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Map of southern California showing the 20 discharges sites locations. Names of the discharge sites are listed sequential from north to south in the right hand pannel. Off shore bathymetry contours are also shown in units of meters below sea-level.
Source publication
The dominant source of coastal pollution adversely affecting the regional coastal water quality is the seasonally variable urban runoff discharged via southern California's rivers. Here, we use a surface transport model of coastal circulation driven by current maps from high frequency radar to compute two-year hindcasts to assess the temporal and s...
Contexts in source publication
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... this study, all discharges are assumed to be passive with no dynamical impact on the flow, allowing the mapped surface currents to be the initial current field into which the discharge occurs. The Monte Carlo simulations using the formulation in Eqs. (1) and (2) were computed using 50 trajectories constantly being released each hour at each source location (Fig. 1). Trajectories were computed for the two-year hindcast period and each tracked for three days, con- sistent with estimates for the efficacy of Fecal Indicator Bacteria (FIB) ( Noble et al., 2000Noble et al., , 2004Ackerman and Weisberg, ...
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... exposure maps at the 20 discharge sites ( Fig. 1) are computed using the hourly hindcasts over a two-year period (Fig. 2) to provide a statistical convergent depiction of the modes of plume transport. The statistics from the hindcasts analysis are computed for annual and seasonal patterns and 6 different rain events. The annual exposure maps are based upon hourly compu- tations from January 1, 2008 to December 31, 2009 while the sea- sonal maps used surface current data observed during southern California's wet and dry seasons defined as October through April and May through September, respectively. In addition, targeted storm event maps for four 2008 rainfall events (January 24, Febru- ary 23, November 28, December 20) and two 2009 rainfall events (February 8, December 9) were generated as examples of discharge variability (Figs. S2-S21, Supporting ...
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... urban nature of the southern California coastal landscape creates numerous stormwater discharges, many of which are often in close proximity to one other. The spatial and temporal resolution of the hindcast model allows the assessment of neigh- boring plumes to provide insight on which discharge may be impactful to a particular stretch of coast. To discriminate multiple plumes we conduct a case-study of the Newport Bay discharge, which is located north of the Santa Ana River. We created daily probability exposure maps averaged over 24 h for the Santa Ana River discharge (upcoast plume) and the Newport Bay plume (downcoast plume), which we overlaid with a surface current field averaged for the same period (Fig. 4). On December 15, a predom- inantly onshore current direction restricted the cross-shore extent of both plumes as observed in the probability exposure map's nar- row overlapping alongshore distribution (Fig. 4A). A poleward coastal current flow is observed as the storm strengthened from December 16 to 17 resulting in a northwestward alongshore shift in direction of the Santa Ana plume, which persists through peak discharge observed on December 18 ( Fig. 4B and C). As the plume advects upcoast, it shifts to a westward direction as a result of the strong curvature of the San Pedro Bay coastline (Fig. 2). During the same period, a localized current field with mean offshore transport developed within the receiving waters of the Newport Bay dis- charge which resulted in a probability exposure map that was independent of the observed regional flow field (Fig. 4B and C). The sub-mesoscale current variability resulted in two spatially unique probability exposure maps for the close proximity dis- charges ( Fig. 3B and C, December 15, 2008 column). ...
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... work presented in this paper extends the surface transport hindcast approach developed by Kim et al. (2009) to assess the potential transport of 20 stormwater coastal discharges (Fig. 1) located throughout southern California. Exposure maps of each dis- charge are computed to define the spatial extent of the plume for each day the discharge was active. We term these active days ''release days''. The hindcast approach allows for the identification of annual and seasonal circulation patterns as well as targeted storm events. These exposure maps provide a tool to assess how Areas of Special Biological Significance (ASBS) in Southern California will be exposed to stormwater. ASBS have been designated by the California State Water Resources Control Board (SWRCB) to protect and pre- serve biological communities that are diverse and abundant with marine life. The SWRCB mandates that ASBS receive ''no discharge of waste'' and maintain ''natural water quality'' (State Water Resources Control Board, 2005) (Fig. S1, Supporting ...
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... work presented in this paper extends the surface transport hindcast approach developed by Kim et al. (2009) to assess the potential transport of 20 stormwater coastal discharges (Fig. 1) located throughout southern California. Exposure maps of each dis- charge are computed to define the spatial extent of the plume for each day the discharge was active. We term these active days ''release days''. The hindcast approach allows for the identification of annual and seasonal circulation patterns as well as targeted storm events. These exposure maps provide a tool to assess how Areas of Special Biological Significance (ASBS) in Southern California will be exposed to stormwater. ASBS have been designated by the California State Water Resources Control Board (SWRCB) to protect and pre- serve biological communities that are diverse and abundant with marine life. The SWRCB mandates that ASBS receive ''no discharge of waste'' and maintain ''natural water quality'' (State Water Resources Control Board, 2005) (Fig. S1, Supporting ...
Citations
... These events deliver a spectrum of bacteria and viruses, including human pathogens, stemming from a multitude of sources into the coastal ocean that can even be transported offshore (Ahn et al., 2005). In addition, various pollutants such as pesticides, fertilizers, sediment(s), and heavy metals are routinely introduced into coastal waters during these runoff events (DiGiacomo et al., 2004;Ahn et al., 2005;Rogowski et al., 2015;Vikas et al., 2015). Our results demonstrating elevated levels of cyanotoxin contamination in lagoonal waters add an additional issue to consider along the SCB coastline during rain and erosion events. ...
The contamination of coastal ecosystems from a variety of toxins of marine algal origin is a common and well-documented situation along the coasts of the United States and globally. The occurrence of toxins originating from cyanobacteria along marine coastlines is much less studied, and little information exists on whether toxins from marine and freshwater sources co-occur regularly. The current study focused on the discharge of cyanotoxins from a coastal lagoon (Santa Clara River Estuary) as a consequence of an extreme tide event (King Tides; December 3-5, 2017) resulting in a breach of the berm separating the lagoon from the ocean. Monthly monitoring in the lagoon throughout 2017 documented more than a dozen co-occurring cyanobacterial genera, as well as multiple algal and cyanobacterial toxins. Biotoxin monitoring before and following the King Tide event using Solid Phase Adsorption Toxin Tracking (SPATT) in the lagoon and along the coast revealed the co-occurrence of microcystins, anatoxin, domoic acid, and other toxins on multiple dates and locations. Domoic acid was ubiquitously present in SPATT deployed in the lagoon and along the coast. Microcystins were also commonly detected in both locations, although the beach berm retained the lagoonal water for much of the year. Mussels collected along the coast contained microcystins in approximately half the samples, particularly following the King Tide event. Anatoxin was observed in SPATT only in late December, following the breach of the berm. Our findings indicate both episodic and persistent occurrence of both cyanotoxins and marine toxins may commonly contaminate coastlines in proximity to cyanobacteria-laden creeks and lagoons.
... given the variable nature of storms, tides, nearshore marine currents (e. g., Rogowski et al., 2015), and the unpredictable and patchy deposition of adherent embryos on rocks, macroalgae, and other subtidal strata. On the response side, resource managers should anticipate individual losses that are delayed in time. ...
Understanding how aquatic organisms respond to complex chemical mixtures remains one of the foremost challenges in modern ecotoxicology. Although oil spills are typically high-profile disasters that release hundreds or thousands of chemicals into the environment, there is growing evidence for a common adverse outcome pathway (AOP) for the vulnerable embryos and larvae of fish species that spawn in oiled habitats. Molecular initiating events involve the disruption of excitation-contraction coupling in individual cardiomyocytes, which then dysregulate the form and function of the embryonic heart. Phenanthrenes and other three-ring (tricyclic) polycyclic aromatic hydrocarbons (PAHs) are key drivers for this developmental cardiotoxicity and are also relatively enriched in land-based urban runoff. Similar to oil spills, stormwater discharged from roadways and other high-traffic impervious surfaces contains myriad contaminants, many of which are uncharacterized in terms of their chemical identity and toxicity to aquatic organisms. Nevertheless, given the exceptional sensitivity of the developing heart to tricyclic PAHs and the ubiquitous presence of these compounds in road runoff, car-diotoxicity may also be a dominant aspect of the stormwater-induced injury phenotype in fish early life stages. Here we assessed the effects of traffic-related runoff on the embryos and early larvae of Pacific herring (Clupea pallasii), a marine forage fish that spawns along the coastline of western North America. We used the well-characterized central features of the oil toxicity AOP for herring embryos as benchmarks for a detailed analysis of embryolarval cardiotoxicity across a dilution gradient ranging from 12 to 50% stormwater diluted in clean seawater. These injury indicators included measures of circulatory function, ventricular area, heart chamber looping, and the contractility of both the atrium and the ventricle. We also determined tissue concentrations of phenanthrenes and other PAHs in herring embryos. We find that tricyclic PAHs are readily bioavailable during cardiogenesis, and that stormwater-induced toxicity is in many respects indistinguishable from canonical crude oil toxicity. Given the chemical complexity of urban runoff, non-tricyclic PAH-mediated mechanisms of developmental toxicity in fish remain likely. However, from the standpoint of managing wild herring populations, our results suggest that stormwater-driven threats to individual survival (both near-term and delayed mortality) can be understood from decades of past research on crude oil toxicity. Moreover, Pacific herring embryos are promising sentinels for water quality monitoring in nearshore marine habitats, as in situand sensitive indicators of both toxic runoff and the effectiveness of pollution reduction efforts such as green stormwater infrastructure.
... Engineering studies do not address larger plumes, presumably because the importance of the design of the engineered structure at the discharge point becomes less important to the plume as scale increases. Thus, a gap remains between the two bodies of literature, with a few recent exceptions (Ohlmann et al., 2007;Osadchiev & Sedakov, 2019;Pritchard & Huntley, 2006;Rodriguez et al., 2018;Rogowski et al., 2015;Romero et al., 2013)-and the gap is at the scale of many natural discharges that are critically important in environmental management. ...
Plain Language Summary
The fate of outflow from small rivers and mountainous streams has not been studied as much as the dynamics of large river plumes. These flows form low‐salinity surface plumes that are strongly affected by tidal currents, advected alternatively to the left and right of the river mouth like the wagging tail of a dog. In this study, a three‐dimensional numerical model is used to study outflows with discharge rates of 10 m³ s⁻¹ or less. We identify three distinct zones within the plume (near field, midfield, and far field) that together determine the path and concentration of river waters entering the ocean. As the river/estuarine water enters the ocean (near field), the inertia of the flow is countered by friction. Then as it slows down, buoyancy becomes an important force, resulting in offshore spreading of the plume (midfield). And ultimately, the plume is advected by ocean currents (i.e., tidal flows) in the far field, with only secondary effects of Coriolis forcing. Without the effect of Coriolis, these plumes typically remain separated from the shore, only contacting the shore away from the mouth briefly and at low concentrations. We model different outflow rates to see the effect on plume size, shape, and mixing with ocean waters. We also model a hypothetical seawater outflow to assess the importance of buoyancy forcing due to the difference in density between freshwater and seawater—specifically, we show that the buoyancy effect changes the plume from a narrow jet to a radially expanding surface layer that extends further offshore. Stronger flow rates reduce the effect of vertical mixing so that the plume becomes thinner and waters are well mixed in the plume. These results are important for understanding patterns of pollution as well as the positive biogenic effects of freshwater along the shoreline of regions with small rivers (e.g., California).
... HF Radar data are increasingly being used in support of environmental management, including short-term pollution events and long-term resource management. Specifically, data have been used in tracking the fate of runoff (Rogowski et al., 2015) and wastewater discharges in southern California, residence time in Monterey Bay (Coulliette et al., 2007), and source-sink of water parcels off northern California (Kaplan and Largier, 2006). Further, HFR data have been used in identifying circulation features that account for plankton blooms, including harmful algal blooms imported to the Ria de Vigo and phytoplankton delivery to the rich ecosystems of Cordell Bank and the Gulf of Farallones (Halle and Largier, 2011). ...
Academic, government, and private organizations from around the globe have established High Frequency radar (hereinafter, HFR) networks at regional or national levels. Partnerships have been established to coordinate and collaborate on a single global HFR network (http://global-hfradar.org/). These partnerships were established in 2012 as part of the Group on Earth Observations (GEO) to promote HFR technology and increase data sharing among operators and users. The main product of HFR networks are continuous maps of ocean surface currents within 200 km of the coast at high spatial (1–6 km) and temporal resolution (hourly or higher). Cutting-edge remote sensing technologies are becoming a standard component for ocean observing systems, contributing to the paradigm shift toward ocean monitoring. In 2017 the Global HFR Network was recognized by the Joint Technical WMO-IOC Commission for Oceanography and Marine Meteorology (JCOMM) as an observing network of the Global Ocean Observing System (GOOS). In this paper we will discuss the development of the network as well as establishing goals for the future. The U.S. High Frequency Radar Network (HFRNet) has been in operation for over 13 years, with radar data being ingested from 31 organizations including measurements from Canada and Mexico. HFRNet currently holds a collection from over 150 radar installations totaling millions of records of surface ocean velocity measurements. During the past 10 years in Europe, HFR networks have been showing steady growth with over 60 stations currently deployed and many in the planning stage. In Asia and Oceania countries, more than 110 radar stations are in operation. HFR technology can be found in a wide range of applications: for marine safety, oil spill response, tsunami warning, pollution assessment, coastal zone management, tracking environmental change, numerical model simulation of 3-dimensional circulation, and research to generate new understanding of coastal ocean dynamics, depending mainly on each country’s coastal sea characteristics. These radar networks are examples of national inter-agency and inter-institutional partnerships for improving oceanographic research and operations. As global partnerships grow, these collaborations and improved data sharing enhance our ability to respond to regional, national, and global environmental and management issues.
... Realistic simulations spacing of the true rectangular grid. The region near the baseline, which is a straight line between the two radar sites, is an area where it is not possible to estimate the vector solutions from nearly parallel radial velocities because the vector solutions normal to the baseline are weakly constrained (e.g., Lipa and Barrick 1983;Graber et al. 1997;Kim et al. 2011;Kim 2015). ...
... However, a constant value representing the noise level over the given period (e.g., two years) is applied in this paper. For instance, a standard deviation of the sum of the nearby radial pairs obtained from multiple radars [see Kim et al. (2008) and Kim (2015) for more details]-that is, the sum of the sampling error and the measurement error of the observed radial velocities in the area of interest-is used as g. Thus, the estimated vector currentsû are given bŷ ...
... The observational error of the observed radial velocities is quantified as approximately 10 cm s 21 and is represented by 0.1765 (p 5 g 2 /s 2 5 0:1765) because the minimum correlation is equal to 20.85 when the paired radial velocities are oppositely faced (e.g., Kim et al. 2008;Kim 2015): r min 5 2 s 2 s 2 1 g 2 5 20:85, ...
This paper addresses how well a two-dimensional orthogonal vector current field can be reconstructed from a set of nonorthogonally and irregularly sampled scalar velocity data. High-frequency radar (HFR)- derived surface radial scalar velocities are sampled on a polar or elliptical coordinate grid as a directional projection of two-dimensional vector currents for a viewing angle of the individual HFRs. Synthetic radial velocity maps are generated by sampling two-dimensional surface vector currents obtained from a simple spectral model and a realistic regional circulation model on the polar or elliptical grid points configured similarly as the operational HFRs. Then, the sampled radial velocity maps are combined into a vector current field using inverse methods: least squares fitting and optimal interpolation. In this paper, uncertainty and misfit are defined as the degrees of insufficiency to resolve the vector current and the difference between the true and estimated vector currents, respectively. The uncertainty and misfit are evaluated in terms of several simulation parameters built into the simple spectral model and the degrees of the quality and the observational error of the radial velocity maps associated with the simulated missing data and noise level, respectively. A greater number of missing data and higher observational errors correspond to an increase in the standard deviation of the misfit and a significant reduction in the effective spatial coverage of the vector current fields. This paper provides technical details for resolving a vector current field and guidelines for the practical design of the spatial sampling of the current field using the HFRs.
... Monitoring and studying the environmental impacts of urban stormwater runoff in near-shore waters commonly relies on sparse sampling onboard coastal research vessels. The sporadic nature of rain events, high cost of boat operations, and coarse spatial sampling, makes it difficult to determine the full extent and dispersal of pollutants by stormwater plumes in coastal waters using field measurements alone (Ahn et al., 2005;Svejkovsky and Jones, 2001;Reifel et al., 2009;Rogowski et al., 2015). Employing satellite data to study stormwater plumes helps fill in both spatial and temporal gaps left by in situ monitoring. ...
... The cumulative discharge for the rain event from the three watersheds combined was 12.08 × 10 6 m 3 , a low to medium level event for this study (Fig. 4B). Coincidently, the recent study by Rogowski et al. (2015, their Fig. 2) also highlights the same storm, showing a westerly particle trajectory of the Santa Ana River stormwater plume based on HF radar data from December 15-17, qualitatively matching the MODIS plume extent (Fig. 7B). On Feb. 7, 2009, the Envisat ASAR image shows three stormwater surface plumes, slicks of low backscatter, entering the San Pedro Shelf, from the Los Angeles, San Gabriel, and Santa Ana Rivers (Fig. 8A), with each showing flow patterns to the west and along the coast. ...
... Coastal circulation maps derived from coastal high frequency (HF) radar were shown to provide useful estimates of the transport of sediment plumes in the SCB (e.g. Rogowski et al., 2015). Using HF data provides a routine source of coastal circulation information that is not subject to the vagaries of clouds and intermittent sampling by satellite sensors, with a limitation that it does not provide a direct observation of a runoff plume, but rather a way to predict its transport. ...
Stormwater runoff is the largest source of pollution in the Southern California Bight (SCB), resulting from untreated runoff and pollutants from urban watersheds entering the coastal waters after rainstorms. We make use of both satellite SAR and MODIS-Aqua ocean color imagery to examine two different components of runoff plumes, the surface slick and the sediment discharge. We expand on earlier satellite SAR studies by examining an extensive collection of multi-platform SAR imagery, spanning from 1992 to 2014, that provides a more comprehensive view of the plume surface slick characteristics, illustrated with distribution maps of the extent and flow direction of the plumes. The SAR-detected surface plumes are compared with coincident rain and runoff measurements, and with available measured shoreline fecal bacteria loads. We illustrate differences in the detection of SAR surface plumes with the sediment-related discharge plumes derived from MODIS imagery. A conceptual satellite stormwater runoff monitoring approach is presented.
... The model's skill in assessing water quality in the surf zone was evaluated using receiver operating characteristic (ROC) analysis, which showed 70% accuracy over a four-year period [36]. Additionally, Rogowski et al. utilized the surface transport model to determine potential stormwater exposure areas within the boundaries of MPAs [37]. High probability exposure areas were delineated by estimating the probabilistic spatial extent of 20 river discharges along the southern California coast. ...
In order to protect the diverse ecosystems of coastal California, a series of marine protected
areas (MPAs) have been established. The ability of these MPAs to preserve and potentially
enhance marine resources can only be assessed if these habitats are monitored through
time. This study establishes a baseline for monitoring the spawning activity of fish in the
MPAs adjacent to Scripps Institution of Oceanography (La Jolla, CA, USA) by sampling fish
eggs from the plankton. Using vertical plankton net tows, 266 collections were made from
the Scripps Pier between 23 August 2012 and 28 August 2014; a total of 21,269 eggs were
obtained. Eggs were identified using DNA barcoding: the COI or 16S rRNA gene was ampli-
fied from individual eggs and sequenced. All eggs that were successfully sequenced could
be identified from a database of molecular barcodes of California fish species, resulting in
species-level identification of 13,249 eggs. Additionally, a surface transport model of
coastal circulation driven by current maps from high frequency radar was used to construct
probability maps that estimate spawning locations that gave rise to the collected eggs.
These maps indicated that currents usually come from the north but water parcels tend to
be retained within the MPA; eggs sampled at the Scripps Pier have a high probability of hav-
ing been spawned within the MPA. The surface transport model also suggests that although
larvae have a high probability of being retained within the MPA, there is also significant spill-
over into nearby areas outside the MPA. This study provides an important baseline for
addressing the extent to which spawning patterns of coastal California species may be
affected by future changes in the ocean environment.
... Since HFR-derived surface current observations resolve coastal surface circulation from the shoreline (except for the surfzone) to O(100) km offshore at a resolution of hours in time and kilometers in space, they have supported studies of submesoscale coastal circulation and the development of relevant environmental applications (e.g., Shay et al. 1995;Kim et al. 2011;Paduan and Washburn 2013;Essen et al. 1999). For instance, scientific studies on submesoscale vortices and fronts (e.g., Shay et al. 1998;Chavanne et al. 2010b;Kim 2010) and practical applications for tracking pollutants and larvae and for assisting search and rescue missions (e.g., Ullman et al. 2006;Kaplan and Largier 2006;Kim et al. 2009b;Rogowski et al. 2015) have been conducted. Moreover, large-scale coastal surface circulation, including alongshore variation in surface tidal currents and the signals of coastally trapped waves, has been explored with a network of HFRs off the U.S. West Coast (e.g., Kim et al. 2011;Bjorkstedt et al. 2010). ...
... Wind transfer function analysis provides a spectral relationship in the wind-current system using a statistical framework and is interpreted with coastal dynamics (e.g., Gonella 1972;Kim et al. 2009aKim et al. , 2015. Using a linear parameterization between wind stress (t) and radial velocity (r) in the frequency domain (s), ...
This paper presents examples of the data quality assessment of surface radial velocity maps obtained from shore-based single and multiple high-frequency radars (HFRs) using statistical and dynamical approaches in a hindcast mode. Since a single radial velocity map contains partial information regarding a true current field, archived radial velocity data embed geophysical signals, such as tides, wind stress, and near-inertial and low-frequency variance. The spatial consistency of the geophysical signals and their dynamic relationships with driving forces are used to conduct the quality assurance and quality control of radial velocity data. For instance, spatial coherence, tidal amplitudes and phases, and wind-radial transfer functions are used to identify a spurious range and azimuthal bin. The uncertainty and signal-to-noise ratio of radial data are estimated with the standard deviation and cross correlation of paired radials sampled at nearby grid points that belong to two different radars. This review paper can benefit HFR users and operators and those who are interested in analyzing HFR-derived surface radial velocity data.
Dry weather pollution sources cause coastal water quality problems that are not accounted for in existing beach advisory metrics. A 1D wave-driven advection and loss model was developed for a 30 km nearshore domain spanning the United States/Mexico border region. Bathymetric nonuniformities, such as the inlet and shoal near the Tijuana River estuary mouth, were neglected. Nearshore alongshore velocities were estimated by using wave properties at an offshore location. The 1D model was evaluated using the hourly output of a 3D regional hydrodynamic model. The 1D model had high skill in reproducing the spatially averaged alongshore velocities from the 3D model. The 1D and 3D models agreed on tracer exceedance or nonexceedance above a human illness probability threshold for 87% of model time steps. 1D model tracer was well-correlated with targeted water samples tested for DNA-based human fecal indicators. This demonstrates that a simple, computationally fast, 1D nearshore wave-driven advection model can reproduce nearshore tracer evolution from a 3D model over a range of wave conditions ignoring bathymetric nonuniformities at this site and may be applicable to other locations.
Cities across the globe manage stormwater to enhance water supplies. Capturing and using stormwater in urban watersheds can have benefits for groundwater recharge, reduced pollutant loading in downstream watersheds, and habitat management. In California, metropolitan areas in the southern coastal regions of the state have for decades captured an average of 493 Million Cubic Meters (400,000 acre-feet) of runoff annually to recharge groundwater. But in a state with highly managed watersheds and seasonal precipitation, capturing stormwater for water supply goals can affect urban streamflows. Using a model with simulation and optimization of regional urban water resources management in Los Angeles County (Artes), we analyze the potential effects of increasing stormwater capture and infiltration on urban streamflow volumes. Results indicate that for many watersheds in LA, further increasing stormwater capture and use would significantly reduce urban streamflow volumes, especially in downstream basins. But in some basins, streamflows are increased to preferentially direct water to existing stormwater capture basins. Results illustrate potential tradeoffs in water supply, in-stream water flows, and aquatic habitat that must be considered when looking to increase use of local water sources through more stormwater capture.
