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At least 1,099 records · Page 61Linked to original sources
USGS2018

A comparison of synthetic flowpaths derived from light detection and ranging topobathymetric data and National Hydrography Dataset High Resolution Flowlines

Bathymetric and topobathymetric light detection and ranging (lidar) digital elevation models created for the Delaware River were provided to the National Geospatial Program and used to evaluate synthetic flowpath extraction from bathymetric/topobathymetric lidar survey data as a data source for improving the density, distribution, and connectivity of the National Hydrography Dataset High Resolution Flowline Network. As the surface-water component of The National Map, the National Hydrography Dataset maintains the Nation’s drainage network flow information and geometries for surface-water features used in hydrologic, hydraulic, and other science and engineering disciplines. The regional lidar survey for the Delaware River between Hancock, New York, and Trenton, New Jersey, was collected for the U.S. Geological Survey using the Experimental Advanced Airborne Research Lidar sensor system and processed by the Coastal National Elevation Database Applications Program. Using 1 percent of the maximum flow accumulation value for the surveyed Delaware River corridor as the flow accumulation threshold for grid cells at 1-, 5-, and 10-meter resolution created 223 to 283 kilometers of synthetic flowpaths potentially representing the river channel thalweg, which is the deepest point in a riverbed cross-section. There was potential for improving the High Resolution National Hydrography Dataset (HR NHD) Flowline network in places where the Delaware River channel, depicted as an Artificial Path in the HR NHD, is offset from the extracted synthetic river flowpath which sometimes appeared better positioned than the Artificial Path to represent the river thalweg. For the same area, using 0.05 percent of the maximum flow accumulation at the 1-, 5-, and 10-meter resolutions extracted 744 to 1,317 kilometers of synthetic flowpaths, with extracted synthetic flowpaths representing the main river channel and additional synthetic flowpaths representing tributaries or streams adjacent to the main channel. Overlaying these results with the HR NHDFlowline Network indicates that some of the additional synthetic flowpaths are connected to or extend HR NHD stream/river feature types. Some disconnected or isolated synthetic flowpaths not included in stream/river feature types were validated in orthoimagery and U.S. Topo Maps and provide examples of how extracted synthetic flowpaths could be used to delineate new stream/river features. Other additional extracted synthetic flowpaths depict linear features such as canals, tree lines, roads, or linear topographic depressions. For some river reaches where obstructions to flow or where low-relief topographic or bathymetric surfaces alter the flow direction, the software tool used to develop the flow direction grid did not calculate a primary flowpath for the river channel. Based on the results of this analysis, site conditions for the Delaware River corridor did not affect the quality of lidar bathymetric survey data. However, depending on the resolution of the lidar bathymetric digital elevation models (BDEMs), site conditions do have different effects on results for extracted synthetic flowpaths. We found that synthetic flowpaths extracted from 1-meter resolution lidar DEMs had more varied flow directions around in-channel landforms that obstructed flow than synthetic flowpaths extracted from 5- or 10-meter resolution lidar DEMs. As a result the 1-meter resolution DEM created some isolated or discontinuous synthetic flowpath segments where the 5- and 10-meter DEMs developed more continuous flowpaths. In this case the river bed upstream from the in-channel obstruction is shallower than the river bed downstream. Under these conditions the 1-meter resolution DEM provided synthetic flowpaths delineating a potential river thalweg. In this same area, the software solution modified (virtually raised) the river bed in the 5- and 10-meter resolution DEMs and flattened the bathymetric surface to create a continuous downstream flow direction, which caused trellis-patterned synthetic flowpaths to form. Under different site conditions and converse to the above development of synthetic flowpaths at different resolutions, at an abandoned river flood plain (terrace) with low relief that is adjacent to the river channel, the flow direction grid for the 1-meter resolution DEM developed continuous synthetic flowpath corresponding to a HR NHD Flowline network stream/river feature that connected to the main river channel but the larger resolution DEMs created isolated or disconnected synthetic flowpaths. A project to continue an evaluation of benefits of or issues caused by extracting synthetic flowpaths to enhance the HR NHD could include a study to assess the potential for merging surface-water flowpaths extracted from lidar topobathymetry and 3D Elevation Program digital elevation models. The merged DEM approach to synthetic flowpath extraction could extend the HR NHDFlowline network and enhance flow accumulations that might develop better flow direction grids in low-relief areas. Because of the confined lateral extent of the Delaware River, the lidar DEMs were not used to create catchments or watersheds; however, the merged DEM approach could also be tested as a resource for enhancing HR NHD catchments and watersheds. This lidar DEM synthetic flowpath extraction project supports the National Geospatial Program efforts to collect and produce high-quality lidar data to provide 3-dimensional representations of natural feature and aligns with the National Spatial Data Infrastructure to improve utilization of geospatial data. The results also can be useful for understanding strategies that can help maintain quality data in the HR NHD programs. KEYWORDS: bathymetric, digital elevation model, extracted synthetic flowpath, lidar, High Resolution National Hydrography Dataset, topobathymetric

New Jersey↗
USGS2025

Automated generation of an urban synthetic elevation checkpoint network across the North Carolina coastline, USA

Lidar and structure from motion-derived digital elevation and surface models have widespread application. Consideration of a topographic model's vertical root mean squared error (RMSEz) and systematic directional bias is important for many of these applications, particularly landscape change detection and measurement. Due to logistic, resource, and time constraints, wide area remotely sensed topographic surveys are not always accompanied by an in situ checkpoint network for validating and characterizing survey error. Here we describe and test a method for automatically generating synthetic elevation checkpoints in bulk across hundreds of kilometers using a publicly available lidar-derived DEM time-series, road vector network, and landcover classification map. Our method produced 6000–10,000 synthetic checkpoints across the developed barrier island coastline of North Carolina. These checkpoints characterized vertical error metrics in a statistically similar way as in situ checkpoints when assessing the vertical accuracy of a contemporary lidar-derived DEM and produced RMSEz metrics an average of 0.018 m from the RMSEz of historical lidar DEMs published with tested accuracy metrics. This new method has the potential to A) lower the cost and time required to validate new remotely sensed topographic surveys by reducing or eliminating the field work associated with in situ checkpoint surveys, B) provide a means of retroactively assessing the absolute vertical accuracy and systematic bias of historical topographic datasets that were not published with tested accuracy metrics, and C) generate reference networks to assess and correct spatially variable patterns of vertical bias in topographic datasets.

North Carolina↗
USGS2020

Geologic map of the northern Harrat Rahat volcanic field, Kingdom of Saudi Arabia

Harrat Rahat, in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 Cenozoic harrats (Arabic for “volcanic field”) distributed on the Arabian plate. It extends more than 300 km north-south and 50 to 75 km east-west, and it covers an area of approximately 20,000 km 2 , has a volume of approximately 2,000 km 3 , and encompasses more than 900 observable vents. Volcanism commenced around 10 Ma and has continued into historic time, the most recent eruption occurring in 1256 C.E. Volcanic products are dominated by alkali basalt and hawaiite lava flows, with subordinate mugearite lava flows, as well as benmoreite and trachyte lava flows, domes, and pyroclastic flows. This geologic map distinguishes 239 eruptive units that cover an area of 3,340 km 2 in northern Harrat Rahat and the adjacent city of Al-Madinah. Results are presented as a geologic map of the study area at 1:75,000 scale and of smaller regions of particular interest at 1:25,000 scale, along with interpretive text. Most units are basaltic lava flows that erupted from the broadly north-northwest-trending main vent axis that constructed the topographic crest of the volcanic field. This 300- to 400-m-high vent axis, which has a width of 6 to 10 km, lies in the eastern one-third of northern Harrat Rahat. Basalt and hawaiite lava flows can extend as far as 27 km from their vents, but most are 10 to 15 km long. Evolved products such as mugearites, benmoreites, and trachytes are less extensive; the trachytic pyroclastic flows extend as far as 9 km from their source vents, although most only reach 4 to 6 km. Vents of the evolved products are restricted to the main vent axis or its flanks. No volcanic rocks older than 1.2 Ma are exposed in the map area, and about 90 percent of the exposed volcanic rocks erupted during the past 570 thousand years. As depicted on the geologic maps, eruption ages and field relations define 12 eruptive stages for northern Harrat Rahat for the past 1.2 million years. Other important geochronological findings include (1) several late Pleistocene lava flows near Al-Madinah, which previously were interpreted as Holocene from archeological evidence; (2) the eruption age of a cluster of cinder cones and small lava flows in the western outskirts of Al-Madinah (previously ascribed to an eruption in 641 C.E.) is actually 13.3±1.9 ka, close to the Pleistocene-Holocene boundary; and (3) only two Holocene eruptions have been identified in the map area, those of the historically described basalt of Al Labah in 1256 C.E. and the dome and pyroclastic flows of the trachyte of Um Rgaibah at 4.2±5.2 ka.

Scientific Investigations Map↗
USGS1963

Structure-contour map of the Olive Hill Clay Bed in northeastern Kentucky

The gently dipping Olive Hill Clay Bed of Crider (1913) crops out in belt about 15 miles \vidc and 60 miles long from the Ohio River near Portsmouth, Ohio, south-southwesterly to Frenchburg, Ky. (see inset map). The purpose of the structure-contour map presented here is to aid exploration by showing the elevations at which the Olive Hill Clay Bed occurs. The strudure contours indicate the depths that mu;,t be reached in prospecting for the clay. The approximate depth of the clay at any one point is the difference between elevations of the structure and topographic contours. The clay has been thoroughly prospected along its out.crop belt and in most areas \Vhe re it lies under overburden less than 200 feet thick. The depth of the clay bed increase,; eastward from the outcrop belt, and large potential resources are likely to occur at depths greater than 200 feet.

Kentucky↗
USGS2012

Intelligent estimation of spatially distributed soil physical properties

Spatial analysis of soil samples is often times not possible when measurements are limited in number or clustered. To obviate potential problems, we propose a new approach based on the self-organizing map (SOM) technique. This approach exploits underlying nonlinear relation of the steady-state geomorphic concave–convex nature of hillslopes (from hilltop to bottom of the valley) to spatially limited soil textural data. The topographic features are extracted from Shuttle Radar Topographic Mission elevation data; whereas soil textural (clay, silt, and sand) and hydraulic data were collected in 29 spatially random locations (50 to 75 cm depth). In contrast to traditional principal component analysis, the SOM identifies relations among relief features, such as, slope, horizontal curvature and vertical curvature. Stochastic cross-validation indicates that the SOM is unbiased and provides a way to measure the magnitude of prediction uncertainty for all variables. The SOM cross-component plots of the soil texture reveals higher clay proportions at concave areas with convergent hydrological flux and lower proportions for convex areas with divergent flux. The sand ratio has an opposite pattern with higher values near the ridge and lower values near the valley. Silt has a trend similar to sand, although less pronounced. The relation between soil texture and concave–convex hillslope features reveals that subsurface weathering and transport is an important process that changed from loss-to-gain at the rectilinear hillslope point. These results illustrate that the SOM can be used to capture and predict nonlinear hillslope relations among relief, soil texture, and hydraulic conductivity data.

Geoderma↗
USGS2020

The influence of climate variability on the accuracy of NHD perennial and non-perennial stream classifications

National Hydrography Dataset (NHD) stream permanence classifications (SPC; perennial, intermittent, and ephemeral) are widely used for data visualization and applied science, and have implications for resource policy and management. NHD SPC were assigned using a combination of topographic field surveys and interviews with local residents. However, previous studies indicate that non‐NHD, in situ streamflow observations (NNO) frequently disagree with NHD SPC. We hypothesized that differences in annual climate conditions between map creation years and the years NNO were collected contributed to disagreement between NNO and NHD SPC. We compared NHD SPC to 10,055 NNO (classified as “wet” or “dry”) collected in the Pacific Northwest between 1977 and 2015. Annual climate conditions were described with the Palmer Drought Severity Index (PDSI). Stream order was added as a covariate to account for different effects along the stream network. NHD SPC agreed with 80.5% of NNO. “Dry” NNO were five times more likely to disagree with NHD than “wet” NNO ( p < 0.0001). Disagreement was greatest on first‐order streams. When NHD SPC were collected during a wetter period than NNO the probability of disagreement increased by a factor of 1.17 ( p < 0.0001) per unit difference in PDSI. The influence of climate on disagreements between NNO and NHD SPC provides support for the continued development of dynamic models representing SPC as opposed to static NHD classifications.

Journal of the American Water Resources Associatio↗
USGS2010

Star crossings and stone monuments-Field astronomy by the Wheeler Survey in 1870s Colorado

The decade of the 1870s was a time of extensive exploration and surveying in the American West. The nation needed knowledge of the cultural features, topography, natural resources, and geology of this land to promote and aid the 'rapid development of an empire.' The need was particularly acute in the region that still was known in the early 1870s as Colorado Territory. There, cities and towns were springing up along the base of the Front Range, railroads were expanding, and in the mountains prospectors and miners were exploring the countryside seeking and extracting the region's abundant mineral resources. Also, recurring conflicts between the newcomers and Native Americans made it desirable to have accurate maps for military purposes. Four major government-sponsored scientific surveys formed the principal organized effort to provide critical knowledge of the land. Civilian scientists led three of these: John Wesley Powell ('Geographical and Topographical Survey of the Colorado River of the West'); Ferdinand V. Hayden ('Geological and Geographical Survey of the Territories'); and Clarence King ('Geological Exploration of the Fortieth Parallel'). Lt. George Montague Wheeler, a young graduate of West Point (Class of 1866) and a member of the U.S. Army Corps of Engineers, led the fourth and most ambitious project ('United States Geographical Surveys West of the One Hundredth Meridian').

Circular↗
USGS2002

Preliminary report on geophysical data in Yavapai County, Arizona

Recently acquired geophysical data provide information on the geologic framework and its effect of groundwater flow and on stream/aquifer interaction in Yavapai County, Arizona. High-resolution aeromagnetic data reflect diverse rock types at and below the topographic surface and have permitted a preliminary interpretation of faults and underlying rock types (in particular, volcanic) that will provide new insights on the geologic framework, critical input to future hydrologic investigations. Aeromagnetic data map the western end of the Bear Wallow Canyon fault into the sedimentary fill of Verde Valley. Regional gravity data indicate potentially significant accumulations of low-density basin fill in Big Chino, Verde, and Williamson Valleys. Electrical and seismic data were also collected and help evaluate the approximate depth and extent of recent alluvium overlying Tertiary and Paleozoic sediments. These data will be used to ascertain the potential contribution of shallow ground-water subflow that cannot be measured by gages or flow meters and whether stream flow in losing reaches is moving as subflow or is being lost to the subsurface. The geophysical data will help produce a more robust groundwater flow model of the region.

Arizona↗
USGS2008

GIS Representation of Coal-Bearing Areas in Africa

The African continent contains approximately 5 percent of the world's proven recoverable reserves of coal (World Energy Council, 2007). Energy consumption in Africa is projected to grow at an annual rate of 2.3 percent from 2004 through 2030, while average consumption in first-world nations is expected to rise at 1.4 percent annually (Energy Information Administration, 2007). Coal reserves will undoubtedly continue to be part of Africa's energy portfolio as it grows in the future. A review of academic and industrial literature indicates that 27 nations in Africa contain coal-bearing rock. South Africa accounts for 96 percent of Africa's total proven recoverable coal reserves, ranking it sixth in the world. This report is a digital compilation of information on Africa's coal-bearing geology found in the literature and is intended to be used in small scale spatial investigations in a Geographic Information System (GIS) and as a visual aid for the discussion of Africa's coal resources. Many maps of African coal resources often include points for mine locations or regional scale polygons with generalized borders depicting basin edges. Point locations are detailed but provide no information regarding extent, and generalized polygons do not have sufficient detail. In this dataset, the polygons are representative of the actual coal-bearing lithology both in location and regional extent. Existing U.S. Geological Survey (USGS) digital geology datasets provide the majority of the base geologic polygons. Polygons for the coal-bearing localities were clipped from the base geology that represented the age and extent of the coal deposit as indicated in the literature. Where the 1:5,000,000-scale geology base layer's ages conflicted with those in the publications, polygons were generated directly from the regional African coal maps (1:500,000 scale, approximately) in the published material. In these cases, coal-bearing polygons were clipped to the literature's indicated coal extent, without regard to the underlying geology base or topographic constraints. Indication of the presence of African coal is based on multiple sources. However, the quality of the sources varies and there is often disagreement in the literature. This dataset includes the rank, age, and location of coal in Africa as well as the detailed source information responsible for each coal-bearing polygon. The dataset is not appropriate for use in resource assessments of any kind. Attributes necessary for tasks, such as number of coal seams, thickness of seams, and depth to coal are rarely provided in the literature and accordingly not represented in this data set. Small-scale investigations, representations and display uses are most appropriate for this product. This product is the first to show coal distribution as bounded by actual geologic contacts for the entire African continent. In addition to the spatial component of this dataset, complete references to source material are provided for each polygon, making this product a useful first step resource in African coal research. Greater detail regarding the creation of this dataset as well as the sources used is provided in the metadata file for the Africa_coal.shp file.

Open-File Report↗
USGS1984

Preliminary map showing the potentiometric surface of the Aquia Aquifer in southern Maryland, September 1982

A map was prepared that shows the potentiometric surface of the Aquia aquifer in southern Maryland in September 1982. The map is based on measurements from a network of 78 observation wells. The highest measured level of the potentiometric surface, 34 ft above sea level, was near the outcrop of the aquifer in a topographically high area of Anne Arundel County. The potentiometric surface slopes downward to the extensive cone of depression--much of it more than 40 ft below sea level--has developed around the well fields in the vicinity of Lexington Park. The network of observation wells was developed as part of the cooperative program between the U.S. Geological Survey, the Maryland Geological Survey, and the Maryland Energy Administration.

Maryland↗
USGS2008

Modeling landslide recurrence in Seattle, Washington, USA

To manage the hazard associated with shallow landslides, decision makers need an understanding of where and when landslides may occur. A variety of approaches have been used to estimate the hazard from shallow, rainfall-triggered landslides, such as empirical rainfall threshold methods or probabilistic methods based on historical records. The wide availability of Geographic Information Systems (GIS) and digital topographic data has led to the development of analytic methods for landslide hazard estimation that couple steady-state hydrological models with slope stability calculations. Because these methods typically neglect the transient effects of infiltration on slope stability, results cannot be linked with historical or forecasted rainfall sequences. Estimates of the frequency of conditions likely to cause landslides are critical for quantitative risk and hazard assessments. We present results to demonstrate how a transient infiltration model coupled with an infinite slope stability calculation may be used to assess shallow landslide frequency in the City of Seattle, Washington, USA. A module called CRF (Critical RainFall) for estimating deterministic rainfall thresholds has been integrated in the TRIGRS (Transient Rainfall Infiltration and Grid-based Slope-Stability) model that combines a transient, one-dimensional analytic solution for pore-pressure response to rainfall infiltration with an infinite slope stability calculation. Input data for the extended model include topographic slope, colluvial thickness, initial water-table depth, material properties, and rainfall durations. This approach is combined with a statistical treatment of rainfall using a GEV (General Extreme Value) probabilistic distribution to produce maps showing the shallow landslide recurrence induced, on a spatially distributed basis, as a function of rainfall duration and hillslope characteristics.

Washington↗
USGS2019

Multiorder hydrologic position in the conterminous United States: A set of metrics in support of groundwater mapping at regional and national scales

The location of a point on the landscape within a stream network (hydrologic position) can be an important predictive measure in hydrology. Hydrologic position is defined here by two metrics: lateral position and distance from stream to divide, both measured horizontally. Lateral position (dimensionless) is the relative position of a point between the stream and its watershed divide. Distance from stream to divide (units of length) is an indicator of position within a watershed: generally small near a confluence and generally large in headwater areas. Watersheds and watershed divides are defined here by Thiessen polygons rather than topographic divides. Lateral position and distance from stream to divide are also defined in the context of hydrologic order. Hydrologic order “ n ” is defined as the network of streams, and associated divides, of order n and higher. And given that a point can have different positions in different hydrologic orders the term multiorder hydrologic position (MOHP) is used to describe the ensemble of hydrologic positions. MOHP was mapped across the conterminous United States for nine hydrologic orders at a spatial resolution of 30 m (about 8.7 billion pixels). There are 18 metrics for each pixel. Four case studies are presented that use MOHP metrics as explanatory factors in random forest machine learning models. The case studies show that lower order MOHP metrics can serve as indicators of hydrologic process while higher‐order metrics serve as indicators of location. MOHP is shown to have utility as a predictor variable across a large range of scales (50,000 to 8,000,000 km 2 ).

Water Resources Research↗
USGS2019

Digital database of the geologic map of the middle east rift geothermal subzone, Kīlauea Volcano, Hawai‘i

This database release contains all the information used to produce Geologic Investigations Series I-2614 ( https://pubs.usgs.gov/imap/2614/ ). The main component of this digital release is a geodatabase prepared using ArcGIS, but Esri shapefiles are included as well. Kīlauea is an active shield volcano in the southeastern part of the Island of Hawai‘i. The middle East Rift Zone (MERZ) map includes about 27 square kilometers of the MERZ and shows the distribution of the products of 34 separate eruptions during late Holocene time. Lava flows erupted during 1983–86 have reached the mapped area. The subaerial part of the MERZ is 3–4 km wide and about 18 km long. It is a constructional ridge, 50–150 m above the adjoining terrain, marked by low spatter ramparts and cones as high as 60 m. Lava typically flowed either northeast or southeast, depending on vent location relative to the topographic crest of the rift zone. The MERZ receives more than 100 inches of rainfall annually and is covered by tropical rain forest. Vegetation begins to grow on lava a few months after its eruption. Relative heights of trees can be a guide to relative ages of underlying lava flows, but proximity to faults, presence of easily weathered cinders, and human activity also affect the rate of growth. The rocks have been grouped into five basic age groups. The framework for the ages assigned is provided by eight radiocarbon ages from nearby mapping by the authors and a single date from within this investigation area. The numerical ages are supplemented by observations of stratigraphic relations, degree of weathering, soil development, and vegetative cover.

Hawaii↗
USGS2006

Geologic map of the middle east rift geothermal subzone, Kīlauea Volcano, Hawaiʻi

Kīlauea is an active shield volcano in the southeastern part of the Island of Hawai'i. The middle east rift zone (MERZ) map includes about 27 square kilometers of the MERZ and shows the distribution of the products of 37 separate eruptions during late Holocene time. Lava flows erupted during 1983-96 have reached the mapped area. The subaerial part of the MERZ is 3-4 km wide and about 18 km long. It is a constructional ridge, 50-150 m above the adjoining terrain, marked by low spatter ramparts and cones as high as 60 m. Lava typically flowed either northeast or southeast, depending on vent location relative to the topographic crest of the rift zone. The MERZ receives more than 100 in. of rainfall annually and is covered by tropical rain forest. Vegetation begins to grow on lava a few months after its eruption. Relative heights of trees can be a guide to relative ages of underlying lava flows, but proximity to faults, presence of easily weathered cinders, and human activity also affect the rate of growth. The rocks have been grouped into five basic age groups. The framework for the ages assigned is provided by eight radiocarbon ages from previous mapping by the authors and a single date from the current mapping effort. The numerical ages are supplemented by observations of stratigraphic relations, degree of weathering, soil development, and vegetative cover.

Hawaii↗
USGS2019

Cerulean Warbler (Setophaga cerulea) response to operational silviculture in the central Appalachian region

The Cerulean Warbler ( Setophaga cerulea ) is a species of conservation need, with declines linked in part to forest habitat loss on its breeding grounds. Active management of forests benefit the Cerulean Warbler by creating the complex structural conditions preferred by the species, but further research is needed to determine optimal silvicultural strategies. We quantified and compared the broad-scale influence of timber harvests within central Appalachian hardwood forests on estimated abundance and territory density of Cerulean Warblers. We conducted point counts at seven study areas across three states within the central Appalachian region (West Virginia [n = 4], Kentucky [n = 1], Virginia [n = 2]) and territory mapping at two of the study areas in West Virginia, pre- and post-harvest, for up to five breeding seasons from 2013 to 2017. Our primary objective was to relate change in abundance to topographic and vegetation metrics to evaluate the effectiveness of current Cerulean Warbler habitat management guidelines. We used single-species hierarchical ( N -mixture) models to estimate abundance while accounting for detection biases. Pre-harvest mean basal area among study areas was 29.3 m 2 /ha. Harvesting reduced mean basal area among study areas by 40% (mean 17.2 m 2 /ha) at harvest interior and harvest edge points. Territory density increased 100% ( P = 0.003) from pre-harvest to two years post-harvest. Cerulean Warbler abundance increased with increasing percentage of basal area that comprised tree species preferred for foraging and nesting (i.e., white oak species, sugar maple [ Acer saccharum ], hickories) or of large diameter trees (≥40.6 cm diameter at breast height). Positive population growth was predicted to occur where these vegetation metrics were >50% of residual basal area. Post-harvest abundance at harvest interior points was greater than at reference points and when accounting for years-post-harvest in modeling abundance, Cerulean Warbler abundance increased at harvest interior and reference points two years post-harvest and subsequently decreased three years post-harvest. Modeled abundance remained the same at harvest edge points. Increases in abundance and territory density were greater in stands with low pre-harvest densities (<2 birds/point or <0.40 territory/ha) of Cerulean Warblers, whereas populations within stands with higher densities pre-harvest had minimal changes in abundance and territory density. Overall, our results indicate that harvests based on the Cerulean Warbler Management Guidelines for Enhancing Breeding Habitat in Appalachian Hardwood Forests, at all available slope positions and aspects where pre-harvest densities are <0.40 territory/ha, may provide breeding habitat for Cerulean Warblers for at least two years post-harvest in the central Appalachian region.

West Virginia↗
USGS2013

Human and biophysical influences on fire occurrence in the United States

National-scale analyses of fire occurrence are needed to prioritize fire policy and management activities across the United States. However, the drivers of national-scale patterns of fire occurrence are not well understood, and how the relative importance of human or biophysical factors varies across the country is unclear. Our research goal was to model the drivers of fire occurrence within ecoregions across the conterminous United States. We used generalized linear models to compare the relative influence of human, vegetation, climate, and topographic variables on fire occurrence in the United States, as measured by MODIS active fire detections collected between 2000 and 2006. We constructed models for all fires and for large fires only and generated predictive maps to quantify fire occurrence probabilities. Areas with high fire occurrence probabilities were widespread in the Southeast, and localized in the Mountain West, particularly in southern California, Arizona, and New Mexico. Probabilities for large-fire occurrence were generally lower, but hot spots existed in the western and south-central United States The probability of fire occurrence is a critical component of fire risk assessments, in addition to vegetation type, fire behavior, and the values at risk. Many of the hot spots we identified have extensive development in the wildland–urban interface and are near large metropolitan areas. Our results demonstrated that human variables were important predictors of both all fires and large fires and frequently exhibited nonlinear relationships. However, vegetation, climate, and topography were also significant variables in most ecoregions. If recent housing growth trends and fire occurrence patterns continue, these areas will continue to challenge policies and management efforts seeking to balance the risks generated by wildfires with the ecological benefits of fire.

Ecological Applications↗
USGS2006

Potentiometric surface of the Upper Floridan aquifer in the St. Johns River water management district and vicinity, Florida, September 2005

This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2005. Potentiometric contours are based on water-level measurements collected at 643 wells during the period September 12-28, near the end of the wet season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and springflow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

Open-File Report↗
USGS2006

Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May 2006

Introduction: This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2006. Potentiometric contours are based on water-level measurements collected at 599 wells during the period May 14-31, near the end of the dry season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and springflow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

Open-File Report↗