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At least 1,675 records · Page 93Linked to original sources

USGS2018

Elevated aeolian sediment transport on the Colorado Plateau, USA: The role of grazing, vehicle disturbance, and increasing aridity

Dryland wind transport of sediment can accelerate soil erosion, degrade air quality, mobilize dunes, decrease water supply, and damage infrastructure. We measured aeolian sediment horizontal mass flux ( q ) at 100 cm height using passive aspirated sediment traps to better understand q variability on the Colorado Plateau. Measured q ‘hot spots’ rival the highest ever recorded including 7,460 g m −2 day −1 in an off‐highway vehicle (OHV) area, but were more commonly 50‐2,000 g m −2 day −1 . Overall mean q on rangeland sites was 5.14 g m −2 day −1 , considerably lower than areas with concentrated livestock use (9‐19 g m −2 day −1 ), OHV use (414 g m −2 day −1 ), and downwind of unpaved roads (13.14 g m −2 day −1 ), but were higher than areas with minimal soil disturbance (1.60 g m −2 day −1 ). Rangeland q increased with increasing annual temperature, increased winds, and decreasing precipitation. Spatial modeling suggests that ~92‐93% of regional q occurs in rangelands versus ~7‐8% along unpaved roads. Four of the five largest road q values (n=33) measured were along roads used primarily for oil or gas wells. Our findings indicate that predicted future mega‐droughts will increase q disproportionately in disturbed rangelands, and potentially further compromise air quality, hydrologic cycles, and other ecosystem services.

Colorado Plateau↗

USGS2025

Hotter temperatures alter riparian plant outcomes under regulated river conditions

Climate change and river regulation alter environmental controls on riparian plant occurrence and cover worldwide. Simultaneous changes to river flow and air temperature could result in unanticipated plant responses to novel environmental conditions. Increasing temperature could alter riparian plant response to hydrology and other factors, while river regulation may exacerbate environmental stress through novel flows like those resulting from power generation. Further, plant establishment and growth may require differing conditions, which may be decoupled by novel conditions. Using a large dataset that spans a natural 5°C mean annual temperature (MAT) gradient and a Bayesian model that integrates plant occurrence and cover, we address four questions: (1) Does hotter MAT modify plant response to hydrology, substrate composition, topography, and cover of co-occurring plant species? (2) Does the timing of hydropower tides benefit some species over others? (3) Does dam-induced erosion hinder riparian species more than upland species? (4) Do occurrence and cover respond to different environmental variables, allowing for decoupling of life history processes? We addressed these questions with data collected along 364 km of the Colorado River downstream of Glen Canyon Dam, Arizona, United States of America. Occurrence and cover class were recorded in >10,000 plots from 2016 to 2020, along with environmental covariates that repeat across the climate gradient. For 36 species, plant occurrence and cover were modeled with respect to MAT, hydrology, substrate, topography, other plant cover, and their interactions with MAT. There were four key results. (1) Increasing MAT will not only directly influence plants but will mediate their responses to the environment, including greater dependence on stable water supplies. (2) The timing of hydropower tides shapes plant community composition. (3) Dam-related erosion has an outsized effect on riparian species, which could lead to a loss of regionally unique plant species. (4) For all species, the most important covariates driving occurrence differed from those for cover, suggesting the potential for these life stages to be decoupled. Not only will climate change and river regulation independently alter plant distributions, interactions among hotter temperature, dam-controlled flow patterns, and limited fine sediments will determine which species flourish or perish under future conditions.

Arizona↗

USGS2015

Drought monitoring and assessment: Remote sensing and modeling approaches for the Famine Early Warning Systems Network

Drought monitoring is an essential component of drought risk management. It is usually carried out using drought indices/indicators that are continuous functions of rainfall and other hydrometeorological variables. This chapter presents a few examples of how remote sensing and hydrologic modeling techniques are being used to generate a suite of drought monitoring indicators at dekadal (10-day), monthly, seasonal, and annual time scales for several selected regions around the world. Satellite-based rainfall estimates are being used to produce drought indicators such as standardized precipitation index, dryness indicators, and start of season analysis. The Normalized Difference Vegetation Index is being used to monitor vegetation condition. Several satellite data products are combined using agrohydrologic models to produce multiple short- and long-term indicators of droughts. All the data sets are being produced and updated in near-real time to provide information about the onset, progression, extent, and intensity of drought conditions. The data and products produced are available for download from the Famine Early Warning Systems Network (FEWS NET) data portal at http://earlywarning.usgs.gov . The availability of timely information and products support the decision-making processes in drought-related hazard assessment, monitoring, and management with the FEWS NET. The drought-hazard monitoring approach perfected by the U.S. Geological Survey for FEWS NET through the integration of satellite data and hydrologic modeling can form the basis for similar decision support systems. Such systems can operationally produce reliable and useful regional information that is relevant for local, district-level decision making.

Book chapter↗

USGS1997

Dynamic deformations and the M6.7, Northridge, California earthquake

A method of estimating the complete time-varying dynamic formation field from commonly available three-component single station seismic data has been developed and applied to study the relationship between dynamic deformation and ground failures and structural damage using observations from the 1994 Northridge, California earthquake. Estimates from throughout the epicentral region indicate that the horizontal strains exceed the vertical ones by more than a factor of two. The largest strains (exceeding ∼100 pstrain) correlate with regions of greatest ground failure. There is a poor correlation between structural damage and peak strain amplitudes. The smallest strains,∼35 pstrain, are estimated in regions of no damage or ground failure. Estimates in the two regions with most severe and well mapped permanent deformation, Potrero Canyon and the Granada-Mission Hills regions, exhibit the largest strains; peak horizontal strains estimates in these regions equal ∼1351 and ∼229 μstrain respectively. Of note, the dynamic principal strain axes have strikers consistent with the permanent failure features suggesting that, while gravity, sub-surface materials, and hydrologic conditions undoubtedly played fundamental roles in determining where and what types of failures occurred, the dynamic deformation field may have been favorably sized and oriented to initiate failure processes. These results support other studies that conclude that the permanent deformation resulted from ground shaking, rather than from static strains associated with primary or secondary faulting. They also suggest that such an analysis, either using data or theoretical calculations, may enable observations of paleo-ground failure to be used as quantitative constraints on the size and geometry of previous earthquakes.

California↗

USGS1964

Sedimentology: general introduction and definitions : fluvial sediment and channel morphology

Sedimentology, the study of sedimentary rocks and the processes by which they are formed, includes and is related to a large number of phenomena. Sedimentology includes the five fundamental processes defined by the term sediaentation --weathering, erosion, transportation, deposition and diagenesis. Sedimentology shares with geomorphology the study of the surface features of the earth. Sedimentology also shares with hydrology the study of river.--channels. River channels are formed in part or in total as a result of flowing water and sediment transport, commonly called the "work of the rivers." This survey of published literature was made to aid in arriving at definitions which would be acceptable to, and representative of, a majority of professional personnel actively engaged in laboratory and field investigations related to the "work of the river." The definitions in this list are intended to explain the terms used in studies of fluvial sediment and channel morphology. No set of definitions can expect universal acceptance, however, i t is hoped that this compilation will be considered a summary and synthesis of present and past usage and that it will serve as a starting point for future usage. Multiple references are cited from textbooks, glossaries and dictionaries, scientific journals and u.s. Government publications. To obtain a mutual understanding and enhance precision, many of the proposed definitions are a composite of those selected from papers or reports covering research studies and field investigations. A draft of this glossary has been reviewed by a group of interested personnel. The results of this review have been carefully considered and the originally-suggested definitions have been revised accordingly, resulting in the present compilation. R. G. Wolff, with the help of Mrs. v. Blatcher, carried out the literature search and compilation of terms and the review results. Paul c. Benedict approved or composed the definitions as presented in this report.

Open-File Report↗

USGS2012

Sediment fluxes from California Coastal Rivers: the influences of climate, geology, and topography

The influences of geologic and climatic factors on erosion and sedimentation processes in rivers draining the western flank of the California Coast Range are assessed. Annual suspended, bedload, and total sediment fluxes were determined for 16 river basins that have hydrologic records covering all or most of the period from 1950 to 2006 and have been relatively unaffected by flow storage, regulation, and depletion, which alter the downstream movement of water and sediment. The occurrence of relatively large annual sediment fluxes are strongly influenced by the El Nino–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). The frequency of relatively large annual sediment fluxes decreases from north to south during La Nina phases and increases from north to south during El Nino phases. The influence of ENSO is modulated over a period of decades by the PDO, such that relatively large annual sediment fluxes are more frequent during a La Nina phase in conjunction with a cool PDO and during an El Nino phase in conjunction with a warm PDO. Values of mean annual sediment flux, , were regressed against basin and climatic characteristics. Basin area, bedrock erodibility, basin relief, and precipitation explain 87% of the variation in from the 16 river basins. Bedrock erodibility is the most significant characteristic influencing . Basin relief is a superior predictor of compared with basin slope. is nearly proportional to basin area and increases with increasing precipitation. For a given percentage change, basin relief has a 2.3-fold greater effect on than a similar change in precipitation. The estimated natural from all California coastal rivers for the period 1950–2006 would have been approximately 85 million tons without flow storage, regulation, and depletion; the actual has been approximately 50 million tons, because of the effects of flow storage, regulation, and depletion.

California↗

USGS2019

Monitoring plans for Louisiana’s system-wide assessment and monitoring program (SWAMP). Version IV

The System-Wide Assessment and Monitoring Program (SWAMP) has been envisioned as a long-term monitoring program to ensure a comprehensive network of coastal data collection activities is in place to support the development, implementation, and adaptive management of the coastal protection and restoration program within coastal Louisiana. The Coastwide Reference Monitoring System (CRMS) and Barrier Island Comprehensive Monitoring (BICM) programs have been implemented under SWAMP, while other aspects of system dynamics, including offshore and inland water-body boundary conditions, nontidal freshwater habitats, riverine conditions, risk status, and protection performance, are not presently the subject of CPRA-coordinated (Coastal Protection and Restoration Authority) monitoring. In order to implement these additional aspects of SWAMP, CPRA partnered with The Water Institute of the Gulf and others to develop 1) a programmatic monitoring plan for evaluating the effectiveness of the coastal protection and restoration program on a coastwide scale, and 2) basinwide monitoring plans that will incorporate the elements of the programmatic plan with specific data collection activities designed to capture effects within the basin. Monitoring plans were developed for Barataria Basin, Pontchartrain Region (includes Breton Sound, Pontchartrain and Mississippi River Delta Basins), and the western basins (Calcasieu-Sabine, Mermentau, Teche-Vermilion, Atchafalaya, and Terrebonne) for both the natural and human systems using a process to identify the monitoring variables, objectives, and sampling design. The monitoring variables and objectives identified fall under the general categories of weather and climate, biotic integrity, water quality, hydrology, physical terrain, population and demographics, housing and community characteristics, economy and employment, ecosystem dependency, residential properties protection, and critical infrastructure and essential services protection. A rigorous statistical analysis, examination of modeling needs, and thorough reviews of previous planning and monitoring efforts were conducted to develop the sampling designs for the natural and human system monitoring plans. The plan relies heavily on the use of existing data, thus, coordination with other agencies (e.g., LDEQ , LDWF) and CPRA’s existing monitoring programs (e.g., BICM, CRMS) is critical to the plan’s success. Implementation of the plans will require development of quality control and quality assurance protocols, specific standardized operating procedures for each of the data collection efforts, a data management plan, and a reporting framework to contribute to decision making and reducing uncertainty in management actions.

Louisiana↗

USGS2024

Remote sensing evapotranspiration in ensemble-based framework to enhance cascade routing and re-infiltration concept in integrated hydrological model applied to support decision making

Integrated hydrological models (IHMs) help characterize the complexity of surface–groundwater interactions. The cascade routing and re-infiltration (CRR) concept, recently applied to a MODFLOW 6 IHM, improved conceptualization and simulation of overland flow processes. The CRR controls the transfer of rejected infiltration and groundwater exfiltration from upslope areas to adjacent downslope areas where that water can be evaporated, re-infiltrated back to subsurface, or discharged to streams as direct runoff. The partitioning between these three components is controlled by uncertain parameters that must be estimated. Thus, by quantifying and reducing those uncertainties, next to uncertainties of the other model parameters (e.g. hydraulic and storage parameters), the reliability of the CRR is improved and the IHM is better suited for decision support modelling, the two key objectives of this work. To this end, the remotely sensed MODIS-ET product was incorporated into the calibration process for complementing traditional hydraulic head and streamflow observations. A total of approximately 150,000 observations guided the calibration of a 13-year MODFLOW 6 IHM simulation of the Sardon catchment (Spain) with daily stress periods. The model input uncertainty was represented by grid-cell-scale parameterization, yielding approximately 500,000 unknown input parameters to be conditioned. The calibration was carried out through an iterative ensemble smoother. Incorporating the MODIS-ET data improved the CRR implementation, and reduced uncertainties associated with other model parameters. Additionally, it significantly reduced the uncertainty associated with net recharge, a critical flux for water management that cannot be directly measured and rather is commonly estimated by IHM simulations.

Sardon catchment↗

USGS2000

Origin of the Colorado River experimental flood in Grand Canyon

The Colorado River is one of the most highly regulated and extensively utilized rivers in the world. Total reservoir storage is approximately four times the mean annual runoff of −17 × 10 9 m 3 year −1 . Reservoir storage and regulation have decreased annual peak discharges and hydroelectric power generation has increased daily flow variability. In recent years, the incidental impacts of this development have become apparent especially along the Colorado River through Grand Canyon National Park downstream from Glen Canyon Dam and caused widespread concern. Since the completion of Glen Canyon Dam, the number and size of sand bars, which are used by recreational river runners and form the habitat for native fishes, have decreased substantially. Following an extensive hydrological and geomorphic investigation, an experimental flood release from the Glen Canyon Dam was proposed to determine whether sand bars would be rebuilt by a relatively brief period of flow substantially greater than the normal operating regime. This proposed release, however, was constrained by the Law of the River, the body of law developed over 70 years to control and distribute Colorado River water, the needs of hydropower users and those dependent upon hydropower revenues, and the physical constraints of the dam itself. A compromise was reached following often difficult negotiations and an experimental flood to rebuild sand bars was released in 1996. This flood, and the process by which it came about, gives hope to resolving the difficult and pervasive problem of allocation of water resources among competing interests.

Arizona↗

USGS2016

Toward improved simulation of river operations through integration with a hydrologic model

Advanced modeling tools are needed for informed water resources planning and management. Two classes of modeling tools are often used to this end–(1) distributed-parameter hydrologic models for quantifying supply and (2) river-operation models for sorting out demands under rule-based systems such as the prior-appropriation doctrine. Within each of these two broad classes of models, there are many software tools that excel at simulating the processes specific to each discipline, but have historically over-simplified, or at worse completely neglected, aspects of the other. As a result, water managers reliant on river-operation models for administering water resources need improved tools for representing spatially and temporally varying groundwater resources in conjunctive-use systems. A new tool is described that improves the representation of groundwater/surface-water (GW-SW) interaction within a river-operations modeling context and, in so doing, advances evaluation of system-wide hydrologic consequences of new or altered management regimes.

Environmental Modelling and Software↗

USGS2019

Controls on debris‐flow initiation on burned and unburned hillslopes during an exceptional rainstorm in southern New Mexico, USA

AbstractUsing observations from 688 debris flows, we analyse the hydrologic and landscape characteristics that influenced debris‐flow initiation mechanisms and locations in a watershed that had been partially burned by the 2012 Whitewater‐Baldy Complex Fire in the Gila Mountains, southern New Mexico. Debris flows can initiate due to different processes. Slopes can fail as discrete landslides and then become fluidized and move downstream as debris flows (landslide initiated) or progressive bulking of sediment from a distributed area can become channelized and concentrated as it moves downslope (runoff generated). In this study, we have an unusual opportunity to investigate both types of debris‐flow initiation mechanisms in our observations of debris flows, triggered by an exceptional rainstorm in the autumn of 2013. Additionally, we compare our observations with those of a dataset of 1138 debris flows in the Colorado Front Range, triggered during the same weather system. We found that runoff‐generated debris flows dominated in burn areas, and runoff required to start these flows could be well characterized by the Shields stress. Landslide‐initiated debris flows were dominant in unburned areas. Debris‐flow densities were tied to total rainfall and precipitation intensities. Like the observations in the Colorado Front Range, debris‐flow initiation locations were found primarily in areas of relatively sparse vegetation on south‐facing slopes between 25 and 40°, and with upslope contributing areas less than 1000 m 2 . In terms of preferential locations for debris‐flow initiations, 2013 vegetation coverage, approximated by Green–Red Vegetation Index metrics, proved to be more influential than the 2012 burn‐severity designation. The uniformity of observations between our study area and those in the Colorado Front Range indicate that the underlying hydrologic and landscape patterns of the debris‐flow initiation locations documented in these studies could be applicable to the wider southwest and Rocky Mountain regions.

New Mexico↗

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↗

USGS2006

Preliminary Surficial Geologic Map of the Mesquite Lake 30' X 60' Quadrangle, California and Nevada

The Quaternary surficial geologic map of the Mesquite Lake, California-Nevada 30'X60' quadrangle depicts deposit age and geomorphic processes of erosion and deposition, as identified by a composite of remote sensing investigations, laboratory analyses, and field work, in the arid to semi-arid Mojave Desert area, straddling the California-Nevada border. Mapping was motivated by the need to address pressing scientific and social issues such as understanding and predicting the effects of climate and associated hydrologic changes, human impacts on landscapes, ecosystem function, and natural hazards at a regional scale. As the map area lies just to the south of Las Vegas, Nevada, a rapidly expanding urban center, land use pressures and the need for additional construction materials are forecasted for the region. The map contains information on the temporal and spatial patterns of surface processes and hazards that can be used to model specific landscape applications. Key features of the geologic map include: (1) spatially extensive Holocene alluvial deposits that compose the bulk of Quaternary units (~25%), (2) remote sensing and field studies that identified fault scarps or queried faults in the Kingston Wash area, Shadow Mountains, southern Pahrump Valley, Bird Spring Range, Lucy Gray Mountains and Piute Valley, (3) a lineament indicative of potential fault offset is located in Mesquite Valley, (4) active eolian dunes and sand ramps located on the east side of Mesquite, Ivanpah, and Hidden Valleys adjacent to playas, (4) groundwater discharge deposits in southern Pahrump Valley, Spring Mountains, and Lucy Gray Mountains and (5) debris-flow deposits spanning almost the entire Quaternary period in age.

Open-File Report↗

USGS2019

Wildfire as a catalyst for hydrologic and geomorphic change

Wildfire has been a constant presence on the Earth since at least the Silurian period, and is a landscape-scale catalyst that results in a step-change perturbation for hydrologic systems, which ripples across burned terrain, shaping the geomorphic legacy of watersheds. Specifically, wildfire alters two key landscape properties: (1) overland flow, and (2) soil erodibility. Overland flow and soil erodibility have both been seen to increase after wildfires, resulting in order-of-magnitude increases in erosion rates during rainstorms with relatively frequent recurrence intervals. On short timescales, wildfire increases erosion and leads to natural hazards that are costly and threatening to society. Over longer timescales, wildfire-induced erosion can account for the majority of total denudation in certain settings with long- term implications for landscape evolution. There is a special focus on debris flows in this document because they are the most destructive geomorphic process that is observed to follow wildfires after high severity burns. In the past several decades researchers have investigated important aspects of post-wildfire debris flows, such as: the provenance of sediment that is moved in debris flows, the hydrologic and soil properties required to produce debris flows, and debris flow initiation mechanisms. Herein we highlight the relevant research articles showing the current state of progress in debris flow research as well as pointing to the fundamental research on post-wildfire hydrology and erosion that is necessary for understanding how water and sediment behave after wildfires.

Environmental Science↗

USGS2024

Current advances in coastal wetland elevation dynamics: Introduction to the special issue

The thematic issue entitled, “Current Advances in Coastal Wetland Elevation Dynamics,” draws on topics from two special sessions at the CERF 2021 conference plus additional recent research describing scientific insights gained from the Surface Elevation Table–Marker Horizon (SET–MH) method and its application across the globe to quantify and understand subsurface process influences on wetland elevation change and wetland responses to sea-level rise. The findings group articles within each of five thematic topics. (1) A 30-year retrospective on the scientific insights gained on surface and shallow subsurface process dynamics. (2) Investigations of the subsurface soil process influences on wetland elevation. (3) How the scientific community applies the SET–MH method to quantify and understand wetland responses to RSLR and other environmental drivers such as altered hydrology and sediment supply. (4) How SET–MH data are used in long-term monitoring networks at different geographic scales. (5) Pairing the SET-MH method with (a) survey techniques to increase lateral coverage of wetland elevation trends and (b) geodetic measurements to increase vertical coverage of vertical land motion.

Estuaries and Coasts↗

USGS2011

A multi-year comparison of IPCI scores for prairie pothole wetlands: implications of temporal and spatial variation

In the prairie pothole region of North America, development of Indices of Biotic Integrity (IBIs) to detect anthropogenic impacts on wetlands has been hampered by naturally dynamic inter-annual climate fluctuations. Of multiple efforts to develop IBIs for prairie pothole wetlands, only one, the Index of Plant Community Integrity (IPCI), has reported success. We evaluated the IPCI and its ability to distinguish between natural and anthropogenic variation using plant community data collected from 16 wetlands over a 4-year-period. We found that under constant anthropogenic influence, IPCI metric scores and condition ratings varied annually in response to environmental variation driven primarily by natural climate variation. Artificially forcing wetlands that occur along continuous hydrologic gradients into a limited number of discrete classes (e.g., temporary, seasonal, and semi-permanent) further confounded the utility of IPCI metrics. Because IPCI scores vary significantly due to natural climate dynamics as well as human impacts, methodology must be developed that adequately partitions natural and anthropogenically induced variation along continuous hydrologic gradients. Until such methodology is developed, the use of the IPCI to evaluate prairie pothole wetlands creates potential for misdirected corrective or regulatory actions, impairment of natural wetland functional processes, and erosion of public confidence in the wetland sciences.

Wetlands↗

USGS2009

Phosphorus and nitrogen legacy in a restoration wetland, upper Klamath lake, Oregon

The effects of sediment, ground-water, and surface-water processes on the timing, quantity, and mechanisms of N and P fluxes were investigated in the Wood River Wetland 57 years after agricultural practices ceased and seasonal and permanent wetland hydrologies were restored. Nutrient concentrations in standing water largely reflected ground water in winter, the largest annual water source in the closed-basin wetland. High concentrations of total P (22 mg L -1 ) and total N (30 mg L -1 ) accumulated in summer when water temperature, air temperature, and evapotranspiration were highest. High positive benthic fluxes of soluble reactive P and ammonium (NH 4 -N) were measured in two sections of the study area in June and August, averaging 46 and 24 mg m -2 d -1 , respectively. Nonetheless, a wetland mass balance simultaneously indicated a net loss of P and N by assimilation, denitrification (1.110.1 mg N m -2 h -1 ), or solute repartitioning. High nutrient concentrations pose a risk for water quality management. Shifts in the timing and magnitude of water inflows and outflows may improve biogeochemical function and water quality by optimizing seed germination and aquatic plant distribution, which would be especially important if the Wood River Wetland was reconnected with hyper-eutrophic Agency Lake. ?? 2009, The Society of Wetland Scientists.

Wetlands↗

USGS1998

Field methods for measurement of fluvial sediment

The complexity of hydrologic and physical environments and man's ever-increasing data needs make it essential for those who collect sediment data to be aware of basic concepts involved in the processes of erosion, transport, and deposition of sediment, and of the equipment and procedures necessary to representatively sample sediment and measure its concentration. This report describes equipment and procedures for the collection and measurement of fluvial sediment.

Techniques of Water-Resources Investigations↗