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At least 487 records · Page 27Linked to original sources

USGS2002

Coupling of hydrologic transport and chemical reactions in a stream affected by acid mine drainage

Experiments in St. Kevin Gulch, an acid mine drainage stream, examined the coupling of hydrologic transport to chemical reactions affecting metal concentrations. Injection of LiCl as a conservative tracer was used to determine discharge and residence time along a 1497-m reach. Transport of metals downstream from inflows of acidic, metal-rich water was evaluated based on synoptic samples of metal concentrations and the hydrologic characteristics of the stream. Transport of SO 4 and Mn was generally conservative, but in the subreaches most affected by acidic inflows, transport was reactive. Both 0.1-um filtered and particulate Fe were reactive over most of the stream reach. Filtered Al partitioned to the particulate phase in response to high instream concentrations. Simulations that accounted for the removal of SO 4 , Mn, Fe, and Al with first-order reactions reproduced the steady-state profiles. The calculated rate constants for net removal used in the simulations embody several processes that occur on a stream-reach scale. The comparison between rates of hydrologie transport and chemical reactions indicates that reactions are only important over short distances in the stream near the acidic inflows, where reactions occur on a comparable time scale with hydrologic transport and thus affect metal concentrations.

Environmental Science & Technology↗

USGS2007

Integrating hydrologic and geophysical data to constrain coastal surficial aquifer processes at multiple spatial and temporal scales

Since 1997, repeated, coincident geophysical surveys and extensive hydrologic studies in shallow monitoring wells have been used to study static and dynamic processes associated with surface water-groundwater interaction at a range of spatial scales at the estuarine and ocean boundaries of an undeveloped, permeable barrier island in the Georgia part of the U.S. South Atlantic Bight. Because geophysical and hydrologic data measure different parameters, at different resolution and precision, and over vastly different spatial scales, reconciling the coincident data or even combining complementary inversion, hydrogeochemcial analyses and well-based groundwater monitoring, and, in some cases, limited vegetation mapping to demonstrate the utility of an integrative, multidisciplinary approach for elucidating groundwater processes at spatial scales (tens to thousands of meters) that are often difficult to capture with traditional hydrologic approaches. The case studies highlight regional aquifer characteristics, varying degrees of lateral saltwater intrusion at estuarine boundaries, complex subsurface salinity gradients at the ocean boundary, and imaging of submarsh groundwater discharge and possible free convection in the pore waters of a clastic marsh. This study also documents the use of geophysical techniques for detecting temporal changes in groundwater salinity regimes under natural (not forced) gradients at intratidal to interannual (1998-200 Southeastern U.S.A. drought) time scales.

Book chapter↗

USGS2000

Hydrological responses to dynamically and statistically downscaled climate model output

Daily rainfall and surface temperature series were simulated for the Animas River basin, Colorado using dynamically and statistically downscaled output from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) re-analysis. A distributed hydrological model was then applied to the downscaled data. Relative to raw NCEP output, downscaled climate variables provided more realistic stimulations of basin scale hydrology. However, the results highlight the sensitivity of modeled processes to the choice of downscaling technique, and point to the need for caution when interpreting future hydrological scenarios.

Geophysical Research Letters↗

USGS2005

Tropical cyclones and the flood hydrology of Puerto Rico

Some of the largest unit discharge flood peaks in the stream gaging records of the U.S. Geological Survey (USGS) have occurred in Puerto Rico. Many of these flood peaks are associated with tropical cyclones. Hurricane Georges, which passed directly over the island on 21–22 September 1998, produced record flood peaks at numerous USGS stations in Puerto Rico. The hydrology and hydrometeorology of extreme flood response in Puerto Rico are examined through analyses of rainfall, based on Weather Surveillance Radar–1988 Doppler (WSR‐88D) radar reflectivity observations and USGS rain gage observations and discharge from USGS stream gaging stations. Peak rainfall accumulations of more than 700 mm occurred in the central mountain region of the island. The largest unit discharge flood peaks, however, were located in the eastern portion of the island in areas with smaller storm total rainfall accumulations but markedly larger rainfall rates at 5–60 min timescale. Orographic precipitation mechanisms played an important role in rainfall distribution over the island of Puerto Rico. Amplification of rainfall accumulations was associated with areas of upslope motion. Elevated low‐level cloud water content in regions of upslope motion played an important role in the maximum rainfall accumulations in the central mountain region of Puerto Rico. The largest unit discharge flood peaks, however, were produced by a decaying eye wall mesovortex, which resulted in a 30–45 min period of extreme rainfall rates over the eastern portion of the island. This storm element was responsible for the record flood peak of the Río Grande de Lóiza. The role of terrain in development and evolution of the eye wall mesovortex is unclear but is of fundamental importance for assessing extreme flood response from the storm. Hydrologic response is examined through analyses of rainfall and discharge from five pairs of drainage basins, extending from east to west over the island. These analyses point to the importance of short‐term rainfall rates for extreme flood response. The hydrologic response of Puerto Rico is compared with two other extreme flood environments, the central Appalachians and Edwards Plateau of Texas. These analyses suggest that the high rainfall environment of Puerto Rico is linked to the development of a hydraulically efficient drainage system.

Water Resources Research↗

USGS2008

Framework for Understanding Structural Errors (FUSE): A modular framework to diagnose differences between hydrological models

The problems of identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure remain outstanding research challenges for the discipline of hydrology. Progress on these problems requires understanding of the nature of differences between models. This paper presents a methodology to diagnose differences in hydrological model structures: the Framework for Understanding Structural Errors (FUSE). FUSE was used to construct 79 unique model structures by combining components of 4 existing hydrological models. These new models were used to simulate streamflow in two of the basins used in the Model Parameter Estimation Experiment (MOPEX): the Guadalupe River (Texas) and the French Broad River (North Carolina). Results show that the new models produced simulations of streamflow that were at least as good as the simulations produced by the models that participated in the MOPEX experiment. Our initial application of the FUSE method for the Guadalupe River exposed relationships between model structure and model performance, suggesting that the choice of model structure is just as important as the choice of model parameters. However, further work is needed to evaluate model simulations using multiple criteria to diagnose the relative importance of model structural differences in various climate regimes and to assess the amount of independent information in each of the models. This work will be crucial to both identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure. To facilitate research on these problems, the FORTRAN‐90 source code for FUSE is available upon request from the lead author.

Water Resources Research↗

USGS2010

Hillslope hydrologic connectivity controls riparian groundwater turnover: Implications of catchment structure for riparian buffering and stream water sources

Hydrologic connectivity between catchment upland and near stream areas is essential for the transmission of water, solutes, and nutrients to streams. However, our current understanding of the role of riparian zones in mediating landscape hydrologic connectivity and the catchment scale export of water and solutes is limited. We tested the relationship between the duration of hillslope‐riparian‐stream (HRS) hydrologic connectivity and the rate and degree of riparian shallow groundwater turnover along four HRS well transects within a set of nested mountain catchments (Tenderfoot Creek Experimental Forest, MT). Transect HRS water table connectivity ranged from 9 to 123 days during the annual snowmelt hydrograph. Hillslope water was always characterized by low specific conductance (∼27 μ S cm −1 ). In transects with transient hillslope water tables, riparian groundwater specific conductance was elevated during base flow conditions (∼127 μ S cm −1 ) but shifted toward hillslope signatures once a HRS groundwater connection was established. The degree of riparian groundwater turnover was proportional to the duration of HRS connectivity and inversely related to the riparian: hillslope area ratios (buffer ratio; r 2 = 0.95). We applied this relationship to the stream network in seven subcatchments within the Tenderfoot Creek Experimental Forest and compared their turnover distributions to source water contributions measured at each catchment outlet. The amount of riparian groundwater exiting each of the seven catchments was linearly related ( r 2 = 0.92) to their median riparian turnover time. Our observations suggest that the size and spatial arrangement of hillslope and riparian zones along a stream network and the timing and duration of groundwater connectivity between them is a first‐order control on the magnitude and timing of water and solutes observed at the catchment outlet.

Water Resources Research↗

USGS2012

The influence of reservoirs, climate, land use and hydrologic conditions on loads and chemical quality of dissolved organic carbon in the Colorado River

Longitudinal patterns in dissolved organic carbon (DOC) loads and chemical quality were identified in the Colorado River from the headwaters in the Rocky Mountains to the United States-Mexico border from 1994 to 2011. Watershed- and reach-scale climate, land use, river discharge and hydrologic modification conditions that contribute to patterns in DOC were also identified. Principal components analysis (PCA) identified site-specific precipitation and reach-scale discharge as being correlated with sites in the upper basin, where there were increases in DOC load from the upstream to downstream direction. In the lower basin, where DOC load decreased from upstream to downstream, sites were correlated with site-specific temperature and reach-scale population, urban land use and hydrologic modification. In the reaches containing Lakes Powell and Mead, the two largest reservoirs in the United States, DOC quantity decreased, terrestrially derived aromatic DOC was degraded and/or autochthonous less aromatic DOC was produced. Taken together, these results suggest that longitudinal patterns in the relatively unregulated upper basin are influenced by watershed inputs of water and DOC, whereas DOC patterns in the lower basin are reflective of a balance between watershed contribution of water and DOC to the river and loss of water and DOC due to hydrologic modification and/or biogeochemical processes. These findings suggest that alteration of constituent fluxes in rivers that are highly regulated may overshadow watershed processes that would control fluxes in comparable unregulated rivers. Further, these results provide a foundation for detailed assessments of factors controlling the transport and chemical quality of DOC in the Colorado River.

Arizona, California, Colorado, Nevada, New Mexico,↗

USGS2018

Hydrologic controls of methane dynamics in karst subterranean estuaries

Karst subterranean estuaries (KSEs) extend into carbonate platforms along 12% of all coastlines. A recent study has shown that microbial methane (CH 4 ) consumption is an important component of the carbon cycle and food web dynamics within flooded caves that permeate KSEs. In this study, we obtained high‐resolution (~2.5‐day) temporal records of dissolved methane concentrations and its stable isotopic content (δ 13 C) to evaluate how regional meteorology and hydrology control methane dynamics in KSEs. Our records show that less methane was present in the anoxic fresh water during the wet season (4,361 ± 89 nM) than during the dry season (5,949 ± 132 nM), suggesting that the wet season hydrologic regime enhances mixing of methane and other constituents into the underlying brackish water. The δ 13 C of the methane (−38.1 ± 1.7‰) in the brackish water was consistently more 13 C‐enriched than fresh water methane (−65.4 ± 0.4‰), implying persistent methane oxidation in the cave. Using a hydrologically based mass balance model, we calculate that methane consumption in the KSE was 21–28 mg CH 4 ·m − 2 ·year − 1 during the 6‐month dry period, which equates to ~1.4 t of methane consumed within the 102‐ to 138‐km 2 catchment basin for the cave. Unless wet season methane consumption is much greater, the magnitude of methane oxidized within KSEs is not likely to affect the global methane budget. However, our estimates constrain the contribution of a critical resource for this widely distributed subterranean ecosystem.

Global Biogeochemical Cycles↗

USGS2020

Hydrologic export is a major component of coastal wetland carbon budgets

Coastal wetlands are among the most productive habitats on Earth and sequester globally significant amounts of atmospheric carbon (C). Extreme rates of soil C accumulation are widely assumed to reflect efficient C storage. Yet the fraction of wetland C lost via hydrologic export has not been directly quantified, since comprehensive budgets including direct estimates of lateral C loss are lacking. We present a complete net ecosystem C budget (NECB), demonstrating that lateral losses of C are a major component of the NECB for the largest stable brackish tidal marsh on the U.S. Pacific coast. Mean annual net ecosystem exchange of CO 2 with the atmosphere (NEE = −185 g C m 2 year −1 , negative NEE denoting ecosystem uptake) was compared to long-term soil C burial (87–110 g C m 2 year −1 ), suggesting only 47–59% of fixed atmospheric C accumulates in soils. Consistently, direct monitoring in 2017–2018 showed NEE of −255 g C m −2 year −1 , and hydrologic export of 105 g C m −2 year −1 (59% of NEE remaining on site). Despite their high C sequestration capacity, lateral losses from coastal wetlands are typically a larger fraction of the NECB when compared to other terrestrial ecosystems. Loss of inorganic C (the least measured NECB term) was 91% of hydrologic export and may be the most important term limiting C sequestration. The high productivity of coastal wetlands thus serves a dual function of C burial and estuarine export, and the multiple fates of fixed C must be considered when evaluating wetland capacity for C sequestration.

Global Biogeochemical Cycles↗

USGS2025

Over, under, and through: Hydrologic connectivity and the future of coastal landscape salinization

Seawater intrusion (SWI) affects coastal landscapes worldwide. Here we describe the hydrologic pathways through which SWI occurs - over land via storm surge or tidal flooding, under land via groundwater transport, and through watersheds via natural and artificial surface water channels—and how human modifications to those pathways alter patterns of SWI. We present an approach to advance understanding of spatiotemporal patterns of salinization that integrates these hydrologic pathways, their interactions, and how humans modify them. We use examples across the East Coast of the United States that exemplify mechanisms of salinization that have been reported around the planet to illustrate how hydrologic connectivity and human modifications alter patterns of SWI. Finally, we suggest a path for advancing SWI science that includes (a) deploying standardized and well-distributed sensor networks at local to global scales that intentionally track SWI fronts, (b) employing remote sensing and geospatial imaging techniques targeted at integrating above and belowground patterns of SWI, and (c) continuing to develop data analysis and model-data fusion techniques to measure the extent, understand the effects, and predict the future of coastal salinization.

Water Resources Research↗

USGS2011

A history of paleoflood hydrology in the United States

The origins of paleoflood hydrology in the United States can be traced back to the beginning of the 19th century, when windgaps and watergaps in the Applachians were believed to have been eroded by extraordinary floods as large lakes that were ponded behind the ridges rapidly drained. Sediment evidence for extraordinary floods was evoked several decades later when glacial sediments in New England were interpreted as deposits from the great Biblical deluge, and estimates of the depth and velocity of the great flood were attempted. The popularization of the glacial origins of drift by Agassiz by 1840 resulted in strong beliefs in uniformitarianism and waning interests in paleoflood investigations. The documentation of the origins of the channeled scablands in eastern Washington by catastrophic glacial outbreak floods, begun by Bretz in the early 1920s, led to renewed interest in paleoflood hydrology. Subsequent efforts to reconstruct hydraulic variables of past floods used conventional open channel flow equations applied to other enormous Pleistocene floods. The elevation of sediments was used as a paleostage estimator in the 1880s, and botanical techniques for estimating paleoflood frequency and magnitude were well documented by the mid-1960s. Since 1970, an exponential expansion has occurred in the recognition and use of paleoflood hydrology in the United States.

Eos, Earth and Space Science News↗

USGS2014

The international hydrological decade

Work toward establishing a program of international cooperative studies in scientific hydrology began about 4 years ago, and the IHD ( International Hydrological Decade ) will begin under international auspices in January 1965. This program will be highly important for hydrology and hydrologists, and it should contribute greatly to human welfare in the future. Fortuitously, the opening year coincides with International Cooperation Year of the United Nations Organization. American participation in the program will contribute to the purpose avowed by the President [Johnson, 1964] in a commencement address at Holy Cross early in June 1964: “to dedicate this year to finding new techniques for making Man's knowledge serve Man's welfare. Let this be a year of science.”

Eos, Transactions, American Geophysical Union↗

USGS2010

Classification of the hydrologic settings of lakes in the north central United States

The hydrologic settings of 150 lakes in the north central United States were investigated by principal component analysis as a first attempt to develop a general classification of the hydrologic settings of lakes. Precipitation-evaporation balance and the water quality variables have high loadings on the first principal component. Highest loadings on component 2 are for streamflow in and out of the lakes. Components 3 and 4 are characterized by geologic and groundwater flow variables. The drainage basin area/lake area ratio, the overland runoff variable, has the highest loading on component 5. The stability of the principal components was tested by randomly splitting the data and comparing a principal component analysis of each subsample. This showed the first two principal components to be the most stable. The components described by the groundwater variables are less stable, but there is justification for using them with caution. Of the variables examined in this study the distribution of dissolved solids of groundwater is most closely related to the distribution of lake types as determined by other limnological typologies in the north central United States. The study indicates that the following are the most important variables to be considered in classifying the hydrologic settings of lakes: dissolved solids concentration of groundwater, precipitation-evaporation balance, streamflow inlet and outlet, the ratio of drainage basin area to lake area, and lake depth. Of the groundwater variables, local relief and regional slope are more important than is regional position. Texture of the drift and bedrock, which is related to hydraulic conductivity of the rocks, is very important.

Water Resources Research↗

USGS2023

Importance of subsurface water for hydrological response during storms in a post-wildfire bedrock landscape

Wildfire alters the hydrologic cycle, with important implications for water supply and hazards including flooding and debris flows. In this study we use a combination of electrical resistivity and stable water isotope analyses to investigate the hydrologic response during storms in three catchments: one unburned and two burned during the 2020 Bobcat Fire in the San Gabriel Mountains, California, USA. Electrical resistivity imaging shows that in the burned catchments, rainfall infiltrated into the weathered bedrock and persisted. Stormflow isotope data indicate that the amount of mixing of surface and subsurface water during storms was similar in all catchments, despite higher streamflow post-fire. Therefore, both surface runoff and infiltration likely increased in tandem. These results suggest that the hydrologic response to storms in post-fire environments is dynamic and involves more surface-subsurface exchange than previously conceptualized, which has important implications for vegetation regrowth and post-fire landslide hazards for years following wildfire.

California↗

USGS2012

Flood risk awareness during the 2011 floods in the central United States: showcasing the importance of hydrologic data and interagency collaboration

Floods have long had a major impact on society and the environment, evidenced by the more than 1,500 federal disaster declarations since 1952 that were associated with flooding. Calendar year 2011 was an epic year for floods in the United States, from the flooding on the Red River of the North in late spring to the Ohio, Mississippi, and Missouri River basin floods in the spring and summer to the flooding caused by Hurricane Irene along the eastern seaboard in August. As a society, we continually seek to reduce flood impacts, with these efforts loosely grouped into two categories: mitigation and risk awareness. Mitigation involves such activities as flood assessment, flood control implementation, and regulatory activities such as storm water and floodplain ordinances. Risk awareness ranges from issuance of flood forecasts and warnings to education of lay audiences about the uncertainties inherent in assessing flood probability and risk. This paper concentrates on the issue of flood risk awareness, specifically the importance of hydrologic data and good interagency communication in providing accurate and timely flood forecasts to maximize risk awareness. The 2011 floods in the central United States provide a case study of the importance of hydrologic data and the value of proper, timely, and organized communication and collaboration around the collection and dissemination of that hydrologic data in enhancing the effectiveness of flood forecasting and flood risk awareness.

Leadership and Management in Engineering↗

USGS2025

Impact of a place-based role-playing exercise on student sense of classroom community and science identity in a hydrology class

Fostering a sense of classroom community in earth science classes supports students’ sense of belonging within the classroom and the broader scientific community, helping them build a sense of identity as a geoscientist. This study examines the effects of incorporating a 2-week, collaborative role-playing activity on sense of classroom community and science identity in an introductory hydrology class. Students assumed roles of residents, medical center representatives, government employees, and environmental activists to learn about flooding through a community-centered lens, focusing on a flood event in Harris County, Texas during Tropical Storm Allison. Pre-post-surveys were given immediately before and after the learning module to evaluate classroom community, science identity using Likert scales, and hydrologist identity using a pictorial scale. Qualitative analysis of a short-answer question in which students defined “hydrologist” provided context for quantitative identity data. Post-survey data on classroom community shows an increase in mean agreement as compared to the pre-survey. This increase was statistically significant for four classroom community statements. Paired science identity data show small effect size and no significant change, but pictorial identity as a hydrologist shows significant growth. Social aspects of the role-playing activity did not significantly alter student’s already high science identity but altered their conceptions of the social implications of hydrology and increased identity as hydrologists. The significant increase in classroom community has important implications for using role-playing as an active learning strategy to enhance student learning experience by creating a positive classroom climate and connecting hydrology concepts to community needs.

Journal of Geoscience Education↗

USGS2019

Potential shifts in zooplankton community structure in response to changing ice regimes and hydrologic connectivity

Changing Arctic climate may alter freshwater ecosystems as a result of warmer surface waters, longer open-water periods, reduced wintertime lake ice growth, and altered hydrologic connectivity. This study aims to characterize zooplankton community composition and size structure in the context of hydrologic connectivity and ice regimes in Arctic lakes. Between 2011 and 2016, we sampled the phytoplankton, zooplankton, and fish communities from a set of representative lakes on the Arctic Coastal Plain (ACP) of northern Alaska to determine potential food web responses to changing Arctic ecosystems. Multivariate analyses showed that time from ice-out had a strong influence on zooplankton community structure and that seasonal succession of zooplankton differed between lakes with varying hydrologic connectivity. Trends were observed suggesting that large-bodied zooplankton ( Daphnia , calanoid copepods) may be more prevalent in poorly connected lakes with low fish diversity. Large-bodied zooplankton displayed higher biomass in lakes with high occurrences of bedfast ice, while small-bodied zooplankton ( Bosmina , rotifers) displayed highest biomass in deeper lakes with low occurrences of bedfast ice. Our results contribute to limited knowledge of zooplankton in remote lakes of the ACP and suggest that the anticipated changes to aquatic ecosystems in the Arctic may include energetically less efficient plankton food webs.

Alaska↗

USGS2017

Predictability and selection of hydrologic metrics in riverine ecohydrology

The natural flow regime is critical to the health of riverine ecosystems. Many hydrologic metrics (HMs) have been developed to describe natural flow regimes, quantify flow alteration, and provide the hydrologic foundation for the development of environmental flow standards. Many applications require the use of models to predict expected natural values of HMs from basin characteristics at sites with no observed records of unimpaired flows. However, the error associated with HM estimation has not been evaluated. The primary goal of our study was to provide guidance for river scientists and managers in the selection, use, and interpretation of HMs for stream classification and hydroecological investigations of river ecosystems. We evaluated the predictability of a broad suite of HMs for the conterminous USA based on random forest statistical models. We also examined how the predictability of metrics varied among unique components of the flow regime. Roughly 40% of 612 HMs we examined could be predicted reliably from basin characteristics. The predictable metrics were disproportionately represented in 5 flow components: asymmetry, seasonality, magnitude, variability, and average monthly flows. Most metrics that represent extreme hydrological events (i.e., high and low flows) could not be reliably predicted. Roughly ⅔ of the evaluated HMs were incalculable or highly biased at intermittent/ephemeral streams because of the need for logarithmic transformations or scaling by other HMs, such as mean flows or percentile flow thresholds. Scaling metrics by drainage area tended to improve predictability. We recommend that the predictability of HMs be given greater consideration in studies and applications in which they are used to characterize and assess alteration of streamflow regimes.

Freshwater Science↗