growing seasons, an abundance of exposed bedrock, and a lack of well-developed soils. This sensitivity is reflected in the dilute chemistry of the lakes, which was documented in the U.S. Environmental Protection Agency's Western Lake Survey of 1985. Sixty-nine lakes in seven national parks sampled during the 1985 survey were resampled during fall 1999 to investigate possible decadal-scale changes in lake chemistry. In most lakes, SO 4 concentrations were slightly lower in 1999 than in 1985, consistent with a regional decrease in precipitation SO 4 concentrations and in SO 2 emissions in the western United States. Nitrate concentrations also tended to be slightly lower in 1999 than in 1985, in contrast with generally stable or increasing inorganic N deposition in the west. Differences in alkalinity were variable among parks but were relatively consistent within each park. Possible effects of annual and seasonal-scale variations in precipitation amount on lake chemistry were evaluated based on climate data available for the parks and an analysis of climatic effects at two research watersheds with long-term records. Results suggest that rain prior to sampling in 1985 may have caused elevated NO 3 in some lakes due to direct runoff of precipitation and flushing of NO 3 from alpine soils, which may explain some of the decrease in NO 3 concentrations observed in survey lakes.

Water Resources Research↗
USGS2008

Biomorphodynamics: Physical-biological feedbacks that shape landscapes

Plants and animals affect morphological evolution in many environments. The term "ecogeomorphology" describes studies that address such effects. In this opinion article we use the term "biomorphodynamics" to characterize a subset of ecogeomorphologic studies: those that investigate not only the effects of organisms on physical processes and morphology but also how the biological processes depend on morphology and physical forcing. The two-way coupling precipitates feedbacks, leading to interesting modes of behavior, much like the coupling between flow/sediment transport and morphology leads to rich morphodynamic behaviors. Select examples illustrate how even the basic aspects of some systems cannot be understood without considering biomorphodynamic coupling. Prominent examples include the dynamic interactions between vegetation and flow/sediment transport that can determine river channel patterns and the multifaceted biomorphodynamic feedbacks shaping tidal marshes and channel networks. These examples suggest that the effects of morphology and physical processes on biology tend to operate over the timescale of the evolution of the morphological pattern. Thus, in field studies, which represent a snapshot in the pattern evolution, these effects are often not as obvious as the effects of biology on physical processes. However, numerical modeling indicates that the influences on biology from physical processes can play a key role in shaping landscapes and that even local and temporary vegetation disturbances can steer large-scale, long-term landscape evolution. The prevalence of biomorphodynamic research is burgeoning in recent years, driven by societal need and a confluence of complex systems-inspired modeling approaches in ecology and geomorphology. To make fundamental progress in understanding the dynamics of many landscapes, our community needs to increasingly learn to look for two-way, biomorphodynamic feedbacks and to collect new types of data to support the modeling of such emergent interactions. Copyright 2008 by the American Geophysical Union.

Water Resources Research↗
USGS2003

Selected applications of hydrologic science and research in Maryland, Delaware, and Washington, D.C., 2001-2003

One of the roles of the U.S. Geological Survey (USGS) is to provide reliable water data and unbiased water science needed to describe and understand the Nation?s water resources. This fact sheet describes selected techniques that were used by the USGS to collect, transmit, evaluate, or interpret data, in support of investigations that describe the quantity and quality of water resources in Maryland (MD), Delaware (DE), and the District of Columbia (D.C.). These hydrologic investigations generally were performed in cooperation with universities, research centers, and other Federal, State, and local Government agencies. The applications of hydrologic science and research that were selected for this fact sheet were used or tested in the MD-DE-DC District from 2001 through 2003, and include established methods, new approaches, and preliminary research. The USGS usually relies on standard methods or protocols when conducting water-resources research. Occasionally, traditional methods must be modified to address difficult environmental questions or challenging sampling conditions. Technologies developed for other purposes can sometimes be successfully applied to the collection or dissemination of water-resources data. The USGS is continually exploring new ways to collect, transmit, evaluate, and interpret data. The following applications of hydrologic science and research illustrate a few of the recent advances made by scientists working for and with the USGS.

Fact Sheet↗
USGS2005

Naturally Occurring Arsenic in Ground Water, Norman, Oklahoma, 2004, and Remediation Options for Produced Water

In 2000, the U.S. Environmental Protection Agency (EPA) reviewed the arsenic drinking water standard for public water supplies. Considering the available research and statistics on the health effects of arsenic ingestion, the EPA reduced the Maximum Contaminant Level (MCL) for public drinking water from 50 micrograms per liter (?g/L) to 10 ?g/L (U.S. Environmental Protection Agency, 2001a). As a result of the more stringent standard, the EPA estimates that about 3,000 public water providers across the United States must take action to meet the new standard before it becomes effective on January 23, 2006 (U.S. Environmental Protection Agency, 2001b). The City of Norman (City) is one of several Oklahoma municipalities affected by the new arsenic standard. About 20 percent of Norman?s water is supplied by wells completed in the Central Oklahoma (Garber-Wellington) aquifer; the rest is supplied by Lake Thunderbird (fig. 1) or purchased from Oklahoma City. The Norman well field is composed of 24 active wells, and water produced from about half of the wells will not be in compliance with the new MCL (figs. 2 and 3). Chemical treatment of water with elevated arsenic is possible, but it is generally cost prohibitive. Another costly solution is simply to abandon the high-arsenic wells and replace them with new wells in low-arsenic areas. In the next phase of well construction beginning in 2005, the City plans to construct as many as 30 new wells in northeast Norman (Bryan Mitchell, City of Norman, oral commun., 2005). The new wells will replace production lost to the new arsenic standard and add new production to keep pace with rapidly growing consumer demand. Well modification to exclude arsenic-bearing water from existing wells is a more cost-effective solution, but it requires a great deal of knowledge about local aquifer properties and individual well dynamics to decide which wells are good candidates for modification. With the goal of determining if well modification can be used to bring some of Norman?s high-arsenic wells into compliance with the new arsenic standard, the EPA Office of Research and Development (ORD) initiated a three-year research project in 2003 with participation from the U.S. Geological Survey (USGS), Oklahoma State University, and the City of Norman. The primary objectives of the project are to: (1) determine where naturally occurring arsenic is entering wells by collecting water samples at different depths, (2) investigate the utility of new methods for collecting water-quality data in a pumping well, (3) better understand the stratigraphy and composition of aquifer rocks, (4) assess 10 wells for the possibility of arsenic remediation by well modification, and (5) evaluate the effectiveness of well modification in bringing marginal wells into compliance with the new arsenic MCL. The purpose of this report is to describe the occurrence of arsenic in ground water near Norman, Oklahoma, and available options for reducing arsenic concentrations in produced ground water.

Fact Sheet↗
USGS2017

Science programs in Kansas

The U.S. Geological Survey (USGS) is a non-regulatory Earth science agency within the Department of the Interior that provides impartial scientific information to describe and understand the health of our ecosystems and environment; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. The USGS cooperates with Federal, State, tribal, and local agencies in Kansas to deliver long-term data in real-time and interpretive reports describing what those data mean to the public and resource management agencies. USGS science programs in Kansas provide real-time groundwater monitoring at more than 19 locations; streamflow monitoring at more than 216 locations; water-quality and trends in the Little Arkansas and Kansas Rivers; inflows and outflows of sediment to/from reservoirs and in streams; harmful algal bloom research in the Kansas River, Milford Lake, and Cheney Reservoir; water-quantity and water-quality effects of artificial groundwater recharge for the Equus Beds Aquifer Storage and Recovery project near Wichita, Kansas; compilation of Kansas municipal and irrigation water-use data statewide; the occurrence, effects, and movement of environmental pesticides, antibiotics, algal toxins, and taste-and-odor compounds; and funding to the Kansas Water Resources Research Institute to further research and education through Kansas universities.

Kansas↗
USGS2000

Panola Mountain, Georgia: A Water, Energy, and Biogeochemical Budgets Program Site

The Panola Mountain Research Watershed (PMRW) is a 41-hectare forested watershed in the southern Piedmont physiographic province near Atlanta, Georgia. The watershed contains a naturally regenerated second-growth forest on abandoned agricultural land, typical of the Piedmont. Research at PMRW has focused on how streamflow is generated, and in particular, on how water and solutes move from hillslopes to the stream. The research shows that streamflow and solute concentrations of precipitation, throughfall, soil water and streamwater change rapidly during rainstorms. Furthermore, these variations are strongly associated with the soil-moisture conditions, the soil type and thickness, and the rainfall intensity, all of which effect the chemical interactions and mixing of water traveling along hydrological pathways over and through the bedrock and soils.

Georgia↗
USGS2024

Advancing water security in Africa with new high-resolution discharge data

VegDischarge v1 is a comprehensive river discharge across Africa (2000–2021), produced by coupling the agro-hydrologic VegET model and the mizuRoute routing framework. Using remote sensing data and hydrological modeling, the 1-km runoff field simulated by VegET, and routed with mizuRoute, covers over 64,000 river segments in Africa. The VegET model simulates runoff based on vegetation and soil moisture dynamics, while mizuRoute processes this runoff through a detailed river network. Performance metrics show strong model reliability, with R² ranging from 0.5 to 0.9, NSE between 0.6 and 0.9, and KGE from 0.5 to 0.8. The total annual average discharge for Africa is quantified at 3238.1 km³ . year-1, with contributions to various oceanic basins: 989.9 km³ . year-1 to the North Atlantic, primarily from West African rivers like the Senegal, Gambia, Volta, and Niger; 1313.7 km³ . year-1 to the South Atlantic, largely from the Congo River; 212.5 km³ . year-1 to the Mediterranean Sea, predominantly from the Nile River; and 722.0 km³ . year-1 to the Indian Ocean, with substantial inputs from rivers such as the Zambezi. This VegDischarge v1 is valuable for policymakers, stakeholders, and researchers to better understand water availability, its temporal and spatial variations, that impact water-related infrastructure planning, sustainable resource allocation, and the development of climate resilience mitigation strategies.

Scientific Data↗
USGS2012

Invasive zebra mussels ( Driessena polymorpha ) and Asian clams ( Corbicula fluminea ) survive gut passage of migratory fish species: implications for dispersal

The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus ) as a dispersal mechanism for two invasive bivalves: zebra mussel ( Driessena polymorpha ) and Asian clam ( Corbicula fluminea ). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures.

Biological Invasions↗
USGS2025

One-hundred fundamental, open questions to integrate methodological approaches in lake ice research

The rate of technological innovation within aquatic sciences outpaces the collective ability of individual scientists within the field to make appropriate use of those technologies. The process of in situ lake sampling remains the primary choice to comprehensively understand an aquatic ecosystem at local scales; however, the impact of climate change on lakes necessitates the rapid advancement of understanding and the incorporation of lakes on both landscape and global scales. Three fields driving innovation within winter limnology that we address here are autonomous real-time in situ monitoring, remote sensing, and modeling. The recent progress in low-power in situ sensing and data telemetry allows continuous tracing of under-ice processes in selected lakes as well as the development of global lake observational networks. Remote sensing offers consistent monitoring of numerous systems, allowing limnologists to ask certain questions across large scales. Models are advancing and historically come in different types (process-based or statistical data-driven), with the recent technological advancements and integration of machine learning and hybrid process-based/statistical models. Lake ice modeling enhances our understanding of lake dynamics and allows for projections under future climate warming scenarios. To encourage the merging of technological innovation within limnological research of the less-studied winter period, we have accumulated both essential details on the history and uses of contemporary sampling, remote sensing, and modeling techniques. We crafted 100 questions in the field of winter limnology that aim to facilitate the cross-pollination of intensive and extensive modes of study to broaden knowledge of the winter period.

Water Resources Research↗
USGS1998

Base cation concentrations in subsurface flow from a forested hillslope: The role of flushing frequency

A 20-m-wide trench was excavated to bedrock on a hillslope at the Panola Mountain Research Watershed in the Piedmont region of Georgia to determine the effect of upslope drainage area from the soil and bedrock surfaces on the geochemical evolution of base cation concentrations in subsurface flow. Samples were collected from ten 2-m sections and five natural soil pipes during three winter rainstorms in 1996. Base cation concentrations in hillslope subsurface flow were generally highest early and late in the storm response when flow rates were low, but during peak flow, concentrations varied little. Base cation concentrations in matrix flow from the 10 trench sections were unrelated to the soil surface drainage area and weakly inversely related to the bedrock surface drainage area. Base cation concentrations in pipe flow were lower than those in matrix flow and were also consistent with the inverse relation to bedrock surface drainage area found in matrix flow. The left side of the trench, which has the highest bedrock surface drainage area, had consistently lower mean base cation concentrations than the right side of the trench, which has the lowest bedrock surface drainage area. During moderate size rain events of about 20–40 mm, subsurface flow occurred only on the left side of the trench. The greater volume of water that has flowed through the left side of the trench appears to have resulted in greater leaching of base cations from soils and therefore lower base cation concentrations in subsurface flow than in flow from the right side of the trench. Alternatively, a greater proportion of flow that bypasses the soil matrix may have occurred through the hillslope on the left side of the trench than on the right side. Flushing frequency links spatial hillslope water flux with the evolution of groundwater and soil chemistry.

Georgia↗
USGS2025

Water quality-based risk assessment for zebra mussel establishment: A case study of single- and multiple-factor methods in northern temperate lakes

Most previous research has used an individual water quality parameter, such as calcium, to predict likelihood of zebra mussel establishment in lakes; we employed two multiple-factor methods, our own susceptibility index for zebra mussels in lakes (SIZL) and aragonite saturation state, to evaluate the risk of mussel establishment. Thirty sites in Voyageurs National Park (VNP) were sampled in 2023 for water quality conditions, including those that play a key role in mussel survivability. These results were combined with existing data sets to determine which lakes, and which locations within the larger lakes, are at greatest risk for zebra mussel establishment. Results for VNP indicate that physical lake characteristics and water quality conditions (both single- and multiple-factor methods) put the large, interconnected lakes in VNP at greater risk of zebra mussel establishment than the smaller interior lakes. All sampled interior lakes had alkalinity and calcium concentrations below thresholds conducive to zebra mussel establishment, although Mukooda and O’Leary lakes were identified as the most at-risk interior lakes. The area in the large lakes most at risk was Sullivan Bay in Kabetogama Lake, where water quality conditions were found to be conducive to zebra mussel establishment. Results from this study could be used by resource managers to focus additional inspections, decontaminations, and regulations to protect the most at-risk lakes. These multiple-factor methods may be useful in determining the risk of zebra mussel infestation in other water bodies.

Minnesota↗
USGS2001

Confidence intervals for expected moments algorithm flood quantile estimates

Historical and paleoflood information can substantially improve flood frequency estimates if appropriate statistical procedures are properly applied. However, the Federal guidelines for flood frequency analysis, set forth in Bulletin 17B, rely on an inefficient “weighting” procedure that fails to take advantage of historical and paleoflood information. This has led researchers to propose several more efficient alternatives including the Expected Moments Algorithm (EMA), which is attractive because it retains Bulletin 17B's statistical structure (method of moments with the Log Pearson Type 3 distribution) and thus can be easily integrated into flood analyses employing the rest of the Bulletin 17B approach. The practical utility of EMA, however, has been limited because no closed‐form method has been available for quantifying the uncertainty of EMA‐based flood quantile estimates. This paper addresses that concern by providing analytical expressions for the asymptotic variance of EMA flood‐quantile estimators and confidence intervals for flood quantile estimates. Monte Carlo simulations demonstrate the properties of such confidence intervals for sites where a 25‐ to 100‐year streamgage record is augmented by 50 to 150 years of historical information. The experiments show that the confidence intervals, though not exact, should be acceptable for most purposes.

Water Resources Research↗
USGS2000

A compartmentalized solute transport model for redox zones in contaminated aquifers: 2. Field‐scale simulations

This paper, the second of two parts [see Abrams and Loague , this issue], reports the field‐scale application of COMPTRAN (compartmentalized solute transport model) for simulating the development of redox zones. COMPTRAN is fully developed and described in the companion paper. Redox zones, which are often delineated by the relative concentrations of dissolved oxygen, have been observed around the globe. The distribution of other redox‐sensitive species is affected by redox zonation. At the U.S. Geological Survey's Cape Cod research site, an anoxic zone containing high concentrations of dissolved iron has been observed. Field data were abstracted from the Cape Cod site for the one‐dimensional and two‐dimensional COMPTRAN simulations reported in this paper. The purpose of the concept‐development simulations was to demonstrate that the compartmentalized approach reported by Abrams et al . [1998] can be linked with a solute transport model to simulate field‐scale phenomena. The results presented in this paper show that COMPTRAN successfully simulated the development of redox zones at the field scale, including trends in p H and alkalinity. Thermodynamic constraints were used to prevent lower‐energy redox reactions from occurring under infeasible geochemical conditions without imposing equilibrium among all redox species. Empirical methods of reaction inhibition were not needed for the simulations conducted for this study. COMPTRAN can be extended easily to include additional compartments and reactions and is capable of handling complex velocity fields in more than one dimension.

Water Resources Research↗
USGS2003

Time‐lapse imaging of saline‐tracer transport in fractured rock using difference‐attenuation radar tomography

Accurate characterization of fractured‐rock aquifer heterogeneity remains one of the most challenging and important problems in groundwater hydrology. We demonstrate a promising strategy to identify preferential flow paths in fractured rock using a combination of geophysical monitoring and conventional hydrogeologic tests. Cross‐well difference‐attenuation ground‐penetrating radar was used to monitor saline‐tracer migration in an experiment at the U.S. Geological Survey Fractured Rock Hydrology Research Site in Grafton County, New Hampshire. Radar data sets were collected every 10 min in three adjoining planes for 5 hours during each of 12 tracer tests. An innovative inversion method accounts for data acquisition times and temporal changes in attenuation during data collection. The inverse algorithm minimizes a combination of two functions. The first is the sum of weighted squared data residuals. Second is a measure of solution complexity based on an a priori space‐time covariance function, subject to constraints that limit radar‐attenuation changes to regions of the tomograms traversed by high difference‐attenuation ray paths. The time series of tomograms indicate relative tracer concentrations and tracer arrival times in the image planes; from these we infer the presence and location of a preferential flow path within a previously identified zone of transmissive fractures. These results provide new insights into solute channeling and the nature of aquifer heterogeneity at the site.

New Hampshire↗
USGS2015

A Bayesian kriging approach for blending satellite and ground precipitation observations

Drought and flood management practices require accurate estimates of precipitation. Gauge observations, however, are often sparse in regions with complicated terrain, clustered in valleys, and of poor quality. Consequently, the spatial extent of wet events is poorly represented. Satellite-derived precipitation data are an attractive alternative, though they tend to underestimate the magnitude of wet events due to their dependency on retrieval algorithms and the indirect relationship between satellite infrared observations and precipitation intensities. Here we offer a Bayesian kriging approach for blending precipitation gauge data and the Climate Hazards Group Infrared Precipitation satellite-derived precipitation estimates for Central America, Colombia, and Venezuela. First, the gauge observations are modeled as a linear function of satellite-derived estimates and any number of other variables—for this research we include elevation. Prior distributions are defined for all model parameters and the posterior distributions are obtained simultaneously via Markov chain Monte Carlo sampling. The posterior distributions of these parameters are required for spatial estimation, and thus are obtained prior to implementing the spatial kriging model. This functional framework is applied to model parameters obtained by sampling from the posterior distributions, and the residuals of the linear model are subject to a spatial kriging model. Consequently, the posterior distributions and uncertainties of the blended precipitation estimates are obtained. We demonstrate this method by applying it to pentadal and monthly total precipitation fields during 2009. The model's performance and its inherent ability to capture wet events are investigated. We show that this blending method significantly improves upon the satellite-derived estimates and is also competitive in its ability to represent wet events. This procedure also provides a means to estimate a full conditional distribution of the “true” observed precipitation value at each grid cell.

Water Resources Research↗
USGS2003

GCIP water and energy budget synthesis (WEBS)

As part of the World Climate Research Program's (WCRPs) Global Energy and Water-Cycle Experiment (GEWEX) Continental-scale International Project (GCIP), a preliminary water and energy budget synthesis (WEBS) was developed for the period 1996-1999 fromthe "best available" observations and models. Besides this summary paper, a companion CD-ROM with more extensive discussion, figures, tables, and raw data is available to the interested researcher from the GEWEX project office, the GAPP project office, or the first author. An updated online version of the CD-ROM is also available at http://ecpc.ucsd.edu/gcip/webs.htm/. Observations cannot adequately characterize or "close" budgets since too many fundamental processes are missing. Models that properly represent the many complicated atmospheric and near-surface interactions are also required. This preliminary synthesis therefore included a representative global general circulation model, regional climate model, and a macroscale hydrologic model as well as a global reanalysis and a regional analysis. By the qualitative agreement among the models and available observations, it did appear that we now qualitatively understand water and energy budgets of the Mississippi River Basin. However, there is still much quantitative uncertainty. In that regard, there did appear to be a clear advantage to using a regional analysis over a global analysis or a regional simulation over a global simulation to describe the Mississippi River Basin water and energy budgets. There also appeared to be some advantage to using a macroscale hydrologic model for at least the surface water budgets. Copyright 2003 by the American Geophysical Union.

Journal of Geophysical Research D: Atmospheres↗