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At least 1,189 records · Page 66Linked to original sources
USGS2018

Status of groundwater-level altitudes and long-term groundwater-level changes in the Chicot, Evangeline, and Jasper aquifers, Houston-Galveston region, Texas, 2018

Since the early 1900s, most of the groundwater withdrawals in the Houston-Galveston region, Texas, have been from the three primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers. Withdrawals from these aquifers are used for municipal supply, industrial, and irrigation purposes. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of groundwater-level altitudes and long-term groundwater-level changes in the Chicot, Evangeline, and Jasper aquifers in the Houston-Galveston region. This report contains regional-scale maps depicting approximate 2018 groundwater-level altitudes (represented by measurements made during December 2017 through March 2018) and long-term groundwater-level changes for the Chicot, Evangeline, and Jasper aquifers. In 2018, groundwater-level-altitude contours for the Chicot aquifer ranged from 200 feet (ft) below the North American Vertical Datum of 1988 (hereinafter referred to as “datum”) to 200 ft above datum. The 1977–2018 groundwater-level-change contours for the Chicot aquifer depict a large area of decline in groundwater-level altitudes (120 ft) in northwestern Harris County. The largest rise in groundwater-level altitudes in the Chicot aquifer from 1977 to 2018 (180 ft) was in southeastern Harris County. Groundwater-level-altitude contours for the Evangeline aquifer ranged from 250 ft below datum to 200 ft above datum in 2018. The 1977–2018 groundwater-level-change contours for the Evangeline aquifer depict broad areas where groundwater-level altitudes either declined or rose. The largest decline in groundwater-level altitudes (320 ft) was in southern Montgomery County. The largest rise in groundwater-level altitudes in the Evangeline aquifer from 1977 to 2018 (240 ft) was in southeastern Harris County. In 2018, groundwater-level-altitude contours for the Jasper aquifer ranged from 200 ft below datum to 200 ft above datum. The 2000–18 groundwater-level-change contours for the Jasper aquifer depict groundwater-level declines throughout most of the study area where groundwater-level-altitude data from the Jasper aquifer were collected, with the largest decline (200 ft) in southern Montgomery County.

Texas↗
USGS2018

Modeling hydrodynamics, water temperature, and water quality in Klamath Straits Drain, Oregon and California, 2012–15

Executive Summary Located southwest of Klamath Falls, Oregon, Klamath Straits Drain is a 10.1-mile-long canal that conveys water uphill and northward through the use of pumps before discharging to the Klamath River. Klamath Straits Drain traverses an area that historically encompassed Lower Klamath Lake. Currently, the Drain receives water from farmland and from parts of the Lower Klamath Lake National Wildlife Refuge. To support water-quality improvement in Klamath Straits Drain, a hydrodynamic and water-temperature model was constructed and calibrated for calendar years 2012–15 with the two-dimensional model CE-QUAL-W2 (version 4.0). Water quality was calibrated for a subset of that time, from April 1, 2012 to March 31, 2015. Flows in calendar year 2012 were within the normal range, while calendar years 2013–15 were dry years. Significant findings from this study include: In the years studied, only limited flow entered Klamath Straits Drain at the upstream Headworks (KSDH) site. Most flow entered the Drain between KSDH and the E-EE pumps near Township Road through several irrigation channels and ditches. Few data were available to describe the quality of this water for the period of study. The E-EE and F-FF pumps along Klamath Straits Drain mainly operated automatically to keep water levels relatively steady. Ten-minute flow data at streamgage 11509340, downstream of the F-FF pumps, showed high-frequency on/off switching of the F-FF pumps. Combined with daily mean flow data from the F-FF pumps, the downstream 10-minute flow data allowed estimation of 10-minute pumping rates for the F-FF pumps. Paper pump charts showed the existence of short-term variability at the E-EE pumps; however, daily pump data were used at the E-EE pump location in the model. Water temperature in Klamath Straits Drain varied from less than 5 degrees Celsius (°C) (with occasional ice cover in December–January) to greater than 20 °C in May–September. In the years studied, specific conductance was typically 250–850 microsiemens per centimeter, higher than Klamath River specific conductance (typically 100–200 microsiemens per centimeter). Increased chlorophyll a in autumn and winter, along with supersaturated oxygen concentrations, indicated algal blooms in the Drain at that time of year. The blooms were most likely diatoms, based on the timing of blooms sampled elsewhere. Total nitrogen concentration was as much as 5.5 mg/L, with most in dissolved organic and particulate forms, and lower amounts in ammonia and nitrate+nitrite. Total phosphorus concentrations were distributed between orthophophorus (at a median concentration of 0.15 mg/L) and organic and particulate forms (at a median concentration of 0.13 mg/L). Most of the organic carbon in the Klamath Straits Drain was in dissolved rather than particulate form. Newly collected water-quality data for April 1, 2012–March 31, 2015 helped provide the impetus for this modeling study. However, a lack of some data still hindered the construction and calibration of this model. The model would benefit from additional data to describe water-quality boundary conditions, water-quality calibration data upstream of the F-FF pumps, short-term E-EE pump operations, and channel bathymetry in the reach between Highway 97 and the confluence with the Klamath River. Klamath River water mixed upstream into the Klamath Straits Drain, up to the Klamath Straits Drain F-FF pumps at Highway 97, when the F-FF pumps were not operating for periods of hours to days. The F-FF pumps were off for many days during this study, especially during dry years. The boundary between Klamath Straits Drain and the Klamath River was best modeled with an external head condition, which allows exchange of water between the river and the drain in both directions, upstream and downstream. Currently there is a flow gage, water-quality monitor, and a water-quality sampling site located downstream of the F-FF pumps, in the reach where Klamath Straits Drain water can mix with Klamath River water. To sample solely Klamath Straits Drain water, water samples would need to be collected only when the F-FF pumps are actively pumping. Alternately, the sampling location could be moved upstream of the pumps. Interpretation and use of historical water-quality data at the Klamath Straits Drain at Highway 97 site should be done in conjunction with information on pump activity to help inform whether mixing with Klamath River water may have occurred. Total 2014 (a dry year) phosphorus loads from the Drain to the Klamath River were lower and closer to total maximum daily load (TMDL) allocations, as compared to 2013, a year with greater flow and pumping. Modeled travel time through the Klamath Straits Drain, from Headworks to its confluence with the Klamath River, ranged from approximately 24 hours at high flow to 16 days or more, depending on how many days the pumps were turned off. The longer travel times are sufficient for important water-quality transformations, such as algal growth and organic-matter decomposition. This newly constructed model of the Klamath Straits Drain simulates flow, water levels, water temperature, and water quality with acceptable accuracy but with certain data limitations. This model should prove useful in evaluating potential strategies for flow and water-quality management and restoration.

California, Oregon↗
USGS2019

Flood-inundation maps for the Yellow River from River Drive to Centerville Highway, Gwinnett County, Georgia

Digital flood-inundation maps for a 16.4-mile reach of the Yellow River in Gwinnett County, Georgia, from 0.5 mile upstream from River Drive to Centerville Highway (Georgia State Route 124) were developed to depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at two U.S. Geological Survey (USGS) streamgages in the mapped area. The maps for the 9.0-mile reach from 0.5 mile upstream from River Drive to Stone Mountain Highway (U.S. Route 78) are referenced to the streamgage Yellow River near Snellville, Ga. (station 02206500), and the maps for the 7.4-mile reach from Stone Mountain Highway to Centerville Highway are referenced to the streamgage Yellow River at Ga. 124, near Lithonia, Ga. (02207120). Real-time stage information from these streamgages can be used with these maps to estimate near real-time areas of inundation. The forecasted peak-stage information for the USGS streamgages Yellow River near Snellville, Ga. (02206500), and Yellow River at Ga. 124, near Lithonia, Ga. (02207120), can be used in conjunction with the maps developed for this study to show predicted areas of flood inundation. A one-dimensional step-backwater model was developed using the U.S. Army Corps of Engineers Hydrologic Engineering Center's River Analysis System (HEC–RAS) software for the Yellow River and was used to compute flood profiles for a 16.4-mile reach of the Yellow River. The hydraulic model was then used to simulate 16 water-surface profiles at 1.0-foot (ft) intervals at the Yellow River near Snellville streamgage and 17 water-surface profiles at 1.0-ft intervals at the Yellow River near Lithonia streamgage. At the Yellow River near Snellville streamgage, the profiles ranged from a stage of 18.0 ft, which is 819.1 ft above the North American Vertical Datum of 1988 (NAVD 88), to a stage of 33.0 ft, which is 834.1 ft above NAVD 88. At the Yellow River near Lithonia streamgage, the profiles ranged from the National Weather Service action stage of 13.0 ft, which is 732.5 ft above NAVD 88, to a stage of 29.0 ft, which is 748.5 ft above NAVD 88. The simulated water-surface profiles were then combined with a geographic information system digital elevation model—derived from light detection and ranging (lidar) data having a 5.0-ft horizontal resolution—to delineate the area flooded at each 1.0-ft interval of stream stage for both streamgages.

Georgia↗
USGS2019

Status of groundwater-level altitudes and long-term groundwater-level changes in the Chicot, Evangeline, and Jasper aquifers, Houston-Galveston region, Texas, 2019

Since the early 1900s, most of the groundwater withdrawals in the Houston-Galveston region, Texas, have been from the three primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers. Withdrawals from these aquifers are used for municipal supply, commercial and industrial use, and irrigation. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of groundwater-level altitudes and long-term groundwater-level changes in the Chicot, Evangeline, and Jasper aquifers in the Houston-Galveston region. This report contains regional-scale maps depicting approximate 2019 groundwater-level altitudes (represented by measurements made during December 2018 through March 2019) and long-term groundwater-level changes in the Chicot, Evangeline, and Jasper aquifers. In 2019, groundwater-level-altitude contours for the Chicot aquifer ranged from 200 feet (ft) below the North American Vertical Datum of 1988 (hereinafter referred to as “datum”) to 200 ft above datum. The 1977–2019 groundwater-level-change contours for the Chicot aquifer depict a large area of decline in groundwater-level altitudes (100 ft) in northwestern Harris County. The largest rise in groundwater-level altitudes in the Chicot aquifer from 1977 to 2019 (200 ft) was in southeastern Harris County. In 2019, groundwater-level-altitude contours for the Evangeline aquifer ranged from 300 ft below datum to 200 ft above datum. The 1977–2019 groundwater-level-change contours for the Evangeline aquifer depict broad areas where groundwater-level altitudes either declined or rose. The largest decline in groundwater-level altitudes (280 ft) was in southern Montgomery and northern Harris Counties. The largest rise in groundwater-level altitudes in the Evangeline aquifer from 1977 to 2019 (240 ft) was in southeastern Harris County. In 2019, groundwater-level-altitude contours for the Jasper aquifer ranged from 200 ft below datum to 250 ft above datum. The 2000–19 groundwater-level-change contours for the Jasper aquifer depict groundwater-level declines throughout most of the study area where groundwater-level-altitude data from the Jasper aquifer were collected, with the largest decline (200 ft) in southern Montgomery County.

Texas↗
USGS2020

Sediment lithology and borehole erosion testing, American and Sacramento Rivers, California

Executive Summary A field investigation intended to measure the potential for erosion of sediments beside the American and Sacramento Rivers near Sacramento, California, is described. The study featured two primary components: (1) drilling and soil sampling to reveal lithology, down to depths matching the local river thalweg, where possible, and (2) borehole erosion tests (BETs) as described by Briaud and others (2017) at many of the same locations. The latter test involved drilling a vertical hole, measuring its diameter profile, inserting a hollow drilling rod to almost the bottom of the hole, and pumping fluid through the drilling rod at a known discharge for a chosen time interval. The hole was then resurveyed to establish an erosion rate (change in borehole radius divided by duration of flow event) as a function of depth, and the test was repeated. This test was performed with water as the erosive fluid at 12 locations, with 1 test repeated with drilling mud. Lithology holes were drilled at these same locations and an additional five locations. Drilling operations took place on river left and river right on the American River and river left (left bank, when looking downstream) on the Sacramento River. The drilling to acquire sediment samples and reveal lithology involved the use of a mobile drilling rig equipped with a 6-inch (in.) auger, a 140-pound pneumatic hammer to drive split spoon and Calmod samplers, and a piston to push Shelby tube samplers to obtain samples of clayey material. Blow count (hammer blows per 6-in. sampler advance) was recorded while sampling, and the process was logged using standard U.S. Army Corps of Engineers (USACE), Sacramento District procedures. Sediment samples were identified and described in the field per ASTM D2488 and then delivered to a USACE laboratory and to Texas A&M University for additional laboratory analysis. The BETs were performed with the same drilling rig that performed the drilling for definition of lithology. In most instances, tests were limited to regions above the water table, to avoid slumping of the borehole and heaving sands pushing into the hole. Most of the tests featured sediments that were primarily silty sand or sandy silt. The testing procedure involved comparing borehole profiles before and after passing an assumed constant discharge through a drilling rod to the bottom of the drilled hole. Discharge and water losses were logged during the testing procedure, and water losses into the walls of the drilled hole were typically less than 5 percent of the introduced volume. For the tests performed with water, the coefficient of variation of the discharge ranged from 4.5 to 28 percent, with a mean of 13 percent, but the mean discharge appeared to be reasonably steady over the typical test duration of 10–30 minutes. It was thus assumed that discharge was constant and water losses during the tests were neglected. Coefficients of variation of the discharge for the three tests performed with drilling mud were much higher (20–50 percent), but erosion rates were much smaller. Resolution of the borehole caliper-reported diameter was 0.1 in. and several of the tests lasted for 10 minutes. With boreholes measured twice, before and after each test, and averaged, these numbers correspond to an apparent erosion rate (radius change divided by test duration) of 0.3 inches per hour (in/hr), which is a theoretical lower bound on what could be measured with this approach and equipment. In practice, 0.5 in/hr appears to be a more realistic lower bound on the detectable erosion rate, based on inspection of computed changes and erosion rates. Three flow speeds (5, 8, and 12 feet per second; ft/s) were targeted for the tests. Because of equipment limitations, it was not possible in the field to reach an average of 12 ft/s throughout any given borehole, although much higher flow speeds were reached locally in some cases. Most tests featured at least two different flow rates, and the borehole was typically surveyed at least twice for each condition, to allow averaging to reduce the influence of random diameter measurement errors. Errors arising from out-of-round boreholes appeared to be uncommon. Briaud and others (2017) recommend stepped increases in the flow rate during a borehole test. This approach was taken during initial testing but proved to be problematic. The drilled hole would be enlarged by the first (smaller) discharge, and then it would be difficult to reach the desired higher flow speed because of the larger annulus between the drilled hole and the drilling rod that supplied the water for testing. This was largely solved by starting with a high discharge and, in many cases, maintaining it for subsequent tests with the average flow speed decreasing as the hole enlarged. Several different measures of erosion rate were computed and investigated by comparison to lithological profiles. The vertically averaged erosion rate for each hole was computed, but this result does not reveal vertical variability of erodibility; and the mean flow speed within the hole is not a good representation of the speed when attempting to determine a relationship between erosion rate and flow speed. Instead, for each 6-inch layer within the hole, vertically averaged erosion rates and local flow speeds were computed and plotted. Where possible, the soil type for each layer was identified. For later laboratory analysis, project protocol dictated collection of Shelby tube samples whenever clay was encountered. Plots of erosion rate versus flow speed displayed scatter that indicate that several other factors influence the erosion potential of the soil. Blow count was not a good predictor variable; it is better correlated with soil type than erodibility. Soils were classified as sand, silt, or clay, depending on which soil type dominated within a sample. In general, those classified as sand and silt did not reveal clear patterns allowing erosion rate to be computed directly from flow speed, but the test results define the range and bounds on the erosion rate. Results for clay were slightly clearer with the erosion rate increasing with flow speed, once a threshold had been reached. In this case, the erosion rate appeared to change near a speed of 7 ft/s; above this threshold, erosion rates jumped from less than 2 in/hr to greater than 3 in/hr. Even for soils with similar classifications, large differences in erodibility were observed between sites and in different layers within an individual hole. One potential means of dealing with this problem would be to perform more tests at each site to allow establishment of relationships between flow speed and erodibility for individual layers within a borehole. The maximum number of tests performed at a site in this study was four, but in some cases, results are available for only one or two flow events. Comparison of data to a set of Erosion Function Apparatus tests that provide better resolution of the vertical variation in the erosion rate versus flow speed relationship would allow further investigation of this idea. It was hypothesized that drilling mud could expand the utility of the test in soft sands by reducing the likelihood of slumping that would be interpreted as erosion. The one test that was performed with drilling mud indicated that it greatly reduced the erosion rate of the soils encountered. It yielded very different results from the test performed at the same site with water. Erosion rate is often expressed as a function of shear stress applied to a soil. In order to compute shear stress on the walls of the drilled hole, one must assume a form for the relationship between flow speed and shear stress and select a friction factor that is often estimated empirically from head loss, observed water-surface profiles, surface roughness, or other data not available in this report. One methodology for computing shear stress from flow speed is discussed in this report, but the test results have been presented in terms of erosion rate versus flow speed to avoid assuming values that are not verifiable via the field data collected in this study. Erosion rate was computed from directly measured values (sequential borehole profiles) and flow speed was computed directly from measured quantities (discharge and borehole geometry). The BET has seen limited application, primarily in clayey soils, whereas most of the soils encountered in this study were primarily sand or silt. The objective of the BET is to determine the erodibility of in situ soil below the ground or riverbed surface. The BET is simple in principle and has the advantage of revealing erodibility of in situ sediments below the ground or riverbed surface; it appears to be very useful in clayey soils, based on previously published work, but is more difficult to apply in sandy soils where slumping and water losses within the hole during testing are more likely to occur. The BET did reveal a large variation in the results both laterally and vertically, even for the same soil-type classification. It is thus recommended that the results be applied considering these spatial variations rather than attempting to universally assign an erosion-rate relationship to a particular soil type. Results have been provided showing the results by site and by sediment classification (sand, silt, and clay), to allow either approach. Where possible, it is important to rely on site-specific results because the erosion-rate relationship for a given soil type varied by site. Data collected during this project have been made publicly available online via the U.S. Geological Survey (USGS) Sciencebase database. The measured borehole profiles, discharge, lithology log sheets, and photos are available in the data release that accompanies this report (see Work and Livsey (2019) in the “Selected References” section for the appropriate link).

California↗
USGS2020

Stressor identification framework of biological impairment in Mississippi streams to support watershed restoration and TMDL development

The Clean Water Act (CWA) requires States to identify waters that are impaired for designated uses. These waters are published through a State’s §303(d) list. The CWA also requires that a total maximum daily load (TMDL) be completed for each water body to calculate the maximum amount of contaminants that can be present in that water body and still meet water-quality standards. The Mississippi Department of Environmental Quality (MDEQ) uses a statewide monitoring and assessment strategy to collect benthic macroinvertebrate community data to assess the health of streams and rivers and to identify impaired waters. Waters that are found to be impaired based on the macroinvertebrate community data are listed on the Mississippi §303(d) list, and the cause of impairment is listed as “biological impairment.” Although the CWA requires TMDLs to be developed for applicable contaminants identified in the §303(d) list, TMDLs cannot be computed for stream reaches in Mississippi listed for biological impairment because the actual stressors causing the impairment have not yet been determined. The MDEQ and other water-resource managers in Mississippi require a framework for stressor identification in biologically impaired streams and rivers. This report is organized to (1) provide a general overview of biological impairment and stressor identification in stream ecosystems and (2) provide a detailed framework for stressor identification of Mississippi streams that are biologically impaired. The intent is for the framework to reduce subjectivity, provide consistency, and allow for adaptation as the science evolves. The stressor identification framework for Mississippi involves six key steps: Define the impairment, List the candidate causes of impairment and develop a conceptual model, Compile all relevant data, Evaluate the data, Identify probable causes of impairment by using a weight-of-evidence approach, and Generate a report of results.

Mississippi↗
USGS2024

Simulation of hydrodynamics and water temperature in a 21-mile reach of the upper Illinois River, Illinois, 2020–22

This report describes the development of a CE-QUAL-W2 river hydrodynamics and temperature model of a 21-mile reach of the Illinois River including a 3-mile reach of a major tributary, the Fox River. Model outputs consist of streamflow, water velocity, water-surface elevation, and water-temperature time series that can be used to simulate summer conditions in years with and without extensive development of harmful algal blooms (HABs). These analyses may provide a better understanding of some complex factors contributing to HAB development along the Illinois River. Such an understanding may provide more accurate HAB timing and location predictions and may help determine potential mitigating activities to prevent or limit the size and duration of HABs. Using the observed and simulated hydrodynamic conditions in the Illinois River study reach, it was possible to compare and contrast streamflow, velocity, and temperature conditions in years with varying HAB distributions. Occurrences of extensive HABs were documented in the study reach in June 2020 and June 2021, but only a small HAB restricted to the Marseilles Lock and Dam pool occurred in the summer of 2022. The objective then was to find similarities in site conditions between 2020 and 2021 that may contrast with the conditions in 2022. Among the 3 years included in the study, the variability in simulated water temperature exceeded variability in observed streamflow and simulated velocities. The longest period of water temperatures greater than 27 degrees Celsius (°C) in the selected locations in June of the three analysis years was in the second half of June 2022, yet no study-area wide HAB was documented in 2022. Simulations indicated that after warm water temperatures were established in the reach in June 2022, a cooling period broke up the warming period. This period of cooling was greater in magnitude and duration downstream from the location of a localized HAB perhaps limiting the spread of the bloom. Residence times differed substantially in segments representing different channel features; values ranged from 0.28 to 17.3 (days per 500 meters of channel) between the main stem and backwater areas, respectively. Variation in average June residence times was also greater among different channel features than among different years in the study period. The HABs in 2020 and 2021 at Starved Rock Dam were documented when water temperatures were about 26 °C. River backwater areas at some locations did attain these temperatures 2 to 3 days before the conditions in the main stem. Residence times in the backwater areas, however, generally exceeded 9 days, thus limiting the exchange of water carrying algal biomass into the main channel. Hydrodynamic model calibration involved adjusting model parameters until observed and simulated daily water-surface elevations, daily streamflows, discrete velocities, and channel areas were similar. Temperature calibration was done with near-surface continuous time-series data and discrete vertical profile temperatures. Observed and simulated water temperatures generally were within 1 °C at all monitoring locations.

Illinois↗
USGS2017

Reconstruction of spatio-temporal temperature from sparse historical records using robust probabilistic principal component regression

Scientific records of temperature and precipitation have been kept for several hundred years, but for many areas, only a shorter record exists. To understand climate change, there is a need for rigorous statistical reconstructions of the paleoclimate using proxy data. Paleoclimate proxy data are often sparse, noisy, indirect measurements of the climate process of interest, making each proxy uniquely challenging to model statistically. We reconstruct spatially explicit temperature surfaces from sparse and noisy measurements recorded at historical United States military forts and other observer stations from 1820 to 1894. One common method for reconstructing the paleoclimate from proxy data is principal component regression (PCR). With PCR, one learns a statistical relationship between the paleoclimate proxy data and a set of climate observations that are used as patterns for potential reconstruction scenarios. We explore PCR in a Bayesian hierarchical framework, extending classical PCR in a variety of ways. First, we model the latent principal components probabilistically, accounting for measurement error in the observational data. Next, we extend our method to better accommodate outliers that occur in the proxy data. Finally, we explore alternatives to the truncation of lower-order principal components using different regularization techniques. One fundamental challenge in paleoclimate reconstruction efforts is the lack of out-of-sample data for predictive validation. Cross-validation is of potential value, but is computationally expensive and potentially sensitive to outliers in sparse data scenarios. To overcome the limitations that a lack of out-of-sample records presents, we test our methods using a simulation study, applying proper scoring rules including a computationally efficient approximation to leave-one-out cross-validation using the log score to validate model performance. The result of our analysis is a spatially explicit reconstruction of spatio-temporal temperature from a very sparse historical record.

Advances in Statistical Climatology, Meteorology a↗
USGS2017

Accounting for sampling patterns reverses the relative importance of trade and climate for the global sharing of exotic plants

Aim The distributions of exotic species reflect patterns of human-mediated dispersal, species climatic tolerances and a suite of other biotic and abiotic factors. The relative importance of each of these factors will shape how the spread of exotic species is affected by ongoing economic globalization and climate change. However, patterns of trade may be correlated with variation in scientific sampling effort globally, potentially confounding studies that do not account for sampling patterns. Location Global. Time period Museum records, generally from the 1800s up to 2015. Major taxa studied Plant species exotic to the United States. Methods We used data from the Global Biodiversity Information Facility (GBIF) to summarize the number of plant species with exotic occurrences in the United States that also occur in each other country world-wide. We assessed the relative importance of trade and climatic similarity for explaining variation in the number of shared species while evaluating several methods to account for variation in sampling effort among countries. Results Accounting for variation in sampling effort reversed the relative importance of trade and climate for explaining numbers of shared species. Trade was strongly correlated with numbers of shared U.S. exotic plants between the United States and other countries before, but not after, accounting for sampling variation among countries. Conversely, accounting for sampling effort strengthened the relationship between climatic similarity and species sharing. Using the number of records as a measure of sampling effort provided a straightforward approach for the analysis of occurrence data, whereas species richness estimators and rarefaction were less effective at removing sampling bias. Main conclusions Our work provides support for broad-scale climatic limitation on the distributions of exotic species, illustrates the need to account for variation in sampling effort in large biodiversity databases, and highlights the difficulty in inferring causal links between the economic drivers of invasion and global patterns of exotic species occurrence.

Global Ecology and Biogeography↗
USGS2011

Coulomb stress change sensitivity due to variability in mainshock source models and receiving fault parameters: A case study of the 2010-2011 Christchurch, New Zealand, earthquakes

Strong aftershocks following major earthquakes present significant challenges for infrastructure recovery as well as for emergency rescue efforts. A tragic instance of this is the 22 February 2011 M w 6.3 Christchurch aftershock in New Zealand, which caused more than 100 deaths while the 2010 M w 7.1 Canterbury mainshock did not cause a single fatality (Figure 1). Therefore, substantial efforts have been directed toward understanding the generation mechanisms of aftershocks as well as mitigating hazards due to aftershocks. Among these efforts are the prediction of strong aftershocks, earthquake early warning, and aftershock probability assessment. Zhang et al. (1999) reported a successful case of strong aftershock prediction with precursory data such as changes in seismicity pattern, variation of b-value, and geomagnetic anomalies. However, official reports of such successful predictions in geophysical journals are extremely rare, implying that deterministic prediction of potentially damaging aftershocks is not necessarily more scientifically feasible than prediction of mainshocks.

Christchurch↗
USGS2008

Cartography for lunar exploration: 2008 status and mission plans

The initial spacecraft exploration of the Moon in the 1960s-70s yielded extensive data, primarily in the form of film and television images, which were used to produce a large number of hardcopy maps by conventional techniques. A second era of exploration, beginning in the early 1990s, has produced digital data including global multispectral imagery and altimetry, from which a new generation of digital map products tied to a rapidly evolving global control network has been made. Efforts are also underway to scan the earlier hardcopy maps for online distribution and to digitize the film images so that modern processing techniques can be used to make high-resolution digital terrain models (DTMs) and image mosaics consistent with the current global control. The pace of lunar exploration is accelerating dramatically, with as many as eight new missions already launched or planned for the current decade. These missions, of which the most important for cartography are SMART-1 (Europe), Kaguya/SELENE (Japan), Chang'e-1 (China), Chandrayaan-1 (India), and Lunar Reconnaissance Orbiter (USA), will return a volume of data exceeding that of all previous lunar and planetary missions combined. Framing and scanner camera images, including multispectral and stereo data, hyperspectral images, synthetic aperture radar (SAR) images, and laser altimetry will all be collected, including, in most cases, multiple data sets of each type. Substantial advances in international standardization and cooperation, development of new and more efficient data processing methods, and availability of resources for processing and archiving will all be needed if the next generation of missions are to fulfill their potential for high-precision mapping of the Moon in support of subsequent exploration and scientific investigation.

The International Archives of the Photogrammetry, ↗
USGS2007

Cartography for lunar exploration: Current status and planned missions

The initial spacecraft exploration of the Moon in the 1960s–70s yielded extensive data, primarily in the form of film and television images, that were used to produce a large number of hardcopy maps by conventional techniques. A second era of exploration, beginning in the early 1990s, has produced digital data including global multispectral imagery and altimetry, from which a new generation of digital map products tied to a rapidly evolving global control network has been made. Efforts are also underway to scan the earlier hardcopy maps for online distribution and to digitize the film images themselves so that modern processing techniques can be used to make high-resolution digital terrain models (DTMs) and image mosaics consistent with the current global control. The pace of lunar exploration is about to accelerate dramatically, with as many of seven new missions planned for the current decade. These missions, of which the most important for cartography are SMART-1 (Europe), SELENE (Japan), Chang'E-1 (China), Chandrayaan-1 (India), and Lunar Reconnaissance Orbiter (USA), will return a volume of data exceeding that of all previous lunar and planetary missions combined. Framing and scanner camera images, including multispectral and stereo data, hyperspectral images, synthetic aperture radar (SAR) images, and laser altimetry will all be collected, including, in most cases, multiple datasets of each type. Substantial advances in international standardization and cooperation, development of new and more efficient data processing methods, and availability of resources for processing and archiving will all be needed if the next generation of missions are to fulfil their potential for high-precision mapping of the Moon in support of subsequent exploration and scientific investigation.

Conference Paper↗
USGS2006

Cartography for lunar exploration: 2006 status and planned missions

The initial spacecraft exploration of the Moon in the 1960s–70s yielded extensive data, primarily in the form of film and television images, that were used to produce a large number of hardcopy maps by conventional techniques. A second era of exploration, beginning in the early 1990s, has produced digital data including global multispectral imagery and altimetry, from which a new generation of digital map products tied to a rapidly evolving global control network has been made. Efforts are also underway to scan the earlier hardcopy maps for online distribution and to digitize the film images themselves so that modern processing techniques can be used to make high-resolution digital terrain models (DTMs) and image mosaics consistent with the current global control. The pace of lunar exploration is about to accelerate dramatically, with as many of seven new missions planned for the current decade. These missions, of which the most important for cartography are SMART-1 (Europe), SELENE (Japan), Chang'E-1 (China), Chandrayaan-1 (India), and Lunar Reconnaissance Orbiter (USA), will return a volume of data exceeding that of all previous lunar and planetary missions combined. Framing and scanner camera images, including multispectral and stereo data, hyperspectral images, synthetic aperture radar (SAR) images, and laser altimetry will all be collected, including, in most cases, multiple datasets of each type. Substantial advances in international standardization and cooperation, development of new and more efficient data processing methods, and availability of resources for processing and archiving will all be needed if the next generation of missions are to fulfil their potential for high-precision mapping of the Moon in support of subsequent exploration and scientific investigation.

Conference Paper↗
USGS2011

Hydrography of and biogeochemical inputs to Liberty Bay, a small urban embayment in Puget Sound, Washington

This multi-chapter report describes scientific and logistic understanding gained from a 2 year proof-of-concept study in Liberty Bay, a small urban embayment in central Puget Sound, Washington. The introductory chapter describes the regional and local setting, the high-level study goals, the site-specific urban stressors, and the interdisciplinary study approach. Subsequent data chapters describe detailed studies of various components of the Liberty Bay ecosystem: the aquatic environment (Chapter 2), surface and groundwater quantity and quality (Chapter 3), sediment quality (Chapter 4), eelgrass habitat (Chapter 5), carbon and nitrogen sources (Chapter 6), and a statistical model relating herring spawn probability to shoreline attributes (Chapter 7). The final chapter synthesizes knowledge about individual components into a system-wide understanding of how urbanization may affect the Liberty Bay ecosystem. The Liberty Bay study was conducted as part of the U.S. Geological Survey's Coastal Habitats in Puget Sound project, an interdisciplinary collaboration to understand physical and biological processes that affect nearshore ecosystems.

Scientific Investigations Report↗
USGS2012

Flood-inundation maps for the Suncook River in Epsom, Pembroke, Allenstown, and Chichester, New Hampshire

Digital flood-inundation maps for a 16.5-mile reach of the Suncook River in Epsom, Pembroke, Allenstown, and Chichester, N.H., from the confluence with the Merrimack River to U.S. Geological Survey (USGS) Suncook River streamgage 01089500 at Depot Road in North Chichester, N.H., were created by the USGS in cooperation with the New Hampshire Department of Homeland Security and Emergency Management. The inundation maps presented in this report depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage at Suncook River at North Chichester, N.H. (station 01089500). The current conditions at the USGS streamgage may be obtained on the Internet (http://waterdata.usgs.gov/nh/nwis/uv/?site_no=01089500&PARAmeter_cd=00065,00060). The National Weather Service forecasts flood hydrographs at many places that are often collocated with USGS streamgages. Forecasted peak-stage information is available on the Internet at the National Weather Service (NWS) Advanced Hydrologic Prediction Service (AHPS) flood-warning system site (http://water.weather.gov/ahps/) and may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. These maps along with real-time stream stage data from the USGS Suncook River streamgage (station 01089500) and forecasted stream stage from the NWS will provide emergency management personnel and residents with information that is critical for flood-response activities, such as evacuations, road closures, disaster declarations, and post-flood recovery. The maps, along with current stream-stage data from the USGS Suncook River streamgage and forecasted stream-stage data from the NWS, can be accessed at the USGS Flood Inundation Mapping Science Web site http://water.usgs.gov/osw/flood_inundation/.

New Hampshire↗
USGS2017

Geologic map of Meridiani Planum, Mars

Introduction and Background The Meridiani Planum region of Mars—originally named due to its proximity to the Martian prime meridian—contains a variety of geologic units, including those that are crater‑related, that span the Early Noachian to Late Amazonian Epochs. Mars Global Surveyor (MGS) data indicate this area contains extensive layered deposits, some of which are rich in the mineral hematite. The National Aeronautics and Space Administration’s (NASA) Mars Exploration Rover (MER) Opportunity landed in Meridiani Planum in early 2004 and, at the time of this writing, is still conducting operations. A variety of water-altered bedrock outcrops have been studied and contain indications of prolonged surface and near-surface fluid/rock interactions. The purpose of this study is to use the more recent orbiter data to place the rover’s findings in a broader context by assessing the geologic and hydrologic histories of the region.

Scientific Investigations Map↗
USGS2004

Evaluation of pier-scour equations for coarse-bed streams

Streambed scour at bridge piers is among the leading causes of bridge failure in the United States. Several pier-scour equations have been developed to calculate potential scour depths at existing and proposed bridges. Because many pier-scour equations are based on data from laboratory flumes and from cohesionless silt- and sand-bottomed streams, they tend to overestimate scour for piers in coarse-bed materials. Several equations have been developed to incorporate the mitigating effects of large particle sizes on pier scour, but further investigations are needed to evaluate how accurately pier-scour depths calculated by these equations match measured field data. This report, prepared in cooperation with the Montana Department of Transportation, describes the evaluation of five pier-scour equations for coarse-bed streams. Pier-scour and associated bridge-geometry, bed-material, and streamflow-measurement data at bridges over coarse-bed streams in Montana, Alaska, Maryland, Ohio, and Virginia were selected from the Bridge Scour Data Management System. Pier scour calculated using the Simplified Chinese equation, the Froehlich equation, the Froehlich design equation, the HEC-18/Jones equation and the HEC-18/Mueller equation for flood events with approximate recurrence intervals of less than 2 to 100 years were compared to 42 pier-scour measurements. Comparison of results showed that pier-scour depths calculated with the HEC-18/Mueller equation were seldom smaller than measured pier-scour depths. In addition, pier-scour depths calculated using the HEC-18/Mueller equation were closer to measured scour than for the other equations that did not underestimate pier scour. However, more data are needed from coarse-bed streams and from less frequent flood events to further evaluate pier-scour equations.

Scientific Investigations Report↗
USGS2005

Two-dimensional resistivity investigation of the North Cavalcade Street site, Houston, Texas, August 2003

The North Cavalcade Street site was first developed for wood treating in 1946. By 1955, pentachlorophenol wood preservation services and other support facilities, such as creosote ponds, pentachlorophenol and creosote storage structures, various tanks, lumber sheds, a treatment facility, and other buildings had been added. In 1961, the property was closed. To protect public health and welfare and the environment from release or threatened releases of hazardous substances, the U.S. Environmental Protection Agency added the North Cavalcade Street site to the National Priorities List on October 5, 1984. Between September 1985 and November 1987, the U.S. Environmental Protection Agency conducted a remedial investigation which, through exploratory drilling, determined the locations of two contaminated source areas and a normal fault. During August 2003, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, conducted a two-dimensional (2D) resistivity investigation at the North Cavalcade Street site to provide additional characterization of the dense non-aqueous phase liquids and the lithologies that can influence contaminant migration. The 2D resistivity investigation used a capacitively coupled (CC) resistivity method as a reconnaissance tool to locate geophysical anomalies that could be associated with possible areas of creosote contamination. The inversion results of the CC resistivity survey identified resistive anomalies in the subsurface near the eastern and western contaminated source areas. A direct-current (DC) resistivity survey conducted near the CC resistivity survey confirmed the occurrence of subsurface resistive anomalies. The inversion results of the DC resistivity survey were used to define the subsurface distribution of resistivity at each line. Forward modeling was used as an interpretative tool to relate the subsurface distribution of resistivity from four DC resistivity lines to known, assumed, and hypothetical information on subsurface lithologies. The final forward models were used as an estimate of the true resistivity structure for the field data. The forward models and the inversion results of the forward models show the depth, thickness, and extent of strata as well as the resistive anomalies occurring along the four lines and the displacement of strata resulting from the Pecore Fault along two of the four DC resistivity lines. Ten additional DC resistivity lines show similarly distributed shallow subsurface lithologies of silty sand and clay strata. Eight priority areas of resistive anomalies were identified for evaluation in future studies. The interpreted DC resistivity data allowed subsurface stratigraphy to be extrapolated between existing boreholes resulting in an improved understanding of lithologies that can influence contaminant migration.

Scientific Investigations Report↗