Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Review Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
USGS1973

Streamflow, sediment, and turbidity in the Mad River basin, Humboldt and Trinity Counties, California

The Mad River discharged an average suspended-sediment load of 2,710,000 tons per year during a 13-year period beginning October 1957. Preliminary analysis of data collected during the 1971 water year indicated that about 66 percent of the suspended sediment was derived from sources upstream from a proposed reservoir site on the Mad River near Butler Valley. The high rate of suspended-sediment discharge and the corresponding sediment-induced turbidity of the streamflow constitute potential problems in the operation of the proposed reservoir. This study is part of an ongoing study by the U.S. Geological Survey intended to determine streamflow, sediment discharge, and turbidity characteristics as they relate to the proposed reservoir and the river system downstream from it. Data from 15 sites in the Mad River basin available through the 1970 water year were reviewed, and the collection of additional data at three of the sites was begun in the 1971 water year. Reconnaissance trips were made in 1971 and 1972 to locate existing or potential problem areas related to sediment and turbidity in the basin. This report presents the interpretations of the data available through September 1971, and indicates the intended direction of the ongoing study.

California↗
USGS2011

Upper Cretaceous bituminous coal deposits of the Olmos Formation, Maverick County, Texas

This report describes the bituminous coal deposits of the Olmos Formation (Navarro Group, Upper Cretaceous; Figures 1, 2) of Maverick County in south Texas. Although these were not evaluated quantitatively as part of the current Gulf Coastal Plain coal-resource assessment, a detailed review is presented in this chapter. Prior to the late 1920s, these coal beds were mined underground on a large scale in the vicinity of Eagle Pass, Texas (Figure 1). Since the 1970s, Olmos Formation coals have been mined extensively in both underground and surface mines in nearby Coahuila, Mexico, to supply mine-mouth fuel for power generation at a plant nearby. A tract northeast of Eagle Pass was permitted in the late 1990s for surface mining. In east-central Maverick County, a coalbed methane field is being developed in coal beds of the lower part of the Olmos Formation (Barker et al., 2002; Scott, 2003).

Texas↗
USGS2010

Surveys for presence of Oregon spotted frog (Rana pretiosa): background information and field methods

The Oregon spotted frog (Rana pretiosa) is the most aquatic of the native frogs in the Pacific Northwest. The common name derives from the pattern of black, ragged-edged spots set against a brown or red ground color on the dorsum of adult frogs. Oregon spotted frogs are generally associated with wetland complexes that have several aquatic habitat types and sizeable coverage of emergent vegetation. Like other ranid frogs native to the Northwest, Oregon spotted frogs breed in spring, larvae transform in summer of their breeding year, and adults tend to be relatively short lived (3-5 yrs). Each life stage (egg, tadpole, juvenile and adult) has characteristics that present challenges for detection. Breeding can be explosive and completed within 1-2 weeks. Egg masses are laid in aggregations, often in a few locations in large areas of potential habitat. Egg masses can develop, hatch, and disintegrate in <2 weeks during warm weather. Tadpoles can be difficult to identify, have low survival, and spend most of their 3-4 months hidden in vegetation or flocculant substrates. Juveniles and adults are often difficult to capture and can spend summers away from breeding areas. Moreover, a substantial portion of extant populations are of limited size (<100 breeding adults), and field densities of all life stages are often low. An understanding of the biology of the species and use of multiple visits are thus important for assessing presence of Oregon spotted frogs. This report is meant to be a resource for USDA Region 6 Forest Service (FS) and OR/WA Bureau of Land Management (BLM) personnel tasked with surveying for the presence of Oregon spotted frogs. Our objective was to summarize information to improve the efficiency of field surveys and increase chances of detection if frogs are present. We include overviews of historical and extant ranges of Oregon spotted frog. We briefly summarize what is known of Oregon spotted frog habitat associations and review aspects of behavior and ecology that are likely to affect detectability in the field. We summarize characteristics that can help differentiate Oregon spotted frog life stages from other northwestern ranid frogs encountered during surveys. Appendices include examples of data collection formats and a protocol for disinfecting field gear.

Interagency Special Status / Sensitive Species Pro↗
USGS1950

Mineral resources of Colombia (other than petroleum)

The following report summarizes data acquired during 1942-45, in Colombia, by geologists and engineers of the Foreign Economic Administration, with whom the United States Geological Survey cooperated. Twenty-nine mineral commodities are considered, but the data for five of them are scant because they were of no interest to FEA personnel. Petroleum is not considered. Preliminary to a review of individual mineral commodities, resumes are given of the general geography and geology of Colombia and of the country's mining laws. The principal mineral commodities, besides petroleum, produced in Colombia are (1) emeralds, gold, platinum, and silver, mainly for export, and (2) barite, cement, clay, coal, gypsum, salt, sand and gravel, silica, and stone, mainly for the domestic market. A large number of other mineral commodities are known in "raw" prospects, some of which may eventually become productive. Their distribution and apparent potentialities, as of 1945, are given. Factors unfavorable to mining are the ruggedness of the terrain, the scarcity of outcrops, and the very high transportation costs.

Bulletin↗
USGS2002

Logs and data from trenches across the Hayward Fault at Tyson's Lagoon (Tule Pond), Fremont, Alameda County, California

INTRODUCTION The purpose of this publication is to make available detailed trench logs (sheets 1, 2), radiocarbon dates (table 1) and pollen data (fig. 1) obtained as a result of an intensive subsurface investigation of the Hayward Fault at Tyson's Lagoon (Tule Pond) from August to November 2000 (figs. 1, 2 on sheet 1). The Hayward Fault is recognized to be among the most hazardous in the United States (Working Group on California Earthquake Probabilities, 1999). This document makes available geologic evidence for historical and prehistoric surfacerupturing earthquakes that were recorded at the site. Prehistoric earthquakes deduced from geologic evidence are called paleoearthquakes. Establishing a chronology of paleoearthquakes is of immediate use in resolving the level of hazard posed by the Hayward Fault for producing large earthquakes in the future. Preliminary findings of this investigation have been presented in Lienkaemper and others (2001). A formal report on our conclusions based on these data is in preparation. The investigation at Tyson's Lagoon is ongoing, so these products should not be considered final. Lienkaemper, Dawson, and Personius interpreted the geology and logged the trenches. Seitz and Reidy performed analyses on radiocarbon and pollen samples, respectively. Schwartz led the critical-review field team. Previous trenching work was done at Tyson's Lagoon (figs. 2, 3 on sheet 1). Lienkaemper (1992) references the location of most of those trenches. The earlier trenching was generally for the evaluation of local faultrupture hazard, except for the study of Williams (1993), which was a paleoearthquake investigation. An unpublished study by J.N. Alt in 1998 (shown on our site map as trenches 98A and 98B, fig. 3, on sheet 1), also sought evidence of paleoearthquakes. Alt's study and one by Woodward-Clyde and Associates (1970; trenches 70A to 70G, fig. 3) were located south of Walnut Avenue in one of the few areas that still remain undisturbed and were, thus, useful in planning our work in 2000.

Miscellaneous Field Studies Map↗
USGS2020

Chemist postcard

Chemists design analytical methods, analyze samples, and review instrument results to ensure high-quality, defensible data are provided to our Nation’s decision makers. For more information, visit https://www.usajobs.gov .

General Information Product↗
USGS2007

Science Review for the Scott Bar Salamander (Plethodon asupak) and the Siskiyou Mountains Salamander (P. stormi): Biology, Taxonomy, Habitat, and Detection Probabilities/Occupancy

The Plethodon elongatus Complex in the Klamath-Siskiyou Ecoregion of southern Oregon and northern California includes three species: the Del Norte salamander, Plethodon elongatus; the Siskiyou Mountains salamander, P. stormi; and the Scott Bar salamander, P. asupak. This review aims to summarize the current literature and information available on select topics for P. stormi and P. asupak. These are both terrestrial salamanders belonging to the Family Plethodontidae, which contains more species and has a wider geographic distribution than any other family of salamanders (Wake 1966, 2006; Pough 1989). The genera of this family have greatly diversified ecologically across North America, Central America, northern South America, Sardinia, southeastern France and northwestern Italy, and have recently been discovered on the Korean peninsula (Min et al. 2005). The genus Plethodon is found exclusively in North America and is split into three distinct clades, based upon morphology and phylogenetics (Highton and Larson 1979): eastern small Plethodon, eastern large Plethodon, and the western Plethodon. The western Plethodon are the greatest representation of Plethodontidae in the Pacific Northwest, with 8 species. The two species with the most restricted ranges of these regional congeners are the Siskiyou Mountains and Scott Bar salamanders. These salamanders occupy the interior of the Klamath-Siskiyou Ecoregion which straddles the California and Oregon state lines, between Siskiyou County (CA) and Jackson and Josephine Counties (OR). The relatively recent discovery of P. asupak (Mead et al. 2005) and the limited range of both species have created an environment of uncertain conservation status for these species. This review will focus on four central topics of concern for land and resource managers: Biology; Taxonomy; Habitat; and Detection Probabilities/Occupancy.

Open-File Report↗
USGS2021

Historical and paleoflood analyses for probabilistic flood-hazard assessments—Approaches and review guidelines

Paleoflood studies are an effective means of providing specific information on the recurrence and magnitude of rare and large floods. Such information can be combined with systematic flood measurements to better assess the frequency of large floods. Paleoflood data also provide valuable information about the linkages among climate, land use, flood-hazard assessments, and channel morphology. This document summarizes methods and techniques for the preparation, gathering, evaluation, and interpretation of paleoflood information, including uncertainties, especially with respect to new statistical approaches available to efficiently use such data. We summarize best practices and strategies for assessing and mitigating uncertainties and provide guidelines on appropriate technical review of paleoflood analyses based on project goals and requirements.

Techniques and Methods↗
USGS2003

Hyla gratiosa (barking treefrog) intestinal hernia

Deformities and malformations in anurans occur in a variety of manifestations (Meteyer 2000. Field Guide to Malformations of Frogs and Toads with Radiographic Interpretations. Biol. Sci. Rep., USGS/BRD/BSR-2000-0005, 18 pp.). Most of those described in the literature are visible externally (e.g., ectromelia, brachydactyly, polydactyly, brachygnathia, kyphosis) (Ouellet et al. 1997. J. Wildlife Dis. 33:95-104). Internal malformations are less well known and seldom reported (Reeder et al. 1998. Environ. Health Persp. 106:261-266). Here we describe an unusual condition heretofore unreported for a hylid frog.

North Carolina↗
USGS2017

Retrospective analysis of the epidemiologic literature, 1990–2015, on wildlife-associated diseases from the Republic of Korea

To assess the status of research on wildlife diseases in the Republic of Korea (ROK) and to identify trends, knowledge gaps, and directions for future research, we reviewed epidemiologic publications on wildlife-associated diseases in the ROK. We identified a relatively small but rapidly increasing body of literature. The majority of publications were focused on public or livestock health and relatively few addressed wildlife health. Most studies that focused on human and livestock health were cross-sectional whereas wildlife health studies were mostly case reports. Fifteen diseases notifiable to the World Organisation for Animal Health were identified and 21 diseases were identified as notifiable to either the Korean Ministry of Health, Welfare, and Family Affairs or the Korean Ministry of Agriculture. Two diseases were reported as occurring as epidemics; highly pathogenic avian influenza (HPAI) and virulent Newcastle disease. Six diseases or disease agents were described in the literature as emerging including HPAI, rabies, Babesia microti , avian coronaviruses, scrub typhus, and severe fever thrombocytopenia syndrome virus. The diseases for which there were the largest number of publications were HPAI and rabies. The majority of wildlife-associated zoonotic disease publications focused on food-borne parasitic infections or rodent-associated diseases. Several publications focused on the potential of wildlife as reservoirs of livestock diseases; in particular, water deer ( Hydropotes inermis ) and wild boar ( Sus scrofa ). In contrast, there were few publications on diseases of concern for wildlife populations or research to understand the impacts of these diseases for wildlife management. Increased focus on prospective studies would enhance understanding of disease dynamics in wildlife populations. For the high-consequence diseases that impact multiple sectors, a One Health approach, with coordination among the public health, agricultural, and environmental sectors, would be important. This type of review can provide useful information for countries or regions planning or implementing national wildlife health programs.

Journal of Wildlife Diseases↗
USGS2009

Final Report for Emergency Stabilization and Rehabilitation Treatment Monitoring of the Keeney Pass, Cow Hollow, Double Mountain, and Farewell Bend Fires

A strategy for monitoring post-fire seedings in the sagebrush steppe of the Intermountain West was developed and used to monitor four example fires in the Vale, Oregon District of the Bureau of Land Management (BLM). We began to develop a potential approach by (1) reviewing previous vegetation monitoring manuals produced by the Federal government to determine what techniques and approaches had been approved for use, and (2) monitoring a set of example fire rehabilitation projects from 2006 through 2008. We reviewed seven vegetation monitoring manuals approved for use by the Federal government. From these seven manuals, we derived a set of design elements appropriate for monitoring post-fire rehabilitation and stabilization projects. These design elements consisted of objectives, stratification, control plots, random sampling, data quality, and statistical analysis. Additionally, we chose three quantitative vegetation field procedures that were objective and repeatable to be used in conjunction with these six design elements. During the spring and summer of 2006 to 2008, U.S. Geological Survey personnel monitored vegetation in seven post-fire seeding treatments in four burned areas in the Vale district of the BLM in eastern Oregon. Treatments monitored included a native and non-native seeding in each of the Farewell Bend, Double Mountain, and Keeney Pass fires, and a native seeding at the Cow Hollow fire. All fires occurred in 2005. There generally was a low level of plant establishment for all seedings by 2008. The quantitative objective established by the BLM was to achieve 5 seeded grass plants/m2 by the end of 3 years as a result of the seeding. There was an estimated 3.97 and 6.28 plants/m2 in 2006 and 1.06 and 0.85 plants/m2 seeded perennial grasses in 2008 from the Keeney Pass non-native and native seeding, respectively. The Cow Hollow seeding resulted in the lowest establishment of perennial seeded grasses of the four project areas with 0.69 plants/m2 in 2006 and 0.09 plants/m2 in 2008. Density of seeded perennial grasses at the Double Mountain non-native and native seeding were 2.72 and 3.86 plants/m2 in 2006 and 0.90 and 1.74 plants/m2 in 2008, respectively. The Farewell Bend non-native seeding resulted in 5.62 plants/m2 in 2006 and 0.42 plants/m2 in 2008 while the native seeding had 2.22 seeded grass plants/m2 in 2006 and 0.44 plants/m2 by 2008. The primary reason for low level of establishment on most treatments except the Cow Hollow seeding was most likely the unfavorable timing and amount of precipitation in 2007 and 2008. Measurements of density within the first 3 years provide the best estimate of initial seeding success. Increases in cover due to the seedings were not detectable in the first 3 years following seeding in this monitoring effort. Changes in cover resulting from the treatments may be detectable in cases where the seedings were very successful in the first 3 years following seeding, but in areas with lower annual average precipitation, may not occur consistently. As a result, cover of seeded species may not be a good indication of seeding success in the early years after treatment. However, cover is useful for monitoring initial patterns of abundance of naturally recovering vegetation, exotic annual grasses and forbs, and bare ground. Cover measurements at these four sites revealed patterns common to most of the treatment areas in cover of litter, bare ground, and exotic annuals in response to drill seeding and weather patterns. There was a rapid increase in litter at all treatments after the fire. Additionally, there was less litter in treatment plots than in the control plots in 2006 probably due to the mechanical action of the seed drill. There also was a corresponding decrease in bare ground from 2006 to 2008. Initially, higher bare ground cover at treatment plots appears to be due to the mechanical action of the seed drill. Cover of annual grasses, primarily Bromus tectorum,

Open-File Report↗
USGS2011

Ducks and passerines nesting in northern mixed-grass prairie treated with fire

Prescribed fire is an important, ecology-driven tool for restoration of grassland systems. However, prescribed fire remains controversial for some grassland managers because of reported reductions in bird use of recently burned grasslands. Few studies have evaluated effects of fire on grassland bird populations in the northern mixed-grass prairie region. Fewer studies yet have examined the influence of fire on nest density or survival. In our review, we found no studies that simultaneously examined effects of fire on duck and passerine nesting. During 1998&mdash;2003, we examined effects of prescribed fire on the density of upland-nesting ducks and passerines nesting in north-central North Dakota, USA. Apparent nest densities of gadwall ( Anas strepera ), mallard ( A. platyrhynchos ), and all duck species combined, were influenced by fire history of study units, although the degree of influence was not compelling. Fire history was not related to nest densities of blue-winged teal ( A. discors ), northern shoveler ( A. clypeata ), or northern pintail ( A. acuta ); however, apparent nest densities in relation to the number of postfire growing seasons exhibited a strikingly similar pattern among all duck species. When compared to ducks, fire history strongly influenced apparent nest densities of clay-colored sparrow ( Spizella pallida ), Savannah sparrow ( Passerculus sandwichensis ), and bobolink ( Dolichonyx oryzivorus ). For most species examined, apparent nest densities were lowest in recently burned units, increased during the second postfire growing season, and stabilized or, in some cases, decreased thereafter. Prescribed fire is critical for restoring the ecology of northern mixed-grass prairies and our findings indicate that reductions in nest densities are limited mostly to the first growing season after fire. Our results support the premise that upland-nesting ducks and several grassland passerine species are adapted to periodic fires occurring at a frequency similar to that of pre-Euro-American settlement of the region.

North Dakota↗
USGS1992

Approach to data exchange: the spatial data transfer standard

Significant developments have taken place in the disciplines of cartography and geography in recent years with the advent of computer hardware and software that manipulate and process digital cartographic and geographic data more efficiently. The availability of inexpensive and powerful hardware and software systems offers the capability of displaying and analyzing spatial data to a growing number of users. As a result, developing and using existing digital cartographic databases are becoming very popular. However, the absence of uniform standards for the transfer of digital spatial data is hindering the exchange of data and increasing costs. Several agencies of the U.S. government and the academic community have been working hard over the last few years to develop a spatial data transfer standard that includes definitions of standard terminology, a spatial data transfer specification, recommendations on reporting digital cartographic data quality, and standard topographic and hydrographic entity terms and definitions. This proposed standard was published in the January 1988 issue of The American Cartographer. Efforts to test and promote this standard were coordinated by the U.S. Geological Survey. A Technical Review Board was appointed with representatives from the U.S. government, the private sector, and the academic community to complete the standard for submittal to the National Institute of Standards and Technology for approval as a Federal Information Processing Standard. The proposed standard was submitted in February 1992 for final approval.

Conference Paper↗
USGS2014

Summary of preliminary step-trend analysis from the Interagency Whitebark Pine Long-termMonitoring Program—2004-2013

In mixed and dominant stands, whitebark pine ( Pinus albicaulis ) occurs in over two million acres within the six national forests and two national parks that comprise the Greater Yellowstone Ecosystem (GYE). Currently, whitebark pine, an ecologically important species, is impacted by multiple ecological disturbances; white pine blister rust ( Cronartium ribicola ), mountain pine beetle ( Dendroctonus ponderosae ), wildfire, and climate change all pose significant threats to the persistence of whitebark pine populations. Substantial declines in whitebark pine populations have been documented throughout its range. Under the auspices of the Greater Yellowstone Coordinating Committee (GYCC), several agencies began a collaborative, long-term monitoring program to track and document the status of whitebark pine across the GYE. This alliance resulted in the formation of the Greater Yellowstone Whitebark Pine Monitoring Working Group (GYWPMWG), which consists of representatives from the U.S. Forest Service (USFS), National Park Service (NPS), U.S. Geological Survey (USGS), and Montana State University (MSU). This groundbased monitoring program was initiated in 2004 and follows a peer-reviewed protocol (GYWPMWG 2011). The program is led by the Greater Yellowstone Inventory and Monitoring Network (GRYN) of the National Park Service in coordination with multiple agencies. More information about this monitoring effort is available at: http://science. nature.nps.gov/im/units/gryn/monitor/whitebark_pine.cfm. The purpose of this report is to provide a draft summary of the first step-trend analysis for the interagency, long-term monitoring of whitebark pine health to the Interagency Grizzly Bear Study Team (IGBST) as part of a synthesis of the state of whitebark pine in the GYE. Due to the various stages of the analyses and reporting, this is the most efficient way to provide these results to the IGBST.

Natural Resource Data Series↗
USGS1949

Fourth special report of the Hawaiian Volcano Observatory of the U.S. Geological Survey and the Hawaiian Volcano Research Association: Steam blast volcanic eruptions: A study of Mount Pelée in Martinique as type volcano

The investigation is concerned with the author's expedition to Martinique and St. Vincent in 1902 and comparison of the experience of investigators and sufferers with that of others in so-called "explosive" eruptions. The Hawaiian mechanism is reviewed with special reference to rifts, underground water, intrusion furnace, wedge rupture, and lowering of magma. These features of structure are applied to Martinique, St. Vincent, Kilauea, Tarawera, Sakurajima, Katmai, Taal and Tomboro as a series of steam blasts old and new. The comparison is found to be applicable and the analogy with Hawaii considered as fundamentally magmatic for gas and basaltic slag, brings out the contrast that lies in steam eruptions. For all volcanoes they are believed features of ground water and of collapse. Ground water stimulates lava eruptions. The Pelée disaster at St. Pierre May 8, 1902, followed by a dacite dome with spines, which renewed activity in 1929, is examined for paroxysms of downblast. These are distinguished sharply from the Carib migratory upblasts along valley fissures which are not uncommon elsewhere. The valleys are on rifts recognized as deep fumaroles. The Ghyben-Herzberg laws of ground water are applicable. Geyser rhythm was followed by Pelée, Soufriére of St. Vincent, and Kilauea in their sequence of paroxysms. Structure sections are drawn to scale, and the structural reactions of intrusion, rifts, boiler, gas effervescence, heat, and timing are thus outlined. The bearing of this machinery on volcanism in general, on world ignisepta and on reaction of magma is suggested. It is contended that steamblast is a climax of eruption in the water zone and should be sharply delimited from the rising and intrusion of fundamental earth magma, and from the high pressure water reactions of ocean bottoms. Rising magma is considered an age-long elevatory force along volcanic lines, modified by cyclical yielding. Compared with oceanic volcanism continental irruption in sediments is a separate science in experimental field geophysics. Every locality supramarine or submarine of warm ground and steep thermal gradient is a subject for volcanology, if pulsating ground water is critically, thermally and chemically measured. Authors are referred to herein by names and dates in parentheses, as listed in the appendices.

Martinique↗
USGS2008

Ethoxyresorufin-O-deethylase (EROD) activity in fish as a biomarker of chemical exposure

This review compiles and evaluates existing scientific information on the use, limitations, and procedural considerations for EROD activity (a catalytic measurement of cytochrome P4501A induction) as a biomarker in fish. A multitude of chemicals induce EROD activity in a variety of fish species, the most potent inducers being structural analogs of 2,3,7,8-tetracholordibenzo- p -dioxin. Although certain chemicals may inhibit EROD induction/activity, this interference is generally not a drawback to the use of EROD induction as a biomarker. The various methods of EROD analysis currently in use yield comparable results, particularly when data are expressed as relative rates of EROD activity. EROD induction in fish is well characterized, the most important modifying factors being fish species, reproductive status and age, all of which can be controlled through proper study design. Good candidate species for biomonitoring should have a wide range between basal and induced EROD activity (e.g., common carp, channel catfish, and mummichog). EROD activity has proven value as a biomarker in a number of field investigations of bleached kraft mill and industrial effluents, contaminated sediments, and chemical spills. Research on mechanisms of CYP1A-induced toxicity suggests that EROD activity may not only indicate chemical exposure, but also may also precede effects at various levels of biological organization. A current research need is the development of chemical exposure-response relationships for EROD activity in fish. In addition, routine reporting in the literature of EROD activity in standard positive and negative control material will enhance confidence in comparing results from different studies using this biomarker.

Critical Reviews in Toxicology↗
USGS2008

An evaluation of selected extraordinary floods in the United States reported by the U.S. Geological Survey and implications for future advancement of flood science

Thirty flood peak discharges determine the envelope curve of maximum floods documented in the United States by the U.S. Geological Survey. These floods occurred from 1927 to 1978 and are extraordinary not just in their magnitude, but in their hydraulic and geomorphic characteristics. The reliability of the computed discharge of these extraordinary floods was reviewed and evaluated using current (2007) best practices. Of the 30 flood peak discharges investigated, only 7 were measured at daily streamflow-gaging stations that existed when the flood occurred, and 23 were measured at miscellaneous (ungaged) sites. Methods used to measure these 30 extraordinary flood peak discharges consisted of 21 slope-area measurements, 2 direct current-meter measurements, 1 culvert measurement, 1 rating-curve extension, and 1 interpolation and rating-curve extension. The remaining four peak discharges were measured using combinations of culvert, slope-area, flow-over-road, and contracted-opening measurements. The method of peak discharge determination for one flood is unknown. Changes to peak discharge or rating are recommended for 20 of the 30 flood peak discharges that were evaluated. Nine floods retained published peak discharges, but their ratings were downgraded. For two floods, both peak discharge and rating were corrected and revised. Peak discharges for five floods that are subject to significant uncertainty due to complex field and hydraulic conditions, were re-rated as estimates. This study resulted in 5 of the 30 peak discharges having revised values greater than about 10 percent different from the original published values. Peak discharges were smaller for three floods (North Fork Hubbard Creek, Texas; El Rancho Arroyo, New Mexico; South Fork Wailua River, Hawaii), and two peak discharges were revised upward (Lahontan Reservoir tributary, Nevada; Bronco Creek, Arizona). Two peak discharges were indeterminate because they were concluded to have been debris flows with peak discharges that were estimated by an inappropriate method (slope-area) (Big Creek near Waynesville, North Carolina; Day Creek near Etiwanda, California). Original field notes and records could not be found for three of the floods, however, some data (copies of original materials, records of reviews) were available for two of these floods. A rating was assigned to each of seven peak discharges that had no rating. Errors identified in the reviews include misidentified flow processes, incorrect drainage areas for very small basins, incorrect latitude and longitude, improper field methods, arithmetic mistakes in hand calculations, omission of measured high flows when developing rating curves, and typographical errors. Common problems include use of two-section slope-area measurements, poor site selection, uncertainties in Manning’s n -values, inadequate review, lost data files, and insufficient and inadequately described high-water marks. These floods also highlight the extreme difficulty in making indirect discharge measurements following extraordinary floods. Significantly, none of the indirect measurements are rated better than fair, which indicates the need to improve methodology to estimate peak discharge. Highly unsteady flow and resulting transient hydraulic phenomena, two-dimensional flow patterns, debris flows at streamflow-gaging stations, and the possibility of disconnected flow surfaces are examples of unresolved problems not well handled by current indirect discharge methodology. On the basis of a comprehensive review of 50,000 annual peak discharges and miscellaneous floods in California, problems with individual flood peak discharges would be expected to require a revision of discharge or rating curves at a rate no greater than about 0.10 percent of all floods. Many extraordinary floods create complex flow patterns and processes that cannot be adequately documented with quasi-steady, uniform one-dimensional analyses. These floods are most accurately described by multidimensional flow analysis. Within the U.S. Geological Survey, new approaches are needed to collect more accurate data for floods, particularly extraordinary floods. In recent years, significant progress has been made in instrumentation for making direct discharge measurements. During this same period, very little has been accomplished in advancing methods to improve indirect discharge measurements. Greater use of paleoflood hydrology could fill many shortcomings of U.S. Geological Survey flood science today, such as enhanced knowledge of flood frequency. Additional links among flood runoff, storm structure, and storm motion would provide more insight to flood hazards. Significant improvement in understanding flood processes and characteristics could be gained from linking radar rainfall estimation and hydrologic modeling. Additionally, more could be done to provide real-time flood-hazard warnings with linked rainfall/runoff and flow models. Several important recommendations are made to improve the flood-documentation capability of the U.S. Geological Survey. When very large discharges are measured by current meter or hydroacoustics, water-surface slope should be measured as well. This measurement would allow validation of roughness values that can significantly extend the discharge range of verified Manning’s n for 1-dimensional and 2-dimensional flow analyses. At least two of the floods investigated may have had flow so unstable that large waves affected the interpretation of high-water marks. Instability criteria should be considered for hydraulic analysis of large flows in high-gradient, smooth channels. The U.S. Geological Survey needs to modernize its toolbox of field and office practices for making future indirect discharge measurements. These practices could include, first and foremost, a new peak-flow file database that allows greater description and interpretation of flow events, such as stability criteria in high-gradient, smooth channels, debris flow documentation, and details of flood genesis (hurricane, snowmelt, rain-on-snow, dam failure, and the like). Other modernized practices could include (a) establishment of calibrated stream reaches in chronic flash flood basins to expedite indirect computation of flow; (b) development of process-based theoretical rating curves for streamflow-gaging stations; (c) adoption of step-backwater models as the standard surface-water modeling tool for U.S. Geological Survey field offices; (d) development and support for multidimensional flow models capable of describing flood characteristics in complex terrain and high-gradient channels; (e) greater use of the critical-depth method in appropriate locations; (f) deployment of non-contact instruments to directly measure large floods, rather than attempting to reconstruct them; (g) increased use of paleoflood hydrology; and (h) assurance that future collection of hydro-climatic data meets the needs of more robust watershed models.

Scientific Investigations Report↗