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J. E. Costa

Publications and source records attributed to J. E. Costa.

At least 19 recordsLinked to original sources

Buzzards Bay salt marshes: Vulnerability and adaptation potential

Salt marshes with lush grass meadows teeming with shorebirds are iconic features of the Buzzards Bay coast and provide opportunities for recreation, aesthetic enjoyment, as well as important environmental benefits. These productive coastal wetlands are important because they protect properties from storm surges, remove nutrients from the water and carbon from the atmosphere, and provide critical habitats for fish, shellfish, and birds. Found where the land meets the sea, salt marshes are naturally dynamic features that change with rising seas, waves, ice, and storms. In the past, humans purposely altered salt marshes by filling them to create buildable land or digging drainage ditches. These major alterations harmed marsh structure and health. In recent decades, however, marshes are degrading because of more diffuse and complex pressures such as nutrient pollution, sea level rise, major storms, and crab overgrazing. As a result, at many places along the East Coast, marshes have crumbling banks and large areas where the plants have died, leaving behind mudflats. The Buzzards Bay Coalition and the Buzzards Bay National Estuary Program began field monitoring of salt marshes around Buzzards Bay in 2019 to document changes (map below shows sites). We partnered with the U.S. Geological Survey and the Woodwell Climate Research Center to use aerial tools to investigate how different characteristics of the long-term marsh sites and their watersheds affect the marsh’s current health and likely future. This report brings together the results of on the ground monitoring with data from aerial imagery to look at marsh status at 12 long-term monitoring sites based on existing stressors, current marsh conditions, and potential for adaptation.

Massachusetts

Digital Data for Volcano Hazards of the Mount Hood Region, Oregon

Snow-clad Mount Hood dominates the Cascade skyline from the Portland metropolitan area to the wheat fields of Wasco and Sherman Counties. The mountain contributes valuable water, scenic, and recreational resources that help sustain the agricultural and tourist segments of the economies of surrounding cities and counties. Mount Hood is also one of the major volcanoes of the Cascade Range, having erupted repeatedly for hundreds of thousands of years, most recently during two episodes in the past 1,500 yr. The last episode ended shortly before the arrival of Lewis and Clark in 1805. When Mount Hood erupts again, it will severely affect areas on its flanks and far downstream in the major river valleys that head on the volcano. Volcanic ash may fall on areas up to several hundred kilometers downwind. The purpose of the volcano hazard report USGS Open-File Report 97-89 (Scott and others, 1997) is to describe the kinds of hazardous geologic events that have happened at Mount Hood in the past and to show which areas will be at risk when such events occur in the future. This data release contains the geographic information system (GIS) data layers used to produce the Mount Hood volcano hazard map in USGS Open-File Report 97-89. Both proximal and distal hazard zones were delineated by scientists at the Cascades Volcano Observatory and depict various volcano hazard areas around the mountain. A second data layer contains points that indicate estimated travel times of lahars.

Oregon

GSA committees: Progress through service the Annual Program Committee

The GSA's Annual Program Committee (APC) is directly responsible for the GSA's meeting and other responsibilities especially before the main event. It decides on the locations, the number and content of the technical sessions, annual membership surveys, hospitality for the guests, field trips and more. In addition, it pays significant attention to creative thinking about geoscience discoveries and directions as well as identify new and emerging areas of earth science. APC is also looking for new ideas, approaches and directions.

GSA Today

Use of radars to monitor stream discharge by noncontact methods

Conventional measurements of river flows are costly, time‐consuming, and frequently dangerous. This report evaluates the use of a continuous wave microwave radar, a monostatic UHF Doppler radar, a pulsed Doppler microwave radar, and a ground‐penetrating radar to measure river flows continuously over long periods and without touching the water with any instruments. The experiments duplicate the flow records from conventional stream gauging stations on the San Joaquin River in California and the Cowlitz River in Washington. The purpose of the experiments was to directly measure the parameters necessary to compute flow: surface velocity (converted to mean velocity) and cross‐sectional area, thereby avoiding the uncertainty, complexity, and cost of maintaining rating curves. River channel cross sections were measured by ground‐penetrating radar suspended above the river. River surface water velocity was obtained by Bragg scattering of microwave and UHF Doppler radars, and the surface velocity data were converted to mean velocity on the basis of detailed velocity profiles measured by current meters and hydroacoustic instruments. Experiments using these radars to acquire a continuous record of flow were conducted for 4 weeks on the San Joaquin River and for 16 weeks on the Cowlitz River. At the San Joaquin River the radar noncontact measurements produced discharges more than 20% higher than the other independent measurements in the early part of the experiment. After the first 3 days, the noncontact radar discharge measurements were within 5% of the rating values. On the Cowlitz River at Castle Rock, correlation coefficients between the USGS stream gauging station rating curve discharge and discharge computed from three different Doppler radar systems and GPR data over the 16 week experiment were 0.883, 0.969, and 0.992. Noncontact radar results were within a few percent of discharge values obtained by gauging station, current meter, and hydroacoustic methods. Time series of surface velocity obtained by different radars in the Cowlitz River experiment also show small‐amplitude pulsations not found in stage records that reflect tidal energy at the gauging station. Noncontact discharge measurements made during a flood on 30 January 2004 agreed with the rated discharge to within 5%. Measurement at both field sites confirm that lognormal velocity profiles exist for a wide range of flows in these rivers, and mean velocity is approximately 0.85 times measured surface velocity. Noncontact methods of flow measurement appear to (1) be as accurate as conventional methods, (2) obtain data when standard contact methods are dangerous or cannot be obtained, and (3) provide insight into flow dynamics not available from detailed stage records alone.

Water Resources Research

The Piedmont landscape of Maryland: a new look at an old problem.

Both equilibrium and episodic erosion features can be recognized in the modern landscape. An equilibrium condition is suggested by adjustment of first and second order streams to rock structure and lithology, entrenchment of some streams against gneiss domes, altitudinal zonation of rock types around gneiss domes, correlation of lithology with overburden thickness on uplands, etc. The long-term episodic character of erosion is suggested by clastic wedges on the adjacent Coastal Plain, an upland of low relief that truncates non-carbonate rocks of different lithologies, isovolumetric chemical weathering of alumino-silicate rocks, clastic deposition in marble valleys, and weathering profile truncation by modern drainage. The upland surface preserved in the eastern Piedmont developed by the Late Cretaceous. In the interval from the Late Cretaceous to the Late Miocene, low input of terrigenous sediments to the Coastal Plain, dominance of marine sedimentation, and spotty evidence of saprolite formation on crystalline rocks, suggest that the Maryland Piedmont was an area of low relief undergoing intense weathering. Incised valleys were formed during a cycle of erosion probably initiated in the Late Miocene and extensive colluvial sediments were deposited on hillslopes by periglacial processes during the Pleistocene.-after Authors

Earth Surface Processes and Landforms

River discharge measurements by using helicopter-mounted radar

The United States Geological Survey and the University of Washington collaborated on a series of initial experiments on the Lewis, Toutle, and Cowlitz Rivers during September 2000 and a detailed experiment on the Cowlitz River during May 2001 to determine the feasibility of using helicopter-mounted radar to measure river discharge. Surface velocities were measured using a pulsed Doppler radar, and river depth was measured using ground-penetrating radar. Surface velocities were converted to mean velocities, and horizontal registration of both velocity and depth measurements enabled the calculation of river discharge. The magnitude of the uncertainty in velocity and depth indicate that the method error is in the range of 5 percent. The results of this experiment indicate that helicopter-mounted radar can make the rapid, accurate discharge measurements that are needed in remote locations and during regional floods.

Washington

Looking to the Future: Non-contact Methods for Measuring Streamflow

We have conducted a series of proof-of-concept experiments to demonstrate whether it is possible to make completely non-contact open-channel discharge measurements. After an extensive evaluation of potential technologies, we concluded a combination of high-frequency (microwave) radar (for measuring surface velocity) and low-frequency radar (ground-penetrating radar) for measuring channel cross-section, had the best chance for success. The first experiment in 1999 on the Skagit River, Washington, using non-contact methods, produced a discharge value nearly exactly the same as from an ADCP and current meter. Surface-velocity data were converted to mean velocity based on measurements of the velocity profile (multiplied by 0.85), and radar signal speed in impure fresh water was measured to be 0.11-0.12 ft/ns. The weak link was thought to be the requirement to suspend the GPR antenna over the water, which required a bridge or cableway. Two contractors, expert with radar, were unsuccessful in field experiments to measure channel cross-section from the riverbank. Another series of experiments were designed to demonstrate whether both radar systems could be mounted on a helicopter, flown back and forth across a river, and provide data to compute flow. In Sept. 2000 and May 2001, a series of helicopter flights with mounted radar systems successfully measured surface velocity and channel cross-section of the Cowlitz River, Washington.

Conference Paper

Measuring stream discharge by non-contact methods: A proof-of-concept experiment

This report describes an experiment to make a completely non-contact open-channel discharge measurement. A van-mounted, pulsed doppler (10GHz) radar collected surface-velocity data across the 183-m wide Skagit River, Washington at a USGS streamgaging station using Bragg scattering from short waves produced by turbulent boils on the surface of the river. Surface velocities were converted to mean velocities for 25 sub-sections by assuming a normal open-channel velocity profile (surface velocity times 0.85). Channel cross-sectional area was measured using a 100 MHz ground-penetrating radar antenna suspended from a cableway car over the river. Seven acoustic doppler current profiler discharge measurements and a conventional current-meter discharge measurement were also made. Three non-contact discharge measurements completed in about a 1-hour period were within 1 % of the gaging station rating curve discharge values. With further refinements, it is thought that open-channel flow can be measured reliably by non-contact methods.

Geophysical Research Letters

Sediment yield following severe volcanic disturbance - A two-decade perspective from Mount St. Helens

Explosive volcanic eruptions perturb water and sediment fluxes in watersheds; consequently, posteruption sediment yields can exceed pre-eruption yields by several orders of magnitude. Annual suspended-sediment yields following the catastrophic 1980 Mount St. Helens eruption were as much as 500 times greater than typical background level, and they generally declined nonlinearly for more than a decade. Although sediment yields responded primarily to type and degree of disturbance, streamflow fluctuations significantly affected sediment-yield trends. Consecutive years (1995–1999) of above-average discharge reversed the nonlinear decline and rejuvenated yields to average values measured within a few years of the eruption. After 20 yr, the average annual suspended-sediment yield from the 1980 debris-avalanche deposit remains 100 times (10 4 Mg [megagrams]/km 2 ) above typical background level (∼10 2 Mg/km 2 ). Within five years of the eruption, annual yields from valleys coated by lahar deposits roughly plateaued, and average yields remain about 10 times (10 3 Mg/km 2 ) above background level. Yield from a basin devastated solely by a blast pyroclastic current diminished to background level within five years. These data demonstrate long-term instability of eruption-generated detritus, and show that effective mitigation measures must remain functional for decades.

Washington

Measuring flood discharge in unstable stream channels using ground-penetrating radar

Field experiments were conducted to test the ability of ground-penetrating radar (GPR) to measure stream-channel cross sections at high flows without the necessity of placing instruments in the water. Experiments were conducted at four U.S. Geological Survey gaging stations in southwest Washington State. With the GPR antenna suspended above the water surface from a bridge or cableway, traverses were made across stream channels to collect radar profile plots of the streambed. Subsequent measurements of water depth were made using conventional depth-measuring equipment (weight and tape) and were used to calculate radar signal velocities. Other streamflow-parameter data were collected to examine their relation to radar signal velocity and to clarity of streambed definition. These initial tests indicate that GPR is capable of producing a reasonably accurate (±20%) stream-channel profile and discharge far more quickly than conventional stream-gaging procedures, while avoiding the problems and hazards associated with placing instruments in the water.

Geology

Hydraulic modeling for lahar hazards at cascades volcanoes

The National Weather Service flood routing model DAMBRK is able to closely replicate field-documented stages of historic and prehistoric lahars from Mt. Rainier, Washington, and Mt. Hood, Oregon. Modeled time-of-travel of flow waves are generally consistent with documented lahar travel-times from other volcanoes around the world. The model adequately replicates a range of lahars and debris flows, including the 230 million km3 Electron lahar from Mt. Rainier, as well as a 10 m3 debris flow generated in a large outdoor experimental flume. The model is used to simulate a hypothetical lahar with a volume of 50 million m3 down the East Fork Hood River from Mt. Hood, Oregon. Although a flow such as this is thought to be possible in the Hood River valley, no field evidence exists on which to base a hazards assessment. DAMBRK seems likely to be usable in many volcanic settings to estimate discharge, velocity, and inundation areas of lahars when input hydrographs and energy-loss coefficients can be reasonably estimated.

Environmental & Engineering Geoscience

Volcano hazards in the Mount Hood region, Oregon

Mount Hood is a potentially active volcano close to rapidly growing communities and recreation areas. The most likely widespread and hazardous consequence of a future eruption will be for lahars (rapidly moving mudflows) to sweep down the entire length of the Sandy (including the Zigzag) and White River valleys. Lahars can be generated by hot volcanic flows that melt snow and ice or by landslides from the steep upper flanks of the volcano. Structures close to river channels are at greatest risk of being destroyed. The degree of hazard decreases as height above a channel increases, but large lahars can affect areas more than 30 vertical meters (100 vertical feet) above river beds. The probability of eruption-generated lahars affecting the Sandy and White River valleys is 1-in-15 to l-in-30 during the next 30 years, whereas the probability of extensive areas in the Hood River Valley being affected by lahars is about ten times less. The accompanying volcano-hazard-zonation map outlines areas potentially at risk and shows that some areas may be too close for a reasonable chance of escape or survival during an eruption. Future eruptions of Mount Hood could seriously disrupt transportation (air, river, and highway), some municipal water supplies, and hydroelectric power generation and transmission in northwest Oregon and southwest Washington.

Oregon

The potential for catastrophic dam failure at Lake Nyos maar, Cameroon

The upper 40 m of Lake Nyos is bounded on the north by a narrow dam of poorly consolidated pyroclastic rocks, emplaced during the eruptive formation of the Lake Nyos maar a few hundred years ago. This 50-m-wide natural dam is structurally weak and is being eroded at an uncertain, but geologically alarming, rate. The eventual failure of the dam could cause a major flood (estimated peak discharge, 17000 m3/s) that would have a tragic impact on downstream areas as far as Nigeria, 108 km away. This serious hazard could be eliminated by lowering the lake level, either by controlled removal of the dam or by construction of a 680-m-long drainage tunnel about 65 m below the present lake surface. Either strategy would also lessen the lethal effects of future massive CO2 gas releases, such as the one that occurred in August 1986. ?? 1988 Springer-Verlag.

Bulletin of Volcanology

Evaluation of the flood hydrology in the Colorado Front Range using precipitation, streamflow, and paleoflood data for the Big Thompson River basin

A multidisciplinary study of precipitation and streamflow data and paleohydrologic studies of channel features was made to analyze the flood hydrology of foothill and mountain streams in the Front Range of Colorado, with emphasis on the Big Thompson River basin, because conventional hydrologic analyses do not adequately characterize the flood hydrology. In the foothills of Colorado, annual floodflows are derived from snowmelt at high elevations in the mountain regions, from rainfall at low elevation in the plains or plateau regions, or from a combination of rain falling on snow or mixed population hydrology. Above approximately 7,500 ft, snowmelt dominates; rain does not contribute to the flood potential. Regional flood-frequency relations were developed and compared with conventional flood-estimating technique results, including an evaluation of the magnitude and frequency of the probable maximum flood. Evaluation of streamflow data and paleoflood investigations provide an alternative for evaluating flood hydrology and the safety of dams. The study indicates the need for additional data collection and research to understand the complexities of the flood hydrology in mountainous regions, especially its effects on flood-plain management and the design of structures in the flood plain. (USGS)

Water-Resources Investigations Report

Hydraulics and basin morphometry of the largest flash floods in the conterminous United States

The maximum rainfall-runoff floods measured by indirect methods in small basins (0.39-370 km 2 ) in the conterminous United States are examined. This analysis identified twelve floods that were the largest ever measured. These floods all occurred in semiarid to arid areas. For eleven of the twelve largest rainfall-runoff floods measured in small basins by the slope-area method, values of hydraulic depth; hydraulic radius; width-depth ratio; n value; mean velocity; velocity-head coefficient; Froude number; water-surface, energy, and channel slopes; shear stress; and unit stream power are tabulated. Estimated composite n values weighted by subsection conveyance range from 0.028 to 0.048 with a mean of 0.038. Mean velocities ranged from 3.47 to 9.97 m s −1 . Froude numbers ranged from 0.81 to 2.49, with 9 of 12 floods having values greater than 1.00. Water-surface, energy, and channel slopes vary considerably for each flood. Energy slope always was less than water-surface slope by values of 1–104%. Channel slope was greater than energy slope in eight floods. Shear stresses ranged between 61 and 855 N m −2 , and unit stream power from 212 to 8131 w m −1 . Floods in these small basins produced shear stresses and unit stream powers several hundred times greater than floods in large rivers. Floods on other small streams, with smaller unit discharges, produced greater shear stresses and stream powers. This indicates that the force of a flood is controlled by the depth-slope product, not absolute discharge. In the twelve watersheds studied, basin relief ranged from 165 to 1280 m, elongation ratios ranged from 0.55 to 0.80, the number of first-order streams (basin magnitude) ranged from 10 to 4297, drainage density ranged from 4.1 to 10.9 km km −2 , basin slope ranged from 0.0043 to 0.2486, relief ratio ranged from 0.0097 to 0.34, ruggedness number ranged from 0.69 to 7.17, and first-order channel frequency ranged from 5.1 to 38.6 km −2 . Elongation ratios were larger, and drainage density and first-order channel frequency lower, than other small flash-flood prone basins in the United States. These twelve basins have neither the most favorable morphometric characteristics which contribute to flash-flood peaks, nor did the storms causing these flash floods have the greatest short-duration intensities. Maximum flood peaks originate from an optimal combination of basin morphology and physiography, and storm intensity.

conterminous United States

A comparison of the largest rainfall-runoff floods in the United States with those of the People's Republic of China and the world

The maximum historic rainfall-runoff floods measured in the United States, the People's Republic of China and the world all plot close to a smooth curve of drainage area versus discharge. In the United States, the possibility that flood peaks were overestimated and the closeness of these peaks to the probable maximum floods suggest that this limiting curve of maximum floods will not significantly change position with more data. Data for future floods that plot above this curve need to be examined carefully. The most likely interpretations for new data points above the curve would be the confusion of a mud or debris flow with a water-dominated flood, or the damming of channels by debris or a landslide and subsequent bursting. In the United States, excluding Hawaii, the largest measured historic floods in basins less than about 1000 km 2 , all occurred in arid and semi-arid areas. In China, the majority of the largest measured historic floods occurred in the east and southeast in basins on the windward side of mountainous areas, and in locations affected by typhoons. One extraordinary flood that exceeds any other recorded flood in the world for the size of the drainage basin in which it occurred is the New Caledonia flood of December 24, 1981 on the Ouaieme River. Worldwide, the largest measured historic floods occurred primarily between 40°N and 40°S latitude on streams and rivers near coastal areas.

Journal of Hydrology

The formation and failure of natural dams

Of the numerous kinds of dams that form by natural processes, dams formed from landslides, glacial ice, and neoglacial moraines present the greatest threat to people and property. The most common types of mass movements that form landslide dams are rock and debris avalanches, rock and soil slumps and slides, and mud, debris, and earth flows. The most common initiation mechanisms for dam-forming landslides are excessive rainfall and snowmelt and earthquakes. Landslide dams can be classified into six categories based on their relation with the valley floor. Type I dams (11%) of the 81 landslide dams around the world that were classifed do not reach from one valley side to the other. Type II dams (44%) span the entire valley flood, occasionally depositing material high up on opposite valley sides. Type III dams (41%) move considerable distances both upstream and downstream from the landslide failure. Type IV dams (1%) are rare and involve the contemporaneous failure of material from both sides of a valley. Type V dams (1%) are also rare, and are created when a single landslide sends multiple tongues of debris into a valley forming two or more landslide dams in the same surfaces, that extend under the stream or valley and emerge on the opposite valley side. Many landslide dams fail shortly after formation. Overtopping is by far the most common cause of failure. Glacial ice dams can produce at least nine kinds of ice-dammed lakes. The most dangerous are lakes formed in main valleys dammed by tributary glaciers. Failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam. Cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel. Warmer temperate-ice dams tend to fail by sudden englacial or subglacial breaching and drainage. Late neoglacial moraine-dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries. The most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake, generated by icefalls, rockfalls, or snow or rock avalanches. Melting of ice-cores or frozen ground and piping and seepage are other possible failure mechanisms. (Lantz-PTT)

Open-File Report