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USGS2025

Integrating refugia modeling and decision science to support climate-adaptive conservation in the Sierra Nevada

To reduce detrimental impacts of anthropogenic change, natural resource managers often look for place-based solutions to minimize biodiversity loss. Climate-change refugia, areas buffered from contemporary climate change, can enable the persistence of valued natural resources and prolong the benefits of conservation action. Here we combine climate-change refugia modeling with structured decision-making to inform conservation decisions for the endangered foothill yellow-legged frog ( Rana boylii ) in the Sierra Nevada region of California, USA. We used an ensemble of species distribution models to identify areas projected to remain suitable into the 2040s and the 2080s under an RCP 8.5 emissions scenario, as well as areas projected to transition to suitable habitat during this time. We integrated these projections with a structured decision-making process to align management strategies with refugia model outcomes for R. boylii in a subset of the study area. Habitat suitability for R. boylii is projected to decline in the study area by over 90% by the 2040s and by a subsequent 15% by the 2080s. Climate-change refugia are projected to occupy ~7% of present-day suitable habitat, with high agreement between GCMs and model timesteps. Areas projected to transition to suitable habitat within the existing R. boylii clade boundaries are negligible. Collectively, climate-change refugia modeling and structured decision-making provide opportunities to improve resource allocation and empower conservation practitioners in climate change adaptation for at-risk species.

California↗

USGS2020

Simulation of discharge, water-surface elevations, and water temperatures for the St. Louis River estuary, Minnesota-Wisconsin, 2016–17

The St. Louis River estuary is a large freshwater estuary, next to Duluth, Minnesota, that encompasses the headwaters of Lake Superior. The St. Louis River estuary is one of the most complex and compromised near-shore systems in the upper Great Lakes with a long history of environmental contamination caused by logging, mining, paper mills, and other heavy industrial activities. Presently (2020), a widely available, science-based assessment tool capable of evaluating ecosystem-level responses to remediation and restoration projects has not existed for the estuary. To address this need, the U.S. Geological Survey (USGS) built a predictive, mechanistic, three-dimensional hydrodynamic model for the estuary using the Environmental Fluid Dynamics Code framework. In the current version, the model can simulate continuous discharge, water-surface elevations, water temperature, and flow velocity, although the modular framework allows for future additions of water-quality modeling. The model was calibrated using data collected from April 2016 through November 2016 and validated with data collected from April 2017 through November 2017. The four types of data used to evaluate model performance were water-surface elevations, discharge, water temperature, and flow velocities. Streamflow and temperature boundary condition data included a mixture of USGS streamgage data, Minnesota Department of Natural Resources gage data, and estimates derived from the gage data. The model was able to simulate the water-surface elevations with generally good agreement between the simulated and measured values for both years at the daily time step. Specifically, the model was able to demonstrate excellent agreement with the measured data with Nash-Sutcliffe efficiency coefficients greater than 0.8 for all three locations; however, the model was unable to produce hourly water-surface elevations with such accuracy for 2016–17. Discharge was more dynamic than the water-surface elevations, both for the measured and simulated data. Generally, most of the discharge ranged from −650 to 1,200 cubic meters per second, but the constantly changing flux exiting the estuary into Lake Superior (positive flows) and entering the estuary from Lake Superior (negative flows) occurred throughout the year. Even upstream at the St. Louis River at Oliver, Wisconsin, gage (USGS station 0402403250), the effect of flows into the estuary from Lake Superior did occur, demonstrating the strong effect of the Lake Superior seiche on flows for the estuary. From a performance standpoint, the model was able to simulate discharge with generally good agreement in both years, although the 2017 validation was better than the 2016 calibration period. For the daily Nash-Sutcliffe efficiency coefficients, the simulated values were 0.98, 0.62, 0.49, and 0.71 for the Oliver gage; the Superior Bay entry channel at Superior, Wisc., (USGS station 464226092005600); the Superior Bay Duluth Ship Canal at Duluth, Minn., (USGS station 464646092052900); and total entries (combination of the Superior entry and Duluth entry), respectively. For the hourly evaluation criteria, the model performed poorly, with Nash-Sutcliffe efficiency coefficients less than 0 for the two entries into Lake Superior; therefore, as a predictor of discharge at the hourly scale, the model performed worse than using the measured data average. Similar to discharge, the model was a good predictor of flow velocity at the daily time scale but had difficulty matching the measured data at the hourly scale. For discharge and flow velocity, matching at subdaily time steps for a system as complicated as the St. Louis River estuary is considered difficult because the match is highly sensitive to coordinating the exact measurement location to the simulated value. The final calibration target was water temperature, calibrated for the Oliver gage and the Duluth entry. For calibration purposes, the Duluth entry was the more important water temperature target because the Oliver gage was more of an internal check on the model. The Nash-Sutcliffe efficiency coefficients for the Duluth entry were high; hourly Nash-Sutcliffe efficiency coefficients at the Duluth entry were either at or greater than 0.7 for both years, and daily values were 0.84 and 0.82 for 2016 and 2017, respectively.

Minnesota, Wisconsin↗

USGS2023

The 3D Elevation Program—Supporting Maine’s economy

Introduction Inland flooding, sea-level rise, and pollution pose challenges for Maine’s infrastructure and natural resources. A highly detailed, three-dimensional (3D) model of the Earth’s surface is allowing the State of Maine to address these challenges in an increasingly comprehensive and timely manner. In addition, highly accurate elevation data facilitate land development, forest management, agricultural practices, and wildlife conservation, all of which are key pillars of Maine’s economy. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed 3D model of the Earth’s surface and aboveground features.

Maine↗

USGS1997

Time of travel of solutes in the Sabine River basin, Texas, August-November 1996

The U.S. Geological Survey (USGS), in cooperation with the Sabine River Authority, did a time-of-travel study in the Sabine River Basin during low flow from August to November 1996. The study was done to provide accurate estimates of the time-of-travel and dispersion characteristics for solutes during low flow in a 1.8-mile (mi) reach of Grace Creek, a 23.9-mi reach of the mainstem Sabine River, a 3.4-mi reach of Hawkins Creek, and a 1.9-mi reach of Rocky Creek. This report explains the approach and documents the results of the study. The results of the study will be used by the Texas Natural Resource Conservation Commission in a water-quality model to determine waste-load allocation in Segment 0505 of the Sabine River Basin. The time-of-travel and dispersion characteristics also provide useful information on the probable behavior of soluble contaminants that might be introduced into the streams measured in this study.

Texas↗

USGS1996

Numerical simulation of solute transport in southwestern Salt Lake Valley, Utah

Contaminated ground water characterized by high concentrations of dissolved solids and dissolved sulfate, and in areas, by low pH and elevated concentrations of metals, is present near public-supply wells in the southwestern Salt Lake Valley. To provide State officials and water users with information concerning the potential movement of contaminated ground water to points of withdrawal in the area, an analysis of solute transport using computer models was done by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, and local municipalities and water users. A three-dimensional solute-transport model was developed and couples with an existing ground-water flow model of Salt Lake Valley to simulate the movement of dissolved sulfate in ground water in southwestern Salt Lake Valley. Development and calibration of the transport model focused mainly on sulfate movement down-gradient from the Bingham Creek Reservoirs and the South Jordan evaporation ponds east of the mouth of Bingham Canyon. Estimates of transport parameters were adjusted during a calibration simulation representing conditions during 1965-93. After calibration, the transport model was used to simulate future sulfate movement for 1994-2043. Because of uncertainty in estimated transport-parameter values, three projection transport simulations incorporating a range of probable parameter values were done to evaluate future sulfate movement and changes in sulfate concentrations at selected public-supply wells. These projection simulations produced a possible range of computed transport rates and patterns. In general, the projection simulations indicated movement of the sulfate plume east of the Bingham Creek reservoir toward public-supply wells northeast of the reservoirs and then eastward toward the Jordan River. Ground water with high concentrations of sulfate east of the South Jordan evaporation ponds is simulated as moving west to east under the Jordan River towards public-supply wells during the final 25 years of the simulation period. An increase in sulfate concentration from 200 mg/l in 2006 to 4,100 mg/l in 2022 was the largest simulated increase at public-supply wells northeast of the reservoirs. An increase in sulfate concentration from 150 mg/l in 2024 to 340 mg/l in 2043 was the largest simulated increase at public-supply wells in the south-central Salt Lake Valley just east of the Jordan River.

Utah↗

USGS2014

Water movement through the unsaturated zone of the High Plains Aquifer in the Central Platte Natural Resources District, Nebraska, 2008-12

Uncertainty about the effects of land use and climate on water movement in the unsaturated zone and on groundwater recharge rates can lead to uncertainty in water budgets used for groundwater-flow models. To better understand these effects, a cooperative study between the U.S. Geological Survey and the Central Platte Natural Resources District was initiated in 2007 to determine field-based estimates of recharge rates in selected land-use areas of the Central Platte Natural Resources District in Nebraska. Measured total water potential and unsaturated-zone profiles of tritium, chloride, nitrate as nitrogen, and bromide, along with groundwater-age dates, were used to evaluate water movement in the unsaturated zone and groundwater recharge rates in the central Platte River study area. Eight study sites represented an east-west precipitation contrast across the study area—four beneath groundwater-irrigated cropland (sites 2, 5, and 6 were irrigated corn and site 7 was irrigated alfalfa/corn rotation), three beneath rangeland (sites 1, 4, and 8), and one beneath nonirrigated cropland, or dryland (site 3). Measurements of transient vertical gradients in total water potential indicated that periodic wetting fronts reached greater mean maximum depths beneath the irrigated sites than beneath the rangeland sites, in part, because of the presence of greater and constant antecedent moisture. Beneath the rangeland sites, greater temporal variation in antecedent moisture and total water potential existed and was, in part, likely a result of local precipitation and evapotranspiration. Moreover, greater variability was noticed in the total water potential profiles beneath the western sites than the corresponding eastern sites, which was attributed to less mean annual precipitation in the west. The depth of the peak post-bomb tritium concentration or the interface between the pre-bomb/post-bomb tritium, along with a tritium mass balance, within sampled soil profiles were used to estimate water fluxes in the unsaturated zone at three of the eight study sites: site 2 (irrigated), site 3 (dryland), and site 8 (rangeland). Estimates for recharge were about 68 millimeters per year [(mm/yr), post-bomb peak], 133 to 159 mm/yr (tritium interface), and 137 mm/yr (mass balance) at site 2 (irrigated); about 63 mm/yr (tritium interface) and 12 mm/yr (mass balance) at site 3 (dryland); and about 53 mm/yr (tritium interface) and 10 mm/yr (mass balance) at site 8 (rangeland). Recharge values from the mass balance at site 2 were more than an order of magnitude greater than recharge values at site 3, suggesting irrigation is an important control on water movement through the unsaturated zone. For the remaining five sites, the post-bomb tritium had flushed through the system and recharge was considered modern (within 10 years of sampling). The chloride mass-balance method was used to determine water fluxes below the root zone (less than 2 meters below land surface) at the rangeland sites: sites 1, 4, and 8. At these rangeland sites, water fluxes ranged from 1.8 to 96 mm/yr at site 1, 1.1 to 9.6 mm/yr at site 4, and 1.1 to 68 mm/yr at site 8, with mean rates of 21, 4.3, and 13 mm/yr, respectively. Site 1 had a greater mean water flux, which was consistent with the greater precipitation in the east than at site 8 in the west. Chloride mass balance was not calculated at the irrigated and dryland sites because of uncertainty about additional sources of chloride. Concentrations of nitrate as nitrogen in pore water in the unsaturated zone were larger beneath the irrigated and dryland (agricultural) sites compared with the rangeland sites. The larger concentrations at the agricultural sites are consistent with the application of nitrogen fertilizer at the agricultural sites and no substantial accumulation at the rangeland sites. The shape of the nitrate as nitrogen and chloride concentration profiles at site 1 (rangeland) indicate a reasonably larger and more consistent water flux in the UZ than beneath the other two rangeland sites (sites 4 or 8). Excluding site 7, the general shape of the nitrate as nitrogen profiles was similar beneath the agricultural sites and supports the estimates of water movement and recharge rates determined from the tritium and chloride methods. Movement of bromide through the unsaturated zone indicated greater water fluxes are found beneath irrigated lands than beneath rangeland. Bromide profiles in the unsaturated zone, determined from center of mass and peak displacement methods, document water fluxes ranged from 58 to 394 mm/yr beneath irrigated sites and 9 to 201 mm/yr beneath rangeland sites. Water-flux estimates from the potassium bromide tests at most sites did not represent overall recharge rates because the bromide remained primarily in the root zone. Apparent groundwater age was used to determine the groundwater residence time at the eight sites and to estimate recharge rates. Groundwater ages in the study area ranged from old water (defined here as groundwater that was recharged more than 50 years ago) to modern (defined here as groundwater that has recharged within the past 10 years). Groundwater ages indicated that the shallow monitoring wells generally had younger residence times, whereas the deeper monitoring wells generally had the older residence times. Groundwater dates from the shallowest monitoring wells were used to determine recharge rates at the water table. These rates generally were similar to recharge rates determined from tritium and chloride mass-balance methods. Groundwater recharge rates generally increased with well depth, and the deeper monitoring wells likely do not represent local recharge conditions but recharge from a regional flow system that receives recharge from distant sources. Overall, these data generally indicate that water movement within the unsaturated zone primarily is affected by spatial contrasts in mean annual precipitation and by the land use or land cover. The eight unsaturated-zone sites each generated unique, valuable datasets that likely will improve the understanding of water movement and recharge rates in the central Platte River valley.

Nebraska↗

USGS1977

Verification of a model for predicting the effect of inconstant temperature on embryonic development of lake whitefish (Coregonus clupeaformis)

Eggs stripped from lake whitefish (Coregonus clupeaformis) spawning in Lake Michigan were incubated in the laboratory at temperatures similar to those on whitefish spawning grounds in Lake Michigan during December-April. Observed times from fertilization to attainment of each of 21 developmental stages were used to test a model that predicts the rate of development at daily fluctuating temperatures; the model relates rate of development for any given stage j, expressed as the reciprocal of time (Rj), to temperature (T). The generalized equation for a developmental stage is Rj = abTcT??. Observed times agreed well (5.5% mean difference for all stages) with times predicted by the model; the observed time of 135 days from fertilization to hatching (stage 21) was only 5 days (3.7%) less than the predicted time of 140 days. The model was further verified by applying it to unpublished data supplied by the Ontario Ministry of Natural Resources, for eggs from Lake Huron whitefish incubated in the laboratory in untempered Lake Huron water. The model was used to predict the effects of small temperature increases (caused by a hypothetical waste-heat discharge) on the rate of development and time of hatching of lake whitefish eggs. According to this simulation, continuous addition of waste heat sufficient to raise the temperature 1, 2, or 3 C above ambient on the spawning grounds during December-April would advance the time of hatching 8, 16, or 21 days, respectively. Possible effects of this advancement on the reproductive success of whitefish are discussed.

Technical Paper↗

USGS2011

Structured decision making as a proactive approach to dealing with sea level rise in Florida

Sea level rise (SLR) projections along the coast of Florida present an enormous challenge for management and conservation over the long term. Decision makers need to recognize and adopt strategies to adapt to the potentially detrimental effects of SLR. Structured decision making (SDM) provides a rigorous framework for the management of natural resources. The aim of SDM is to identify decisions that are optimal with respect to management objectives and knowledge of the system. Most applications of SDM have assumed that the managed systems are governed by stationary processes. However, in the context of SLR it may be necessary to acknowledge that the processes underlying managed systems may be non-stationary, such that systems will be continuously changing. Therefore, SLR brings some unique considerations to the application of decision theory for natural resource management. In particular, SLR is expected to affect each of the components of SDM. For instance, management objectives may have to be reconsidered more frequently than under more stable conditions. The set of potential actions may also have to be adapted over time as conditions change. Models have to account for the non-stationarity of the modeled system processes. Each of the important sources of uncertainty in decision processes is expected to be exacerbated by SLR. We illustrate our ideas about adaptation of natural resource management to SLR by modeling a non-stationary system using a numerical example. We provide additional examples of an SDM approach for managing species that may be affected by SLR, with a focus on the endangered Florida manatee.

Florida↗

USGS2011

U.S. Geological Survey: A synopsis of Three-dimensional Modeling

The U.S. Geological Survey (USGS) is a multidisciplinary agency that provides assessments of natural resources (geological, hydrological, biological), the disturbances that affect those resources, and the disturbances that affect the built environment, natural landscapes, and human society. Until now, USGS map products have been generated and distributed primarily as 2-D maps, occasionally providing cross sections or overlays, but rarely allowing the ability to characterize and understand 3-D systems, how they change over time (4-D), and how they interact. And yet, technological advances in monitoring natural resources and the environment, the ever-increasing diversity of information needed for holistic assessments, and the intrinsic 3-D/4-D nature of the information obtained increases our need to generate, verify, analyze, interpret, confirm, store, and distribute its scientific information and products using 3-D/4-D visualization, analysis, modeling tools, and information frameworks. Today, USGS scientists use 3-D/4-D tools to (1) visualize and interpret geological information, (2) verify the data, and (3) verify their interpretations and models. 3-D/4-D visualization can be a powerful quality control tool in the analysis of large, multidimensional data sets. USGS scientists use 3-D/4-D technology for 3-D surface (i.e., 2.5-D) visualization as well as for 3-D volumetric analyses. Examples of geological mapping in 3-D include characterization of the subsurface for resource assessments, such as aquifer characterization in the central United States, and for input into process models, such as seismic hazards in the western United States.

Book chapter↗

USGS2023

Gulf Islands National Seashore regional sediment budget research and data needs—Workshop series summary

Executive Summary The National Park Service (NPS), in collaboration with the U.S. Geological Survey (USGS), recognizes the need to quantify the sediment budget of the barrier islands within the Gulf Islands National Seashore (GINS) to understand the coastal processes affecting island resiliency. To achieve this goal, identifying and quantifying the physical parameters that drive long-term change is necessary to model the processes that are both generative and terminal in island evolution and capture island response to long-term human alteration and climatic patterns. For example, measuring change across periods of storminess is more effective at assessing island resiliency than measuring change resulting from a single storm impact. Understanding changes to the physical environment over time is key to successfully predicting island responses to future storm impacts, human alteration, and sea-level rise and is necessary for effective decision making and management response. Yet, the diversity of factors affecting natural and cultural resources necessitates a strategic approach to data collection priorities that can inform sediment budget quantification and integrated resource management. This study sought to advance sediment budget modeling efforts by conducting a “Needs Assessment Workshop” at the GINS. The purpose of the workshop was to identify and prioritize the specific research and data needs regarding the sediment budget at the GINS that can enhance the NPS efforts to conserve the islands’ natural resources, cultural resources, and the facilities and infrastructure that support both conservation and visitor use of those resources. This effort explored two research questions: (1) “what research and data needs exist for the sediment budget at Gulf Islands National Seashore” (research question 1) and (2) “how can research to address these needs capitalize on regional partnerships to advance natural and cultural resource conservation at Gulf Islands National Seashore” (research question 2)? The workshop was conducted virtually in a two-part, two-day series. The workshop series was organized by researchers from North Carolina State University in collaboration with NPS and USGS staff and was facilitated by National Oceanographic and Atmospheric Administration staff. The workshop series (two paired, sequential, partial-day workshops) addressed two target audiences: (1) NPS and USGS staff (April workshop) and (2) regional Federal, State, county, and nongovernmental organization staff, including NPS and USGS staff (May workshop). A total of four workshop sessions were held, comprising two sessions with each target audience. The workshop series intended to identify sediment management research and data needs that could enhance natural and cultural resource stewardship at the GINS. One objective was to share information about regional sediment transport and management, available sediment management plans, and predictive modeling capabilities, including geomorphologic and hydrodynamic predictive models. This information was shared through a series of presentations by park managers and NPS and USGS researchers that identified park issues and available capabilities and data. The second objective was to elicit research and data needs, with a primary goal of assessing the importance and urgency of the identified needs. This assessment was partly determined by requesting that the workshop participants identify and prioritize research themes through polls, comments, and discussion. The polls explicitly asked participants to qualitatively evaluate the importance (not at all, slightly, somewhat, very, or extremely) and urgency (not at all, slightly, somewhat, very, or extremely) of the thematically grouped research and data needs. These evaluations were plotted and shared during the workshop to visualize how the relative importance ( x -axis) and relative urgency ( y -axis) of each “need,” relative to other needs, to identify the most necessary (importance) and time-sensitive (urgent) items, thereby allowing an enhanced, holistic understanding of the sediment budget at GINS. Results of the poll are published as a USGS data release. The assessment results revealed that the most important and urgent research and data needs included mapping (for example, elevation, habitat, and cultural resources), a regional sediment budget and management plan, and the dynamic modeling of sediment processes. During the workshop, these issues were visualized using scatter plots to demonstrate the relative importance and urgency of each theme, provide descriptive statistics, and elicit discussion. This format of iterative presentation, discussion, and prioritization allowed the project team to effectively accomplish their objective of identifying important and urgent research needs for natural and cultural resource stewardship at the GINS. Through the workshop, it was determined that expanded communication with the broader research community was needed to coordinate research activities and streamline potential funding opportunities and that research and policy should be integrated through a structured decision-making process. At the conclusion of the workshop, an administered poll showed that the presentations effectively identified data and research needs and that the goals of the workshop were achieved. The results suggest that this type of needs-assessment workshop can effectively identify existing research capabilities and data, determine and prioritize research and data needs, and address how these efforts can use regional partnerships to aid natural and cultural resource conservation and management at National Parks.

Florida, Mississippi↗

USGS2024

Matching decision support modeling frameworks to disease emergence stages and associated management objectives

Wildlife disease management decisions often require rapid responses to situations that are fraught with uncertainty. By recognizing that management is implemented to achieve specific objectives, resource managers and science partners can identify an analysis technique and develop a monitoring plan to evaluate management effectiveness. For emerging infectious diseases, objectives may take several distinct forms, dependent on the perceived stage of disease emergence (i.e., pre-epidemic, early outbreak, mid-epidemic, and endemic), the expected rate of spread, and the anticipated effect of the disease on host populations. Identifying modeling techniques and metrics that are linked to management objectives will require early and consistent communication between managers and science partners. We link modeling approaches that can be used to forecast and evaluate the performance of intervention strategies with a range of disease management objectives. Our aim is to help scientists recognize alternative modeling approaches which may better align with different forms of disease management objectives, and to help managers evaluate the relevance of proposed modeling approaches to their specified objectives for disease management. Recognizing that disease management objectives can take different forms, and thus require different modeling approaches, can help wildlife disease response teams (i.e., natural resource managers, scientists, and stakeholders working collaboratively) better prepare and respond to disease threats.

Conservation Science and Practice↗

USGS2023

Near surface sediments introduce low frequency noise into gravity models

3D geologic modeling and mapping often relies on gravity modeling to identify key geologic structures, such as basin depth, fault offset, or fault dip. Such gravity models generally assume either homogeneous or spatially uncorrelated densities within modeled rock bodies and overlying sediments, with average densities typically derived from surface and drill-hole sampling. The noise contributed to the gravity anomaly by these density assumptions is zero in the homogeneous case and typically <200 μGal in the uncorrelated case. Rock bodies and sediments, however, show both a range of densities and spatial correlation of these densities, in both surface and drill-hole samples, and this correlation causes an increase in power in the low frequency content of the resulting gravity anomaly. Spatial correlation of densities can be modeled as a Gaussian random field (GRF), with the random field parameters derived from drill-hole and geologic map data. Data from alluvial fan sediments in southern Nevada indicate correlation lengths of up to 300 m in the vertical dimension and kilometers in the horizontal dimension. The resulting GRF density models show that the noise contributed to the measured gravity anomaly is of low frequency and can be several mGal in amplitude, contradicting the common attribution of lower frequencies to deeper sources. This low-frequency noise increases in power with an increase in sediment thickness. Its presence increases the ambiguity of interpretations of subsurface geologic body shape, such as basin analyses that attempt to quantify concealed basement fault depths, offsets, and dip angles. In the southwestern United States, where basin analyses are important for natural resource applications, such ambiguity increases the uncertainty of subsequent process modeling.

Applied Computing and Geosciences↗

USGS2024

Mass-balance-consistent geological stock accounting: A new approach toward sustainable management of mineral resources

Global resource extraction raises concerns about environmental pressures and the security of mineral supply. Strategies to address these concerns depend on robust information on natural resource endowments, and on suitable methods to monitor and model their changes over time. However, current mineral resources and reserves reporting and accounting workflows are poorly suited for addressing mineral depletion or answering questions about the long-term sustainable supply. Our integrative review finds that the lack of a robust theoretical concept and framework for mass-balance (MB)-consistent geological stock accounting hinders systematic industry-government data integration, resource governance, and strategy development. We evaluate the existing literature on geological stock accounting, identify shortcomings of current monitoring of mine production, and outline a conceptual framework for MB-consistent system integration based on material flow analysis (MFA). Our synthesis shows that recent developments in Earth observation, geoinformation management, and sustainability reporting act as catalysts that make MB-consistent geological stock accounting increasingly feasible. We propose first steps for its implementation and anticipate that our perspective as “resource realists” will facilitate the integration of geological and anthropogenic material systems, help secure future mineral supply, and support the global sustainability transition.

Environmental Science and Technology↗

USGS2012

Mapping the potential distribution of the invasive Red Shiner, Cyprinella lutrensis (Teleostei: Cyprinidae) across waterways of the conterminous United States

Predicting the future spread of non-native aquatic species continues to be a high priority for natural resource managers striving to maintain biodiversity and ecosystem function. Modeling the potential distributions of alien aquatic species through spatially explicit mapping is an increasingly important tool for risk assessment and prediction. Habitat modeling also facilitates the identification of key environmental variables influencing species distributions. We modeled the potential distribution of an aggressive invasive minnow, the red shiner (Cyprinella lutrensis), in waterways of the conterminous United States using maximum entropy (Maxent). We used inventory records from the USGS Nonindigenous Aquatic Species Database, native records for C. lutrensis from museum collections, and a geographic information system of 20 raster climatic and environmental variables to produce a map of potential red shiner habitat. Summer climatic variables were the most important environmental predictors of C. lutrensis distribution, which was consistent with the high temperature tolerance of this species. Results from this study provide insights into the locations and environmental conditions in the US that are susceptible to red shiner invasion.

Aquatic Invasions↗

USGS2019

Constraining parameter uncertainty in modeling debris-flow initiation during the September 2013 Colorado Front Range storm

The occurrence of debris flows during the September 2013 northern Colorado floods took the emergency management community by surprise. The September 2013 debris flows in the Colorado Front Range initiated from shallow landslides in colluvium. Most occurred on south- and east-facing slopes on the walls of steep canyons in crystalline rocks and on sedimentary hogbacks. Previous studies showed that most debris flows occurred in areas of high storm-total rainfall and that strength added by tree roots accounts for the low number of landslides in densely forested areas. Given the lack of rainfall thresholds for debris flow occurrence in northern Colorado, we want to parameterize a numerical model to assess potential for debris flows in advance of heavy rainfall. Natural Resources Conservation Service (NRCS) soil mapping of the area, supplemented by laboratory testing and field measurements, indicates that soil textures and hydraulic properties of landslide source materials vary considerably over the study area. As a step toward modeling storm response, available soil and geologic mapping have been interpreted to define zones of relatively homogeneous properties. A new, simplified modeling approach for evaluating model input parameters in the context of slope and depth of observed debris flow source areas and recorded debris-flow inducing rainfall helps narrow the range of possible parameters to those most likely to produce model results consistent with observed debris flow initiation. Initial results have narrowed the strength parameters to about one third of possible combinations of cohesion and internal friction angle and narrowed hydraulic conductivity to a range spanning slightly more than one order of magnitude.

Colorado↗

USGS2016

Integrating remote sensing with species distribution models; Mapping tamarisk invasions using the Software for Assisted Habitat Modeling (SAHM)

Early detection of invasive plant species is vital for the management of natural resources and protection of ecosystem processes. The use of satellite remote sensing for mapping the distribution of invasive plants is becoming more common, however conventional imaging software and classification methods have been shown to be unreliable. In this study, we test and evaluate the use of five species distribution model techniques fit with satellite remote sensing data to map invasive tamarisk ( Tamarix spp.) along the Arkansas River in Southeastern Colorado. The models tested included boosted regression trees (BRT), Random Forest (RF), multivariate adaptive regression splines (MARS), generalized linear model (GLM), and Maxent. These analyses were conducted using a newly developed software package called the Software for Assisted Habitat Modeling (SAHM). All models were trained with 499 presence points, 10,000 pseudo-absence points, and predictor variables acquired from the Landsat 5 Thematic Mapper (TM) sensor over an eight-month period to distinguish tamarisk from native riparian vegetation using detection of phenological differences. From the Landsat scenes, we used individual bands and calculated Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), and tasseled capped transformations. All five models identified current tamarisk distribution on the landscape successfully based on threshold independent and threshold dependent evaluation metrics with independent location data. To account for model specific differences, we produced an ensemble of all five models with map output highlighting areas of agreement and areas of uncertainty. Our results demonstrate the usefulness of species distribution models in analyzing remotely sensed data and the utility of ensemble mapping, and showcase the capability of SAHM in pre-processing and executing multiple complex models.

Journal of Visualized Experiments↗

USGS2020

Integrated hydro-terrestrial modeling: Development of a national capability

Water is one of our most important natural resources and is essential to our national economy and security. Multiple federal government agencies have mission elements that address national needs related to water. Each water-related agency champions a unique science and/or operational mission focused on advancing a portion of the nation’s ability to meet our water-related challenges, often in close collaboration with scientists from the academic community. These diverse mission needs have engendered a rich and extensive base of water-related data and modeling capabilities. While useful for their intended purposes, these capabilities are not well integrated to address complex regional problems and overarching national problems. These major investments by several federal agencies and their scientific partners, however, lay the foundation for an integrated hydro-terrestrial modeling and data infrastructure that will enhance knowledge, understanding, prediction, and management of the nation’s diverse water challenges.

Report↗

USGS2006

Simulation of nutrient and sediment concentrations and loads in the Delaware inland bays watershed: Extension of the hydrologic and water-quality model to ungaged segments

Rapid population increases, agriculture, and industrial practices have been identified as important sources of excessive nutrients and sediments in the Delaware Inland Bays watershed. The amount and effect of excessive nutrients and sediments in the Inland Bays watershed have been well documented by the Delaware Geological Survey, the Delaware Department of Natural Resources and Environmental Control, the U.S. Environmental Protection Agency’s National Estuary Program, the Delaware Center for Inland Bays, the University of Delaware, and other agencies. This documentation and data previously were used to develop a hydrologic and water-quality model of the Delaware Inland Bays watershed to simulate nutrients and sediment concentrations and loads, and to calibrate the model by comparing concentrations and streamflow data at six stations in the watershed over a limited period of time (October 1998 through April 2000). Although the model predictions of nutrient and sediment concentrations for the calibrated segments were fairly accurate, the predictions for the 28 ungaged segments located near tidal areas, where stream data were not available, were above the range of values measured in the area. The cooperative study established in 2000 by the Delaware Department of Natural Resources and Environmental Control, the Delaware Geological Survey, and the U.S. Geological Survey was extended to evaluate the model predictions in ungaged segments and to ensure that the model, developed as a planning and management tool, could accurately predict nutrient and sediment concentrations within the measured range of values in the area. The evaluation of the predictions was limited to the period of calibration (1999) of the 2003 model. To develop estimates on ungaged watersheds, parameter values from calibrated segments are transferred to the ungaged segments; however, accurate predictions are unlikely where parameter transference is subject to error. The unexpected nutrient and sediment concentrations simulated with the 2003 model were likely the result of inappropriate criteria for the transference of parameter values. From a model-simulation perspective, it is a common practice to transfer parameter values based on the similarity of soils or the similarity of land-use proportions between segments. For the Inland Bays model, the similarity of soils between segments was used as the basis to transfer parameter values. An alternative approach, which is documented in this report, is based on the similarity of the spatial distribution of the land use between segments and the similarity of land-use proportions, as these can be important factors for the transference of parameter values in lumped models. Previous work determined that the difference in the variation of runoff due to various spatial distributions of land use within a watershed can cause substantialloss of accuracy in the model predictions. The incorporation of the spatial distribution of land use to transfer parameter values from calibrated to uncalibrated segments provided more consistent and rational predictions of flow, especially during the summer, and consequently, predictions of lower nutrient concentrations during the same period. For the segments where the similarity of spatial distribution of land use was not clearly established with a calibrated segment, the similarity of the location of the most impervious areas was also used as a criterion for the transference of parameter values. The model predictions from the 28 ungaged segments were verified through comparison with measured in-stream concentrations from local and nearby streams provided by the Delaware Department of Natural Resources and Environmental Control. Model results indicated that the predicted edge-of-stream total suspended solids loads in the Inland Bays watershed were low in comparison to loads reported for the Eastern Shore of Maryland from the Chesapeake Bay watershed model. The flatness of the terrain and the low annual surface runoff are important factors in determining the amount of detached sediment from the land that is delivered to streams. The highest predicted total suspended solids loads were found in the southern part of the watershed, where the values are associated with high total streamflow and a high surface-runoff component, and related to soil and aquifer permeability and land use. Nutrient loads from model segments in the southern part of the Inland Bays watershed were also higher than those measured in the northern part of the basin, due to relatively high runoff and the substantial amount of available organic fertilizer (animal waste) that results in over-application of organic fertilizer to crops. Time series of simulated hourly concentrations indicated a seasonal pattern in the simulated base flow for total nitrogen, with the lowest values occurring during the summer and the highest values during the winter months. Total phosphorus and total-suspended-solids concentrations were less seasonal and were more storm-dependent; in general, base-flow concentrations of total phosphorus and total suspended solids were low. During storm events, the total nitrogen concentrations tended to be diluted and total phosphorus concentrations tended to rise sharply. Nitrogen was transported mainly in the aqueous phase and largely through ground water, whereas phosphorus was strongly associated with sediment, which washes off during rainfall events.

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