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USGS2025

Woods Hole Coastal and Marine Science Center—2023 annual report

The 2023 annual report of the U.S. Geological Survey Woods Hole Coastal and Marine Science Center highlights accomplishments of 2023, includes a list of 2023 publications, and summarizes the work of the center, as well as the work of each of its science groups. This product allows readers to gain a general understanding of the focus areas of the center’s scientific research and learn more about specific projects and progress made throughout 2023, all while enjoying photographs taken in various environments and laboratories, and applicable maps and figures.

Circular↗
USGS2026

Woods Hole Coastal and Marine Science Center—2024 annual report

The 2024 annual report of the U.S. Geological Survey Woods Hole Coastal and Marine Science Center highlights accomplishments of 2024, includes a list of 2024 publications, and summarizes the work of the center, as well as the work of each of its science groups. This product allows readers to gain a general understanding of the focus areas of the center’s scientific research and learn more about specific projects and progress made throughout 2024, all while enjoying photographs taken in various environments and laboratories, and applicable maps and figures.

Circular↗
USGS1953

Radioactive source materials in Los Estados Unidos de Venezuela

This report summarizes the data available on radioactive source materials in Los Estados Unidos de Venezuela accumulated by geologists of the Direccions Tecnica de Geolgia and antecedent agencies prior to June 1951, and the writers from June to November 1951. The investigation comprised preliminary study, field examination, office studies, and the preparation of this report, in which the areas and localities examined are described in detail, the uranium potentialities of Venezuela are summarized, and recommendations are made. Preliminary study was made to select areas and rock types that were known or reported to be radioactive or that geologic experience suggests would be favorable host for uranium deposits, In the office, a study of gamma-ray well logs was started as one means of amassing general radiometric data and of rapidly scanning many of ye rocks in northern Venezuela; gamma-ray logs from about 140 representative wells were examined and their peaks of gamma intensity evaluated; in addition samples were analyzed radiometrically, and petrographically. Radiometic reconnaissance was made in the field during about 3 months of 1951, or about 12 areas, including over 100 localities in the State of Miranda, Carabobo, Yaracuy, Falcon, Lara, Trujillo, Zulia, Merida, Tachira, Bolivar, and Territory Delta Amacuro. During the course of the investigation, both in the filed and office, information was given about geology of uranium deposits, and in techniques used in prospecting and analysis. All studies and this report are designed to supplement and to strengthen the Direccion Tecnica de Geologias's program of investigation of radioactive source in Venezuela now in progress. The uranium potentialities of Los Estados de Venezuela are excellent for large, low-grade deposits of uraniferous phospahtic shales containing from 0.002 to 0.027 percent uranium; fair, for small or moderate-sized, low-grade placer deposits of thorium, rare-earth, and uranium minerals; poor, for high-grade hydrothermal pitchblende deposits; and highly possible for small, medium- to high-grade despots of carnotite-or copper-uranium bearing sandstone. Recommendations for the Venezuelan uranium program include 1) the systematic collection of a mass general radiometric data by examining sample collections, expanding the gamma-ray program, encouraging the use of Geiger counter by field geologists, and by enlisting the aid of the general public; 2) , the examination of specific areas or localities, chosen on the basis of geologic favorability from the results of the amassing of data, or obtained by hints and rumors; 3), the organization of a unit within the Direccion Tecnica de Geologica to direct, collection, and collate metric data. It is emphasized that to be most fruitful the program requires the application of sounds and imaginative geologic theory.

Trace Elements Investigations↗
USGS2020

Fish and habitat assessment in Rock Creek, Klickitat County, southeastern Washington, 2018

Executive Summary Native steelhead (anadromous form of rainbow trout [ Oncorhynchus mykiss ]) and bridgelip sucker ( Catostomus columbianus ) were historically used by the Kah-miltpah (Rock Creek) Band for sustenance, trade, and traditional practices in Rock Creek, a tributary to the Columbia River in southeastern Washington State. Rock Creek flows south to the Columbia River at river kilometer (rkm) 368 and is an intermittent stream of great significance to the Yakama Nation and to the Kah-miltpah Band in particular. Concern over declines in the abundance of these fish in Rock Creek prompted a research and monitoring program to better understand habitat conditions, population status, and limiting factors. In addition to steelhead and bridgelip sucker, coho salmon ( Oncorhynchus kisutch ) and resident rainbow trout are also present and monitored. Rainbow trout and steelhead will be collectively referred to as O. mykiss . Streamflow is a limiting habitat factor in this system, but steelhead and coho salmon still successfully return to spawn, rear, outmigrate, and survive over summer in many of the isolated pools that provide important refuge for juvenile rearing. We completed a habitat survey during autumn 2018 to assess the perennial pools during low-flow conditions. In Rock Creek, the overall percentage of habitat recorded as dry was 41, non-pool wet was 42, and pool was 17. The number of pools ( n =93) recorded was less than during previous years’ survey efforts (2015–17). The percentage of non-pool wet habitat was generally higher in 2018 than in previous years. This is a likely result of habitat reaches, which in the past, were considered pools but have become shallower and smaller and are now categorized as non-pool wet habitat. However, the fewer habitat reaches categorized as pools in 2018 now have an average length, area, and depth that are generally greater than in past years. In Walaluuks Creek, the percentage of habitat recorded as dry was 53, non-pool wet was 40, and pool was 7. The percentage of pool habitat was the lowest of all years surveyed since 2015. Fish sampling occurred during autumn after habitat surveys were completed from October 1 to November 9. Fish species distribution, relative abundance, length-frequency distribution, and pool fish density were determined using backpack electrofishing in stratified, systematically selected pools. During fish sampling, 855 O. mykiss were handled and 662 were tagged with a passive integrated transponder (PIT) tag, and 718 coho salmon were handled and 567 were PIT tagged. A total of 536 bridgelip suckers and largescale suckers ( Catostomus macrocheilus [ n =6]) were handled and 294 were PIT tagged. In Rock Creek, pool abundance estimates were calculated for six pools for both O. mykiss age classes (age 0 and age 1 or older [age 1+]) and one additional pool for age 1+. For pools where age-0 O. mykiss were present, the average pool population abundance was 0.144 ( n =6; range: 0.052–0.208) fish per square meter. For age-1+ O. mykiss , the average pool population abundance was 0.045 ( n =7; range: 0.002–0.179) fish per square meter. For age-0 O. mykiss in Walaluuks Creek, the average pool abundance was 0.207 fish per square meter ( n =7; range: 0.038–0.416), and for age-1+ fish, the average pool abundance was 0.382 fish per square meter ( n =6; range: 0.009–0.761). In Rock Creek, coho salmon were more abundant than O. mykiss in pools except for three pools upstream from rkm 20. The average pool abundance for coho salmon was 0.256 fish per square meter ( n =8; range: 0.019–0.756) in Rock Creek pools. In Walaluuks Creek, coho salmon were captured in four pools and were not captured in the upstream pools sampled. The average pool abundance for coho salmon in the four lower pools was 0.488 fish per square meter ( n =4; range: 0.417–0.548). Bridgelip suckers were captured in all pools in Rock Creek except the pool sampled at rkm 21.8. The average pool abundance for bridgelip suckers was 0.552 fish per square meter ( n =7; range: 0.015–1.554) in Rock Creek. Bridgelip suckers were captured in three downstream pools in Walaluuks Creek, and the average abundance was 0.044 fish per square meter ( n =3; range: 0.024–0.085). Overwinter and reach survival probabilities were estimated for O. mykiss and coho salmon using a Cormack-Jolly-Seber modeling approach. The best fit survival model for the O. mykiss and coho salmon was a reach only model. The upstream reach includes overwinter survival probability because fish are tagged and released in autumn and primarily migrate the following spring. During 2018, coho salmon (0.568, standard error [SE]=0.027) had a significantly higher probability of overwinter survival than O. mykiss (0.276, SE=0.019). The reach survival probability was higher for O. mykiss than coho salmon in the downstream migratory reaches. Survival was not modeled for bridgelip suckers. For bridgelip suckers, 147 were detected of 294, that were PIT tagged and released in the Rock Creek subbasin (50.0 percent). Information provided in this report increases our understanding of the status and trends of these populations. It further documents how intermittent streams can support salmonid populations. It also provides insight into potential management and restoration actions that could be beneficial and timing and allocation of resources. Ongoing monitoring work of this population will inform progress towards Rock Creek species recovery goals and contribution to recovery goals for the steelhead Middle Columbia River Distinct Population Segment.

Washington↗
USGS1977

Chemical composition of blood and bile of the shovelnose sturgeon

Samples of gallbladder bile and blood from shovelnose sturgeons (Scaphirhynchus platorynchus) collected from the Chippewa River, Wisconsin, contained concentrations of Na + , K + , Ca ++ , Mg ++ , Cl - , inorganic phosphate, and total cholesterol closely comparable with those reported for similar samples from other species of freshwater sturgeons.

Progressive Fish-Culturist↗
USGS1980

Geological Survey research 1980

A summary of recent significant scientific and economic results accompanied by a list of geologic, hydrologic, and cartographic investigations in progress.

Professional Paper↗
USGS1971

Channel movement of meandering Indiana streams

The process of channel movement in a meander system involves rotation and translation of meander loops and an increasing path length. The amount of path-length increase is directly proportional to the impulse supplied by discharge and is inversely proportional to the silt-clay percentage of the material composing the channel perimeter. Comparable paths have been obtained by standardizing measurements with a sine-generated curve and a moving reference axis. Analysis of previous investigations and time-of-travel data indicates that the discharge effective in channel formation consists of the range beginning just higher than the average and continuing throughout all higher discharges. Of six field sites investigated, three meander systems had path-length increases of sufficient magnitude to correlate with above-average discharge volume, one had no discernible change over a 30-year period, and two had changes which were too small for correlation owing to the short period of time covered by the available data. Because of the consistency of yearly above-average discharge volumes, it was possible to develop a general relation between path-length increase per thousand cubic-feet-per-second-days per square mile of drainage area above average discharge and the width-depth ratio of the channel. Little progress was made toward defining relationships for rotation and translation.

Indiana↗
USGS2018

Transport of nitrogen and phosphorus in the Cedar River Basin, Iowa and Minnesota, 2000–15

Nitrate concentrations in the Cedar River in Iowa and Minnesota have increased from an average of less than 1.0 milligram per liter in the early 1900s to more than 5.0 milligrams per liter in the 2000s and have resulted in periodic water-quality impairment of the river. Spatial differences and temporal changes in nitrogen and phosphorus transport in the Cedar River Basin are described for the period from 2000 to 2015. Data used to estimate nitrogen and phosphorus transport were collected by the U.S. Geological Survey as part of six base-flow synoptic studies and by the Minnesota Pollution Control Agency and the Iowa Department of Natural Resources as part of their long-term stream and river monitoring programs. The Cedar River transported an annual average of 53,100 tons of total nitrogen and 2,510 tons of total phosphorus during 2000–15. Three subbasins yielded an annual average of more than 30 pounds per acre (lb/acre) of nitrogen to the Cedar River, whereas two subbasins yielded an annual average of less than 20 lb/acre of nitrogen. The average annual total phosphorus yield from the Little Cedar River subbasin (0.35 lb/acre) was only about 16 percent of the yield from the greatest total phosphorus yielding Lower Cedar River subbasin (more than 1.0 lb/acre). The annual total nitrogen and total phosphorus loads did not change significantly during the study. The relation between annual stream runoff and annual total nitrogen and total phosphorus yields was not spatially uniform across the Cedar River Basin. The Beaver Creek, Black Hawk Creek, and Wolf Creek subbasins yielded the most, and the Main Stem Middle Cedar River, the Lower Cedar River, and the Little Cedar River subbasins yielded the least amount of nitrogen for a given amount of runoff. The Lower Cedar River and Wolf Creek subbasins yielded the most and the West Fork Cedar River and the Little Cedar River subbasins yielded the least phosphorus for a given amount of runoff. The results of this study describe nutrient transport during 2000–15 that can be used to evaluate future progress of nutrient reduction strategies in the Cedar River Basin.

Iowa, Minnesota↗
USGS1957

Geology and ground-water resources of Galveston County, Texas

Galveston County, on the Texas gulf coast, is underlain by alternating beds of sand and clay. These sand and clay strata crop out in belts that roughly parallel the coastline and dip gently southeastward at an angle gre? +,er than the slope of the land, thereby creating artesian aquifers. The formations that yield potable water to wells are the Lissie formation, the "Alta Loma" sand and other sands of the Beaumont clay, and beach and dune sands of Recent aie. Most of the potable water is obtained on the mainland of Galveston County. The water from most wells on Galveston Island is highly mineralized. Before 1948, water for all public use and nearly all industrial use was derived from wells. Most ground water now used in the county is pumped from areas around Alta Loma and Texas City. The average daily pumpage in these areas increased from 6 million gallons in 1938 to 17.8 million gallons in 1940 and reached a peak of about 34 million gallons in 1945. Between 1945 and 1948 the rate of pumpage was nearly constant, but in 1948 surface water was diverted from the Brazos River to supply some of the Texas City industries and, as a result, the use of ground water was reduced about 30 percent. Water levels declined in county wells as the pumpage increased during the years prior to 1948. Since water from the Brazos River has been utilized the levels have risen in many wells and tended to become constant in others. Subsidence of the land in a large part of the county, particularly in the Texas City area, is attributed to the excessive withdrawal of ground water. Salt-water encroachment has been a problem in the county for many years. Salt water was present in the lower part of the "Alta Loma" sand in the Alta Loma and Texas City areas and throughout that sand on Galveston Island when the first wells were drilled. Encroachment from either below or downdip took place with the lowering of artesian pressure in the aquifer in the vicinity of Alta Loma and Texas City. Pumping tests reveal that the average coefficient of transmissibility of the "Alta Loma" sand is 102,000 at Alta Loma and 153,000 at Texas City. The coefficients- of transmissibility of sands in the upper part of the Beaumont clay around Texas City average 27,300. Surface water from the Brazos River, used for the irrigation of rice since 1942, was made available in 1948 to industries in Texas City as a substitute for ground water. The water from the Brazos River is variable in quality, but probably can be utilized on a somewhat larger scale than at present. Much additional ground water could be obtained from both the "Alta Loma" sand and the upper part of the Beaumont clay, especially in the northern and western parts of the county. Before large developments of supplies are planned, however, these areas should be explored by test drilling. The problems of well spacing and pumping rates should be thoroughly studied in order to determine the maximum development permitted by the ground-water supply. Current observations should be continued with special emphasis on the progress of salt-water encroachment.

Water Supply Paper↗
USGS2020

Woods Hole Coastal and Marine Science Center—2019 annual report

The 2019 annual report of the U.S. Geological Survey Woods Hole Coastal and Marine Science Center highlights accomplishments of 2019, includes a list of 2019 publications, and summarizes the work of the center, as well as the work of each of its science groups. This product allows readers to gain a general understanding of the focus areas of the center’s scientific research and learn more about specific projects and progress made throughout 2019, all while enjoying interesting photographs taken in various environments and laboratories, and applicable maps and figures.

Circular↗
USGS1982

Test and calibration of the Digital World-Wide Standardized Seismograph

During the past decade there has been steady progress in the modernization of the global seismograph network operated by the U.S. Geological Survey (USGS). The World-Wide Standardized Seismograph Network (WWSSN) has been augmented by new stations with advanced instrumentation, including the Seismic Research Observatories (SRO) and the modified High-Gain Long-Period (ASRO) stations. One goal in the modernization effort has been to improve signal resolution in the long-period band. A second goal has been to generate a global digital data base to support contemporary computer-based analysis and research. In 1976, a Panel on Seismograph Networks was established by the Committee on Seismology of the National Academy of Sciences to review progress in network seismology and recommend actions that would lead to an improved global data base for seismology. One recommendation in the Panel report (Engdahl, 1977) called for upgrading selected WWSSN stations by the installation of digital recorders. This was viewed as an economical way of expanding the digital network, which had proven itself to be a very promising new tool for earthquake and explosion research. Funds for the development and assembly of 15 digital recorders were provided to the USGS by the Defense Advanced Research Projects Agency and an ad Inoc panel of scientists was convened by the Committee on Seismology to advise the USGS on the selection of stations to be upgraded and on data recording requirements, A total of 19 digital World-Wide Standardized Seismograph (DWWSS) systems will be operational when all are installed. The additional systems were made available through purchase by the USGS and other organizations; for example, the University of Bergen purchased and installed a DWWSS-type recorder and agreed to furnish the USGS with the data. A list of operational and planned DWWSS network stations is given in Table 1.1. As one might expect, the digital recorder turned out to be somewhat more sophisticated than the original concept. It was decided to record three components of long-period data continuously, three components of intermediateperiod data in an event mode, and the vertical-component short-period data in and event mode (with the capability of adding short-period horizontal channels in the future). Special amplifiers were developed for use with the WWSS seismometers, and a 16-bit fixed-point analog-to-digital converter was chosen to provide increased resolution (as opposed to a 16-bit gain-ranged encoder). The microprocessor-based digital recording systems were developed and assembled at the USGS Albuquerque Seismological Laboratory (ASL) and ASL-based technicians began installation at WWSSN stations in 1980. The current and proposed locations of the DWWSSN stations, together with other stations in the Global Digital Seismograph Network (GDSN), are shown on the map in Figure 1.1. A system was operated at Albuquerque for about 18 months, serving as a test bed for evaluation studies. Although the network hardware has been available for some time, the installation of the DWWSSN has proceeded slowly. The National Science Foundation supported installation of six stations and the USGS is funding installation of most of the others; however, the network completion date is conjectural because of funding uncertainties. The DWWSSN stations are supported with supplies and technical assistance from ASL (subject to availability of funds). Data recorded on magnetic tapes are mailed to ASL where they are reviewed for quality, then merged with other GDSN station data on the network-day tapes. Hoffman (1980) provides a description of the network-day tape format. Zirbes and Buland (1981) have developed and published user software for reading and interpreting the day tapes. This report will serve several purposes. One is to provide nominal system transfer functions and calibration information that are needed in the analysis of DWWSSN data. A second purpose is to report on an evaluation of operating characteristics (calibration stability, noise levels, and linearity) that may limit the usefulness of the data and to determine if modifications may be needed to improve the data. It is not an exhaustive study in this respect. We continue to depend mostly on data user feedback to point out deficiencies and we solicit comments whenever anomalies are observed in the data.

Open-File Report↗
USGS2019

Woods Hole Coastal and Marine Science Center—2018 annual report

The 2018 annual report of the U.S. Geological Survey Woods Hole Coastal and Marine Science Center summarizes the work of the center, as well as the work of each of its science groups, highlights accomplishments of 2018, and includes a list of publications published in 2018. This product allows readers to gain a general understanding of the focus areas of the center’s scientific research and learn more about specific projects and progress made throughout 2018, all while enjoying applicable photos taken in the field and of various models, maps, and web pages.

Massachusetts↗
USGS1916

Preliminary report on the diffusion of solids

Although 19 years has elapsed since Roberts-Austen published his classical paper on the diffusion of solid metals, no attempt seems to have been made to verify his important results and conclusions or to extend the investigations to minerals and to the great number of solids in which diffusion may be expected to occur. Progress has been made by means of chemical and electrical methods in the detection of diffusion in a number of metals in the solid state, some progress has been made in explaining the phenomena of diffusion on the basis of osmotic pressure and the kinetic theory, and recent measurements of the vapor pressures of solids have contributed indirectly to the progress of the science, but investigators have not undertaken the difficult and essential task of making definitive determinations of the coefficients of diffusivity at various pressures and temperatures.

Professional Paper↗
USGS2008

Geochemical data for samples collected in 2007 near the concealed pebble porphyry Cu-Au-Mo deposit, southwest Alaska

In the summer of 2007, the U.S. Geological Survey (USGS) began an exploration geochemical research study over the Pebble porphyry copper-gold-molydenum (Cu-Au-Mo) deposit in southwest Alaska. The Pebble deposit is extremely large and is almost entirely concealed by tundra, glacial deposits, and post-Cretaceous volcanic and volcaniclastic rocks. The deposit is presently being explored by Northern Dynasty Minerals, Ltd., and Anglo-American LLC. The USGS undertakes unbiased, broad-scale mineral resource assessments of government lands to provide Congress and citizens with information on national mineral endowment. Research on known deposits is also done to refine and better constrain methods and deposit models for the mineral resource assessments. The Pebble deposit was chosen for this study because it is concealed by surficial cover rocks, it is relatively undisturbed (except for exploration company drill holes), it is a large mineral system, and it is fairly well constrained at depth by the drill hole geology and geochemistry. The goals of the USGS study are (1) to determine whether the concealed deposit can be detected with surface samples, (2) to better understand the processes of metal migration from the deposit to the surface, and (3) to test and develop methods for assessing mineral resources in similar concealed terrains. This report presents analytical results for geochemical samples collected in 2007 from the Pebble deposit and surrounding environs. The analytical data are presented digitally both as an integrated Microsoft 2003 Access? database and as Microsoft 2003 Excel? files. The Pebble deposit is located in southwestern Alaska on state lands about 30 km (18 mi) northwest of the village of Illiamna and 320 km (200 mi) southwest of Anchorage (fig. 1). Elevations in the Pebble area range from 287 m (940 ft) at Frying Pan Lake just south of the deposit to 1146 m (3760 ft) on Kaskanak Mountain about 5 km (5 mi) to the west. The deposit is in an area of relatively subdued topographic relief with an elevation of around 300 m (1000 ft). This portion of Alaska is part of the subarctic regime mountains division, Yukon intermontane plateaus-tayga-meadow province ecoregion, as defined by Bailey (U.S. Forest Service, 2007). Between June 28th and July 12th, 2007, scientists from the USGS collected soil, water, stream sediment, vegetation, heavy-mineral concentrate, till, and rock samples from the deposit area. This report contains analytical results for soil, water, stream sediment, and vegetation samples. Analyses for the heavy-mineral concentrate, till, and rock samples are still in progress. The sampling was undertaken during relatively dry and stable weather conditions. Only minor scattered rain showers occurred during the sampling period, so surface conditions were largely unaffected by weather. The predominant sample media collected were soils and surface waters. Soil and water (mostly from ponds and springs, some from small creeks) samples were collected along a single 7.8 km-long (4.8 mi) east-west traverse across the Pebble East and Pebble West zones and from more distal background areas around Koktuli and Kaskanak Mountains. Sample sites are shown on figure 2 and plate 1, and locality coordinates are provided in the accompanying Access and Excel files named FieldSite. Water samples were analyzed by USGS laboratories with one subset analyzed by Activation Laboratories (Actlabs), as indicated below. Soils and stream sediments were analyzed for their total content by SGS Minerals Services under a contract with the USGS. Soil samples were also leached by selected partial-extraction leaching procedures and then analyzed by several commercial laboratories, as described below. Vegetation samples were analyzed as indicated below.

Alaska↗
USGS1980

Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

Environmental chloride has been shown to inhibit methemoglobin formation in fish, thereby offering a protective effect against nitrite toxicity. Channel catfish (Ictalurus punctatus) were simultaneously exposed to various environmental nitrite and chloride levels (as either CaCl 2 or NaCl) in dechlorinated tap water (40 mg/L total hardness, 47 mg/L alkalinity, 4 mg/L chloride, pH = 6.9-7.1, and temperature 21-24°C). Methemoglobin levels in fish simultaneously exposed to 2.5 mg/L nitrite and up to 30 mg/L chloride as either CaCl 2 or NaCl were similar but significantly lower than in unprotected fish. Exposure to 10 mg/L nitrite and 60 mg/L chloride resulted in methemoglobin levels similar to those of the controls; most unprotected fish died. Fish exposed to 10 mg/L nitrite had significantly lower methemoglobin levels when protected with 15.0 mg/L chloride as CaCl 2 than with NaCl. Fish exposed to nitrite in the presence of 60 mg/L chloride (as either CaCl 2 or NaCl) had similar 24-h LC50 values that were significantly elevated above those obtained in the absence of chloride. Calcium had little effect on tolerance to nitrite toxicity in channel catfish in contrast to its large effect reported in steelhead trout (Salmo gairdneri).

Progressive Fish-Culturist↗
USGS2019

Mapping crop residue by combining Landsat and WorldView-3 satellite imagery

A unique, multi-tiered approach was applied to map crop-residue cover on the Eastern Shore of the Chesapeake Bay, USA. Field measurements of crop-residue cover were used to calibrate residue mapping using shortwave infrared (SWIR) indices derived from WorldView-3 imagery for an 8-km x 8-km footprint. The resulting map was then used to calibrate and subsequently classify residue mapping of Landsat imagery at a larger spatial resolution and extent. This manuscript describes how the method was applied and presents results in the form of crop-residue cover maps, validation statistics, and quantification of conservation tillage implementation in the agricultural landscape. Overall accuracy for maps derived from Landsat 7 (ETM+) and Landsat 8 (OLI) were comparable at roughly 92% (+/- 10%). Tillage class specific accuracy was also strong and ranged from 75% to 99%. The approach, which employed a 12-band image stack of six tillage spectral indices and six individual Landsat bands, was shown to be adaptable to variable soil-moisture conditions: under dry conditions (Landsat 7, May 14, 2015) the majority of predictive power was attributed to SWIR indices, and under wet conditions (Landsat 8, May 22, 2015) single band reflectance values were more effective at explaining variability in residue cover. Summary statistics of resulting tillage class occurrence matched closely with conservation tillage implementation totals reported by Maryland and Delaware to the Chesapeake Bay Program. This hybrid method combining WorldView-3 and Landsat imagery sources shows promise for monitoring progress in the adoption of conservation tillage practices and for describing crop-residue outcomes associated with a variety of agricultural management practices.

Maryland↗