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J. A. Moody

Publications and source records attributed to J. A. Moody.

At least 19 recordsLinked to original sources
USGS2021

Large-scale variation in wave attenuation of oyster reef living shorelines and the influence of inundation duration

One of the paramount goals of oyster reef living shorelines is to achieve sustained and adaptive coastal protection, which requires meeting ecological (i.e., develop a self-sustaining oyster population) and engineering (i.e., provide coastal defense) targets. In a large-scale comparison along the Atlantic and Gulf coasts of the United States, the efficacy of various designs of oyster reef living shorelines at providing wave attenuation was evaluated accounting for the ecological limitations of oysters with regard to inundation duration. A critical threshold for intertidal oyster reef establishment is 50% inundation duration. Living shorelines that spent less than one-half of the time (<50%) inundated were not considered suitable habitat for oysters, however, were effective at wave attenuation (68% reduction in wave height). Reefs that experienced >50% inundation were considered suitable habitat for oysters, but wave attenuation was similar to controls (no reef; ~5% reduction in wave height). Many of the oyster reef living shoreline approaches therefore failed to optimize the ecological and engineering goals. In both inundation regimes, wave transmission decreased with an increasing freeboard (difference between reef crest elevation and water level), supporting its importance in the wave attenuation capacity of oyster reef living shorelines. However, given that the reef crest elevation (and thus freeboard) should be determined by the inundation duration requirements of oysters, research needs to be refocused on understanding the implications of other reef parameters (e.g., width) for optimizing wave attenuation. A broader understanding of the reef characteristics and seascape contexts that result in effective coastal defense by oyster reefs is needed to inform appropriate design and implementation of oyster-based living shorelines globally.

Alabama, Florida, Louisiana, New Jersey, Virginia↗
USGS2019

The application of oyster reefs in shoreline protection: Are we over‐engineering for an ecosystem engineer?

Oyster reef living shorelines have been proposed as an effective alternative to traditional coastal defence structures (e.g. bulkheads, breakwaters), with the benefit that they may keep pace with sea‐level rise and provide co‐benefits, such as habitat provision. However, there remains uncertainty about the effectiveness of shoreline protection provided by oyster reefs, which limits their broader application. We draw evidence from studies along the east and gulf coasts of the United States, where much research and implementation of oyster reef restoration has occurred, to better define the existing gaps in our understanding of the use of restored oyster reefs for shoreline protection. We find potential disconnects between ecological and engineering functions of reefs. In response, we outline how engineering and ecological principles are used in the design of oyster reef living shorelines and highlight knowledge gaps where an integration of these disciplines will lead to their more effective application. Synthesis and applications . This work highlights the necessary steps to advance the application of oyster reef living shorelines. Importantly, future research should focus on appropriate designs and conditions needed for these structures to effectively protect our coasts from erosion, while supporting a sustainable oyster population, thereby providing actionable nature‐based alternatives for coastal defence to diverse end‐users.

East Coast of Continental United States↗
USGS2016

Illuminating wildfire erosion and deposition patterns with repeat terrestrial lidar

Erosion following a wildfire is much greater than background erosion in forests because of wildfire-induced changes to soil erodibility and water infiltration. While many previous studies have documented post-wildfire erosion with point and small plot-scale measurements, the spatial distribution of post-fire erosion patterns at the watershed scale remains largely unexplored. In this study lidar surveys were collected periodically in a small, first-order drainage basin over a period of 2 years following a wildfire. The study site was relatively steep with slopes ranging from 17° to > 30°. During the study period, several different types of rain storms occurred on the site including low-intensity frontal storms (2.4 mm h −1 ) and high-intensity convective thunderstorms (79 mm h −1 ). These storms were the dominant drivers of erosion. Erosion resulting from dry ravel and debris flows was notably absent at the site. Successive lidar surveys were subtracted from one another to obtain digital maps of topographic change between surveys. The results show an evolution in geomorphic response, such that the erosional response after rain storms was strongly influenced by the previous erosional events and pre-fire site morphology. Hillslope and channel roughness increased over time, and the watershed armored as coarse cobbles and boulders were exposed. The erosional response was spatially nonuniform; shallow erosion from hillslopes (87% of the study area) contributed 3 times more sediment volume than erosion from convergent areas (13% of the study area). However, the total normalized erosion depth (volume/area) was highest in convergent areas. From a detailed understanding of the spatial locations of erosion, we made inferences regarding the processes driving erosion. It appears that hillslope erosion is controlled by rain splash (for detachment) and overland flow (for transport and quasi-channelized erosion), with the sites of highest erosion corresponding to locations with the lowest roughness. By contrast, in convergent areas we found erosion caused by overland flow. Soil erosion was locally interrupted by immobile objects such as boulders, bedrock, or tree trunks, resulting in a patchy erosion network with increasing roughness over time.

Colorado↗
USGS2010

Spatial variability of steady-state infiltration into a two-layer soil system on burned hillslopes

Rainfall-runoff simulations were conducted to estimate the characteristics of the steady-state infiltration rate into 1-m 2 north- and south-facing hillslope plots burned by a wildfire in October 2003. Soil profiles in the plots consisted of a two-layer system composed of an ash on top of sandy mineral soil. Multiple rainfall rates (18.4-51.2 mm h -1 ) were used during 14 short-duration (30 min) and 2 long-duration simulations (2-4 h). Steady state was reached in 7-26 min. Observed spatially-averaged steady-state infiltration rates ranged from 18.2 to 23.8 mm h -1 for north-facing and from 17.9 to 36.0 mm h -1 for south-facing plots. Three different theoretical spatial distribution models of steady-state infiltration rate were fit to the measurements of rainfall rate and steady-state discharge to provided estimates of the spatial average (19.2-22.2 mm h -1 ) and the coefficient of variation (0.11-0.40) of infiltration rates, overland flow contributing area (74-90% of the plot area), and infiltration threshold (19.0-26 mm h -1 ). Tensiometer measurements indicated a downward moving pressure wave and suggest that infiltration-excess overland flow is the runoff process on these burned hillslope with a two-layer system. Moreover, the results indicate that the ash layer is wettable, may restrict water flow into the underlying layer, and increase the infiltration threshold; whereas, the underlying mineral soil, though coarser, limits the infiltration rate. These results of the spatial variability of steady-state infiltration can be used to develop physically-based rainfall-runoff models for burned areas with a two-layer soil system. ?? 2010 Elsevier B.V.

Journal of Hydrology↗
USGS2009

Causes for the decline of suspended-sediment discharge in the Mississippi River system, 1940-2007

Before 1900, the Missouri-Mississippi River system transported an estimated 400 million metric tons per year of sediment from the interior of the United States to coastal Louisiana. During the last two decades (1987-2006), this transport has averaged 145 million metric tons per year. The cause for this substantial decrease in sediment has been attributed to the trapping characteristics of dams constructed on the muddy part of the Missouri River during the 1950s. However, reexamination of more than 60 years of water- and sediment-discharge data indicates that the dams alone are not the sole cause. These dams trap about 100-150 million metric tons per year, which represent about half the decrease in sediment discharge near the mouth of the Mississippi. Changes in relations between water discharge and suspended-sediment concentration suggest that the Missouri-Mississippi has been transformed from a transport-limited to a supply-limited system. Thus, other engineering activities such as meander cutoffs, river-training structures, and bank revetments as well as soil erosion controls have trapped sediment, eliminated sediment sources, or protected sediment that was once available for transport episodically throughout the year. Removing major engineering structures such as dams probably would not restore sediment discharges to pre-1900 state, mainly because of the numerous smaller engineering structures and other soil-retention works throughout the Missouri-Mississippi system. ?? 2009 John Wiley & Sons, Ltd.

Hydrological Processes↗
USGS2009

Linking hydraulic properties of fire-affected soils to infiltration and water repellency

Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, K f and (2) sorptivity, S ( θ i ), as a function of initial soil moisture content, θ i , ranging from extremely dry conditions ( θ i < 0.02 cm 3 cm −3 ) to near saturation. In the field and in the laboratory replicate measurements were made of ash, reference soils, soils unaffected by fire, and fire-affected soils. Each has a different degrees of water repellency that influences K f and S ( θ i ). Values of K f ranged from 4.5 × 10 −3 to 53 × 10 −3 cm s −1 for ash; from 0.93 × 10 −3 to 130 × 10 −3 cm s −1 for reference soils; and from 0.86 × 10 −3 to 3.0 × 10 −3 cm s −1 , for soil unaffected by fire, which had the lowest values of K f . Measurements indicated that S ( θ i ) could be represented by an empirical non-linear function of θ i with a sorptivity maximum of 0.18–0.20 cm s −0.5 , between 0.03 and 0.08 cm 3 cm −3 . This functional form differs from the monotonically decreasing non-linear functions often used to represent S ( θ i ) for rainfall–runoff modeling. The sorptivity maximum may represent the combined effects of gravity, capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of K f and S ( θ i ) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly, they indicate how existing rainfall–runoff models can be modified to accommodate a possible two-layer system in extremely dry conditions. These modified models can be used to predict floods from burned watersheds under these initial conditions.

Journal of Hydrology↗
USGS2008

Post-wildfire erosion response in two geologic terrains in the western USA

Volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western United States. These volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics. However, by measuring the erosion response as the erodibility efficiency of water to detach and transport sediment on hillslopes and in channels, the erosion response from different geologic terrains can be compared. Specifically, the erodibility efficiency is the percentage of the total available stream power expended to detach, remobilize, or transport a mass of sediment. Erodibility efficiencies were calculated for the (i) initial detachment, and for the (ii) remobilization and transport of sediment on the hillslopes and in the channels after wildfire in two different geological terrains. The initial detachment efficiencies for the main channel and tributary channel in the granitic terrain were 10 ?? 9% and 5 ?? 4% and were similar to those for the volcanic terrain, which were 5 ?? 5% and 1 ?? 1%. No initial detachment efficiency could be measured for the hillslopes in the granitic terrain because hillslope measurements were started after the first major rainstorm. The initial detachment efficiency in the volcanic terrain was 1.3 ?? 0.41%. The average remobilization and transport efficiencies associated with flash floods in the channels also were similar in the granitic (0.18 ?? 0.57%) and volcanic (0.11 ?? 0.41%) terrains. On the hillslope the remobilization and transport efficiency was greater in the volcanic terrain (2.4%) than in the granitic terrain (0.65%). However, this may reflect the reduced sediment availability after the first major rainstorm (30-min maximum rainfall intensity ??? 90??mm h- 1) in the granitic terrain, while easily erodible fine colluvium remained on the hillslope after the first rainstorm (30-min maximum rainfall intensity = 7.2??mm h- 1) in the volcanic terrain. The erosion response in channels and on hillslopes of the granitic and volcanic terrains was similar when compared using erodibility efficiencies.

Geomorphology↗
USGS2008

Terrace aggradation during the 1978 flood on Powder River, Montana, USA

Flood processes no longer actively increase the planform area of terraces. Instead, lateral erosion decreases the area. However, infrequent extreme floods continue episodic aggradation of terraces surfaces. We quantify this type of evolution of terraces by an extreme flood in May 1978 on Powder River in southeastern Montana. Within an 89-km study reach of the river, we (1) determine a sediment budget for each geomorphic feature, (2) interpret the stratigraphy of the newly deposited sediment, and (3) discuss the essential role of vegetation in the depositional processes. Peak flood discharge was about 930??m3 s- 1, which lasted about eight??days. During this time, the flood transported 8.2??million tons of sediment into and 4.5??million tons out of the study reach. The masses of sediment transferred between features or eroded from one feature and redeposited on the same feature exceeded the mass transported out of the reach. The flood inundated the floodplain and some of the remnants of two terraces along the river. Lateral erosion decreased the planform area of the lower of the two terraces (~ 2.7??m above the riverbed) by 3.2% and that of the higher terrace (~ 3.5??m above the riverbed) by 4.1%. However, overbank aggradation, on average, raised the lower terrace by 0.16??m and the higher terrace by 0.063??m. Vegetation controlled the type, thickness, and stratigraphy of the aggradation on terrace surfaces. Two characteristic overbank deposits were common: coarsening-upward sequences and lee dunes. Grass caused the deposition of the coarsening-upward sequences, which had 0.02 to 0.07??m of mud at the base, and in some cases, the deposits coarsened upwards to coarse sand on the top. Lee dunes, composed of fine and very fine sand, were deposited in the wake zone downstream from the trees. The characteristic morphology of the dunes can be used to estimate some flood variables such as suspended-sediment particle size, minimum depth, and critical shear velocity. Information about depositional processes during extreme floods is rare, and therefore, the results from this study aid in interpreting the record of terrace stratigraphy along other rivers.

Geomorphology↗
USGS2008

Anatomy and dynamics of a floodplain, Powder River, Montana, U.S.A.

Centimeter-scale measurements on several Powder River floodplains provide insights into the nature of overbank depositional processes that created the floodplains; during a 20-year period after a major flood in 1978. Rising stages initially entered across a sill at the downriver end of the floodplains. Later, as stages continued to rise, water entered the floodplains through distinct low saddles along natural levees. The annual maximum depth of water over the levee crest averaged 0.19 in from 1983 through 1996, and the estimated flow velocities were approximately 0.15 m s-1. Water ponded in the floodplain trough, a topographic low between the natural levee and the pre-flood riverbank, and mud settled as thin layers of nearly constant thickness. Mud layers alternated with sand layers, which were relatively thick near the channel. Together, these beds created a distinctive natural levee. In some locations, individual flood deposits began as a thin mud layer that gradually coarsened upwards to medium-grained sand. Coarsening-upwards sequences form initially as mud because only the uppermost layers of water in the channel supply the first overbank flows, which are rich in mud but starved of sand. At successively higher stages, fine sands and then medium sands increase in concentration in the floodwater and are deposited as fine- and medium-sand layers overlying the initial mud layer. Theoretical predictions from mathematical models of sediment transport by advection and diffusion indicate that these processes acting alone are unlikely to create the observed sand layers of nearly uniform thickness that extend across much of the floodplain. We infer that other transport processes, notably bedload transport, must be important along Powder River. Even with the centimeter-scale measurements of floodplain deposits, daily hydraulic data, and precise annual surface topographic surveys, we were unable to determine any clear correspondence between the gauged flow record of overbank floods and the depositional layers mapped in the floodplain. These results provide a detailed example of floodplain deposits and depositional processes that should prove useful for interpreting natural levee deposits in a variety of geologic settings. Copyright ?? 2008, SEPM (Society for Sedimentary Geology).

Journal of Sedimentary Research↗
USGS2005

Spatial structures of stream and hillslope drainage networks following gully erosion after wildfire

The drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1-1000 m2) representative of hillslopes, and the small scale (1000 m2 to 1 km2), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1-1000 km2), representative of perennial stream networks, was derived from a 30-m digital elevation model and analysed by computer analysis. Scaling laws used to describe large-scale drainage networks could be extrapolated to the small scale but could not describe the smallest scale of drainage structures observed in the hillslope region. The hillslope drainage network appears to have a second-order effect that reduces the number of order 1 and order 2 streams predicted by the large-scale channel structure. This network comprises two spatial patterns of rills with width-to-depth ratios typically less than 10. One pattern is parallel rills draining nearly planar hillslope surfaces, and the other pattern is three to six converging rills draining the critical source area uphill from an order 1 channel head. The magnitude of this critical area depends on infiltration, hillslope roughness and critical shear stress for erosion of sediment, all of which can be substantially altered by wildfire. Order 1 and 2 streams were found to constitute the interface region, which is altered by a disturbance, like wildfire, from subtle unchannelized drainages in unburned catchments to incised drainages. These drainages are characterized by gullies also with width-to-depth ratios typically less than 10 in burned catchments. The regions (hillslope, interface and chanel) had different drainage network structures to collect and transfer water and sediment. Copyright ?? 2005 John Wiley & Sons, Ltd.

Earth Surface Processes and Landforms↗
USGS2002

Field Measurements of Reynolds Stress near a Riverbank

The Reynolds stress field was measured near the bank of the Powder River in southeastern Montana. The measurements were made from the bank using an aluminum I-beam cantilevered over the water to support a carriage system for positioning an acoustic doppler velocimeter in a vertical plane perpendicular to 1) the bank and 2) the streamwise velocity field. During quasi-steady flow at the peak (71 m3s-1) of the spring snowmelt runoff in May 1996, turbulent velocities were measured at 25 Hertz along six vertical locations spaced 0.5 m apart and within about 3.5 m of the riverbank. When the turbulent velocities are transformed to the ray-isovel coordinate system appropriate for this two-dimension problem, the turbulent characteristics near the bed are consistent with similar field measurements made by others for the one-dimensional problem of uniform flow over a horizontal bed far from lateral boundaries. The three turbulent intensities, (u???2) 1/2, (v???2)1/2 and (w??? 2)1/2, normalized by the local shear velocity, u*, were essentially constant with distance above the bed along a ray and the average values were 2.1, 1.4, and 1.2. Future turbulence measurements could be improved by measuring the streamwise flow first, then determining the approximate location of the rays and isovels so that the turbulence measurements could be made along the approximated rays rather than along verticals. In addition, to improve the possibility making turbulence measurements during steady, uniform flow, the site should be carefully selected to minimize local flow accelerations caused by spatial variability of the riverbank. Also, the measurements should be made at times when the stage is constant, no local erosion or deposition of sediment occurs, and when wind velocities are small.

Conference Paper↗
USGS2001

Post-fire, rainfall intensity-peak discharge relations for three mountainous watersheds in the Western USA

Wildfire alters the hydrologic response of watersheds, including the peak discharges resulting from subsequent rainfall. Improving predictions of the magnitude of flooding that follows wildfire is needed because of the increase in human population at risk in the wildland-urban interface. Because this wildland-urban interface is typically in mountainous terrain, we investigated rainfall-runoff relations by measuring the maximum 30 min rainfall intensity and the unit-area peak discharge (peak discharge divided by the area burned) in three mountainous watersheds (17-26.8 km 2 ) after a wildfire. We found rainfall-runoff relations that relate the unit-area peak discharges to the maximum 30 min rainfall intensities by a power law. These rainfall-runoff relations appear to have a threshold value for the maximum 30 min rainfall intensity (around 10 mm h -1 ) such that, above this threshold, the magnitude of the flood peaks increases more rapidly with increases in intensity. This rainfall intensity could be used to set threshold limits in rain gauges that are part of an early-warning flood system after wildfire. The maximum unit-area peak discharges from these three burned watersheds ranged from 3.2 to 50 m 3 s -1 km -2 . These values could provide initial estimates of the upper limits of runoff that can be used to predict floods after wildfires in mountainous terrain. Published in 2001 by John Wiley and Sons, Ltd.

Hydrological Processes↗
USGS2000

Effects of the flood of 1993 on the chemical characteristics of bed sediments in the Upper Mississippi River

Concentrations of pollutants stored in the surficial bed sediments in the navigation pools of the Upper Mississippi River showed a general decrease after the record flood of 1993. Percent clay and total organic carbon in the surficial sediments decreased as a result of an increase in the proportion of coarser sediment. Decreases in pollutant concentration may have been a result of the dilution by coarser and relatively less polluted sediment that was mobilized and transported into the Upper Mississippi River from its tributaries or from mainstem locations upstream but outside of the sampling area.

Water, Air, & Soil Pollution↗
USGS1998

Evolution of cutoffs across meander necks in Powder River, Montana, USA

Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headctu. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood.

Earth Surface Processes and Landforms↗