
Alexander R. Horner-DevineUniversity of Washington | UW · Department of Civil and Environmental Engineering
Alexander R. Horner-Devine
About
101
Publications
15,739
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,042
Citations
Introduction
Skills and Expertise
Publications
Publications (101)
Salt intrusion poses a global threat to estuaries and deltas, exacerbated by climate change, drought, and sea level rise. This observational study investigates the impact of river discharge, wind, and tidal variations on salt intrusion in a branching river delta during drought. The complexity and spatial extent of deltas make comprehensive measurem...
We present direct measurements of seafloor ripple dimensions, near-bed mean flow Reynolds stresses and near-bed turbulent sediment fluxes on a sandy inner shelf subjected to strong wave and tidal current forcing. The measurements of ripple dimensions (height, wavelength) and Reynolds stresses are used to evaluate the performance of a methodology fo...
Land and ocean ecosystems are strongly connected and mutually interactive. As climate changes and other anthropogenic stressors intensify, the complex pathways that link these systems will strengthen or weaken in ways that are currently beyond reliable prediction. In this review we offer a framework of land–ocean couplings and their role in shaping...
We developed a new rule-based, cellular-automaton algorithm for predicting the hazard extent, sediment transport, and topographic change associated with the runout of a landslide. This algorithm, which we call MassWastingRunout (MWR), is coded in Python and implemented as a component for the package Landlab. MWR combines the functionality of simple...
Arsenic (As), a harmful contaminant present in many urban lakes, can negatively impact lake ecosystem health when aqueous concentrations are elevated. We observed repeated diel oscillations in As concentrations in the bottom waters of a shallow, temperate lake during a weeklong period. In this work, we explore four mechanistic hypotheses to explain...
We developed a new rule-based, cellular-automaton algorithm for predicting the hazard extent, sediment transport and topographic change associated with the runout of a landslide. This algorithm, which we call MassWastingRunout (MWR), is coded in Python and implemented as a component for the package Landlab. Given the location and geometry of an ini...
Subaqueous vortex ripples in equilibrium are characterized by their unique geometry and dimensions. Motivated by the recent direct numerical simulation study of oscillatory turbulent flow over a wavy bottom by Önder & Yuan ( J. Fluid Mech. , vol. 858, 2019, pp. 264–314), the objective of this study is to further investigate the fluid dynamical cont...
This research simulates the morphodynamic evolution of an idealize estuary under four different SLR scenarios of increasing severity to investigate how SLR will influence riverine flooding in estuaries. We find that estuarine response to SLR is influenced by both morphological changes to channel capacity and the associated changes to channel hydrod...
We use salinity observations from drifters and moorings at the Quinault River mouth to investigate mixing and stratification in a surf-zone-trapped river plume. We quantify mixing based on the rate of change of salinity DS / Dt in the drifters’ quasi-Lagrangian reference frame. We estimate a constant value of the vertical eddy diffusivity of salt o...
Arsenic, a neurotoxin and carcinogen, is a legacy contaminant in the sediments of many urban lakes and poses health risks to aquatic ecosystems and lake users. Arsenic uptake into the aquatic food web is enhanced in shallow, polymictic lakes compared to deep, seasonally stratified lakes. We present the results of a 17‐month field study in Lake Kill...
An 11 hours survey was performed on the 17th of September 2014 in the Rhine Region Of Freshwater Influence (Rhine-ROFI) about 10 km downstream of the mouth of the Rotterdam Waterway during calm weather conditions. Suspended Particle Matter (SPM) measurements were performed during a full tidal cycle, near the seabed, at neap tide, and samples were t...
Modeled stream discharge is often used to drive sediment transport models across channel networks. Because sediment transport varies non‐linearly with flow rates, discharge modeled from daily total precipitation distributed evenly over 24‐hr may significantly underestimate actual bedload transport capacity. In this study, we assume bedload transpor...
Plain Language Summary
Small coastal rivers often discharge directly into the surfzone, where the fate of river‐borne materials such as sediment, nutrients and contaminants is determined by the combined effects of buoyant plume processes, wave‐driven dynamics and turbulence. In this work we present field measurements at the mouth of Río Maipo, a sm...
Changes in the severity and likelihood of flooding events are typically associated with changes in the intensity and frequency of streamflows, but temporal adjustments in a river's conveyance capacity can also contribute to shifts in flood hazard. To assess the relative importance of channel conveyance to flood hazard, we compare variations in chan...
En el presente estudio se propone una metodología para evaluar el destino final de las aguas de ríos de pequeña escala que descargan directamente en la zona de rompiente del oleaje. La metodología está basada en el uso combinado de longitudes características asociadas a la dinámica de la interacción río-oleaje costero, propuestas en la literatura y...
Remotely sensed images document the occurrence of multiple packets of internal solitary waves (ISWs) in the Rhine River plume at the same time. We use a combination of field observations, and non‐hydrostatic and hydrostatic modeling to understand the processes that lead to the generation and retention of multiple ISW packets within the Rhine plume....
The Rhine region of freshwater influence (ROFI) is strongly stratified, rotational, relatively shallow and has large tides, resulting in a dynamic field of fronts that are formed by multiple processes. We use a 3D numerical model to obtain a conceptual picture of the frontal structure and the processes responsible for generating this multiple front...
Plain Language Summary
Water flow in rivers, estuaries and shallow coastal areas is controlled by the roughness of the riverbed or seabed. Flow over rocks, sand grains, or sand dunes on the bottom becomes turbulent and the turbulence spreads upwards to the surface. In a river, the largest scales of turbulence take the form of boils, and can be obse...
We performed laboratory experiments to investigate the influence of sand content on the dynamics of wave‐supported gravity flows in mud‐dominant environments. The experiments were carried out in an oscillatory water tunnel with a sediment bed of either 1% or 13% sand. Low and high energy regimes are differentiated based on a Stokes Reynolds number...
The water surface expression of liftoff and its dependence on discharge are examined using numerical simulations with the Regional Ocean Modeling System (ROMS). Liftoff is the process by which buoyant river water separates from the bed and flows over denser saltwater. During low-discharge conditions liftoff occurs in the river and is accompanied by...
Hydrographic measurements of salt wedge structure and dynamics spanning a 20-fold seasonal range of river discharges are used to investigate the seasonal variability in the strongly stratified Duwamish River Estuary. The effect of river discharge on salt wedge length, stratification, pycnocline thickness, and intratidal differences in salinity stru...
This study investigates the influence of tidal straining in the generation of turbidity maximum zones (TMZ), which are observed to extend for tens of kilometers along some shallow, open coastal seas. Idealized numerical simulations are conducted to reproduce the cross-shore dynamics and tidal straining in regions of freshwater influence (ROFIs), wh...
Numerical simulation of fluvial morphodynamic processes can identify important dynamics at time and space scales difficult to observe in the field. However, simulations involving large spatial scales and/or the long timescales characteristic of morphodynamic processes are often untenable because of long computation times. The morphological accelera...
We use observations from the Quinault River, a small river that flows into an energetic surf zone on the West Coast of Washington state, to investigate the interaction between river and wave forcing. By synthesizing data from moorings, drifters, and Unmanned Aerial System video, we develop a conceptual model of this interaction based on three lengt...
Vessel propeller wash has been shown to cause scour in the marine environment. We investigated the hydrodynamic causes of severe erosion at the Washington State Ferries ferry terminal in Kingston, WA, where a cliff-like bathymetric feature has shifted shoreward in recent years, forcing repairs on the slip’s bridge pilings. High resolution measureme...
Wave-supported gravity currents in turbulent wave bottom boundary layer (WBBL) are one of the most important processes causing cross-continental shelf sediment transport. The high numerical accuracy 3D numerical model has been used to investigate the fine sediment transport in the WBBL and several different transport modes have been found due to se...
Liftoff is the hydraulically forced detachment of buoyant freshwater from the channel bottom or seabed that occurs as river water discharges into the coastal ocean. It is a key feature of strongly stratified systems, occurring well upstream in the channel or seaward of the river mouth under sufficiently strong forcing. We present a two-layer hydrau...
This study uses drifter-based observations to investigate the role of wind and waves on spreading and mixing in the Fraser River plume. Local winter wind patterns commonly result in two distinct forcing conditions, moderate winds from the southeast (SE) and strong winds from the northwest (NW). We examine how these patterns influence the spreading...
Airborne light detection and ranging (LiDAR) measurements and model simulations are used to investigate the temporal and spatial variability of the water surface elevation at the mouth of the Columbia River. A series of 15-km transects repeated in 2-3-h flights over a two week period resolve processes at a range of scales that are important to the...
Wave-supported gravity flows (WSGFs) generate rates of sediment flux far exceeding other cross-shelf transport processes, contributing disproportionately to shelf morphology and net cross-shelf fluxes of sediment in many regions worldwide. However, the conditions deemed necessary for the formation of WSGF limit them to a narrow set of shelf conditi...
In this study we used field data and radar images to investigate the influence of winds and tides on the propagation of tidal plume fronts. The measurements were collected in a shallow shelf region off the Dutch coast, 10 km north of the Rhine River mouth, and they clearly show the passage of distinct freshwater lenses and associated fronts at the...
We present results from laboratory experiments that simulate the effects of periodically varying discharge on buoyant coastal plumes. Freshwater is discharged into a two meter diameter tank filled with saltwater on a rotating table. The mean inflow rate, tank rotation period and density of the ambient salt water are varied to simulate a range of in...
A series of laboratory experiments are presented to compare the dynamics of constant-source buoyant gravity currents propagating into laterally confined (channelized) and unconfined (spreading) environments. The plan-form structure of the spreading current and the vertical density and velocity structures on the interface are quantified using the op...
The Sand Engine is a 21.5 million m3 experimental mega-nourishment project that was built in 2011 along the Dutch coast. This intervention created a discontinuity in the previous straight sandy coastline, altering the local hydrodynamics in a region that is influenced by the buoyant plume generated by the Rhine River. This work investigates the res...
We report on direct numerical simulations to examine the spectral behaviour of turbulence close to and at a flat, stress-free surface. We find, consistent with field measurements near such a free surface, that an inertial-range type of behaviour is obtained for the horizontal components of the velocity at and near the stress-free surface, at horizo...
We present a new mechanism for cross-shore transport of fine sediment from the nearshore to the inner shelf resulting from the onshore propagation of river plume fronts. Onshore frontal propagation is observed in moorings and radar images, which show that fronts penetrate onshore through the nearshore and surf zone, almost to the waterline. During...
We present measurements of along and across-shore sediment transport in a region of the Dutch coast 10 kilometers north of the Rhine River mouth. This section of the coast is characterized by strong vertical density stratification because it is within the mid-field region of the Rhine region of freshwater influence, where processes typical of the f...
Gravity currents represent a broad class of geophysical flows including turbidity currents, powder avalanches, pyroclastic flows, sea-breeze fronts, haboobs and river plumes. A defining feature in many gravity currents is the formation of three-dimensional lobes and clefts along the front and researchers have sought to understand these ubiquitous g...
Thermal infrared (IR) imagery is combined with in situ flow measurements to examine the impact of subsurface stratification on boil activity in the tidally influenced Snohomish River. Boils at the river's surface are an expression of bottom-generated turbulence, appearing as a disruption of the cool-skin surface layer in the IR imagery. Boil activi...
This study presents the small scale bedform states found off the South-Holland coast during a 31+ days field
observation of seabed acoustic imagery and near the bed velocities. Six main bed states were encountered: current ripples (C), wave ripples (W), combined wave-current ripples (WC), current ripples with subordinate wave ripples (Cw), wave rip...
The authors develop a two-layer hydraulic model to determine the saline intrusion length in sloped and converging salt wedge estuaries. They find that the nondimensional intrusion length L-* 5 CiL/h(S) depends significantly on the channel bottom slope and the rate and magnitude of landward width convergence, in addition to the freshwater Froude num...
We present results from laboratory experiments in a wave flume with and without a sediment bed to investigate the turbulent structure and sediment dynamics of wave-supported mud layers. The presence of sediment on the bed significantly alters the structure of the wave boundary layer relative to that observed in the absence of sediment, increasing t...
River plumes are generated by the flow of buoyant river water into the coastal ocean, where they significantly influence water properties and circulation. They comprise dynamically distinct regions spanning a large range of spatial and temporal scales, each contributing to the dilution and transport of freshwater as it is carried away from the sour...
The role of wind in the near- and mid-field regions of the Merrimack River plume is quantified using observations from surface drifters released near the river mouth during ebb tide in 2009, 2010 and 2011 under a range of wind and river discharge conditions. Comparison of momentum balance terms, and analysis of plume trajectories suggests that the...
The ability of a three-dimensional hydrodynamic model to reproduce buoyant water entering a coastal sea at laboratory scales of O[1 cm] is studied using Regional Ocean Modeling System (ROMS). ROMS is typically used for geophysical scale simulations. Inflowing water forms a growing anti-cyclonic buoyant bulge and coastal current. Available laborator...
Observations from a field experiment along the south-Holland coast, the Netherlands, were carried out in order to obtain new insights about the impacts of the Rhine ROFI (Region of Freshwater Influence) on the sand transport patterns. The net alongshore sand transport is generally governed by tides. The sediment concentration in the middle shorefac...
The South-Holland coast of the Netherlands undergoes the influence of the Rhine river plume released from the Rotterdam waterways. An experiment, STRAINS, was conducted to study the impact of the fresh water on the nearshore hydrodynamics and sand transport. As part of the experiment, an instrumented bottom frame measured the near-bed hydrodynamics...
[1] We investigate the relationship between turbulence statistics and coherent structures (CS) in an unstratified reach of the Snohomish River estuary using in situ velocity measurements and surface infrared (IR) imaging. Sequential IR images are used to estimate surface flow characteristics via a particle-image-velocimetry (PIV) technique, and are...
The relationship between lateral spreading and mixing in stratified gravity currents is investigated by comparing laterally confined and unconfined currents in a series of laboratory experiments. The vertical turbulent buoyancy flux is determined using a control volume approach with velocity and density fields derived from combined particle image v...
Despite years of research on the dynamics and mixing of gravity currents, there are relatively few detailed observations at geophysical scales. In this chapter, we present measurements of the frontal propagation, and distribution and structure of frontal turbulence and mixing, at a river plume front. The measurements are made using a novel platform...
COHSTREX, the Coherent Structures in Rivers and Estuaries Experiment, was a five-year project to exploit the remotely sensed signatures of coherent flow structures in rivers and estuaries. The purpose of the study was to use remote-sensing measurements of coherent structures at a river surface to characterize and quantify the flow. Two major field...
We compute rates of sediment removal from the Columbia River, USA plume near field using a control volume technique. By using data from repeated transect passes along the plume axis, we account for variations in plume width, depth, and velocity, and we construct a framework for determining the dominant terms in the complete sediment balance. The co...
Estuarine fronts are well known to influence transport of waterborne constituents such as phytoplankton and sediment, yet due to their ephemeral nature, capturing the physical driving mechanisms and their influence on stratification and mixing is difficult. We investigate a repetitive estuarine frontal feature in the Snohomish River Estuary that re...
In this paper, an image processing system for estimating 3-D particle distributions from stereo light scatter images is described. The system incorporates measured, three-component velocity data to mitigate particle blur associated with instrument motion. An iterative background estimation algorithm yields a local threshold operator that dramatical...
Thermal infrared (IR)-based particle image ve locimetry (PIV) is used to measure the evolution of velocity, turbulent kinetic energy (TKE), and the TKE dissipation rate at the water surface in the tidally influenced Snohomish River. Patterns of temperature variability in the IR imagery arise from disruption of the cool-skin layer and are used to es...
We describe a technique for measuring the layer thickness of two interacting buoyant rotating gravity currents. The technique
can be used generally to differentiate between water masses in experiments with multiple sources and is used here to simulate
the dynamics of two adjacent coastal river plumes. The plumes are generated using two identical fr...
We examine near surface turbulence and coherent structures using in situ velocity measurements and velocity derived from infrared imaging acquired over a spring-neap cycle at several locations in the Snohomish River Estuary. Coherent structures such as boils are produced by flow over variable bathymetry and spread through the water column. Near the...
We used a kite-mounted aerial infrared camera to image the two-dimensional horizontal structure of the Merrimack River plume front at scales ranging from 0.2 to 2000 meters as it propagated seaward from the river mouth. Over the entire 3 hour ebb tide sampling period the frontal structure consisted of a repeated series of lobes and clefts similar t...
Open channel flow, as in rivers and estuaries, produces turbulence at a range of scales and is due to flow over bathymetric features, obstructions, and rough bottoms, or from strongly sheared flow. This turbulence is often visible at the surface as eddies, boils, and surface deflections. Measurement and analysis of open channel turbulence including...
1] Large rivers represent gateways for the transport of terrigenous and anthropogenic material to the coastal ocean. Here we document a ∼700 km 2 recirculation or bulge associ-ated with the Columbia River plume that retains recently dis-charged river water sufficiently to create a regional bioreactor. Fueled by a fluvial nitrate source, this featur...
We investigate the generation of a mixing layer in the separated flow
behind an estuarine sill (height H ˜ 4 m) in the Snohomish River,
Washington as part of a larger investigation of coherent structures
using remote and in situ sensing. During increasing ebb flows the depth
d and stratification decrease and a region of sheared flow characterized
b...
Over the past decade, a novel free-fall imaging profiler has been under development at the Scripps Institution of Oceanography to observe and quantify biological and physical structure in the upper 100 m of the ocean. The profiler provided the first detailed view of microscale phytoplankton distributions using in situ planar laser-induced fluoresce...
River Influences on Shelf Ecosystems (RISE) is the first comprehensive
interdisciplinary study of the rates and dynamics governing the mixing of river and coastal
waters in an eastern boundary current system, as well as the effects of the resultant plume
on phytoplankton standing stocks, growth and grazing rates, and community structure.
The RISE S...