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At least 811 records · Page 45Linked to original sources

USGS2024

Stream nitrate dynamics driven primarily by discharge and watershed physical and soil characteristics at intensively monitored sites: Insights from deep learning

We developed a suite of models using deep learning to make hindcast predictions of the 7‐day average backward‐looking nitrate concentration at 46 predominantly agricultural sites across the midwestern and eastern United States. The models used daily observations of discharge and meteorological variables and watershed attributes describing anthropogenic modification to hydrology, nitrogen application, climate, groundwater, land use, watershed physiographic attributes, and soils. Across all sites, discharge and watershed soil and physiographic attributes showed a strong influence on model performance. Analysis of drivers across sites revealed considerable regional differences related to controlling processes such as groundwater contributions. We tested several ways to pool data across sites to develop accurate models and make the most effective use of available data. Single‐site models, in which models are trained and tested at a single location, showed generally strong predictive performance (median Kling‐Gupta Efficiency = 0.66), and accuracy at poorly performing sites could be improved by grouping sites with similar characteristics. Developing a single model for all sites reduced performance at several locations with distinct characteristics, suggesting that there is a threshold of dissimilarity beyond which more data does not improve the model. While many deep learning studies have shown that national or even global models can outperform local models, it is not clear that this is true for water quality constituents. This study demonstrates how data can be combined effectively, using deep learning to develop accurate and interpretable models of instream nitrate at sites where varying processes are responsible for changes in nitrate concentration.

Water Resources Research↗

USGS2026

Fish body midline segmentation using binary search

Body and caudal fin locomotion is ubiquitous in aquatic vertebrates, and kinematic models describing it are used in robotics, biomechanics and fisheries research. This paper presents a new algorithm to translate continuous body midlines of fish into a series of interconnected segments by identifying favorable joint positions along the body. The algorithm employs binary search to generate parsimonious kinematic models, aiming at minimizing the number of segments yet keeping approximation error below a user-defined threshold. To achieve this, the algorithm maximizes the length of each segment by determining the most distal joint position through repetitive shrinking of the search space. Theoretical and empirical analysis using two different datasets show that the binary search algorithm is substantially faster when compared to segment growing algorithm, which employs linear search to generate its models. There is four-fold improvement in computation time when generating models with less than 10 segments, which are typically sufficient to describe fish and fish-inspired robot movements. Furthermore, the multi-segment models generated by the binary search algorithm matched the ground truth models obtained through dynamic programming in over 97% of cases, and on average, contained one fewer segment than those produced by the Ramer–Douglas–Peucker algorithm, which is widely used in curvature simplification tasks. Our findings suggest that the binary search algorithm provides a computationally efficient approach for generating compact kinematic models and may facilitate the analysis of large datasets with high temporal and spatial resolution.

Computers and Electronics in Agriculture↗

USGS2015

Diel activity patterns of juvenile late fall-run Chinook salmon with implications for operation of a gated water diversion in the Sacramento–San Joaquin River Delta

In the Sacramento-San Joaquin River Delta, California, tidal forces that reverse river flows increase the proportion of water and juvenile late fall-run Chinook salmon diverted into a network of channels that were constructed to support agriculture and human consumption. This area is known as the interior delta, and it has been associated with poor fish survival. Under the rationale that the fish will be diverted in proportion to the amount of water that is diverted, the Delta Cross Channel (DCC) has been prescriptively closed during the winter out-migration to reduce fish entrainment and mortality into the interior delta. The fish are thought to migrate mostly at night, and so daytime operation of the DCC may allow for water diversion that minimizes fish entrainment and mortality. To assess this, the DCC gate was experimentally opened and closed while we released 2983 of the fish with acoustic transmitters upstream of the DCC to monitor their arrival and entrainment into the DCC. We used logistic regression to model night-time arrival and entrainment probabilities with covariates that included the proportion of each diel period with upstream flow, flow, rate of change in flow and water temperature. The proportion of time with upstream flow was the most important driver of night-time arrival probability, yet river flow had the largest effect on fish entrainment into the DCC. Modelling results suggest opening the DCC during daytime while keeping the DCC closed during night-time may allow for water diversion that minimizes fish entrainment into the interior delta.

California↗

USGS2016

Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River—A synthesis of science, 2005 to 2012

This report is intended to synthesize the state of the scientific understanding of pallid sturgeon ecological requirements to provide recommendations for future science directions and context for Missouri River restoration and management decisions. Recruitment of pallid sturgeon has been low to non-existent throughout its range. Emerging understanding of the genetic structure of pallid sturgeon populations sets a broad framework for species and river management decisions, including decisions about managing the future genetic diversity of the species, but also decisions about where and what type of river restoration actions will be effective for subpopulations of this highly migratory species. Adult pallid sturgeon may migrate hundreds of kilometers (km) to spawn and their progeny may disperse even greater distances downstream as drifting free embryos. As a result of their complex life history pallid sturgeon naturally exploit a wide range of habitats during their life cycles. The construction of dams and reservoirs has fragmented habitats and may have shifted Missouri River subpopulations downstream. Research has not identified one primary biological or ecological constraint that appears to limit populations of the pallid sturgeon. With the present (2013) state of knowledge many life stages and life-stage transitions cannot be ruled out as contributing to recruitment failure. Biological opinions in 2000 (and amended in 2003) presented the dominant hypotheses for recruitment failure that existed at that time. Emphasis was on the role of the flow regime, specifically spring flow pulses (“spring rises”), to condition spawning substrate and cue reproductive aggregations and migrations, and on low flows and additional slow, shallow-water area to serve as rearing habitat for age-0 to juvenile pallid sturgeon. Studies on spawning habitat dynamics have documented that habitat patches selected for spawning by fish in the Lower Missouri River (Missouri River downstream from Gavins Point Dam to the confluence with the Mississippi River) are dominantly on outside, revetted bends in the deepest, fastest, and most turbulent water. Studies in more natural habitat on the Yellowstone River have documented spawning in convergent flow in the middle of the channel on discrete patches of gravel within a sand-dominated channel, an arrangement that may be more effective in attracting aggregations of reproductive fish compared to the nearly continuous revetment on the Lower Missouri River. Pallid sturgeon spawn in the spring and early summer during periods of increasing day length. Water temperature consistently exerts a threshold effect for spawning at 16–18 °C. In addition, the role of water temperature is indicated by pauses and reversals in upstream migrations that have been associated with cold weather fronts that create a transient decrease in water temperature. From 2005 to 2012 on the Lower Missouri River, no obvious relations between flow pulses and fish movements and spawning behaviors have been apparent. However, pallid sturgeon tracking at the Upper Missouri–Yellowstone confluence indicates that in most years, most telemetered pallid sturgeon migrate out of the Missouri River and into the Yellowstone River in the June–July timeframe in association with the spring pulse. This pattern was disrupted in 2011 when a high flow pulse with warm temperatures and high turbidity emanated from the Milk River, followed by record releases from Fort Peck Dam, and 36–39 percent of the telemetered population migrated up the Upper Missouri. This result supports the hypothesis that sufficiently large flow pulses may trigger migration and aggregation but it is not clear that functional pulses are within reservoir management authorities. Notably, a pallid sturgeon free embryo was captured on the Upper Missouri River in 2011 and another single, genetically confirmed embryo was captured on the Yellowstone River in 2012. Research on free-embryo drift has indicated the potential for hundreds of miles of downstream dispersal. Lack of distance to accommodate the extended downstream dispersal period of free embryos on the Upper Missouri and Yellowstone Rivers is the predominant hypothesis for recruitment failure in the upper basin. Long drift distances in the Lower Missouri River may be responsible for shifting Lower Missouri River sub-populations further into the Middle Mississippi River. Physical understanding of drift processes indicates that mean velocities could be slowed through decreased discharges or increased channel hydraulic radius (width and topographic diversity) to reduce free-embryo dispersal distances. In addition, the probability that free embryos are transported into and retained in channel-margin habitats is theoretically amenable to channel re-engineering that would increase cross-channel secondary currents in bends or channel expansions. Considerable uncertainty persists, however, about whether extended drift of Lower Missouri River larvae is responsible for recruitment failure. If drift distance is limiting, it is important to discern whether it would be advisable to retain larvae within the Missouri River, and where along the river restoration projects should be placed to optimize survival and growth of age-0 and juvenile sturgeon. Longitudinal differences in female pallid sturgeon fecundity lend support to the hypothesis that recruitment failure may be due, in part, to fish having insufficient nutrition to produce the numbers of gametes needed for the population to grow, perhaps because of simultaneous declines in prey-fish populations and their habitats. Establishing a chain of causality from habitat decline, to prey-fish populations, to sturgeon diets, to sturgeon fecundity, and to pallid sturgeon population growth presents a considerable scientific challenge. In addition to the dominant hypotheses relating pallid sturgeon populations to changes in flow regime and channel morphology, other factors have been identified that might be sources of stress and contribute to recruitment failure. Among these are water quality and contaminants. Ambient water-quality monitoring on the Missouri River has demonstrated summer episodes when dissolved oxygen dips below 5 milligrams per liter, a threshold that may be stressful especially to age-0 and juvenile sturgeon. Documented cases of intersex in shovelnose and pallid sturgeon indicate that agricultural and municipal sources of endocrine disrupting chemicals also may have a role in pallid sturgeon recruitment failure. Scientific understanding of the ecological requirements of pallid sturgeon has increased almost exponentially in the last two decades, and efforts are now turning from understanding fundamental biology of the species to quantifying how population dynamics relate to potential management actions. Progress in developing the science needed to inform management actions on the Missouri River may benefit from continuation of monitoring of reproductive cycles, reproductive movements, growth, and survival of telemetry tagged adults, increased emphasis on focused, complementary field and laboratory studies of factors influencing early life history, implementation of studies to resolve the role of food limitations in growth, survival, and reproductive condition, and implementation of studies designed specifically to parameterize models linking management to populations.

Missouri River↗

USGS2007

Concentrations of selected pharmaceuticals and antibiotics in south-central Pennsylvania waters, March through September 2006

This report presents environmental and quality-control data from analyses of 15 pharmaceutical and 31 antibiotic compounds in water samples from streams and wells in south-central Pennsylvania. The analyses are part of a study by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Environmental Protection (PADEP) to define concentrations of selected emerging contaminants in streams and well water in Pennsylvania. Sampling was conducted at 11 stream sites and at 6 wells in 9 counties of south-central Pennsylvania. Five of the streams received municipal wastewater and 6 of the streams received runoff from agricultural areas dominated by animal-feeding operations. For all 11 streams, samples were collected at locations upstream and downstream of the municipal effluents or animal-feeding operations. All six wells were in agricultural settings. A total of 120 environmental samples and 21 quality-control samples were analyzed for the study. Samples were collected at each site in March/April, May, July, and September 2006 to obtain information on changes in concentration that could be related to seasonal use of compounds. For streams, 13 pharmaceuticals and 11 antibiotics were detected at least 1 time. Detections included analytical results that were estimated or above the minimum reporting limits. Seventy-eight percent of all detections were analyzed in samples collected downstream from municipal-wastewater effluents. For streams receiving wastewater effluents, the pharmaceuticals caffeine and para-xanthine (a degradation product of caffeine) had the greatest concentrations, 4.75 μg/L (micrograms per liter) and 0.853 μg/L, respectively. Other pharmaceuticals and their respective maximum concentrations were carbamazepine (0.516 μg/L) and ibuprofen (0.277 μg/L). For streams receiving wastewater effluents, the antibiotic azithromycin had the greatest concentration (1.65 μg/L), followed by sulfamethoxazole (1.34 μg/L), ofloxacin (0.329 μg/L), and trimethoprim (0.256 μg/L). For streams receiving runoff from animal-feeding operations, the only pharmaceuticals detected were acetaminophen, caffeine, cotinine, diphenhydramine, and carbamazepine. The maximum concentration for pharmaceuticals was 0.053 μg/L. Three streams receiving runoff from animal-feeding operations had detections of one or more antibiotic compound--oxytetracycline, sulfadimethoxine, sulfamethoxazole, and tylosin. The maximum concentration for antibiotics was 0.157 μg/L. The average number of compounds (pharmaceuticals and antibiotics) detected in sites downstream from animal-feeding operations was three. The average number of compounds detected downstream from municipal-wastewater effluents was 13. For wells used to supply livestock, four compounds were detected--two pharmaceuticals (cotinine and diphenhydramine) and two antibiotics (tylosin and sulfamethoxazole). There were five detections in all the well samples. The maximum concentration detected in well water was for cotinine, estimated to be 0.024 μg/L. Seasonal occurrence of pharmaceutical and antibiotic compounds in stream water varied by compound and site type. At four stream sites, the same compounds were detected in all four seasonal samples. At other sites, pharmaceutical or antibiotic compounds were detected only one time in seasonal samples. Winter samples collected in streams receiving municipalwastewater effluent had the greatest number of compounds detected (21). Research analytical methods were used to determine concentrations for pharmaceuticals and antibiotics. To assist in evaluating the quality of the analyses, detailed information is presented on laboratory methodology and results from qualitycontrol samples. Quality-control data include results for nine blanks, nine duplicate environmental sample pairs, and three laboratory-spiked environmental samples as well as the recoveries of compounds in laboratory surrogates and laboratory reagent spikes.

Pennsylvania↗

USGS2016

Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less than 150 m deep) in agricultural areas are often contaminated by nitrate. Agricultural and rural nitrate sources include dairy manure, synthetic fertilizers, and septic waste. Knowledge of the relative proportion that each of these sources contributes to nitrate concentration in individual wells can aid future regulatory and land management decisions. We show that nitrogen and oxygen isotopes of nitrate, boron isotopes, and iodine concentrations are a useful, novel combination of groundwater tracers to differentiate between manure, fertilizers, septic waste, and natural sources of nitrate. Furthermore, in this work, we develop a new Bayesian mixing model in which these isotopic and elemental tracers were used to estimate the probability distribution of the fractional contributions of manure, fertilizers, septic waste, and natural sources to the nitrate concentration found in an individual well. The approach was applied to 56 nitrate-impacted private domestic wells located in the San Joaquin Valley. Model analysis found that some domestic wells were clearly dominated by the manure source and suggests evidence for majority contributions from either the septic or fertilizer source for other wells. But, predictions of fractional contributions for septic and fertilizer sources were often of similar magnitude, perhaps because modeled uncertainty about the fraction of each was large. For validation of the Bayesian model, fractional estimates were compared to surrounding land use and estimated source contributions were broadly consistent with nearby land use types.

California↗

USGS2015

Chemicals of emerging concern in water and bottom sediment in the Great Lakes Basin, 2012: collection methods, analytical methods, quality assurance, and study data

In synoptic surveys of surface-water quality across the United States, a large group of organic chemicals associated with agricultural, household, and industrial waste have been detected. These chemicals are referred to collectively as chemicals of emerging concern (CECs) and include prescription drugs and antibiotics, over-the-counter medications, reproductive hormones, personal-care products, detergent metabolites, and flame retardants. The U.S. Geological Survey (USGS) collaborated with the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency on a study to identify the presence of CECs in water and bottom-sediment samples collected during 2012 at 66 sites throughout the Great Lakes Basin. The 2012 effort is part of a long-term study that was initiated in 2010. The purposes of this report are to document the collection and analytical methods, provide the quality-assurance data and analyses, and provide the water and bottom-sediment data for this study of CECs in the Great Lakes Basin for 2012. A previous report documents data collected during 2010 and 2011. The methods used for chemical analyses were identical between the 2010–11 and 2012 studies, with the exception that a method to determine nontarget chemicals was used during 2010–11. The data from this study are published as a USGS Data Series Report to ensure adequate documentation of the original methods and provide a citable source for study data. This report contains no interpretations of the study data. The chemical data are as reported by the laboratory and have not been censored or adjusted unless otherwise noted. Field measurements were recorded and samples were collected in April and May and in September 2012, by U.S. Geological Survey, U.S. Fish and Wildlife Service, and U.S. Environmental Protection Agency personnel. Study sites included tributaries to the Great Lakes located near Duluth, Minnesota; King, Wisconsin; Green Bay, Wis.; Detroit, Michigan; Monroe, Mich.; Toledo, Ohio, and Rochester, New York. Water and bottom-sediment samples were analyzed at the USGS National Water Quality Laboratory in Denver, Colorado, for a broad suite of CECs. During this 2012 study, 140 environmental and 8 field duplicate samples of surface water and wastewater effluent, 1 field blank water sample, and 5 field spike water samples were collected or prepared. Water samples were analyzed at the USGS National Water Quality Laboratory using laboratory schedule 4433 for wastewater indicators, research method 8244 for pharmaceuticals, and laboratory schedule 4434 for steroid hormones, sterols, and bisphenol A. For wastewater indicators in unfiltered water, 61 of the 68 chemicals analyzed using laboratory schedule 4433 had detectable concentrations ranging from 0.002 to 64.4 micrograms per liter. Thirty-eight of the 48 chemicals analyzed using research method 8244 for pharmaceuticals in unfiltered water had detectable concentrations ranging from 0.002 to 3.32 micrograms per liter. Twelve of the 20 chemicals analyzed using laboratory schedule 4434 for steroid hormones, sterols, and bisphenol A in unfiltered water had detectable concentrations ranging from 0.43 to 120,000 nanograms per liter. During this study, 53 environmental samples, 4 field duplicate samples, and 8 field spike samples of bottom sediment and laboratory matrix-spike samples were analyzed for a wide variety of CECs at the USGS National Water Quality Laboratory using laboratory schedule 5433 for wastewater indicators; research method 6434 for steroid hormones, sterols, and bisphenol A; and research method 9008 for human-use pharmaceuticals and antidepressants. Forty of the 57 chemicals analyzed using laboratory schedule 5433 had detectable concentrations ranging from 1 to 49,000 micrograms per kilogram. Fourteen of the 20 chemicals analyzed using research method 6434 had detectable concentrations ranging from 0.04 to 24,940 nanograms per gram. Ten of the 20 chemicals analyzed using research method 9008 had detectable concentrations ranging from 0.59 to 197.5 micrograms per kilogram. Five of the 11 chemicals analyzed using research method 9008 had detectable concentrations ranging from 1.16 to 25.0 micrograms per kilogram.

Great Lakes Basin↗

USGS2007

Hydrogeologic controls on nitrate transport in a small agricultural catchment, Iowa

Effects of subsurface deposits on nitrate loss in stream riparian zones are recognized, but little attention has been focused on similar processes occurring in upland agricultural settings. In this paper, we evaluated hydrogeologic controls on nitrate transport processes occurring in a small 7.6 ha Iowa catchment. Subsurface deposits in the catchment consisted of upland areas of loess overlying weathered pre-Illinoian till, drained by two ephemeral drainageways that consisted of Holocene-age silty and organic rich alluvium. Water tables in upland areas fluctuated more than 4 m per year compared to less than 0.3 m in the drainageway. Water quality patterns showed a distinct spatial pattern, with groundwater in the drainageways having lower nitrate concentrations (<0.5 mg L-1 compared to upland areas (>10 mg L-1) as wells as lower pH, dissolved oxygen and redox, and higher ammonium and dissolved organic carbon levels. Several lines of evidence suggested that conditions are conducive for denitrification of groundwater flowing from uplands through the drainageways. Field-measured nitrate decay rates in the drainageways (???0.02 day-1) were consistent with other laboratory studies and regional patterns. Results from MODFLOW and MT3DMS simulations indicated that soils in the ephemeral drainageways could process all upland groundwater nitrate flowing through them. However, model-simulated tile drainage increased both water flux and nitrate loss from the upland catchment. Study results suggest that ephemeral drainageways can provide a natural nitrate treatment system in our upland glaciated catchments, offering management opportunities to reduce nitrate delivery to streams. Copyright 2007 by the American Geophysical Union.

Journal of Geophysical Research G: Biogeosciences↗

USGS2009

Sediment characterization and dynamics in Lake Pontchartrain, Louisiana

Lake Pontchartrain in southeastern Louisiana is the largest of several shallow estuaries that together cover over 15,000 km 2 . Wetlands, forests, and large urban areas surround the lake. Primary transport mechanisms of sediments to Lake Pontchartrain include urban runoff, major diversions of the Mississippi River, discharge from streams along the north and west shores, and tidal circulation. Sediments deposited in Lake Pontchartrain are subjected to resuspension and mixing by natural and human activities. Bioturbation and water turbulence throughout the lake are the major mixing agents, and mechanical shell dredging has reworked much of the lake bottom over the last century. Sediment characterization through direct sampling and geophysical surveys indicates that these processes continually rework the top meter of sediment. The lake receives discharge from roadways and industrial and agricultural sources. Contaminants from these sources accumulate in the lake sediments and are an important contributor to the degradation of the estuary. Decline in populations of various benthic organisms, such as shrimp and clams, has been documented in the lake. To characterize the health of this important estuary, the U.S. Geological Survey (USGS) conducted a comprehensive evaluation of the geology, geomorphology, coastal processes, and environmental condition of the Pontchartrain Basin from 1994 to 1997. This report presents an assessment of sediment distribution and quality using a multidisciplinary approach to characterize the influence of various physical and chemical parameters: nearsurface stratigraphy, major trace metal concentrations (Cu, Pb, Zn, and Ni), and short-lived radionuclides ( 210 Pb, 7 Be, and 137 Cs). The results are compared with water-circulation patterns to determine high-resolution sedimentation patterns in the lake. The data show a significant increase in trace metals in the top 1 m of lake sediments. Above this horizon, pollen analysis indicates a correlation with land clearing in the area, a proxy for increasing human development of the surrounding landscape and an increase in surface run-off. The data also show that the top meter of sediment undergoes frequent resuspension during high-energy circulation events and via circulation gyres in the lake. This regular turnover does not allow stratification of recently deposited sediments, restricting the sequestration of contaminated material that enters the lake.

Louisiana↗

USGS2016

The effect of restored and native oxbows on hydraulic loads of nutrients and stream water quality

The use of oxbow wetlands has been identified as a potential strategy to reduce nutrient transport from agricultural drainage tiles to streams in Iowa. In 2013 and 2014, a study was conducted in north-central Iowa in a native oxbow in the Lyons Creek watershed and two restored oxbow wetlands in the Prairie Creek watershed (Smeltzer west and Smeltzer east) to assess their effectiveness at reducing nitrogen and phosphorus loads. The tile line inlets carrying agricultural runoff to the oxbows, the outfall from the oxbows, and the surface waters in the streams receiving the outfall water were monitored for discharge and nutrients from February 2013 to September 2015. Smeltzer west and east also had four monitoring wells each, two in the upland and two between the oxbow and Prairie Creek to monitor surface water-groundwater interaction. The Smeltzer west and east oxbow sites also were instrumented to continuously measure the nitrate concentration. Rainfall was measured at one Lyons Creek and one Smeltzer site. Daily mean nitrate-N concentrations in Lyons Creek in 2013 ranged from 11.8 mg/L to 40.9 mg/L, the median daily mean nitrate-N concentration was 33.0 mg/L. Daily mean nitrate-N concentrations in Prairie Creek in 2013 ranged from 0.07 mg/L in August to 32.2 mg/L in June. In 2014, daily mean nitrate-N concentrations in Prairie Creek ranged from 0.17 mg/L in April to 26.7 mg/L in July; the daily mean nitrate-N concentration for the sampled period was 9.78 mg/L. Nutrient load reduction occurred in oxbow wetlands in Lyons and Prairie Creek watersheds in north-central Iowa but efficiency of reduction was variable. Little nutrient reduction occurred in the native Lyons Creek oxbow during 2013. Concentrations of all nutrient constituents were not significantly (P>0.05, Wilcoxon rank sum) different in water discharging from the tile line than in water leaving the Lyons Creek oxbow. A combination of physical features and flow conditions suggest that the residence time of water in the oxbow may not have been sufficient to allow for removal of substantial amounts of nutrients. Approximately 54 percent less nitrate-N was measured leaving the Smeltzer west oxbow than was measured entering from a small 6-inch field tile. The efficiency of nitrate-N removal in the oxbow was not able to be definitively quantified as other hydrologic factors such as overland and groundwater flow into and through the oxbow were not addressed and may provide alternative routes for nutrient transport. Damage to the Smeltzer east oxbow outfall weir prevented analysis of its nutrient load reduction capability. The study provides important information to managers and land owners looking for strategies to reduce nutrient transport from fields. Additional research is needed to understand how increased discharge from larger field tiles and drainage district mains may influence the efficiency of nutrient reduction in relation to the size, type, and landscape setting of a wetland.

Iowa↗

USGS2022

Geomorphic controls on floodplain connectivity, ecosystem services, and sensitivity to climate change: An example from the lower Missouri River

Floodplains of large rivers are exploited for agricultural production, industrial and municipal development, and transportation infrastructure. Recently, increased frequency of costly floods has prompted consideration of whether offsetting benefits might accrue from management of floodplains for ecosystem services. We employed a simple inundation model for 800 km of the Lower Missouri River, USA, to evaluate spatial and temporal distributions of ecological floodplain inundation metrics and how those distributions might vary with levee removal and climatic change. The model evaluates inundation at 30 × 30 m resolution on a daily basis over 82 years of record. We quantified provisioning of waterfowl habitat and potential denitrification. Spatial variability is affected by ongoing geomorphic adjustments that affect floodplain connectivity. Statistical models indicate that available floodplain area and recent aggradation are predictive of most inundation metrics. Connectivity is sensitive to climate-change scenarios that predict increased floodplain inundation during spring waterfowl migrations; the greatest sensitivity to future climate exists where channel-floodplain geomorphology presently enhances floodplain connectivity. Evaluation of floodplain denitrification indicates that on average, the nonleveed part of the floodplain could denitrify 0.05%–1.7% of the mean annual nitrogen load of the river. Levee removal could increase this rate to only 3.6% of the nitrogen load. The capacity of floodplain connectivity to influence certain ecosystem services is highly variable in space along the Lower Missouri River and may be appreciably influenced by climate change. Hence, decisions to optimize management of large-river floodplains are likely to be highly location dependent.

Illinois, Iowa, Kansas, Missouri, Nebraska, South ↗

USGS2008

Not all water becomes wine: Sulfur inputs as an opportune tracer of hydrochemical losses from vineyards

California's widespread and economically important vineyards offer substantial opportunities to understand the interface between hydrology and biogeochemistry in agricultural soils. The common use of native sulfur (S) as a fumigant or soil additive provides a novel way to isotopically differentiate among sulfate (SO 4 2− ) pools, allowing the estimation of water and SO 4 2− budgets. The objectives of this study were (1) to characterize the near‐surface hydrological flow paths in a vineyard during irrigation and storm events and (2) to determine how those flow paths affect the fate and transport of SO 4 2− across seasons. Integrating hydrological theory with measurements of SO 4 2− concentration and sulfate‐S isotopic ratios (expressed as [SO 4 2− ] and δ 34 S, respectively) in inputs, soil water, and leachate provided a means of determining flow paths. Low [SO 4 2− ] and δ 34 S in leachate during 4‐h irrigation events reflect minimal engagement of the soil matrix, indicating that preferential flow was the dominant path for water in the near surface. In contrast, high [SO 4 2− ] and δ 34 S values during 8‐h irrigation and storm events reflect near‐complete engagement of the soil matrix, indicating that lateral flow was the dominant pathway. Because hydrologic response and SO 4 2− mobility are tightly coupled in these soils, the magnitude of water fluxes through the near surface controls S cycling both on and off site. These results indicate that preferential flow is an important loss pathway to consider in managing both water resources and water quality (reactive elements) in vineyard land use systems.

Water Resources Research↗

USGS2017

Hydrologic, land cover, and seasonal patterns of waterborne pathogens in Great Lakes tributaries

Great Lakes tributaries are known to deliver waterborne pathogens from a host of sources. To examine the hydrologic, land cover, and seasonal patterns of waterborne pathogens (i.e. protozoa (2), pathogenic bacteria (4) human viruses, (8) and bovine viruses (8)) eight rivers were monitored in the Great Lakes Basin over 29 months from February 2011 to June 2013. Sampling locations represented a wide variety of land cover classes from urban to agriculture to forest. A custom automated pathogen sampler was deployed at eight sampling locations which provided unattended, flow-weighted, large-volume (120–1630 L) sampling. Human and bovine viruses and pathogenic bacteria were detected by real-time qPCR in 16%, 14%, and 1.4% of 290 samples collected while protozoa were never detected. The most frequently detected pathogens were: bovine polyomavirus (11%), and human adenovirus C, D, F (9%). Human and bovine viruses were present in 16.9% and 14.8% of runoff-event samples (n = 189) resulting from precipitation and snowmelt, and 13.9% and 12.9% of low-flow samples (n = 101), respectively, indicating multiple delivery mechanisms could be influential. Data indicated human and bovine virus prevalence was different depending on land cover within the watershed. Occurrence, concentration, and flux of human viruses were greatest in samples from the three sampling locations with greater than 25% urban influence than those with less than 25% urban influence. Similarly, occurrence, concentration, and flux of bovine viruses were greatest in samples from the two sampling locations with greater than 50 cattle/km 2 than those with less than 50 cattle/km 2 . In seasonal analysis, human and bovine viruses occurred more frequently in spring and winter seasons than during the fall and summer. Concentration, occurrence, and flux in the context of hydrologic condition, seasonality, and land use must be considered for each watershed individually to develop effective watershed management strategies for pathogen reduction.

Great Lakes tributaries↗

USGS2000

Mechanism and rate of denitrification in an agricultural watershed: Electron and mass balance along groundwater flow paths

The rate and mechanism of nitrate removal along and between groundwater flow paths were investigated using a series of well nests screened in an unconfined sand and gravel aquifer. Intensive agricultural activity in this area has resulted in nitrate concentrations in groundwater often exceeding drinking water standards. Both the extent and rate of denitrification varied depending on the groundwater flow path. While little or no denitrification occurred in much of the upland portions of the aquifer, a gradual redox gradient is observed as aerobic upland groundwater moves deeper in the aquifer. In contrast, a sharp shallow redox gradient is observed adjacent to a third‐order stream as aerobic groundwater enters reduced sediments. An essentially complete loss of nitrate concurrent with increases in excess N 2 provide evidence that denitrification occurs as groundwater enters this zone. Electron and mass balance calculations suggest that iron sulfide (e.g., pyrite) oxidation is the primary source of electrons for denitrification. Denitrification rate estimates were based on mass balance calculations using nitrate and excess N 2 coupled with groundwater travel times. Travel times were determined using a groundwater flow model and were constrained by chlorofluorocarbon‐based age dates. Denitrification rates were found to vary considerably between the two areas where denitrification occurs. Denitrification rates in the deep, upland portions of the aquifer were found to range from <0.01 to 0.14 m M of N per year; rates at the redoxcline along the shallow flow path range from 1.0 to 2.7 m M of N per year. Potential denitrification rates in groundwater adjacent to the stream may be much faster, with rates up to 140 m M per year based on an in situ experiment conducted in this zone.

Water Resources Research↗

USGS2012

Factors controlling nitrate fluxes in groundwater in agricultural areas

The impact of agricultural chemicals on groundwater quality depends on the interactions of biogeochemical and hydrologic factors. To identify key processes affecting distribution of agricultural nitrate in groundwater, a parsimonious transport model was applied at 14 sites across the U.S. Simulated vertical profiles of NO 3 - , N 2 from denitrification, O 2 , Cl - , and environmental tracers of groundwater age were matched to observations by adjusting the parameters for recharge rate, unsaturated zone travel time, fractions of N and Cl - inputs leached to groundwater, O 2 reduction rate, O 2 threshold for denitrification, and denitrification rate. Model results revealed important interactions among biogeochemical and physical factors. Chloride fluxes decreased between the land surface and water table possibly because of Cl - exports in harvested crops (averaging 22% of land-surface Cl - inputs). Modeled zero-order rates of O 2 reduction and denitrification were correlated. Denitrification rates at depth commonly exceeded overlying O 2 reduction rates, likely because shallow geologic sources of reactive electron donors had been depleted. Projections indicated continued downward migration of NO 3 - fronts at sites with denitrification rates <0.25 mg-N L -1 yr -1 . The steady state depth of NO 3 - depended to a similar degree on application rate, leaching fraction, recharge, and NO 3 - and O 2 reaction rates. Steady state total mass in each aquifer depended primarily on the N application rate. In addition to managing application rates at land surface, efficient water use may reduce the depth and mass of N in groundwater because lower recharge was associated with lower N fraction leached. Management actions to reduce N leaching could be targeted over aquifers with high-recharge and low-denitrification rates.

Water Resources Research↗

USGS2024

A comparative analysis of OpenET for evaluating evapotranspiration in California almond orchards

The almond industry in California faces water management challenges that are being exacerbated by droughts, climate change, and groundwater sustainability legislation. The Tree-crop Remote sensing of Evapotranspiration eXperiment (T-REX) aims to explore opportunities to improve precision irrigation management for woody perennial cropping systems. Almond orchards in the California Central Valley were equipped with eddy covariance flux measurements to evaluate satellite remote sensing-based evapotranspiration (RSET) models. OpenET provides high-resolution (30-m spatial and daily temporal) RSET data, synthesizing decades of research for practical water management. This study provides an evaluation of OpenET performance at six almond sites covering a large range in soils, age, and variety. It also compares OpenET ensemble evapotranspiration (ET) data with applied irrigation and precipitation records over an additional 148 almond orchards located in the Central Valley of California. Results show OpenET models, including the ensemble ET value, produced reasonable and actionable ET values, with overall coefficient of determination (R 2 ) and mean absolute error values of 0.73- and 0.95-mm d −1 at the daily time step, respectively. However, given the temporal sampling of Landsat (8-day revisit) and the interpolation methods used, the assessed ET models had difficulty in capturing short-term variability in almond ET; for example, the rapid decline in measured ET observed as a response to lack of irrigation preceding and during almond harvest. The study also drew attention to the spatial complexity in scenarios where irrigated orchards are surrounded by hot/dry areas, causing discrepancies between measured and modeled ET values. In comparison with irrigation records, OpenET ensemble ET was capable of quantifying water input (applied irrigation + precipitation) in almond orchards to within 13 % when evaluating monthly data. Initial results presented here reinforce the idea that RSET models, such as in OpenET, are powerful tools, yet their application requires nuanced understanding and careful consideration of local conditions.

California↗

USGS2021

Post-drought groundwater storage recovery in California’s Central Valley

Groundwater depletion is a major threat to agricultural and municipal water supply in California's Central Valley. Recent droughts during 2007–2009 and 2012–2016 exacerbated chronic groundwater depletion. However, it is unclear how much groundwater storage recovered from drought-related overdrafts during post-drought years, and how climatic conditions and water management affected recovery times. We estimated groundwater storage change in the Central Valley for April 2002 through September 2019 using four methods: GRACE satellite data, a water balance approach, a hydrologic simulation model, and monitoring wells. We also evaluated the sensitivity of drought recovery to different climate scenarios (recent climate ± droughts and future climate change scenarios: 20 GCMs and 2 RCPs) using water balance method and statistical sampling of historical climate data. Estimated Central Valley groundwater loss during the two droughts ranged from 19 km 3 (2007–2009) to 28 km 3 (2012–2016) (median of four methods). Median aquifer storage recovery was 34% and 19% of the overdraft during the 2010–2011 and 2017–2019 post-drought years, respectively. Numerical experiments show that recovery times are sensitive to climate forcing, with longer recovery times for a future climate scenario that replicate historical climatology relative to historical forcing with no droughts. Overdraft recovery times decrease by ∼2× with implementation of pumping restrictions (30th to 50th percentiles of historical groundwater depletion) to constrain groundwater depletion relative to no restrictions with a no-drought future climatology. This study highlights the importance of considering water management implications for future drought recoveries within the context of climate change scenarios.

California↗

USGS2012

White-nose syndrome in bats: U.S. Geological Survey updates

White-nose syndrome (WNS) is a devastating disease that has killed millions of hibernating bats since it first appeared in New York in 2007 and has spread at an alarming rate from the northeastern to the central United States and Canada. The disease is named for the white fungus Geomyces destructans that infects the skin of the muzzle, ears, and wings of hibernating bats. The U.S. Geological Survey (USGS) National Wildlife Health Center (NWHC), the USGS Fort Collins Science Center, the U.S. Fish and Wildlife Service, and other partners continue to play a primary role in WNS research. Studies conducted at the NWHC led to the discovery (Blehert and others, 2009), characterization, and naming (Gargas and others, 2009) of the cold-loving fungus G. destructans and to the development of standardized criteria for diagnosing the disease (Meteyer and others, 2009). Additionally, scientists at the NWHC have pioneered laboratory techniques for studying the effects of the fungus on hibernating bats (Lorch and others, 2011). To determine if bats are affected by white-nose syndrome, scientists look for a characteristic microscopic pattern of skin erosion caused by G. destructans (Meteyer and others, 2009). Field signs of WNS can include visible white fungal growth on the bat's muzzle, wings, or both, but these signs alone are not a reliable disease indicator - laboratory examination and testing are required for disease confirmation. Infected bats also arouse from hibernation more frequently than uninfected bats (Warnecke and others, 2012) and often display abnormal behaviors in their hibernation sites, such as congregating at or near cave openings and daytime flights during winter. These abnormal behaviors may contribute to the bat's accelerated consumption of stored fat reserves, causing emaciation, a characteristic documented in some of the bats that die with WNS. During hibernation, bats likely have lowered immunity (Bouma and others, 2010), which may facilitate the ability of G. destructans to colonize and damage large areas of wing membrane (fig. 2). A current hypothesis suggests that erosion or ulceration of wing membrane caused by the fungus has the potential to alter the physiology of hibernating bats, resulting in fatal disruption of hydration, electrolyte balance, circulation, and thermoregulation (Cryan and others, 2010). Current estimates of bat population declines in the northeastern United States since the emergence of WNS are over 80 percent (Turner and others, 2011). This sudden and widespread mortality associated with WNS is unprecedented in hibernating bats, among which large-scale disease outbreaks have not been previously documented. It is unlikely that species of bats affected by WNS will recover quickly because most are long-lived and have only a single pup per year. Consequently, repopulation after widespread mortality of breeding adults will be a slow process. Worldwide, bats play essential roles as pollinators, seed dispersers, and as primary consumers of insects. The true ecological consequences of the recent large-scale reductions in populations of hibernating bats are not yet known. However, farmers might feel the impact. A recent economic analysis indicated that insect control services (ecosystem services) provided by bats to U.S. agriculture is valued between 4 to 50 billion dollars nationwide per year (Boyles and others, 2011). The number of North American bats estimated to have died from WNS thus far had the capacity to consume up to 8,000 tons of insects per year (Boyles and others, 2011). The area of North America affected by WNS continues to expand. Within the last 2 years, the disease has been confirmed in several Central States, including Alabama, Indiana, Kentucky, Ohio, Tennessee, and Missouri. High mortality of bats has not yet been reported at these locations, and it remains to be seen if WNS will develop and manifest in other States with the same severity as that in the Northeast.

Alabama;Connecticut;Delaware;Illinois;Indiana;Iowa↗