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At least 829 records · Page 46Linked to original sources

USGS1988

Hydrogeology of the Great Basin region of Nevada, Utah, and adjacent states

This atlas is a product of the Great Basin Regional Aquifer-System Analysis (RASA), a study that began in 1981. The study is part of a U.S. Geological Survey program for evaluating regional aquifer systems nationwide. A regional aquifer system is defined as “an areally extensive set of aquifers which are linked in some way, such as hydraulically or economically” (Harrill and others, 1983, p. 2). The purpose of the Great Basin RASA is to evaluate aquifer system in the Great Basin by developing a better understanding of recharge and discharge processes, delineating individual ground-water flow systems, and developing mathematical models of representative flow systems. Harrill and others (1983) provide a more complete background of both the national RASA program and the Great Basin RASA. The purpose of this atlas is to delineate and describe the major hydrogeologic units in the Great Basin region and to identify those units that (1) constitute regional aquifers or (2) act as barriers to the movement of ground water. The scope of this atlas, however, is limited to a brief geologic overview of the Great Basin: lithology and areal extent of units, major structural features, and influence of tectonic events. In addition, the water-bearing characteristics of each unit are briefly summarized. This atlas is Chapter A of the three-part Hydrologic Atlas series. Chapter B shows ground-water levels in the Great Basin region, and Chapter C shows inferred directions of ground-water flow and individual flow systems.

Nevada, Utah↗

USGS2001

Land use change and effects on water quality and ecosystem health in the Lake Tahoe basin, Nevada and California

Human activity in the Lake Tahoe Basin has increased substantially in the past four decades, causing significant impacts on the quality and clarity of the lake's famous deep, clear water. Protection of Lake Tahoe and the surrounding environment has become an important activity in recent years. A variety of agencies, including the Tahoe Regional Planning Agency, Tahoe Research Group of the University of California at Davis, Desert Research Institute of the University and Community College System of Nevada, U.S. Geological Survey (USGS), and a host of State (both Nevada and California) and local agencies have been monitoring and conducting research in the Basin in order to understand how the lake functions and to what extent humans have affected its landscape and ecosystem processes. In spite of all of these activities, there remains a lack of comprehensive land use change data and analysis for the Basin. A project is underway that unites the land cover mapping expertise of the USGS National Mapping Discipline with the hydrologic expertise of the Water Resources Discipline to assess the impacts of urban growth and land use change in the Lake Tahoe Basin. Three activities are planned over the next 3 years: (1) mapping the current and historic state of the land surface, (2) conducting analysis to document patterns, rates, and trends in urbanization, land use change, and ecosystem health, and (3) assessing the causes and consequences of land use change with regard to water quality and ecosystem health. We hypothesize that changes in the extent of urban growth and the corresponding increases in impervious surfaces and decreases in natural vegetation have resulted in severe impacts on ecosystem health and integrity, riparian zones and water quality over time. We are acting on multiple fronts to test this hypothesis through the quantification of landscape disturbances and impacts.

California, Nevada↗

USGS1975

Plan of study of the hydrology of the Madison Limestone and associated rocks in Montana, Nebraska, North Dakota, South Dakota, and Wyoming

A major part of the United States ' coal reserves is in the Fort Union coal region of the Northern Great Plains. Large-scale development of these reserves would place a heavy demand on the area 's limited water resources. Surface water is poorly distributed in time and space. Its use for coal development in parts of the area would require storage reservoirs and distribution systems, whereas in the rest of the area surface water is fully appropriated and its use would deprive present users of their supply. Preliminary studies by the U.S. Geological Survey and State agencies in Wyoming, Montana, and South Dakota indicate that the Madison Limestone and associated rocks might provide a significant percentage of the total water requirements for coal development. This report briefly summarized the present knowledge of the geohydrology of the Madison and associated rocks, identifies the need for additional data, and outlines a 5-year plan for a comprehensive study of the hydrology of these rocks. (Woodard-USGS)

Open-File Report↗

USGS1996

Analysis of regional aquifers in the central Midwest of the United States in Kansas, Nebraska, and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: Summary

Large quantities of ground water are available for use from three regional aquifer systems in the central Midwest of the United States. Parts of the lowermost aquifer contain nearly immobile brine and may be hydrologically suitable for material storage or waste disposal. Results of numerical modeling and geochemical analyses confirm general concepts of ground-water flow in the regional aquifer systems.

Arkansas, Colorado, Kansas, Missouri, Nebraska, Ne↗

USGS1999

Hydrogeology of, water withdrawal from, and water levels and chloride concentrations in the major Coastal Plain aquifers of Gloucester and Salem Counties, New Jersey

Eight aquifers underlying Gloucester and Salem Counties in the southwestern Coastal Plain of New Jersey provide nearly all the drinking water for the 295,000 people who live in the area. Ground-water withdrawals in the two-county area and adjoining counties have affected water levels in several of these aquifers. Ground-water withdrawals in the two-county area also have affected the quality of water, increasing the chloride concentration in several of the aquifers as a result of saltwater intrusion. This report contains hydrologic data from the two-county area, including geometry and extent of hydrogeologic units, thickness and altitude of each aquifer, withdrawals from and water levels in major aquifers, and chloride concentrations in water from each aquifer. Reported ground-water withdrawals in Gloucester and Salem Counties during 1975-95 averaged 7,800 Mgal/yr (million gallons per year) for public supply, 4,900 Mgal/yr for industrial use, 700 Mgal/yr for irrigation, 500 Mgal/yr for power plants, 50 Mgal/yr for commercial use, and about 40 Mgal/yr for mining. Withdrawals for domestic self-supply in 1994 are estimated to be about 2,600 Mgal/yr, but only about 20 percent (520 Mgal/yr) is thought to be consumptive use; the remainder is returned to the aquifer through septic systems. The most heavily used aquifer in Salem and Gloucester Counties is the Upper Potomac-Raritan-Magothy aquifer, followed by, in decreasing order of use, the Middle Potomac-Raritan-Magothy aquifer, the Lower Potomac-Raritan-Magothy aquifer, the Kirkwood-Cohansey aquifer system, and the Wenonah-Mount Laurel aquifer. Reported withdrawals from these aquifers during 1975-95 averaged 5,000, 3,700, 3,200, and 330 Mgal/yr, respectively. Withdrawals from the Wenonah-Mount Laurel aquifer in Gloucester County increased during 1993-96 because of New Jersey Department of Environmental Protection restrictions on new withdrawals from the deeper Potomac-Raritan-Magothy aquifer system. Because of the increased rate of withdrawal, water-level altitudes in the Wenonah-Mount Laurel aquifer in some parts of the two counties in 1996 were from 5 to 40 ft lower than water levels measured in 1993 and previous years, reaching a low of almost 40 ft below sea level in Washington Township, Gloucester County. Ground water in the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers in the study area is withdrawn from the outcrop areas near the Delaware River downdip to the Glassboro vicinity. Water-level altitudes in 1993 in the three aquifers were near sea level in the outcrop areas near the Delaware River, but were as low as 80 ft below sea level in parts of Gloucester County that were affected by withdrawals in Camden County and were 20 to 60 ft below sea level near major withdrawal centers in the study area. Chloride concentrations in water samples from selected wells in seven aquifers throughout Gloucester and Salem Counties have been monitored since 1949. These aquifers include the Kirkwood-Cohansey aquifer system, the Vincentown and Wenonah-Mount Laurel aquifers, the Englishtown aquifer system, and the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers. The results of chloride analyses of 4,221 samples from 496 wells indicate the extent and magnitude of saltwater intrusion in these aquifers, six of which have been affected to varying degrees by saltwater intrusion. The confined Piney Point aquifer and the unconfined Kirkwood-Cohansey aquifer system show no measurable effects of saltwater intrusion in the study area. Chloride concentrations in water from selected public-supply wells screened in the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers have increased over time in communities along the Delaware River and further inland in both Gloucester and Salem Counties. Elevated chloride concentrations in the Potomac-Raritan-Magothy aquifer system are widespread in this area but rarely exceed the drinking-water standard of 250 milligrams per liter.

Water-Resources Investigations Report↗

USGS2008

U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, 2008

*INTRODUCTION AND ACKNOWLEDGMENTS* Karst aquifer systems are present throughout parts of the United States and some of its territories. The complex depositional environments that form carbonate rocks combined with post-depositional tectonic events and the diverse climatic regimes under which these rocks were formed result in unique hydrologic systems. The dissolution of calcium carbonate and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in some karst areas of the United States being designated as national or state parks and commercial caverns. Karst aquifers and landscapes that form in tropical areas, such as the north coast of Puerto Rico, differ greatly from karst areas in more arid climates, such as central Texas or western South Dakota. Many of these public and private lands contain unique flora and fauna associated with the hydrologic systems in these karst areas. As a result, multiple Federal, State, and local agencies have an interest in the study of karst terrains. Carbonate sediments and rocks (limestone and dolomite) are composed of greater than 50 percent carbonate minerals and the predominant carbonate mineral is calcium carbonate or limestone (CaCO3). Unlike terrigenous clastic sedimentation, the depositional processes that produce carbonate rocks are complex, involving both biological and physical processes. These depositional processes impact greatly the development of permeability of the sediments. Carbonate minerals readily dissolve or precipitate depending on the chemistry of the water flowing through the rock, thus the study of both marine and meteoric diagenesis of carbonate sediments is multidisciplinary. Even with a better understanding of the depositional environment and subsequent diagenesis, the dual porosity nature of karst aquifers presents challenges to scientists attempting to study ground-water flow and contaminant transport. Many of the major springs and aquifers in the United States are developed in carbonate rocks and karst areas. These aquifers and the springs that discharge from them, serve as major water-supply sources and as unique biological habitats. Commonly, there is competition for the water resources of karst aquifers, and urban development in karst areas can impact the ecosystem and water quality of these aquifers. The concept for developing a Karst Interest Group evolved from the November 1999 National Ground-Water Meeting of the U.S. Geological Survey (USGS), Water Resources Division. As a result, the Karst Interest Group was formed in 2000. The Karst Interest Group is a loose-knit grass-roots organization of USGS employees devoted to fostering better communication among scientists working on, or interested in, karst hydrology studies. The mission of the Karst Interest Group is to encourage and support interdisciplinary collaboration and technology transfer among USGS scientists working in karst areas. Additionally, the Karst Interest Group encourages cooperative studies between the different disciplines of the USGS and other Department of Interior agencies and university researchers or research institutes. The first Karst Interest Group workshop was held in St. Petersburg, Florida, February 13-16, 2001, in the vicinity of karst features of the Floridan aquifer system. The proceedings of that first meeting, Water-Resources Investigations Report 01-4011 are available online at: http://water.usgs.gov/ogw/karst/ The second Karst Interest Group workshop was held August 20-22, 2002, in Shepherdstown, West Virginia, in close proximity to the carbonate aquifers of the northern Shenandoah Valley. The proceedings of the second workshop were published in Water-Resources Investigations Report 02-4174, which is available online at the previously mentioned website. The third workshop of the Karst Interest Group was held September, 12-15, 2005, in Rapid City, South Dakota, which is in close proximity to karst features

Scientific Investigations Report↗

USGS2020

Regional hydrostratigraphic framework of Joint Base McGuire-Dix-Lakehurst and vicinity, New Jersey, in the context of perfluoroalkyl substances contamination of groundwater and surface water

A study was conducted by the U.S. Geological Survey, in cooperation with the U.S. Air Force, to describe the regional hydrostratigraphy of shallow aquifers and confining units underlying Joint Base McGuire-Dix-Lakehurst (JBMDL) and vicinity, New Jersey, in the context of contamination of groundwater and surface water by per- and polyfluoroalkyl substances (PFAS) potentially originating from JBMDL sources. The aquifers studied are two that crop out within JBMDL boundaries—the Kirkwood-Cohansey aquifer system and the Vincentown aquifer—and another aquifer near JBMDL that does not crop out at land surface—the Piney Point aquifer. The unconfined portion of the Vincentown aquifer and portions of the Kirkwood-Cohansey aquifer system that overlie the unconfined portion of the Vincentown aquifer are consolidated into, and described as, a single, separate unconfined aquifer system. Regionally extensive clay subunits that potentially create semiconfined hydrologic conditions within the mostly unconfined Kirkwood-Cohansey aquifer system also are identified. Two confining units were studied—the Manasquan-Shark River confining unit underlying the Kirkwood-Cohansey aquifer system, which includes the basal confining sediment in the Kirkwood Formation, and the Navesink-Hornerstown confining unit underlying the Vincentown aquifer. The hydrostratigraphic units are defined using available borehole geophysical logs, lithologic logs, and (or) drillers’ logs from 131 wells and are presented in a series of 8 aquifer structure maps and 12 cross sections. The framework positions JBMDL into a regional hydrostratigraphic structure for which higher-resolution delineation of the shallow aquifers can be constructed to determine potential pathways of PFAS contamination in groundwater to off-site drinking water wells in areas adjacent to JBMDL.

New Jersey↗

USGS2010

Attributes for NHDPlus catchments (Version 1.1) for the conterminous United States: STATSGO soil characteristics

This data set represents estimated soil variables compiled for every catchment of NHDPlus for the conterminous United States. The variables included are cation exchange capacity, percent calcium carbonate, slope, water-table depth, soil thickness, hydrologic soil group, soil erodibility (k-factor), permeability, average water capacity, bulk density, percent organic material, percent clay, percent sand, and percent silt. The source data set is the State Soil ( STATSGO ) Geographic Database (Wolock, 1997). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5, 7 and 9. MRB4, covering the Missouri River basins, contains NHDPlus Production Units 10-lower and 10-upper. MRB5, covering the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River basins, contains NHDPlus Production Units 8, 11 and 12. MRB6, covering the Rio Grande, Colorado and Great Basin River basins, contains NHDPlus Production Units 13, 14, 15 and 16. MRB7, covering the Pacific Northwest River basins, contains NHDPlus Production Unit 17. MRB8, covering California River basins, contains NHDPlus Production Unit 18.

Data Series↗

USGS1996

Sublake geologic structure from high-resolution seismic-reflection data from four sinkhole lakes in the Lake Wales Ridge, central Florida

Seismic-reflection profiles from Lake Wales, Blue Lake, Lake Letta, and Lake Apthorp located along the Lake Wales Ridge in central Florida provide local detail within the regional hydrogeologic framework as described by litho- and hydrostratigraphic cross sections. Lakes located with the mantled karst region have long been considered to be sinkhole lakes, originating from subsidence activity. High-resolution seismic- reflection data confirm this origin for these four lakes. The geologic framework of the Lake Wales Ridge has proven to be a suitable geologic setting for continuous high-resolution seismic-reflection profiling in lakes; however, the nature of the lake-bottom sediments largely controls the quality of the seismic data. In lakes with significant organic-rich bottom deposits, interpretable record was limited to areas where organic deposits were minimal. In lakes with clean, sandy bottoms, the seismic-reflection methods were highly successful in obtaining data that can be correlated with sublake subsidence features. These techniques are useful in examining sublake geology and providing a better understanding of how confining units are affected by subsidence in a region where their continuity is of significant importance to local lake hydrology. Although local geologic control around each lake generally corresponds to the regional geologic framework, local deviations from regional geologic trends occur in sublake areas affected by subsidence activity. Each of the four lakes examined represents a unique set of geologic controls and provides some degree of structural evidence of subsidence activity. Sublake geologic structures identified include: (1) marginal lake sediments dipping into bathymetric lows, (2) lateral discontinuity of confining units including sags and breaches, (3) the disruption and reworking of overlying unconsolidated siliciclastic sediments as they subside into the underlying irregular limestone surface, and (4) sublake regions where confining units appear to remain intact and unaffected by nearby subsidence activity. Each lake likely is underlain by several piping features rather than one large subsidence feature.

Florida↗

USGS2013

A national streamflow network gap analysis

The U.S. Geological Survey (USGS) conducted a gap analysis to evaluate how well the USGS streamgage network meets a variety of needs, focusing on the ability to calculate various statistics at locations that have streamgages (gaged) and that do not have streamgages (ungaged). This report presents the results of analysis to determine where there are gaps in the network of gaged locations, how accurately desired statistics can be calculated with a given length of record, and whether the current network allows for estimation of these statistics at ungaged locations. The analysis indicated that there is variability across the Nation’s streamflow data-collection network in terms of the spatial and temporal coverage of streamgages. In general, the Eastern United States has better coverage than the Western United States. The arid Southwestern United States, Alaska, and Hawaii were observed to have the poorest spatial coverage, using the dataset assembled for this study. Except in Hawaii, these areas also tended to have short streamflow records. Differences in hydrology lead to differences in the uncertainty of statistics calculated in different regions of the country. Arid and semiarid areas of the Central and Southwestern United States generally exhibited the highest levels of interannual variability in flow, leading to larger uncertainty in flow statistics. At ungaged locations, information can be transferred from nearby streamgages if there is sufficient similarity between the gaged watersheds and the ungaged watersheds of interest. Areas where streamgages exhibit high correlation are most likely to be suitable for this type of information transfer. The areas with the most highly correlated streamgages appear to coincide with mountainous areas of the United States. Lower correlations are found in the Central United States and coastal areas of the Southeastern United States. Information transfer from gaged basins to ungaged basins is also most likely to be successful when basin attributes show high similarity. At the scale of the analysis completed in this study, the attributes of basins upstream of USGS streamgages cover the full range of basin attributes observed at potential locations of interest fairly well. Some exceptions included very high or very low elevation areas and very arid areas.

Puerto Rico↗

USGS2001

Hydrogeology and ground-water flow in the Memphis and Fort Pillow aquifers in the Memphis area, Tennessee

On the basis of known hydrogeology of the Memphis and Fort Pillow aquifers in the Memphis area, a three-layer, finite-difference numerical model was constructed and calibrated as the primary tool to refine understanding of flow in the aquifers. The model was calibrated and tested for accuracy in simulating measured heads for nine periods of transient flow from 1886-1985. Testing and sensitivity analyses indicated that the model accurately simulated observed heads areally as well as through time. The study indicates that the flow system is currently dominated by the distribution of pumping in relation to the distribution of areally variable confining units. Current withdrawal of about 200 million gallons per day has altered the prepumping flow paths, and effectively captured most of the water flowing through the aquifers. Ground-water flow is controlled by the altitude and location of sources of recharge and discharge, and by the hydraulic characteristics of the hydrogeologic units. Leakage between the Fort Pillow aquifer and Memphis aquifer, and between the Memphis aquifer and the water-table aquifers (alluvium and fluvial deposits) is a major component of the hydrologic budget. The study indicates that more than 50 percent of the water withdrawn from the Memphis aquifer in 1980 is derived from vertical leakage across confining units, and the leakage from the shallow aquifer (potential source of contamination) is not uniformly distributed. Simulated leakage was concentrated along the upper reaches of the Wolf and Loosahatchie Rivers, along the upper reaches of Nonconnah Creek, and the surficial aquifer of the Mississippi River alluvial plain. These simulations are supported by the geologic and geophysical evidence suggesting relatively thin or sandy confining units in these general locations. Because water from surficial aquifers is inferior in quality and more susceptible to contamination than water in the deeper aquifers, high rates of leakage to the Memphis aquifer may be cause for concern. A significant component of flow (12 percent) discharging from the Fort Pillow aquifer was calculated as upward leakage to the Memphis aquifer. This upward leakage was generally limited to areas near major pumping centers in the Memphis aquifer, where heads in the Memphis aquifer have been drawn significantly below heads in the Fort Pillow aquifer. Although the Fort Pillow aquifer is not capable of producing as much water as the Memphis aquifer for similar conditions, it is nonetheless a valuable resource throughout the area.

Water-Resources Investigations Report↗

USGS1998

Peak-discharge frequency and potential extreme peak discharge for natural streams in the Brazos River basin, Texas

The 2-, 5-, 10-, 25-, 50-, and 100-year peak discharges were estimated for 186 streamflow-gaging stations with at least 8 years of data for natural streams in and near the Brazos River Basin, Texas. Multiple regression equations were developed to estimate peak-discharge frequency for the 2-, 5-, 10-, 25-, 50-, and 100-year recurrence intervals for each of three hydrologic regions that compose the Brazos River Basin. The equations for each region are a function of significant basin characteristics (explanatory variables). The significant explanatory variables among six that were tested are the contributing drainage area and stream slope for regions 1 and 2 and the contributing drainage area for region 3. For the three sets of equations, the coefficient of determination ranges from 0.59 to 0.93, and the standard error ranges from 0.184 to 0.391 log units. A larger coefficient of determination and a lower standard error generally are associated with the equations for hydrologic regions 2 and 3. Statistics from the regression analysis allow computation of the prediction interval associated with a given significance level for a peak-discharge frequency estimate. The regression equations can be used to estimate peak discharges for sites at, near, or away from sites with streamflow-gaging stations. The potential extreme peak-discharge curves as related to contributing drainage area were estimated for each of the three hydrologic regions from measured extreme peaks of record at 186 sites with streamflow-gaging stations and from measured extreme peaks at 37 sites without streamflow-gaging stations in and near the Brazos River Basin. The potential extreme peak-discharge curves generally are similar for hydrologic regions 1 and 2, and the curve for region 3 consistently is below the curves for regions 1 and 2, which indicates smaller peak discharges.

Texas↗

USGS1962

Data on uranium and radium in ground water in the United States, 1954 to 1957

This report is one of a series resulting from a study by the U.S. Geological Survey to determine the occurrence and distribution of naturally radioactive substances in water. From 1954-57 uranium and radium concentrations were determined in 561 samples, mainly of ground water, having wide geologic and geographic distribution. These concentrations, together with data on the hydrologic and geologic environment, the beta-gamma activity, and the chemical characteristics of each sample, are tabulated by States. The conterminous United States was subdivided into 10 geotectonic regions to facilitate statistical interpretation of the occurrence of uranium and radium in fresh water in approximately homogeneous geologic provinces. For each geotectonic region, the range and median were determined for the concentrations of radium and uranium; for regions from which sufficient data were available, log-normal frequency distribution curves were calculated and superimposed on histograms of radium and uranium concentrations in the samples. An "anomaly threshold" is suggested for both radioelements for each region analyzed statistically. The western stable region had the greatest median and highest "anomaly threshold" for uranium. This region also had the highest "anomaly threshold" for radium, but the largest median for radium was found for samples collected in the Ozark-Ouachita system. The median concentration for uranium was lowest for the Atlantic and Gulf Coastal Plain and the Pacific orogenic belt. This latter region also had the lowest median-radium content.

Professional Paper↗

USGS1970

Hydrologic implications of solid-water disposal

The disposal of more than 1,400 million pounds of solid wastes in the United States each day is a major problem. This disposal in turn often leads to serious health, esthetic, and environmental problems. Among these is the pollution of vital ground-water resources. Of the six principal methods of solid-waste disposal in general use today, four methods-open dumps, sanitary landfill, incineration, and onsite disposal-carry an inherent potential for pollution of water resources. Seepage of rainwater through the wastes leaches undesirable constituents which reach the ground water in the area. This leachate is generally both biologically and chemically contaminated. The extent of the pollution from this leachate is largely dependent upon the geologic environment in which the solid wastes are deposited. Pollution potential is highest in permeable areas with a shallow water table where the wastes are in direct contact with the ground water. In a relatively impermeable area, the pollution is generally confined locally to the vicinity of the waste-disposal site. Site selection for disposal of solid wastes must be based on adequate water-resources information if pollutional potential is to be minimized. This will require regional as well as localized data on the water resources of the area. Only through such an approach can adequate protection be afforded to the environment in general and the water resources in particular.

Circular↗

USGS2018

Spatial relationships of levees and wetland systems within floodplains of the Wabash Basin, USA

Given the unique biogeochemical, physical, and hydrologic services provided by floodplain wetlands, proper management of river systems should include an understanding of how floodplain modifications influence wetland ecosystems. The construction of levees can reduce river–floodplain connectivity, yet it is unclear how levees affect wetlands within floodplains, let alone the cumulative impacts within an entire watershed. This paper explores spatial relationships between levee and floodplain wetland systems in the Wabash Basin, United States. We used a hydrogeomorphic floodplain delineation technique to map floodplain extents and identify wetlands that may be hydrologically connected to river networks. We then spatially examined the relationship between levee presence, wetland area, and other river network attributes within discrete subbasins. Our results show that cumulative wetland area is relatively constant in subbasins that contain levees, regardless of maximum stream order within the subbasin. In subbasins that do not contain levees, cumulative wetland area increases with maximum stream order. However, we found that wetland distributions around levees can be complex, and further studies on the influence of levees on wetland habitat may need to consider finer resolution spatial scales.

Wabash Basin↗

USGS2017

Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States

Early warning of post-fire debris-flow occurrence during intense rainfall has traditionally relied upon a library of regionally specific empirical rainfall intensity–duration thresholds. Development of this library and the calculation of rainfall intensity-duration thresholds often require several years of monitoring local rainfall and hydrologic response to rainstorms, a time-consuming approach where results are often only applicable to the specific region where data were collected. Here, we present a new, fully predictive approach that utilizes rainfall, hydrologic response, and readily available geospatial data to predict rainfall intensity–duration thresholds for debris-flow generation in recently burned locations in the western United States. Unlike the traditional approach to defining regional thresholds from historical data, the proposed methodology permits the direct calculation of rainfall intensity–duration thresholds for areas where no such data exist. The thresholds calculated by this method are demonstrated to provide predictions that are of similar accuracy, and in some cases outperform, previously published regional intensity–duration thresholds. The method also provides improved predictions of debris-flow likelihood, which can be incorporated into existing approaches for post-fire debris-flow hazard assessment. Our results also provide guidance for the operational expansion of post-fire debris-flow early warning systems in areas where empirically defined regional rainfall intensity–duration thresholds do not currently exist.

Geomorphology↗

USGS2021

Hydrometeorology and hydrology of flooding in Cape Fear River basin during Hurricane Florence in 2018

Hurricanes are the major flood generating mechanism dominating the upper tail of the peak discharge distribution over the Cape Fear River Basin (CFRB). In 2018, Hurricane Florence swamped CFRB as the ninth-most-destructive hurricane ever hit the United States and set new records of peak discharges over the main river channel and three out of five of its major tributaries. In this study, we examined the hydrometeorology and hydrology of this flood via combined observation and numerical experiment analyses. Our results suggest that the slow-motion in combination to the “L-shaped” path was the most distinctive feature of the hurricane that incurred catastrophic and widespread rainfall and flooding over CFRB. The total rainfall from the storm played a controlling role in the magnitude and spatial distribution of the flood peaks at basin scale. Above that, the spatial heterogeneities of rainfall distribution and hydrologic characteristics was responsible for the distinctive flood responses within the basin. The bi-peak shape of the flood hydrograph for the Deep River was due to the combined effects of rainfall distribution, land cover, and topographic gradient. The exceptional unit peak discharge over the Black River basin was associated with its drainage network structure, topographic gradient and rainfall distribution. The floodplain downstream of the Cape Fear River temporarily stored flood water and attenuated both the riverine floods from upstream and the compound flood over the coastal area. Furthermore, numerical analyses found that re-infiltration accounted for 76% of the total infiltration on average. Re-infiltration was superior to local infiltration over CFRB during Hurricane Florence.

North Carolina↗

USGS2022

Estimating detection and occupancy of secretive marsh bird species in low and high saline marshes in southwestern Louisiana using automated recording units

Secretive marsh birds (SMBs) are important indicator species of coastal wetlands but are difficult to detect and monitor. In coastal Louisiana, an important stronghold for these species, climate and hydrological models predict that freshwater and intermediate marshes will expand in the next 50 years, while brackish marshes will shrink. We used a multi-species Bayesian hierarchical occupancy model to estimate detection and occupancy probabilities for 11 SMB species in low and high saline marshes using data from automated recording units at 33 sites in southwestern Louisiana from February–June 2012. A quadratic effect of Julian date, but not minimum daily temperature nor precipitation affected detection of SMB species. King Rail ( Rallus elegans ), American Bittern ( Botaurus lentiginosus ), Common Gallinule ( Gallinula galeata ), and Pied-billed Grebe ( Podilymbus podiceps ) occupied mainly freshwater and intermediate marshes. Clapper Rail ( Rallus crepitans ), Seaside Sparrow ( Ammospiza maritima ), and Sora ( Porzana carolina ) predominantly occupied brackish and salt marshes. American Coot ( Fulica americana ), Purple Gallinule ( Porphyrio martinica ), Least Bittern ( Ixobrychus exilis ), and Marsh Wren ( Cistothorus palustris ) occupied both low and high saline marshes, showing flexibility that could maintain populations of these species as marsh salinities change in the future. If the current distribution of SMB species persists as marsh availability changes under future conditions, populations of the 4 species we found in low saline marshes may increase, whereas populations of at least 2 species found primarily in high saline marshes may decrease. Our modeling indicates that automatic recording units can produce comparable detection probabilities to other studies using traditional SMB sampling methods.

Louisiana↗