Download or read book Measuring and Tracking Suspended Sediment on Tidal Flats and Inundated Marshland Relevance for Vertical Accretion Rates and Coastal Protection Measures on the North Frisian Halligen written by Ingo Jürgen Hache and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Inhabited coastal areas around the world have to deal with sea level rise (SLR) and its likely consequences such as increasing natural hazards like heavy storms, flooding events and coastal lowland loss by drowning over the long-term. The latter threat also affects the so-called Halligen, ten island-like marsh areas in the North Frisian Wadden Sea (southern North Sea), Germany. Like marshes in general, periodic inundations of the Halligen have the potential to mitigate or even hamper the risk of drowning by sedimentation and subsequent surface elevation increase. This natural adaptation cap...

Download or read book The Role of Suspended Sediment in Assessing Coastal Wetland Vulnerability written by Daniel J. Coleman and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration on wetland geomorphology from fine-scale processes to global patterns and from thriving systems to those experiencing significant environmental change. In Chapter I, I explore alterations to sediment transport and geomorphology caused by an acute vegetation disturbance in a Georgia saltmarsh. My results showed that the loss of vegetation was reversed the trajectory of the site from a prograding marsh to an eroding marsh. In Chapter II, I investigate how suspended sediment travels across the marsh platform using high frequency, long-term measurements in the Plum Island Estuary, Massachusetts. In contrast to the current paradigm, I found that sediment supply in the marsh interior is largely decoupled from channel sediment supply. Chapter III focuses on the role of sediment transport in mangrove encroachment into salt marshes in Australia. My work suggests that mangroves do not inhibit the ability of salt marsh to accrete vertically and that the removal of mangroves to preserve salt marsh would be ineffective. In Chapter IV, I analyze the relationship between suspended sediment concentration, tidal range, and accretion in salt marshes from around the world. My work emphasizes the importance of mineral accretion and marsh elevation when making predictions about marsh response to sea level rise. These results help bridge the gap between numerical models which predict marshes are capable of surviving high rates of relative sea level rise and field studies which suggest drowning at much lower rates. As a whole, my dissertation demonstrates that physical processes and the ways in which biology mediate these processes are critical to the ability of coastal wetlands to persist. As the rate of sea level rise continues to accelerate, it is increasingly important to understand the controls on vertical elevation growth in coastal wetlands at the scale of several meters to thousands of kilometers and in pristine systems to degraded environments.

Download or read book Marsh Sediment Accumulation and Accretion on a Rapidly Retreating Estuarine Coast written by Conor McDowell and published by . This book was released on 2017 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bombay Hook National Wildlife Refuge in coastal Delaware protects one of the most expansive salt marsh systems on the U.S. Mid-Atlantic seaboard. In recent decades, the Refuge has experienced a substantial decrease in salt marsh area along the Delaware Bay boundary by shoreface erosion and in the marsh interior by inland pool expansion. Although the origin of the pools is unknown, it has been suggested that the supply of allochthonous mineral sediment from tidal waterways to the marsh platform may be a contributing factor. To investigate whether vertical accretion of Refuge marshland is limited by sediment accumulation, a study was conducted to measure rates of mineral sediment and organic matter accumulation (mass/area/time) and accretion (length/time) using 137Cs and 210Pb chronologies developed for 19 marsh sites throughout the Refuge. To establish patterns and rates of recent historical marsh loss, an analysis of historical aerial photographs was undertaken. ☐ Results indicate that Bombay Hook NWR has lost a total of ~8.6 million m2 of marsh area since 1961. This loss was mostly caused by the formation of inland pools (~50% of area lost) and shoreface erosion along the Delaware Bay boundary (~35%), with a smaller contribution by waterway channel widening (~15%). Shoreface erosion was most prevalent in the southern half of the Refuge with some locations experiencing up to ~12 m/yr of retreat since 1961, while the northern section experienced far less retreat at 0.6 m/yr. The formation and expansion of inland pools were mostly concentrated in the northern half of the Refuge, adjacent to three freshwater impoundments constructed by the United States Fish and Wildlife Service in the late 1930s. ☐ Salt marsh accretion and mass accumulation rates measured for this study fall within the middle to upper range of similarly determined rates for undisturbed marshes of the Delaware Estuary, and rates based on 137Cs and 210Pb methods were largely in agreement. Accretion rates (137Cs) for low marsh sites averaged 0.65 cm/yr and were significantly higher than rates at high marsh sites, which averaged 0.42 cm/yr. Combined mineral and organic mass accumulation rates (137Cs) exhibited a similar difference between low and high marsh sites, averaging 0.31 g/cm2/yr and 0.13 g/cm2/yr, respectively. Mineral and organic mass accumulation rates correlated strongly with rates of accretion (R2= .85 and .79 respectively), revealing that both mineral sediment and organic matter drive marsh accretion at the Refuge, and that belowground biomass accumulation and aboveground mineral sediment deposition set the minimum and maximum rates of accretion, respectively. ☐ Marsh accretion rates measured in this study met or exceeded the rate of recent relative sea-level rise for the middle Delaware Estuary, based on the NOAA tide gauge record for Reedy Point (0.35 ± 0.05 mm/yr, 1956-2015). This result, in combination with the high rates of mineral accumulation measured throughout the Refuge, makes clear that there is not a marsh accretionary deficit related to insufficient mineral sediment. Moreover, the marsh soil record provides no evidence that the formation and expansion of marsh pools since the 1960s is related to low rates of marsh accretion or sediment supply. Additional research on historical changes in tidal inundation, marsh accretion, and elevation change is needed to better understand the nature of pool expansion and marsh loss at the Refuge.

Download or read book Field Methods for Measurement of Fluvial Sediment written by Harold P. Guy and published by . This book was released on 1970 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Methods Used in Measurement and Analysis of Sediment Loads in Streams written by and published by . This book was released on 1941 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Methods Used in Measurement and Analysis of Sediment Loads in Streams written by and published by . This book was released on 1941 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantifying Current Sediment Deposition Legacy Sediments and Pre impoundment Vertical Accretion and Carbon Dynamics Following Dam Removal in a Recently Restored Tidal Freshwater Wetland written by Melissa J. Davis and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Damming disrupts natural sediment flow to downstream resulting in legacy sediment accumulation. Legacy sediments have been well investigated in streams throughout the Piedmont region; however, there is no research of legacy sediments following dam removal in low-gradient Coastal Plain streams. Research objectives were to: characterize legacy sediments in a low-gradient stream restoration, quantify pre-impoundment accretion and carbon dynamics, and assess current sediment deposition rates via 14C analyses within sediment cores and sediment collection tiles. Carbon accumulation and accretion rates of modern tidal sediment have reached that of the tidal relic benchmark and current sediment deposition rates are similar between the natural reference and restored tidal wetlands. At this site, the pattern of legacy sediment accumulation and stream incision was reversed relative to previous studies in higher gradient systems. Results suggest in dam impacted Coastal Plain streams, legacy sediment may become a benefit rather than a liability for downstream tidal wetlands.

Download or read book Measurement of Suspended Sediment Concentrations in the Field written by J. Nicholson and published by . This book was released on 1985 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Remote Sensing of Suspended Sediment in San Francisco Bay Using Satellite and Drone Imagery written by Joseph Henry Adelson and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Suspended sediment in San Francisco Bay affects the economic and ecological health of the estuary and its surrounding region by limiting light availability for photosynthesis, transporting contaminants, nourishing marsh restoration projects, infilling shipping channels, and providing protection to the shoreline from sea level rise via accretion on mudflats. Traditional efforts to study sediment transport phenomena have relied upon in situ measurements and numerical modeling, but these approaches have limitations. In situ measurement techniques rely on point measurements with high temporal resolution, yet they are difficult to deploy over large spatial areas. Models provide useful insight into the spatial heterogeneity of sediment processes. However, they rely on initial and boundary conditions and parameterizations that are based on observations, therefore the accuracy of models is also constrained in part by the limitations of in situ measurements. This dissertation presents remote sensing measurements from satellites and unmanned aerial vehicles (UAVs) to understand suspended sediment transport processes in estuaries like San Francisco Bay. Twelve methods for inferring suspended sediment concentration (SSC) from Landsat 7 imagery were compared using k-folds validation and assessed based on their abilities to recreate in situ SSC measurements from one meter below the surface. The best performer was the model of Nechad et al. (2010) using the red wavelength band with coefficients determined via Huber regression, with mean absolute error of 5.94 mg L-1 and bias of 0.15 mg L-1. Satellite-derived SSC observations compare well with USGS transects indicating that the method is well-suited to supplement cruise data that is costly to acquire and therefore limited in its frequency. Remote sensing measurements were aggregated by location, season, or tidal phase to understand the variability of SSC and to compare probability densities with in situ measurements. These results show that surface SSC is heightened in the shoals during summer months and has trended downward in Suisun and Grizzly Bays since 1999. Using satellite imagery from 2014-2017, remotely sensed surface SSC derived from the Nechad method was paired with bottom stress estimates based on two-dimensional hydrodynamic and fetch-limited wave models to investigate the relationship between surface SSC and flow. Observations of SSC closely fit a lognormal distribution though the shape, characterized by the modal value, depend on binning criteria including embayment, depth, and wave height. When binned by model-derived bottom shear stress, the modal value of the SSC distribution exhibited an inflection point at the critical shear stress for erosion. This suggests that remote sensing can be used to derive critical stresses that are otherwise difficult to measure. To account for the limitations of satellite imagery such as low spatial resolution and low temporal resolution (Landsat 7 overpasses occurred roughly once every 16 days), a method was developed to infer surface SSC from UAV-based imagery. While traditional remote sensing platforms take imagery at approximately a nadir viewing angle and provide multispectral images that are aligned with one another, an off-the-shelf camera aboard a UAV may not adhere to those qualities. Low cost multi-spectral cameras often include individual sensors for each band. The slight misalignment between images violates assumptions in two-band glint correction algorithms. Additionally, UAVs must tilt to fly and compensate for wind requiring images to occasionally be taken at angles more oblique than most satellite imagery. The method developed in this dissertation adapts previous techniques for sun glint correction for misaligned multispectral images and offers a novel approach to reduce the effects of camera orientation for oblique angles. During a field campaign, the UAV-based method to capture remote sensing reflectance was validated via comparison with in situ measurements made with a hyperspectral radiometer, and its ability to accurately infer SSC was verified based on in situ water samples. It was found that a polarizing filter is necessary to mitigate much of the glare on the water surface. A series of test flights were conducted to measure the surface SSC along a transect parallel to the Dumbarton Bridge during different phases of the tidal cycle. To reduce the impact of variability of incoming light, the flights were conducted over a period of 12 days at the same solar zenith angle during each day. Because the tide arrives later by roughly 50 minutes each day, consecutive daily transects over 12 days provided the variability over a tidal cycle. Cross-sectional sediment flux was computed from the remotely sensed surface SSC measurements and compared well to flux values estimated from in situ USGS observations.

Download or read book Tide and Wave generated Sediment Transport in a Shallow Tidal Channel and Adjacent Tidal Flat written by Alyson Day and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measuring Suspended Sediment in Small Mountain Streams written by Robert B. Thomas and published by Bear Meadows Research Group. This book was released on 1998-04 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Sediment Transport and Deposition in Marshes of the St Jones River Delaware written by Susanne M. Moskalski and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation advances knowledge of the mechanisms affecting sediment transport and deposition in microtidal rivers and marshes. Multiple field and dataset studies were conducted in the St. Jones River in central Delaware. Four component projects focused on forcing mechanisms influencing water properties and sediment fluxes on multiple timescales, and processes that affect sediment trapping and strata formation on the marsh surface. The St. Jones River estuary is apparently well-mixed and tide-dominated, based on its depth, gauged discharge, and surface tide characteristics. Nevertheless, it is strongly impacted by offshore wind forcing and freshwater discharge. Oceanic forcing mechanisms exert a very strong control on sediment transport and related water properties in the study area, even 12 km upstream of the mouth of the river. Offshore wind stress in the along-shelf direction affects river sea level and salinity through Ekman set-up and set-down of Delaware Bay sea level. This remote wind effect is strongest over timescales of 2 to 14 days. Freshwater discharge into the river is much larger than the amount indicated by a gauging station upstream of the head of tides, with a minimum of 63% of freshwater discharged into the estuarine portion of the river coming from ungauged sources. Sea level, salinity, and turbidity are strongly controlled by tides on less-than-daily timescales, but on monthly and longer timescales, water properties are affected by seasonal differences in freshwater discharge, atmospheric temperature, and storminess. The direction of suspended-sediment transport changes with position in the river, and cannot be predicted from distortions of the vertical tide. Storms temporarily reverse the dominant direction of residual flow and suspended-sediment flux. Northeasters consistently generate water levels that exceed normal tides and turbidity levels. The position of the nearest high pressure system is critical in determining the magnitude of the effect on water level and turbidity of a weak or moderate northeaster. The mechanisms controlling daily sediment deposition on the marsh surface can explain century-scale sediment accumulation in the study area. Rates and patterns of sediment deposition on the marsh surface were controlled by changes in grain/floc size and variations in overmarsh suspended-sediment concentration, rather than tidal hydroperiod. Daily sediment deposition can be scaled up to almost match longer-scale accumulation rates by assuming deposition only during spring tides. The results of these studies have implications for marsh modeling and restoration studies, and the response of the study river to climate change.

Download or read book Measuring Suspended Sediment in Small Mountain Streams written by Robert B. Thomas and published by . This book was released on 1985 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fluvial Processes in Motion written by Scott D. Hamshaw and published by . This book was released on 2018 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excessive erosion and fine sediment delivery to river corridors and receiving waters degrade aquatic habitat, add to nutrient loading, and impact infrastructure. Understanding the sources and movement of sediment within watersheds is critical for assessing ecosystem health and developing management plans to protect natural and human systems. As our changing climate continues to cause shifts in hydrological regimes (e.g., increased precipitation and streamflow in the northeast U.S.), the development of tools to better understand sediment dynamics takes on even greater importance. In this research, advanced geomatics and machine learning are applied to improve the (1) monitoring of streambank erosion, (2) understanding of event sediment dynamics, and (3) prediction of sediment loading using meteorological data as inputs. Streambank movement is an integral part of geomorphic changes along river corridors and also a significant source of fine sediment to receiving waters. Advances in unmanned aircraft systems (UAS) and photogrammetry provide opportunities for rapid and economical quantification of streambank erosion and deposition at variable scales. We assess the performance of UAS-based photogrammetry to capture streambank topography and quantify bank movement. UAS data were compared to terrestrial laser scanner (TLS) and GPS surveying from Vermont streambank sites that featured a variety of bank conditions and vegetation. Cross-sectional analysis of UAS and TLS data revealed that the UAS reliably captured the bank surface and was able to quantify the net change in bank area where movement occurred. Although it was necessary to consider overhanging bank profiles and vegetation, UAS-based photogrammetry showed significant promise for capturing bank topography and movement at fine resolutions in a flexible and efficient manner. This study also used a new machine-learning tool to improve the analysis of sediment dynamics using three years of high-resolution suspended sediment data collected in the Mad River watershed. A restricted Boltzmann machine (RBM), a type of artificial neural network (ANN), was used to classify individual storm events based on the visual hysteresis patterns present in the suspended sediment-discharge data. The work expanded the classification scheme typically used for hysteresis analysis. The results provided insights into the connectivity and sources of sediment within the Mad River watershed and its tributaries. A recurrent counterpropagation network (rCPN) was also developed to predict suspended sediment discharge at ungauged locations using only local meteorological data as inputs. The rCPN captured the nonlinear relationships between meteorological data and suspended sediment discharge, and outperformed the traditional sediment rating curve approach. The combination of machine-learning tools for analyzing storm-event dynamics and estimating loading at ungauged locations in a river network provides a robust method for estimating sediment production from catchments that informs watershed management.

Download or read book Dynamics of Estuarine Muds written by Richard Whitehouse and published by Thomas Telford. This book was released on 2000-11-03 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to predict the movement of cohesive sediment within coastal, estuarine or inland waters has a significant economic and ecological importance in the development of new engineering works and the maintenance of existing installations. Dynamics of estuarine muds clearly describes the most up-to-date developments in this field and contains information about improved procedures and how they can be applied to a variety of engineering projects. Drawing on a wide range of new data and new concepts in mud research, this concise volume presents the main processes of cohesive sediment behaviour, namely, erosion, transport, deposition and consolidation. It includes subsections on Knowledge, intended to show the practising engineer which parameters are important in each of the processes and Procedure, which will enable broad estimates of erosion, transport, deposition and consolidation to be made based on knowledge of the site conditions. Dynamics of estuarine muds is essential reading for the practising engineer who is involved in coastal, estuarine or inland water construction. A companion volume to Dynamics of marine sands, this excellent book provides invaluable information about this complex topic in a readily accessible manner.

Download or read book Sustaining the World s Wetlands written by Richard Smardon and published by Springer Science & Business Media. This book was released on 2009-06-13 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wetlands throughout the world, including those described in this book are among the most sensitive and vulnerable ecosystems. They are critical habitats to the world’s migratory birds and a broad range of endangered mammal, reptile, amphibian, and plant species. They provide a broad range of flood storage, pollution control, water supply, ecotourism functions to indigenous peoples and country populations as a whole. They are also at the center of severe land and water use conflicts. These are conflicts between counties where wetland resources or the water supplies required for such resources involve more than one country. These are conflicts in use such as conflicts between habitat protection and charcoal production in mangroves. These are conflicts between groups of peoples such as indigenous peoples and hydropower advocates. Many wetlands have already been destroyed by water extractions, dams, levees, channelization, and fills. Others have been degraded by water pollution, overfishing and overhunting, timber harvest, and a host of other activities. This book describes these conflicts and international policies and institutions developed to protect and manage wetland resources. Most of the broader literature and other books on wetlands focuses on wildlife. Wildlife is described in the case studies, which follow. But, Richard Smardon provides us with more. He traces the history of conflicts and the development of policies and insti- tions to protect and manage wetland resources.

Download or read book The Storyteller s Thesaurus written by Troll Lord Games and published by Troll Lord Games. This book was released on 2015-04-30 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: Writers, game designers, teachers, and students ~this is the book youve been waiting for! Written by storytellers for storytellers, this volume offers an entirely new approach to word finding. Browse the pages within to see what makes this book different: