William Nardin

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Verified

William verified their affiliation via an institutional email.

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• PhD Environmental Engineer
• Professor (Associate) at University of Maryland Center for Environmental Science

Oyster populations within the Chesapeake Bay have been drastically reduced over the last century mainly due to unregulated human activities and diseases. Regulations and restoration efforts have focused on restoring oyster populations while also considering their ability to provide ecosystem services, such as coastal protection and water quality i...

Living shorelines have been recognized for their potential to attenuate wave energy, reduce shoreline erosion, and enhance coastal resilience, and are gaining traction as a preferred method of shoreline stabilization. Yet much remains uncertain about their resiliency and effectiveness in reducing shoreline erosion during high-energy events. This st...

Tidal marshes provide numerous ecosystem services, but are threatened by recent increases in global sea level rise (SLR). Marsh restoration and creation are important strategies for mitigating marsh loss, restoring ecosystem services, increasing coastal community resilience, and providing much needed habitat for threatened species. Dredged material...

Sea level rise (SLR) and increasing storm frequency threaten coastal environments. Engineering solutions such as breakwaters will become ineffective for wave attenuation and erosion control due to SLR. As a natural alternative, oysters create three‐dimensional, complex reef structures that attenuate wave energy and increase sedimentation rates. If...

Natural or human-induced intra-annual variation of river discharge alters estuarine hydrological regimes and further affects habitat conditions for saltmarsh vegetation, particularly at the river mouth bar. In this study, numerical experiments were performed in Delft3D to simulate the evolution of a schematized river mouth bar under prototypical un...

Marine litter is a global issue, and one way to face this problem is to increase citizen knowledge and awareness. In our study, we analyzed and quantified the abundance of marine litter on 5 pocket beaches located in North Sardinia. From the 7975 collected items, plastic was the most important litter category. Regarding the MLs' sources, no-sourced...

Marine litter (ML) is recognized as one of the main socio-economic and environmental concerns and monitoring operations have been realized worldwide in order to collect information on the types, quantities and distribution of marine debris. In this study, we used Unmanned Aerial Vehicle (UAV) images to map the presence of ML on a coastal spit in re...

Shellfish farming is considered a highly sustainable form of aquaculture that has developed rapidly worldwide. Unfortunately, today biological and chemical pollution of the oceans and marine waters is widespread and has multiple negative impacts on marine ecosystems, which are exacerbated by global climate changes. In addition, such impacts on fish...

As an aggressive invasive salt marsh plant, Spartina alterniflora has been found to invade along tidal channel networks and threaten native salt marsh ecosystems. Previous studies have established patterning correlations between S. alterniflora invasion and tidal channel functions (drainage efficiency). However, a systematic analysis of S. alternif...

Coastal lagoons and salt marshes are rapidly changing under the influence of sea level rise and human induced changes. Within this context, the proposed study describes the evolution of the lagoons of the Po Delta (Italy) and the historical transformations of the salt marshes using historical maps and aerial data from 1892 to 2018. The methodology...

Coastal communities around the world are facing increased coastal flooding and shoreline erosion from factors such as sea-level rise and unsustainable development practices. Coastal engineers and managers often rely on gray infrastructure such as seawalls, levees and breakwaters, but are increasingly seeking to incorporate more sustainable natural...

River deltas and enclosed lagoons represent a zone where fluvial and littoral processes interact through the redistribution, erosion, and deposition of sediment, which have a large impact on coastal management and engineering. The focus of the study is to understand the correct balance between strategies that maintain the navigational efficiency of...

Our study provides a first dataset on marine litter collected at five pocket beaches situated in the northern Sardinia (Italy). The monitoring method refers to the operational guidelines for rapid beach assessment of beach waste described by UNEP. We classified the 7975 items collected according to the eight categories and 99 types. Their analysis...

Over the last several decades, the study of Earth surface processes has progressed from a descriptive science to an increasingly quantitative one due to advances in theoretical, experimental, and computational geosciences. The importance of geomorphic forecasts has never been greater, as technological development and global climate change threaten...

Salt marsh evolution is strongly affected by tidal processes and ecology, which regulate sediment accretion and erosional rates. A balance between marsh erosion and deposition in a restored tidal wetland is crucial for analyzing restoration strategies to adopt in a natural context. Here, we present an integrated approach monitoring salt marsh seaso...

Rising sea levels and the increased frequency of extreme events put coastal communities at serious risk. In response, shoreline armoring for stabilization has been widespread. However, this solution does not take the ecological aspects of the coasts into account. The “living shoreline” technique includes coastal ecology by incorporating natural hab...

Plastic debris in the coastal environment is subject to complex and poorly characterized weathering processes. To better understand how key environmental factors affect plastic degradation in a coastal zone, we conducted an in situ experiment. We deployed strips of high density polyethylene (HDPE) and polystyrene (PS) in paired coastal areas of con...

River deltas are a compelling target for numerical simulation because they contain seemingly organized patterns and shapes at a variety of scales. For instance, most river-dominated deltas, regardless of size, have triangular to semi-circular planform shapes, channel networks, and channel bifurcations. The common presence of these features among mo...

Salt marshes are highly dynamic and important ecosystems that dampen impacts of coastal storms and are an integral part of tidal wetland systems, which sequester half of all global marine carbon. They are now being threatened due to sea-level rise, decreased sediment influx, and human encroachment. This book provides a comprehensive review of the l...

Tidal processes regulating sediment accretion rates and vegetated platform erosion in tidal systems strongly affect salt marsh evolution. A balance between erosion and deposition in a restored salt marsh is crucial for analyzing restoration strategies to be adopted within a natural context. Marsh morphology is also coupled with tidal mudflats and c...

Tides rhythmically flood and drain shorelines. This oscillatory movement of water interact with shallow bottoms near the coast, eroding and depositing sediments. The feedback between tidal propagation and topography gives rise to a landscape rich of unique features. Funneled estuaries, energetic inlets, dendritic networks of tidal channels, expansi...

River-dominated deltas on Earth are composed of diverse shapes and patterns, ranging from small-scale bifurcations that create channel networks to large-scale deltaic lobes that build deltaic plains. Morphodynamic feedbacks among fluid flow, sediment transport, and bed elevation change are ultimately responsible for creating these shapes and patter...

Enhanced deposition is common near river mouths where large amounts of sediment is available. Our study focuses on the effects of sediment deposition on a mangrove forest in the Mekong river delta, Vietnam. At this site, the mangrove forest fringe is characterized by Sonneratia spp. and both mud and sand are present. High deposition rates bury mang...

Plain Language Summary As a key feature of a river, the bed level along the river, i.e., the river longitudinal profile, affects flooding, navigation, etc., and thus greatly influences human societies and natural ecosystems. However, the effects of the seaward progradation of a river mouth on the evolution of the river longitudinal profile are stil...

Biogeomorphology has been expanding as a discipline, due to increased recognition of the role that biology can play in geomorphic processes, as well as due to our increasing capacity to measure and quantify feedbacks between biological and geomorphological systems. Here, we provide an overview of the growth and status of biogeomorphology. This over...

It is widely recognized that waves inhibit river mouth progradation and reduce the avulsion timescale of deltaic channels. Nevertheless, those effects may not apply to downdrift‐deflected channels. In this study, we developed a coupled model to explore the effects of wave climate asymmetry and alongshore sediment bypassing on shoreline‐channel morp...

Salt marshes are dynamic systems able to laterally expand, contract, and vertically accrete in response to sea level rise. Here, we present the grand challenges that need to be addressed to fully characterize marsh morphodynamics. The review focuses on physical processes and quantitative models. Without predictive models, it is impossible to determ...

The potential for rapid coastline modification in the face of sea‐level rise or other stressors is alarming since coasts are often densely populated and support valuable infrastructure. In addition to coastal submergence, nutrient‐related water pollution is a growing concern for coastal wetlands. Previous studies found that the suspended sediment c...

Introduction of fine sand into gravel-bed rivers has surged tremendously as a result of human activities. The ecological concerns for river habitats have called for suitable management strategies for cleaning these particles from gravel bed rivers. This paper is concerned with determining movement threshold of fine sand initially entrapped in the s...

Human encroachment and development on coastlines have led to greater amounts of armoring of shorelines. Breakwaters are a common feature along coastlines, which are used to dampen wave energy and protect shorelines from flash floods or overwash events. Although common, their effects on sediment transport and marsh geomorphology are poorly understoo...

Several coastal regions on Earth have been increasingly affected by intense, often catastrophic, flash floods that deliver significant amounts of sediment along shorelines. One of the critical questions related to the impact of these impulsive runoffs is “are flash floods more efficient in delivering non-cohesive sandy sediment along the coasts?” H...

Tidal marshes form at the confluence between estuarine and marine environments where tidal movement regulates their developmental processes. Here, we investigate how the interplay between tides, channel morphology, and vegetation affect sediment dynamics in a low energy tidal marsh at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Isl...

Rivers, regardless of their scales and geographic locations, are characterized with natural and human‐induced variability in their discharges. While previous studies have established the effects of both interannual and intra‐annual variabilities of unsteady river discharge on delta morphological evolution, the long‐term cumulative effects of intra‐...

Our study investigates the land use evolution of the Po River Delta (Italy, about 18,000 ha) over the last 120 years to evaluate the impacts of human activities. The various land uses and their evolution have been evaluated through the analysis of different historical maps and aerial photographs. The land use maps have been realized using the third...

This work is inspired by the sudden resurgence of the submersed aquatic vegetation (SAV) bed in the Chesapeake Bay (USA). Because the SAV bed occurs at the mouth of the Bay's main tributary (Susquehanna River), it plays a significant role in modulating sediment and nutrient inputs from the Susquehanna to the Bay. Previous model studies on the impac...

River mouth bar formation, a key process in fluvial-deltaic morphodynamics, is subject to both river discharge and waves. Given the increasing variability of both forcings under continuous climate change and human interventions, assessing their combined effects on mouth bar formation is an imperative issue. In this study, an extensive set of combin...

Cheniers are sandy ridges parallel to the coast separated by muddy deposits. Here we explore the development of erosional chenier plains, which form by winnowing during storms, through dimensional analysis and numerical results from the morphodynamic model Delft3D-SWAN. Our results highlight that wave energy and inner-shelf slope play an important...

Both submerged and emergent vegetation plays a fundamental role in coastal bays. Vegetation stabilizes the substrate, increasing resilience to storms. Vegetation also traps sediments favoring accretion and therefore counteracting sea level rise. Previous modeling studies on flow-vegetation-sediment interactions have focused on one specific vegetate...

Mangroves colonize tropical shorelines, protecting coastal communities and providing valuable ecosystem services. Mangroves associated with deltas cope with a very dynamic environment characterized by strong gradients in salinity, deposition triggered by sediment inputs, and erosion caused by waves and currents. Mangroves are adapted to this ever-c...

Time-series analysis of Landsat imagery was used to evaluate trends in species zonation in a restored mangrove forest in the Mekong Delta, Vietnam. Dating back throughout the primary expansion of the forest, the Landsat archive provides a unique opportunity to examine the evolution of a restored forest in all stages of maturity. Through temporal tr...

Mangroves are halophytic plants common in tropical and sub-tropical environments. Their roots and pneumatophores strongly affect intertidal hydrodynamics and related sediment transport. Here, we investigate the role tree and root structures may play in altering tidal currents and the effect of these currents on the development of intertidal landsca...

The broad goal of this project is to distinguish between the influence of saltmarsh and seagrass experiencing different feedback and forcing on sediment deposition. We focus our study on the Virginia Coast Reserve LTER site, where we apply numerical modeling (Delft-3D) and subsequent analyses to determine the sets of environmental conditions under...

GM6.2/BG9.43/SSS9.36 Biogeomorphology: conceptualising and quantifying processes, rates and feedbacks Dear colleague, we are organizing a session on Biogeomorphology at the next EGU General Assembly Meeting in Vienna (23-28 April 2017). The session focusses on the investigation of feedbacks between Ecology and Geomorphology, and includes wetland an...

Mangrove forests exert a strong influence on tropical deltas by trapping sediments discharged by rivers and by stabilizing the substrate with roots. Understanding the dynamics of sediments and morphology in and around mangrove forests is critical in order to assess the resilience of coastlines in a period of accelerated sea level rise. In this rese...

Mangrove forests dominate many tropical coastlines and are one of the most bio-diverse and productive environments on Earth. However, little is known of the large-scale dynamics of mangrove canopies and how they colonize intertidal areas. Here we focus on a fringe mangrove forest located in the Mekong River Delta, Vietnam; a fast prograding shoreli...

River mouths, shoreline locations where fluvial and coastal sediments are partitioned via erosion, trapping, and redistribution, are responsible for the ultimate sedimentary architecture of deltas and, because of their dynamic nature,also pose great management and engineering challenges. To investigate the interaction between fluvial and littoral p...

Cheniers are sandy ridges parallel to the coast established by high energy waves. Here we discuss Chenier plains ontogeny through dimensional analysis and numerical results from the morphodynamic model Delft3D-SWAN. Our results show that wave energy and shelf slope play an important role in the formation of Chenier plains. In our numerical experime...

Multiple stable states are established in coastal tidal wetlands (marshes, mangroves, deltas, seagrasses) by ecological, hydrological, and geomorphological feedbacks. Catastrophic shifts between states can be induced by gradual environmental change or by disturbance events. These feedbacks and outcomes are key to the sustainability and resilience o...

http://onlinelibrary.wiley.com/wol1/doi/10.1002/2014RG000451/abstract Bars and subaqueous levees often form at river mouths due to high sediment availability. Once these deposits emerge and develop into islands, they become important elements of the coastal landscape, hosting rich ecosystems. Sea-level rise and sediment starvation are jeopardizing...

Sediment spatial distribution method on deltaic islands during flood

Bars and subaqueous levees often form at river mouths due to high sediment availability. Once these deposits emerge and develop into islands, they become important elements of the coastal landscape, hosting rich ecosystems. Sea-level rise and sediment starvation are jeopardizing these landforms, motivating a thorough analysis of the mechanisms resp...

A key process for the formation of deltas and their fluvial networks is the deposition of mouth bars. Predicting mouth bar formation on marine coastlines is complex because of the interactions between waves, tides, vegetation, water and sediment discharge. In this work an analytical model for the hydrodynamic interaction between incoming waves and...

Wave-influenced deltas are shaped by wave-driven transport of river-borne sediments. Near the river mouth, combined jet and wave dynamics, along with morphodynamic feedbacks, control the fraction of sediment transported alongshore by littoral currents that can bypass the river channel. Here we study how different bypassing rates influence large-sca...

The world's coastal deltaic wetlands are threatened by relative sea level rise. Protecting these ecosystems requires understanding deltaic growth and few studies have focused on how vegetation influences this growth. Here we explore the ecogeomorphic evolution of Wax Lake Delta (WLD) using a remote sensing database consisting of 1083 Landsat 5 and...

River deltas support a disproportionate percentage of the world’s population and some are drowning as sea level rises. Resilient deltas theoretically balance relative sea-level rise with vertical growth from surface sedimentation.Vegetation generally enhances inorganic sedimentation and resiliency in some settings, such as tidal saltwater marshes,...

In this work extensive numerical simulations have been performed to assess the hydrodynamic and morphodynamic behaviour of a river jet debouching in a large quiescent water body. A refined three-dimensional grid has been used to capture the transition zone between a stable jet and an unstable meandering jet. The model results show that the stabilit...

Abstract In this work a three-dimensional numerical model (Delft3D) has been used to assess the hydrodynamic and morphodynamic behaviour of a river jet debouching in a large quiescent water body. We show that the stability number S, function of friction and river mouth aspect ratio, and the mouth Reynolds number ReB are the two parameters that...

River deltas are complex environments affected by the morphodynamic interaction between flow and sediment transport. This morphodynamic interaction is potentially affected by the freshwater marsh vegetation (e.g. sagittaria and typha) on the exposed surfaces of emergent deltaic islands. As a first step, we present modeling results and remote sensin...

[1] One of the key processes for the formation of deltas and their fluvial networks is the deposition of mouth bars in front of prograding distributaries. Waves influence mouth bar growth, but it is not clear how and to what extent. Toward this end, we conduct a modeling study on deltas forming in sheltered bays, where waves are locally generated a...

River deltas are among the most important environments on earth, housing productive ecosystems and a large fraction of the human population. The key process for delta development is the deposition of mouth bars in front of delta distributaries. Predicting mouth bar formation on marine coastlines is complex because of the interactions between waves,...