scholarly journals Multiphase Storm Deposits Eroded from Andesite Sea Cliffs on Isla San Luis Gonzaga (Northern Gulf of California, Mexico)

2020 ◽  
Vol 8 (7) ◽  
pp. 525
Author(s):  
Rigoberto Guardado-France ◽  
Markes E. Johnson ◽  
Jorge Ledesma-Vázquez ◽  
Miguel A. Santa Rosa-del Rio ◽  
Ángel R. Herrera-Gutiérrez
Keyword(s):  
Gulf Of California ◽  
Subsequent Development ◽  
Historical Record ◽  
Storm Events ◽  
Material Source ◽  
Average Growth ◽  
San Luis ◽  
Intense Storm ◽  
Mathematical Formulas ◽  
Sea Cliffs

The 450-m long spit that extends westward from the northwest corner of Isla San Luis Gonzaga is one of the largest and most complex constructions of unconsolidated cobbles and boulders found anywhere in Mexico’s Gulf of California. The material source derives from episodic but intense storm erosion along the island’s andesitic cliff face with steep northern exposures. A well-defined marine terrace from the late Pleistocene cuts across the same corner of the island and provides a marker for the subsequent development of the spit that post-dates tectonic-eustatic adjustments. A total of 660 individual andesite clasts from seven transects across the spit were measured for analyses of change in shape and size. These data are pertinent to the application of mathematical formulas elaborated after Nott (2003) and subsequent refinements to estimate individual wave heights necessary for lift from parent sea cliffs and subsequent traction. Although the ratio of boulders to clasts diminishes from the proximal to distal end of the structure, relatively large boulders populate all transects and the average wave height required for the release of joint-bound blocks at the rocky shore amounts to 5 m. Based on the region’s historical record of hurricanes, such storms tend to decrease in intensity as they migrate northward through the Gulf of California’s 1100-km length. However, the size and complexity of the San Luis Gonzaga spit suggests that a multitude of extreme storm events impacted the island in the upper gulf area through the Holocene time, yielding a possible average growth rate between 7 and 8 m/century over the last 10,000 years. In anticipation of future storms, a system to track the movement of sample boulders should be emplaced on the San Luis Gonzaga spit and similar localities with major coastal boulder deposits.

scholarly journals The Relevance of Grated Inlets within Surface Drainage Systems in the Field of Urban Flood Resilience. A Review of Several Experimental and Numerical Simulation Approaches

2021 ◽  
Vol 13 (13) ◽  
pp. 7189
Author(s):  
Beniamino Russo ◽  
Manuel Gómez Valentín ◽  
Jackson Tellez-Álvarez
Keyword(s):  
Overland Flow ◽  
Drainage System ◽  
Critical Conditions ◽  
Hydraulic Efficiency ◽  
Storm Events ◽  
Urban Resilience ◽  
Urban Flood ◽  
Drainage Systems ◽  
Surface Drainage ◽  
Intense Storm

Urban drainage networks should be designed and operated preferably under open channel flow conditions without flux return, backwater, or overflows. In the case of extreme storm events, urban pluvial flooding is generated by the excess of surface runoff that could not be conveyed by pressurized sewer pipes, due to its limited capacity or, many times, due to the poor efficiency of surface drainage systems to collect uncontrolled overland flow. Generally, the hydraulic design of sewer systems is addressed more for underground networks, neglecting the surface drainage system, although inadequate inlet spacings and locations can cause dangerous flooding with relevant socio-economic impacts and the interruption of critical services and urban activities. Several experimental and numerical studies carried out at the Technical University of Catalonia (UPC) and other research institutions demonstrated that the hydraulic efficiency of inlets can be very low under critical conditions (e.g., high circulating overland flow on steep areas). In these cases, the hydraulic efficiency of conventional grated inlets and continuous transverse elements can be around 10–20%. Their hydraulic capacity, expressed in terms of discharge coefficients, shows the same criticism with values quite far from those that are usually used in several project practice phases. The grate clogging phenomenon and more intense storm events produced by climate change could further reduce the inlets’ performance. In this context, in order to improve the flood urban resilience of our cities, the relevance of the hydraulic behavior of surface drainage systems is clear.

scholarly journals Changes in Organic Matter Deposition Can Impact Benthic Marine Meiofauna in Karst Subterranean Estuaries

2021 ◽  
Vol 9 ◽  
Author(s):  
David Brankovits ◽  
Shawna N. Little ◽  
Tyler S. Winkler ◽  
Anne E. Tamalavage ◽  
Luis M. Mejía-Ortíz ◽  
...  
Keyword(s):  
Organic Matter ◽  
Ecosystem Functioning ◽  
Storm Events ◽  
Terrestrial Organic Matter ◽  
Core Sediment ◽  
Carbon Isotopic ◽  
Cozumel Island ◽  
Intense Storm ◽  
Terrestrial Environments ◽  
Subterranean Estuaries

Subsurface mixing of seawater and terrestrial-borne meteoric waters on carbonate landscapes creates karst subterranean estuaries, an area of the coastal aquifer with poorly understood carbon cycling, ecosystem functioning, and impact on submarine groundwater discharge. Caves in karst platforms facilitate water and material exchange between the marine and terrestrial environments, and their internal sedimentation patterns document long-term environmental change. Sediment records from a flooded coastal cave in Cozumel Island (Mexico) document decreasing terrestrial organic matter (OM) deposition within the karst subterranean estuary over the last ∼1,000 years, with older sediment likely exported out of the cave by intense storm events. While stable carbon isotopic values (δ13Corg ranging from −22.5 to −27.1‰) and C:N ratios (ranging from 9.9 to 18.9) indicate that mangrove and other terrestrial detritus surrounding an inland sinkhole are the primarily sedimentary OM supply, an upcore decrease in bulk OM and enrichment of δ13Corg values are observed. These patterns suggest that a reduction in the local mangrove habitat decreased the terrestrial particulate OM input to the cave over time. The benthic foraminiferal community in basal core sediment have higher proportions of infaunal taxa (i.e., Bolivina) and Ammonia, and assemblages shift to increased miliolids and less infaunal taxa at the core-top sediment. The combined results suggest that a decrease in terrestrial OM through time had a concomitant impact on benthic meiofaunal habitats, potentially by impacting dissolved oxygen availability at the microhabitat scale or resource partitioning by foraminifera. The evidence presented here indicates that landscape and watershed level changes can impact ecosystem functioning within adjacent subterranean estuaries.

scholarly journals An Efficient GPU Implementation of a Coupled Overland-Sewer Hydraulic Model with Pollutant Transport

Hydrology ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 146
Author(s):  
Javier Fernández-Pato ◽  
Pilar García-Navarro
Keyword(s):  
Water Flow ◽  
Numerical Models ◽  
Global Analysis ◽  
Coupled Model ◽  
Pollutant Transport ◽  
Pollutant Dispersion ◽  
Quality Analysis ◽  
Storm Events ◽  
Graphic Processing Units ◽  
Intense Storm

Numerical simulation of flows that consider interaction between overland and drainage networks has become a practical tool to prevent and mitigate flood situations in urban environments, especially when dealing with intense storm events, where the limited capacity of the sewer systems can be a trigger for flooding. Additionally, in order to prevent any kind of pollutant dispersion through the drainage network, it is very interesting to have a certain monitorization or control over the quality of the water that flows in both domains. In this sense, the addition of a pollutant transport component to both surface and sewer hydraulic models would benefit the global analysis of the combined water flow. On the other hand, when considering a realistic large domain with complex topography or streets structure, a fine spatial discretization is mandatory. Hence the number of grid cells is usually very large and, therefore, it is necessary to use parallelization techniques for the calculation, the use of Graphic Processing Units (GPU) being one of the most efficient due to the leveraging of thousands of processors within a single device. In this work, an efficient GPU-based 2D shallow water flow solver (RiverFlow2D-GPU) is fully coupled with EPA’s Storm Water Management Model (SWMM). Both models are able to develop a transient water quality analysis taking into account several pollutants. The coupled model, referred to as RiverFlow2D-GPU UD (Urban Drainge) is applied to three real-world cases, covering the most common hydraulic situations in urban hydrology/hydraulics. A UK Environmental Agency test case is used as model validation, showing a good agreement between RiverFlow2D-GPU UD and the rest of the numerical models considered. The efficiency of the model is proven in two more complex domains, leading to a >100x faster simulations compared with the traditional CPU computation.

scholarly journals The Role of Sewer Network Structure on the Occurrence and Magnitude of Combined Sewer Overflows (CSOs)

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2675
Author(s):  
Julian Reyes-Silva ◽  
Emmanuel Bangura ◽  
Björn Helm ◽  
Jakob Benisch ◽  
Peter Krebs
Keyword(s):  
Network Structure ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Untreated Wastewater ◽  
Intense Storm ◽  
Combined Sewer ◽  
Sewer Overflows

Combined sewer overflows (CSOs) prevent surges in sewer networks by releasing untreated wastewater into nearby water bodies during intense storm events. CSOs can have acute and detrimental impacts on the environment and thus need to be managed. Although several gray, green and hybrid CSO mitigation measures have been studied, the influence of network structure on CSO occurrence is not yet systematically evaluated. This study focuses on evaluating how the variation of urban drainage network structure affects the frequency and magnitude of CSO events. As a study case, a sewer subnetwork in Dresden, Germany, where 11 CSOs are present, was selected. Scenarios corresponding to the structures with the lowest and with the highest number of possible connected pipes, are developed and evaluated using long-term hydrodynamic simulation. Results indicate that more meshed structures are associated to a decrease on the occurrence and magnitude of CSO. Event frequency reductions vary between 0% and 68%, while reduction of annual mean volumes and annual mean loads ranged between 0% and 87% and 0% and 92%. These rates were mainly related to the additional sewer storage capacity provided in the more meshed scenarios, following a sigmoidal behavior. However, increasing network connections causes investment costs, therefore optimization strategies for selecting intervention areas are needed. Furthermore, the present approach of reducing CSO frequency may provide a new gray solution that can be integrated in the development of hybrid mitigation strategies for the CSO management.

scholarly journals Variability in runoff fluxes of dissolved and particulate carbon and nitrogen from two watersheds of different tree species during intense storm events

2016 ◽  
Vol 13 (18) ◽  
pp. 5421-5432 ◽  
Author(s):  
Mi-Hee Lee ◽  
Jean-Lionel Payeur-Poirier ◽  
Ji-Hyung Park ◽  
Egbert Matzner
Keyword(s):  
Organic Matter ◽  
Tree Species ◽  
Storm Events ◽  
Flow Paths ◽  
Specific Flow ◽  
Near Surface ◽  
Carbon And Nitrogen ◽  
Intense Storm ◽  
N Fluxes ◽  
C And N

Abstract. Heavy storm events may increase the amount of organic matter in runoff from forested watersheds as well as the relation of dissolved to particulate organic matter. This study evaluated the effects of monsoon storm events on the runoff fluxes and on the composition of dissolved (< 0.45 µm) and particulate (0.7 µm to 1 mm) organic carbon and nitrogen (DOC, DON, POC, PON) in a mixed coniferous/deciduous (mixed watershed) and a deciduous forested watershed (deciduous watershed) in South Korea. During storm events, DOC concentrations in runoff increased with discharge, while DON concentrations remained almost constant. DOC, DON and NO3–N fluxes in runoff increased linearly with discharge pointing to changing flow paths from deeper to upper soil layers at high discharge, whereas nonlinear responses of POC and PON fluxes were observed likely due to the origin of particulate matter from the erosion of mineral soil along the stream benches. The integrated C and N fluxes in runoff over the 2-month study period were in the order of DOC > POC and NO3–N > DON > PON. The integrated DOC fluxes in runoff during the study period were much larger at the deciduous watershed (16 kg C ha−1) than at the mixed watershed (7 kg C ha−1), while the integrated NO3–N fluxes were higher at the mixed watershed (5.2 kg N ha−1) than at the deciduous watershed (2.9 kg N ha−1). The latter suggests a larger N uptake by deciduous trees. Integrated fluxes of POC and PON were similar at both watersheds. The composition of organic matter in soils and runoff indicates that the contribution of near-surface flow to runoff was larger at the deciduous than at the mixed watershed. Our results demonstrate different responses of particulate and dissolved C and N in runoff to storm events as a combined effect of tree species composition and watershed specific flow paths.

How do storm events and fair-weather conditions affect sedimentation patterns on salt marshes?

2020 ◽  
Author(s):  
Davide Tognin ◽  
Mattia Pivato ◽  
Andrea D'Alpaos ◽  
Luca Carniello
Keyword(s):  
Salt Marsh ◽  
Salt Marshes ◽  
Weather Conditions ◽  
Marsh Surface ◽  
Sediment Traps ◽  
Vertical Accretion ◽  
Storm Events ◽  
Fair Weather ◽  
Short Term ◽  
Intense Storm

&lt;p&gt;Coastal salt marshes are extremely important ecosystems, occupying the transitional zone between submerged and emerged environments. Since salt marshes are based on a delicate balance between hydrodynamics and sedimentary processes, their future is heavily affected by relative sea-level rise (RSLR), caused by both subsidence and eustatism. If vertical accretion is sufficient, salt marshes can keep pace with RSLR; otherwise, lack of sediment input can eventually lead to plant death and marsh drowning, transforming these landforms into tidal flats and subtidal platforms. Resuspension driven by intense meteorological events can represent an important source of sediment for salt marsh accretion in tidal environments characterized by negligible fluvial sediment supply. However, it is not yet clear what is the mutual role and relative contribution of intense storm events and fair-weather conditions in terms of sedimentation patterns. To better understand sedimentation dynamics on salt marshes, we stared a field campaign in October 2018 to measure vertical accretion rate and sediment accumulation.&lt;/p&gt;&lt;p&gt;In the Venice lagoon (Italy), which is the largest lagoon in the Mediterranean sea and is characterized by a semi-diurnal, microtidal regime, we selected three study areas: the San Felice and Sant&amp;#8217;Erasmo salt marshes in the northern lagoon and the Conche salt marsh in the southern lagoon. Subsidence at all these study sites ranges between 1.0 and 2.0 mm yr&lt;sup&gt;-1&lt;/sup&gt;, and the rate of sea-level rise is of about 2.0 mm yr&lt;sup&gt;-1&lt;/sup&gt;, for a total rate of RSLR of about 3.0-4.0 mm yr&lt;sup&gt;-1&lt;/sup&gt;. At each study area, we considered different transects, where we installed three measurement stations located respectively at 2.5 m, 7.5 m, and 27.5 m from the salt marsh margin. We equipped each station with an artificial marker horizon laid down on the marsh surface to measure the vertical accretion, and three sediment traps for measuring the short-term sedimentation. The material deposited in two sediment traps is collected monthly or after any single storm, whereas sediment deposited in the third trap is collected once a year, in order to compare sediment deposition dynamics at short (single storm event) and annual time scales. We measure accretion rate, grain size distribution, organic and inorganic content.&lt;/p&gt;&lt;p&gt;Short-term sedimentation displays a very high variability (0 &amp;#8211; 320 g d&lt;sup&gt;-1&lt;/sup&gt; m&lt;sup&gt;-2&lt;/sup&gt;) highlighting the importance of particularly intense storm events in resuspending and transporting sediment from tidal flats to the salt-marsh surface. In particular, during the storm events occurred in October 2018 and November 2019, sedimentation increases significantly and displays values much higher compared to fair-weather periods. According to our analysis, sedimentation grows exponentially with daily mean inundation time. Even if the inner part of the salt marsh is characterized by lower elevation and, hence, by greater inundation time, sedimentation shows smaller values compared to the salt marsh margin, since suspended material settles close to the margin and decreases towards the inner part of the marsh.&lt;/p&gt;

scholarly journals Performance Evaluation of a Nowcasting Modelling Chain Operatively Employed in Very Small Catchments in the Mediterranean Environment for Civil Protection Purposes

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 783
Author(s):  
Martina Raffellini ◽  
Federica Martina ◽  
Francesco Silvestro ◽  
Francesca Giannoni ◽  
Nicola Rebora
Keyword(s):  
Environmental Protection Agency ◽  
High Sensitivity ◽  
Civil Protection ◽  
Storm Events ◽  
Event Monitoring ◽  
Rainfall Events ◽  
Intense Storm ◽  
Threshold Exceedances ◽  
Model Chain ◽  
Correct Forecast

The Hydro-Meteorological Centre (CMI) of the Environmental Protection Agency of Liguria Region, Italy, is in charge of the hydrometeorological forecast and the in-event monitoring for the region. This region counts numerous small and very small basins, known for their high sensitivity to intense storm events, characterised by low predictability. Therefore, at the CMI, a radar-based nowcasting modelling chain called the Small Basins Model Chain, tailored to such basins, is employed as a monitoring tool for civil protection purposes. The aim of this study is to evaluate the performance of this model chain, in terms of: (1) correct forecast, false alarm and missed alarm rates, based on both observed and simulated discharge threshold exceedances and observed impacts of rainfall events encountered in the region; (2) warning times respect to discharge threshold exceedances. The Small Basins Model Chain is proven to be an effective tool for flood nowcasting and helpful for civil protection operators during the monitoring phase of hydrometeorological events, detecting with good accuracy the location of intense storms, thanks to the radar technology, and the occurrence of flash floods.

scholarly journals Size-segregated fluxes of mineral dust from a desert area of northern China by eddy covariance

2007 ◽  
Vol 7 (1) ◽  
pp. 2133-2168
Author(s):  
G. Fratini ◽  
P. Ciccioli ◽  
A. Febo ◽  
A. Forgione ◽  
R. Valentini
Keyword(s):  
Eddy Covariance ◽  
Mineral Dust ◽  
Northern China ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Storm Events ◽  
Particle Volume ◽  
Intense Storm ◽  
Desert Areas

Abstract. Mineral dust emission accounts for a substantial portion of particles present in the troposphere. It is emitted most from desert areas, mainly through intense storm episodes. The aim of this work was to quantify size-segregated fluxes of mineral dust particles emitted during storm events occurring in desert areas of northern China (Alashan desert, Inner Mongolia), known to act as one of the strongest sources of mineral dust particles in the Asian continent. Long-range transport of mineral dust emitted in this area is responsible for the high particle concentrations reached in densely populated areas, including the city of Beijing. Based on a theoretical analysis, an eddy covariance system was built to get size-segregated fluxes of mineral dust particles with optical diameters ranging between 0.26 and 7.00 μm. The system was optimised to measure fluxes under intense storm event conditions. It was tested in two sites located in the Chinese portion of the Gobi desert. During the field campaign, an intense storm event was recorded in one of them. Data obtained during this event indicate that particle number fluxes were dominated by the finer fraction, whereas in terms of volume, coarser particle accounted for the largest portion. It was found that during the storm event, ratios of size-segregated particle volume fluxes remained substantially constant and a simple parameterization of particle emission from total volume fluxes was possible. A strong correlation was also found between particle volume fluxes and the friction velocity. This relationship is extremely useful to investigate mechanisms of particle formation by wind erosion.

scholarly journals Boulder accumulations related to extreme wave events on the eastern coast of Malta

2015 ◽  
Vol 3 (10) ◽  
pp. 5977-6019 ◽  
Author(s):  
S. Biolchi ◽  
S. Furlani ◽  
F. Antonioli ◽  
N. Baldassini ◽  
J. Causon Deguara ◽  
...  
Keyword(s):  
Eastern Coast ◽  
Hydrodynamic Equations ◽  
Storm Events ◽  
Sea Waves ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Storm Waves ◽  
Hellenic Arc ◽  
Intense Storm ◽  
Wave Heights

Abstract. The accumulation of large boulders related to waves generated either by tsunamis or extreme storm events has been observed in different areas of the Mediterranean Sea. Along the NE and E low-lying rocky coasts of Malta tens of large boulder deposits have been surveyed, measured and mapped. These boulders have been detached and moved from the seafloor and lowest parts of the coast by the action of sea waves. In the Sicily–Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few severe earthquakes and tsunamis are recorded in historical documents to have hit the Maltese archipelago, originated by seismicity activity related mainly to the Malta Escarpment, the Sicily Channel Rift Zone and the Hellenic Arc. We present a multi-disciplinary study, which aims to define the characteristics of the boulder accumulations along the eastern coast of Malta, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland. The wave heights required to transport coastal boulders were calculated using various hydrodynamic equations. Particular attention was devoted to the quantification of the input parameters required in the workings of these equations. The axis sizes of blocks were measured with 3-D digital photogrammetric techniques and their densities were obtained throughout the use of a N-type Schmidt Hammer. Moreover, AMS ages were obtained from selected marine organisms encrusted on some of the boulders in various coastal sites. The combination of the results obtained by hydrodynamic equations and the radiocarbon dating suggests that the majority of the boulders has been detached and moved by intense storm waves. Nonetheless, it is possible that some of them may have been transported by tsunami.

scholarly journals A Multi-sensor Evaluation of Precipitation Uncertainty for Landslide-triggering Storm Events

2020 ◽  
Author(s):  
Elsa Culler ◽  
Andrew Badger ◽  
J. Minear ◽  
Kristy Tiampo ◽  
Spencer Zeigler ◽  
...  
Keyword(s):  
Real Time ◽  
Data Availability ◽  
Average Intensity ◽  
Large Set ◽  
Storm Events ◽  
Peak Intensity ◽  
Intense Storm ◽  
Wide Range ◽  
The Impact ◽  
Landslide Triggering

Extreme precipitation can have profound consequences for communities, resulting in natural hazards such as rainfall-triggered landslides that cause casualties and extensive property damage. A key challenge to understanding and predicting rainfall-triggered landslides comes from observational uncertainties in the depth and intensity of precipitation preceding the event. Practitioners and researchers must select among a wide range of precipitation products, often with little guidance. Here we evaluate the degree of precipitation uncertainty across multiple precipitation products for a large set of landslide-triggering storm events and investigate the impact of these uncertainties on predicted landslide probability using published intensity-duration thresholds. The average intensity, peak intensity, duration, and NOAA-Atlas return periods are compared ahead of 228 reported landslides across the continental US and Canada. Precipitation data are taken from four products that cover disparate measurement methods: near real-time and post-processed satellite (IMERG), radar (MRMS), and gauge-based (NLDAS-2). Landslide-triggering precipitation was found to vary widely across precipitation products with the depth of individual storm events diverging by as much as 296 mm with an average range of 51 mm. Peak intensity measurements, which are typically influential in triggering landslides, were also highly variable with an average range of 7.8 mm/hr and as much as 57 mm/hr. The two products more reliant upon ground-based observations (MRMS and NLDAS-2) performed better at identifying landslides according to published intensity-duration storm thresholds, but all products exhibited hit-ratios of greater than 0.56. A greater proportion of landslides were predicted when including only manually-verified landslide locations. We recommend practitioners consider low-latency products like MRMS for investigating landslides, given their near-real time data availability and good performance in detecting landslides. Practitioners would be well-served considering more than one product as a way to confirm intense storm signals and minimize the influence of noise and false alarms.

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