Geology topics

Research about United States

Source-linked reports with geographic coverage including United States.

At least 73 records · Page 4Linked to original sources

USGS2026

Tracking water in snow: Bridging sensor and and model simulations

Forecasting wet slab avalanches remains one of the most demanding challenges in operational avalanche forecasting. A key obstacle is the difficulty of observing and quantifying liquid water content (LWC) and tracking its infiltration into the snowpack. Field measurements are labor-intensive, highly variable in space, and often influenced by user application or sensor design — making them impractical for forecasting operations. In this study, we evaluated LWC measurements obtained from two capacitive sensors, the SLF SnowPro-17 and -25, and compared them with simulations from the snow cover model SNOWPACK. We analyzed five selected days with pronounced melt events during spring 2025 at Bridger Bowl Ski Area, Montana. The SnowPro-17 measured LWC on the sidewall and the SnowPro-25 was inserted into the pit wall. We then analyzed measurements from the two sensors to assess consistency and potential bias. For each of the five days, we also analyzed liquid water infiltration by layer, comparing field measurements with model-simulated LWC. This allowed us to assess how well the model captured both the timing and magnitude of infiltration processes relative to in-situ observations. Our results show that, the absolute LWC values differ by approximately 1% by vol. on average between measurements from the capacitive sensors, but the timing of liquid water infiltration is largely consistent across both measurements and model simulations. Within our sample, the SnowPro-17 consistently reports higher mean LWC values than the SnowPro-25, and exhibits greater variability, indicated by a larger standard deviation. We found good agreement when we compared in-situ sensor measurements to LWC infiltration in snow cover model simulations. This suggests that, despite measurement challenges and sensor variability, SNOWPACK can provide valuable information on the timing of LWC infiltration. For practitioners, this work highlights that reliable forecasting of wet slab avalanches depends on understanding when and how liquid water reaches critical layers. Because direct LWC measurements are rarely feasible in operational settings, using physically based models may offer a practical pathway forward.

Montana↗

USGS2026

Applying automated avalanche terrain mapping to wildlife ecology: A case study of Dall's sheep in southcentral Alaska

Avalanche hazard has been studied extensively in the context of human risk, but its role in alpine wildlife ecology remains poorly understood. Long-term telemetry studies have revealed that avalanches are an important source of mortality for some mountain ungulates. Investigating the processes underlying these events is challenging because avalanche activity and snowpack conditions are rarely monitored across the spatial and temporal extent of wildlife studies. Recent advances in automated avalanche terrain mapping provide a new opportunity to address this knowledge gap by quantifying wildlife exposure to modeled avalanche terrain across large landscapes. We demonstrate this application using Dall's sheep (Ovis dalli dalli) in southcentral Alaska, where a 12-year study identified avalanches as the leading known cause of adult mortality. We used GPS locations from 134 adult Dall's sheep (385 sheep-years) collected between 2012 and 2024 across Chugach State Park and the Talkeetna Mountains, Alaska, USA. We characterized seasonal patterns of terrain exposure using the Automated Avalanche Terrain Exposure Scale and complementary metrics representing potential release areas, runout terrain, slope, and aspect. Guided by previous studies of Dall's sheep habitat selection, we developed a priori ecological expectations for seasonal exposure and used descriptive summaries of GPS locations to examine patterns of sheep use. Sheep locations occurred almost exclusively within avalanche terrain throughout the year, with Complex terrain accounting for 61–67% of locations across seasons. Winter and spring locations occurred on slightly steeper slopes while simultaneously having lower potential release area values and lower-value runout terrain than summer and autumn locations. Use of south-facing terrain increased from 64% of locations in summer to 70% in autumn and winter and 83% in spring—coinciding with the highest seasonal concentration of avalanche mortality. These descriptive patterns illustrate how complementary avalanche-terrain metrics can reveal patterns of wildlife exposure that would not be apparent from slope angle and aspect alone. Integrating automated avalanche terrain mapping with wildlife telemetry provides a new approach for identifying patterns of terrain exposure to guide further investigation into factors influencing wildlife avalanche risk.

Alaska↗

USGS2026

Climate-driven shifts in snowpack conditions favorable for wet snow avalanches: Insights from snow cover model simulations

Forecasting wet snow avalanches remains a major challenge due to their temporal and spatial variability. Long-term climate trends are producing more variable and extreme weather, creating conditions outside historical experience, and increasing forecasting uncertainties. To assess how climate change affects the frequency and timing of wet snow avalanches, we examined the long-term conditions that support wet snow formation. Specifically, we ask: Will the onset of wet snow avalanche conditions or season end shift toward the mid century? And will maximum snow height decrease in avalanche starting zones? To address these questions, we analyze long-term snow cover simulations across our study site in Glacier National Park, Montana, located in an intermountain snow climate. We examined trends in simulated snow depth, and timing of liquid water infiltration over the past four decades (1979–2023) using a physically based snow cover model. To force the model with meteorological data, we use the long-term regional hydroclimate reanalysis dataset U.S. Geological Survey CONUS404 with 4 km spatial resolution and 1h temporal resolution. The use of gridded meteorological inputs to drive a one-dimensional point model introduces inherent scale mismatches. To address this limitation, we use multiple grid points within the study area to simulate a more representative, generalized snowpack, and filter the grid points based on elevation to distinguish between upper- and mid-elevation starting zones. Finally, we analyzed shifts in snow depth, melt-out-day, and LWCindex (bulk liquid water content (LWC) normalized by the residual water content). We use snow depth as a proxy for changes in slab thickness, the LWCindexas an indicator of wet snow avalanche conditions, and melt-out date as a measure of shifts in season length. We ran simulations on flat terrain and on north- and south-facing virtual slopes (38°), across mid-elevation (1,600–1,900 m) and upper-elevation (≥1,900 m) sites for the historical dataset as baseline and a Pseudo-Global-Warming (PGW) dataset to identify a warming driven shift. Across all aspects and both elevation bands, PGW forcing produces a consistent reduction in annual maximum snow depth (median shift −0.15 to −0.26 m, p<0.001) over 44 seasons, with the largest reductions on north-facing slopes and a modest but significant strengthening of this reduction over the 44-year simulated record. Melt-out starts 10–14 days earlier under PGW across all aspect–elevation combinations (p<0.001), again most pronounced on north-facing, higher-elevation terrain. The LWCindex threshold-crossing dates likewise shift earlier under PGW, indicating an earlier onset of wet snow avalanche conditions across the domain. Together, these results point to a snowpack that is both thinner and wetter earlier in the season under future warming, with the strongest signal consistently on north-facing slopes at higher elevation. This work lays the groundwork for climate-informed forecasting and mitigation and offers historical context for avalanche operations in a changing climate. Understanding long-term trends can help avalanche professionals interpret current observations, improve wet snow avalanche forecasting, and develop more effective mitigation strategies in a warming climate.

Montana↗

USGS2026

Flood-inundation maps for Río Grande de Arecibo in and near Utuado Municipio, Puerto Rico, 2026

The U.S. Geological Survey (USGS) created digital flood-inundation maps for a 3.4-mile reach of Río Grande de Arecibo in the municipality of Utuado Municipio, Puerto Rico. Water-surface profiles were computed for the stream reach by using a one-dimensional, steady-state, step-backwater model. This model was calibrated to the current (2026) stage-streamflow relation (rating curve number 11.0) for the USGS streamgage 50024950, Río Grande de Arecibo below Utuado, Puerto Rico. The resulting hydraulic model was used to compute 11 water-surface profiles for water levels (flood stages) ranging from 14.00 to 34.00 feet at the streamgage and ranging from what are referred to as “minor flood stage” to above “major flood stage,” as reported by the National Weather Service. The 34.00-foot stage exceeds the peak stage (32.92 feet) recorded at this streamgage in 1998. The simulated water-surface profiles were used in combination with a digital elevation model derived from lidar data to map the inundated areas associated with each flood profile. The flood-inundation maps and the supporting hydraulic model produced by this study can be used by emergency managers and local officials to define flood hazard areas and assess flood mitigation strategies to help protect life and property, to coordinate flood response activities such as evacuations and road closures, and to aid post-flood recovery efforts. Information about map limitations, associated uncertainties, and how to view the maps and access the associated data online is included in this report.

Puerto Rico↗

USGS2026

Considerations for using autonomous recording units to monitor northern bobwhite occupancy at large spatial scales

Northern bobwhites ( Colinus virginianus ) have experienced widespread declines across their range, increasing the need for population monitoring across broad spatial and temporal scales. Yet large-scale monitoring of post-breeding bobwhites remains limited by the time-intensive nature of fall (i.e., autumn) covey counts. Passive acoustic monitoring with autonomous recording units (ARUs) and automatic detection software may help overcome these constraints but requires further study. From 2017 to 2021, we paired in-person observer point counts with ARU surveys during the fall in southern Iowa, USA to 1) evaluate how ARU detections compare to observer detections, 2) assess the accuracy of automatic classification software for covey calls, 3) gauge the influence of weather and ordinal date on detection, and 4) offer best practices for processing ARU acoustic data. We found high correspondence (89.2%) in detection and non-detection outcomes between paired ARU and observer surveys. Across manually processed recordings, 95.7% of covey call detections occurred within a 35-min window (50–15 min before sunrise). Increasing wind speed and cloud cover were associated with reduced detection probabilities. Wind speeds ≥5 m/s resulted in detection probabilities <0.5. The cumulative probability of detecting bobwhites at a site exceeded 0.995 (95% Credible Interval [CrI] = 0.987, 0.999) after 4 survey days when technicians processed the files. Manual processing had the highest mean detection probability (0.75, 95% CrI = 0.66, 0.82) compared with automatic detection software with 2 different confidence thresholds (0.46 [95% CrI = 0.39, 0.53] and 0.45 [95% CrI = 0.36, 0.55]). Automatic detection software allowed for substantially faster processing with relatively few false positives (false positive rate of 0.014 to 0.038). Autonomous recording units coupled with automatic detection software provided a promising alternative to in-person observer point counts of bobwhite covey calls for determining site occupancy and have the potential to greatly increase capacity for landscape-level bobwhite monitoring.

Iowa↗

USGS2026

First application of a coastal-dune model (AeoLiS) to simulate fluvial-aeolian morphodynamics

Quantifying aeolian processes is important to decision-making in river management and for optimizing strategies for ecosystem conservation, natural resource management, and recreation. We applied the AeoLiS aeolian transport model, originally developed for coastal environments, to a dryland river corridor to evaluate its ability to simulate sediment dynamics in a fluvial-aeolian system. The model reproduced spatial and temporal patterns of geomorphic change at a Grand Canyon sandbar, including aeolian dune formation, observed in field data. The model effectively captured trends in observed sediment movement in the spring and summer months. Thus, despite assuming a single grain-size, static vegetation, and not directly accounting for variable sediment supply from fluvial sources, the model performs well at capturing aeolian processes in a complex fluvial-aeolian system. AeoLiS demonstrates strong potential for dryland river applications and management, due to its flexibility and compatibility with coupled modeling frameworks.

Arizona↗

USGS2026

Niobium-bearing minerals from the Sheep Creek carbonatite-related deposits of southwest Montana, USA

The Sheep Creek area in southwest Montana contains a number of small, tabular, carbonatite-related deposits that are rich in Nb and REE minerals. Nb-rich minerals from Sheep Creek and nearby Woods Creek are herein described in detail. The carbonatite veins contain a mix of calcite and Fe-bearing dolomite, with locally abundant apatite, baryte, celsian, actinolite, phlogopite, monazite-(Ce), and allanite-(Ce). Nb-bearing minerals include columbite-(Fe), aeschynite-(Ce), baotite, niobobaotite, chevkinite, fergusonite-(Nd), and two varieties of Ti-Nb-Fe-oxide. An early oxide with Ti/Nb (atomic) near unity later broke down to a fine-grained mixture of columbite + rutile with distinctly lower Nb content. The earlier oxide is tentatively identified as a rare variety of Nb-rich brookite. In both oxide phases, pentavalent Nb entered the TiO 2 structure in coupled substitution with a mixture of Fe 3+ and Fe 2+ . A single zircon crystal intergrown with the Nb-REE minerals was dated by in situ U-Pb methods to 111.6 ± 2 Ma. This age is in agreement with previous dating of monazite (Th-Pb) and molybdenite (Re-Os), and supports the idea that the Sheep Creek deposits are Cretaceous in age.

Montana↗

USGS2026

Elemental and isotope geochemistry of Smackover Formation brines in Alabama and Arkansas: Implications for fluid mixing and water-rock interaction

This study investigates the geochemical characteristics of brines within the Upper Jurassic Smackover Formation in Alabama and Arkansas through elemental and isotopic analyses and geochemical modeling to reveal the extent and nature of fluid mixing and water-rock interactions. Smackover Formation brines exhibit Na-Cl-Ca hydrogeochemical facies and sulfate depletion relative to seawater. Lower sulfate concentrations, coupled with high H 2 S concentrations in some brines (0-364 mg/L) at temperatures >80°C, suggest that thermochemical sulfate reduction occurred. Cl/Br and Na/Br ratios indicate that salinity was controlled by the mixing of meteoric water with evaporated seawater that had reached halite saturation, rather than by halite dissolution. The δ 18 O and δ 2 H values of the brines also suggest mixing between meteoric water and evaporated seawater that had reached gypsum and halite saturation. Geochemical modeling of seawater evaporation predicts a Cl-Na or Cl-Mg facies after halite saturation, contrasting with the observed Cl-Ca dominance of the Smackover Formation brines. The Ca-enriched brines may have evolved from Cl-Mg-dominated evaporated seawater through dolomitization of limestone. The 87 Sr/ 86 Sr ratios range from 0.70740 to 0.71048, higher than the average of Jurassic seawater (0.707). The non-linear relationship between 87 Sr/ 86 Sr and 1000/Sr suggests alteration of brine geochemistry by fluid mixing or by inputs from Sr and 87 Sr-enriched rock sources. Lithium concentrations are positively correlated with 87 Sr/ 86 Sr ratios and TDS in brines enriched in these constituents. These correlations suggest deeper-seated geogenic sources and have implications for Li exploration in the northern Gulf Coast basin. Normal faults associated with the pre-Jurassic topography may have provided potential pathways for brine migration into the Smackover Formation under the influence of overpressure or thermohaline convection in the Gulf Coast.

Alabama↗

USGS2026

Predictability creates vulnerability: Long-term acoustic telemetry reveals hidden threat windows for endangered Atlantic sturgeon

1.Individual movement strategies govern access to important habitats but can expose certain animals to spatially and temporally variable threats, producing consistent, phenotype-specific differences in risk. For endangered Atlantic sturgeon ( Acipenser oxyrinchu s), migration timing shapes exposure risk to vessel strikes, dredging activity, and shifting estuarine conditions, yet management to minimize exposure to these threats is predominantly based on population-average patterns of river occupancy. 2. We analysed a decade of acoustic telemetry data from 195 Atlantic sturgeon in the Hudson River to quantify individual variation in migration timing. We clustered individuals into distinct behavioural phenotypes and evaluated the consistency of these phenotypes across years to determine whether certain individuals may be present in spatiotemporal areas that are not represented in current conservation frameworks. 3. Results identified two persistent phenotypes: the short-residency phenotype exhibiting synchronized occupancy typical of the prescribed Atlantic sturgeon spawning run and an extended-residency group that migrates into the river later, displays prolonged river occupancy and diffuse outmigration into the fall. Extended-residency individuals were last detected approximately 88 days after short-residency individuals and occupied habitats downriver of the presumed spawning grounds, extending the period of sturgeon presence into riverine habitats outside the current spatiotemporal area of conservation focus. 4. Individual phenotypic membership was repeatable across nearly a decade, indicating that these behaviours reflect stable, consistent phenotypes rather than stochastic variation. 5. Synthesis and applications . Our results reveal persistent intrapopulation movement diversity in the largest remaining Atlantic sturgeon population and highlight predictable periods during which a unique phenotype may experience disproportionate exposure to in-river threats. These findings indicate that environmental reviews, permitting decisions and seasonal work windows may benefit from incorporating phenotype-specific occupancy patterns and percentile-based estimates of river residency rather than relying solely on historical spawning dates or population averages. Expanding telemetry and monitoring designs to include broader spatial and seasonal sampling may further improve detection of overlooked movement strategies and reduce potential biases in demographic and habitat use assessments. More broadly, recognizing behavioural diversity in recovery planning may provide a more complete basis for evaluating habitat use, threat exposure, and conservation priorities across sturgeon populations.

New York↗

USGS2026

Does wind disrupt overwintering monarch butterfly clusters? An observational study of western monarchs

Wind protection is a central focus of western monarch butterfly ( Danaus plexippus ) overwintering habitat conservation. The Wind Disruption Hypothesis guiding management decisions predicts that winds at or above 2 m/s disrupt clusters and that cluster abundance decreases as wind speed increases. At two California groves during the 2023–2024 overwintering season, we paired time-lapse estimates of visible cluster size with nearby measurements of maximum wind gust. Stronger gusts were not consistently followed by decreases over 30-min or next-day response windows. In the 30-min analysis, the wind association depended on approximate local temperature and whether visible butterflies were in direct sunlight. Stronger gusts were associated with declines under cool, sunny conditions and increases under warm, sunny conditions. No clear wind association was detected when no visible butterflies were in direct sunlight. The next-day analysis likewise indicated that the wind association varied with sun exposure. Nearby maximum gusts did not measure sustained exposure at butterfly positions, so this was not an exact test of the historical threshold. The results did not support the predicted consistent decline with increasing wind under the monitored conditions. Physiological responses to interacting wind, ambient temperature, and solar exposure offer a plausible hypothesis for future research.

California↗

USGS2026

Inverse modeling for post-wildfire hydrologic process understanding over snow-dominated watersheds

Wildfire-induced changes to vegetation and soil properties can alter snowpack dynamics and hydrologic processes in ways that complicate predictions of post-wildfire water availability. To better understand these effects, we coupled the Parameter ESTimation in C++ (PEST++) software with the Weather Research & Forecasting Hydrologic model (WRF-Hydro) across three burned, snow-dominated watersheds in the western United States. We incorporated three burn-severity-based land cover categories into WRF-Hydro and used an iterative Ensemble Smoother (iES) within PEST++ to estimate model parameters controlling snow accumulation and melt, infiltration, and streamflow generation. This framework supported three complementary objectives: (1) assessing parameter sensitivities under pre- and post-wildfire conditions, (2) comparing pre- and post-wildfire parameter ensembles to identify wildfire-driven shifts in hydrologic processes, and (3) using counterfactual simulations to isolate the hydrologic response to wildfire from interannual climate variability. Our findings indicate that model parameter sensitivity varied by domain and shifted following wildfire. Maximum snow albedo and snow albedo decay were most influential in the higher-elevation East Troublesome domain, while the rain-snow partitioning temperature threshold dominated in the lower-elevation Chippy Creek and Las Conchas domains. Following wildfire, streamflow sensitivity shifted away from snowpack parameters toward soil hydraulic parameters, consistent with wildfire-driven reductions in evapotranspiration and increases in soil moisture. Incorporating wildfire effects led to complex changes in simulated snowpack accumulation and streamflow timing, generally leading to earlier snowmelt freshet initiation and cessation and reduced late season flows. Simulations were more sensitive to interannual climate variations than wildfire land cover changes. These results highlight both the potential and challenges of ensemble-based inverse modeling for understanding post-wildfire hydrologic change in snow-dominated watersheds.

Colorado, Montana, New Mexico↗

USGS2026

Abrupt onset and persistent downstream effects of acid rock drainage on rivers across northwest Arctic Alaska

Arctic streams and rivers are increasingly vulnerable to degradation from permafrost thaw that releases toxic elements via natural acid rock drainage. However, the spatial and temporal evolution of acid rock drainage on river chemistry across diverse mineral settings remain poorly constrained. Here, water chemistry in six watersheds across Alaska's Brooks Range (2022–2024) quantified the effects of acid rock drainage on river chemistry. Point-source acid rock drainage inputs (seeps and impaired tributaries) exhibited lower pH (median; pH: 3.2 and 6.9, respectively), higher sulfate (SO 4 2− : 3,025 and 390 mg L −1 , respectively), and elevated major and trace element concentrations (sum of 23 metals: 451 and 9.2 mg L −1 , respectively), compared to upstream unimpaired mainstem rivers (pH = 8.3, SO 4 2− = 68 mg L −1 ; metals = 0.1 mg L −1 ). Across watersheds, these inputs increased mainstem concentrations of major and trace elements (e.g., Fe, Al, Mn, Zn, Ni, Cd, and rare earth elements) and SO 4 2− ; however, mainstem river pH remained stable due to sufficient buffering. Within the Salmon River, concentrations of filter-passing and particulate fractions of constituents (SO 4 2− , Fe, Zn, Ni, and Cd) were elevated ≤70-fold at >100 km downstream of acidic inputs, documenting long-range transport. Temporal analyses of SO 4 2− and Zn concentration (2015–2024) revealed abrupt increases (≤263%) in two watersheds between 2019 and 2020, aligning with antecedent record warm and snowy winter conditions. Collectively, our results document the abrupt onset of acid rock drainage across Arctic rivers with potential for long-range downstream transport and implications for biogeochemical cycles and ecological and human health.

Alaska↗

USGS2026

Barrier island geomorphic complexity drives storm and post-storm response

Barrier islands are at the forefront of climate-driven changes, with their resiliency threatened by rapid fluctuations in the physical drivers that shape them. Quantifying magnitudes and directions of storm-driven sediment fluxes and rates and modes of sediment recovery is essential for predicting barrier island trajectories. Yet scarce shoreface observations have limited such efforts. Here, shoreface-inclusive measurements of barrier sediment fluxes over five years following an extreme storm reveal distinct sediment redistribution patterns that vary with island geomorphology. Overwash fluxes were low compared with seaward fluxes, inlet-related landward transport, and previously modeled estimates. Without these observations, models may overestimate island elevation-building capacity that is key to sea-level adaptability. Post-storm recovery was incomplete despite human intervention, altering barrier sediment distribution from pre-storm conditions. This may increase vulnerability to future storms and rising water levels and suggests management approaches tailored to island geometry may better compete with climate change effects.

New York↗

USGS2026

Magnitude and frequency of urban floods in Alabama and Mississippi using data through the 2024 water year

To improve flood-frequency estimates for urban streams in Alabama and Mississippi, the U.S Geological Survey, in cooperation with the Alabama and Mississippi Departments of Transportation, estimated streamflows corresponding to selected annual exceedance probabilities (AEPs) for 64 streamgages on urban streams in the two States—48 in Alabama and 16 in Mississippi. Using estimates from 42 of the 64 streamgages, regression equations were developed that can be used to predict streamflows corresponding to the selected AEPs at ungaged locations on urban streams. Annual peak-flow data through September 2024 were used in the at-site flood-frequency analyses. Drainage area and the percentage of developed land use in the drainage basins of the streamgages (from the 2011 National Land Cover Database) were identified as statistically significant explanatory variables. Pseudo coefficient of determination (pseudo-R2) values ranged from 81 percent for the 0.2-percent AEP (500-year flood) to 91 percent for the 4- and 2-percent AEPs (25- and 50-year floods, respectively). Standard errors of prediction ranged from 23.1 percent for the 4-percent AEP (25-year flood) to 36.1 percent for the 2-percent AEP (500-year flood).

Alabama, Mississippi↗

USGS2026

Trends and seasonal patterns of nitrogen and phosphorus concentrations and loads in two Mississippi Alluvial Plain watersheds following nutrient reduction efforts during 2010–22

The Mississippi Alluvial Plain ecoregion in Mississippi was historically part of the largest continuous wetland in North America but was clearcut and converted to row crop agriculture beginning in the late 1800s. To reduce the effects of agriculture on surface waters in the Mississippi Alluvial Plain, nutrient reduction best management practices have been implemented throughout the region, particularly in two small watersheds: Harris Bayou watershed (174.04 square kilometers) and Porter Bayou watershed (267.15 square kilometers). Since 2009, the U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, has collected water-quality samples monthly and during high-flow runoff events, at three locations within each watershed to monitor and assess nutrient trends following best management practice implementation. Here, we have analyzed long-term and seasonal trends in discharge, total nitrogen (TN), and total phosphorus (TP) concentrations and loads using a combination of quantile-Kendall analysis, quantile regression, generalized additive models, and weighted regression on time, discharge, and season. In Harris Bayou watershed, discharge values at a ~0.4–0.5 daily nonexceedance probability increased by 15 percent per year at the uppermost monitoring site. Additionally, TN concentrations decreased throughout the watershed over time, particularly in the spring and winter months. Reductions in TP were less apparent and only observed at one sampling location in Harris Bayou watershed. Nutrient concentrations in Porter Bayou watershed remained consistent over time and increased at one sampling location. However, despite discrepancies in concentration trends, flow-normalized TN and TP loads consistently decreased over time in both watersheds. At the mouth of both watersheds, peak TN and TP loads decreased between 37.7 and 56.9 percent. Collectively, these results provide evidence that best management practices may help reduce the effect of agricultural practices in the region, particularly in Harris Bayou watershed. Additionally, management efforts resulted in greater reductions in TN concentrations than in TP concentrations.

Mississippi↗

USGS2026

Streamflow, water quality, and energy development characteristics and water-quality trends for selected sites in the Green River and Muddy Creek drainage basins, southwestern Wyoming, water years 2006–16

Energy resource development in southwestern Wyoming has been rapidly expanding since the early 2000s to include innovative technologies for extracting oil and gas and enhancing renewable energy. In response to concerns about the potential negative effects of energy development on natural resources, the Wyoming Landscape Conservation Initiative was created to implement a long-term, science-based program of assessing, conserving, and enhancing fish and wildlife habitats while facilitating responsible energy development through local collaborations and partnerships. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, began monitoring streamflow and water quality as part of this initiative in 2006 at four U.S. Geological Survey streamgages within the Green River and Muddy Creek drainage basins to characterize the effects of energy development on streamflow and water quality in these areas. To quantify changes in water quality metrics, trend analyses for the 2006–16 water years were calculated and related to drainage basin characteristics including energy development (wells per square mile). Effects of energy development on water quality varied by watershed and the variability was driven primarily by the runoff efficiency and the geochemistry of the drainage basin. The New Fork River water chemistry was a calcium-bicarbonate type with low ionic strength and showed no statistically significant trends in water quality despite increased energy development. The Green River experienced moderate energy development, with significant upward trends in magnesium and alkalinity, indicating low sensitivity to development. Muddy Creek near Dad had minimal energy development and complex hydrogeochemical characteristics, showing mixed trends in water quality constituents. Muddy Creek near Baggs experienced moderate energy development, with significant upward trends in several water quality indicators indicating a response to the land disturbance associated with development. Overall, geochemistry and runoff efficiency influenced the vulnerability of water quality to energy development activities, highlighting the importance of drainage basin physical characteristics on vulnerability to development.

Wyoming↗

USGS2026

Remote detection of streambank erosion and channel incision using high-resolution, repeat lidar-derived metrics in Raleigh, North Carolina

This study evaluated the use of lidar data to detect streambank erosion and channel incision throughout Raleigh, North Carolina. The study included five components. (1) Generation of lidar-derived rasters, including a digital elevation model of difference that represented channel erosion and positive openness rasters that represented channel incision. (2) Completion of site-based field assessments throughout the study area. (3) Spatial analysis of raster datasets at three spatial scales: erosion patches, channel segments, and subbasins. (4) Comparison of field assessment results with lidar-derived metrics. (5) Pairing of landscape attributes with lidar-derived metrics to evaluate potential causative factors associated with variations in channel incision. Field assessment results indicated 74% of surveyed sites had Bank Erosion Hazard Index ratings ranging from ‘high’ to ‘extreme’ and 77% had ‘high’ or ‘severe’ degrees of channel incision. Select field measures showed agreement with lidar-derived metrics. Lidar-derived erosion patches, ranging in size from 20 to 948 m 2 , were detected in 24.3% of channel segments, and patch density increased with Strahler stream order. Channel segments, ranging from 50 to 150 m, had inconsistent spatial patterns of erosion and incision. Erosion in channel segments increased with Strahler stream order and 36% of channel segments became more incised during the study period. Lidar-derived metrics across subbasins revealed variability of erosion and incision throughout the study area. The assessment of landscape drivers could not explain variability at the channel-segment scale, but subbasins with fewer forests tended to have greater erosion and incision. However, unexplained variability remained, demonstrating the complexity of stream stability in urban watersheds. As lidar datasets become more widespread, pairing remote data with field assessments may be a viable approach to characterize and understand stream geomorphology in urban settings.

North Carolina↗

USGS2026

Effect of land-use change and climate on coral calcification and geochemistry: A 253-year time series from west Maui

Land-use change and climate variability both regulate land-based inputs of sediment and nutrient delivery to coral reefs, yet few records in Hawaii can identify when these land-based inputs began or how they have evolved through time. We present a 253-year (1760–2013) coral core record from Olowalu reef, Maui, spanning pre-colonial settlement through the rise and decline of sugarcane agriculture, water diversion, and modern coastal development. Trace element ratios (e.g., Ba/Ca, Y/Ca, P/Ca, Fe/Ca, Sr/Ca) and coral growth parameters document how watershed disturbance and climate variability have influenced reef conditions. Coral trace element records exhibit coherent variability at annual to decadal timescales consistent with El Niño–Southern Oscillation and Pacific Decadal Oscillation frequencies, suggesting climatic control on runoff and groundwater delivery. Superimposed on this natural variability, Ba/Ca, P/Ca, and Fe/Ca increased by 17–55% from the eighteenth century to the late twentieth century, with the largest increase occurring during the mid-1900s and coinciding with the maximum extent of Maui sugarcane plantations. These shifts indicate prolonged increases in sediment and nutrient inputs to the reef. Coral calcification increased by ~30% prior to ~1970 but declined thereafter, coincident with the peak sugarcane production. The negative correlation between coral calcification rate and terrigenous proxies (e.g., Ba/Ca, Y/Ca, P/Ca, and Fe/Ca) suggests that episodic terrestrial inputs from sugarcane plantations depressed coral calcification. This record provides the first pre-colonial to modern baseline for ridge-to-reef connectivity in Maui and demonstrates that historical land-use change has left a persistent geochemical imprint on the downstream reef ecosystem.

Hawaii↗