The use of Landsat and aerial photography for the assessment of coastal erosion and erosion susceptibility in False Bay, South Africa

CSIR Research Space (South Africa)

Callaghan, k

2015-06-01

Full Text Available susceptibility to coastal erosion. Aerial photographs were used for detailed analysis of four focus areas and results indicated that coastal erosion was taking place at all four areas. The higher resolution available on the aerial photographs was vital...

Coastal erosion: Coast problem of the Colombian Caribbean

International Nuclear Information System (INIS)

Martinez, Jaime Orlando

1986-11-01

The erosion promoted by the sea, affects different sectors of the coast of the Colombian Caribbean. The erosion is particularly clear in the central and western sector of the coast. The coastal problem of Punta Sabanilla - Puerto Salgar - Puerto Colombia; Pueblo Nuevo - Lomarena; Manzanillo del Mar; La Boquilla; sector Tolu - Covenas and Arboletes areas are described. This discussion is presented comform to the data obtained in field and of the revision of maps, pictures and other documents related with the coast design. The coastal erosion is not only affecting to low areas conformed by beaches, but rather this phenomenon impacts on rocky cliffs of different elevation; it is the case of El Castillo and Punta Sabanilla to Barranquilla (west Part) sectors . The causes of the setback that it experiences the coast of the Colombian Caribbean are not known in clear form; however they can be contributing such factors as: the elevation of the sea level, phenomenon that has been checked in different costs of the world; equally it can be due to a decrease in the volume of silts contributed by the Magdalena River, inside the coastal area. A third factor would be related with the diapirism of mud, that possibly would be altering the conformation of the Caribbean littoral

Visualizing Coastal Erosion, Overwash and Coastal Flooding in New England

Science.gov (United States)

Young Morse, R.; Shyka, T.

2017-12-01

Powerful East Coast storms and their associated storm tides and large, battering waves can lead to severe coastal change through erosion and re-deposition of beach sediment. The United States Geological Survey (USGS) has modeled such potential for geological response using a storm-impact scale that compares predicted elevations of hurricane-induced water levels and associated wave action to known elevations of coastal topography. The resulting storm surge and wave run-up hindcasts calculate dynamic surf zone collisions with dune structures using discrete regime categories of; "collision" (dune erosion), "overwash" and "inundation". The National Weather Service (NWS) recently began prototyping this empirical technique under the auspices of the North Atlantic Regional Team (NART). Real-time erosion and inundation forecasts were expanded to include both tropical and extra-tropical cyclones along vulnerable beaches (hotspots) on the New England coast. Preliminary results showed successful predictions of impact during hurricane Sandy and several intense Nor'easters. The forecasts were verified using observational datasets, including "ground truth" reports from Emergency Managers and storm-based, dune profile measurements organized through a Maine Sea Grant partnership. In an effort to produce real-time visualizations of this forecast output, the Northeastern Regional Association of Coastal Ocean Observing Systems (NERACOOS) and the Gulf of Maine Research Institute (GMRI) partnered with NART to create graphical products of wave run-up levels for each New England "hotspot". The resulting prototype system updates the forecasts twice daily and allows users the ability to adjust atmospheric and sea state input into the calculations to account for model errors and forecast uncertainty. This talk will provide an overview of the empirical wave run-up calculations, the system used to produce forecast output and a demonstration of the new web based tool.

Coastal Erosion Control Methods

Science.gov (United States)

Greene, V.

2016-12-01

Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

Pan-European Coastal Erosion and Accretion: translating incomplete data and information for coastal reslience assessments

Science.gov (United States)

van Heteren, Sytze; Moses, Cherith; van der Ven, Tamara

2017-04-01

EMODnet has changed the face of the European marine data landscape and is developing tools to connect national data and information resources to make them easily available for multiple users, for multiple purposes. Building on the results of EUROSION, an EU-project completed some ten years ago, EMODnet-Geology has been compiling coastal erosion and sedimentation data and information for all European shorelines. Coverage is being expanded, and data and information are being updated. Challenges faced during this compilation phase are posed by a) differences between parameters used as indicators of shoreline migration, b) restricted access to third-party data, and c) data gaps. There are many indicators of coastal behaviour, with inherent incompatibilities and variations between low-lying sediment and cliffed rock shorelines. Regionally, low data availability and limited access result in poor coverage. With Sentinel data expected to become increasingly available, it is time to invest in automated methods to derive coastal-erosion data from satellite monitoring. Even so, consistency of data and derived information on coastal erosion and accretion does not necessarily translate into usability in pan-European coastal-zone management. Indicators of shoreline change need to be assessed and weighted regionally in light of other parameters in order to be of value in assessing coastal resilience or vulnerability. There is no single way to portray coastal vulnerability for all of Europe in a meaningful way. A common legend, however attractive intuitively, results in data products that work well for one region but show insufficient or excessive detail elsewhere. For decision making, uniform products are often not very helpful. The ability to zoom in on different spatial levels is not a solution either. It is better to compile and visualize vulnerability studies with different legends, and to provide each map with a confidence assessment and other relevant metadata.

Process-based coastal erosion modeling for Drew Point (North Slope, Alaska)

Science.gov (United States)

Ravens, Thomas M.; Jones, Benjamin M.; Zhang, Jinlin; Arp, Christopher D.; Schmutz, Joel A.

2012-01-01

A predictive, coastal erosion/shoreline change model has been developed for a small coastal segment near Drew Point, Beaufort Sea, Alaska. This coastal setting has experienced a dramatic increase in erosion since the early 2000’s. The bluffs at this site are 3-4 m tall and consist of ice-wedge bounded blocks of fine-grained sediments cemented by ice-rich permafrost and capped with a thin organic layer. The bluffs are typically fronted by a narrow (∼ 5  m wide) beach or none at all. During a storm surge, the sea contacts the base of the bluff and a niche is formed through thermal and mechanical erosion. The niche grows both vertically and laterally and eventually undermines the bluff, leading to block failure or collapse. The fallen block is then eroded both thermally and mechanically by waves and currents, which must occur before a new niche forming episode may begin. The erosion model explicitly accounts for and integrates a number of these processes including: (1) storm surge generation resulting from wind and atmospheric forcing, (2) erosional niche growth resulting from wave-induced turbulent heat transfer and sediment transport (using the Kobayashi niche erosion model), and (3) thermal and mechanical erosion of the fallen block. The model was calibrated with historic shoreline change data for one time period (1979-2002), and validated with a later time period (2002-2007).

THE INFLUENCE OF COASTAL EROSION ON THE DEVELOPMENT OF SOUTHERN ROMANIAN BLACK SEA COASTLINE

OpenAIRE

STAN Mari-Isabella

2014-01-01

The influence of human uses, especially the urbanization and economic activities in the coastal zone have transformed the coastal erosion from a natural phenomenon into a growing problem. The paper aims to analyze and present several important aspects of the influence of the anthropic factors on the coastal erosion along the Romanian Black Sea coast, attempting to answer the following question: what is the framework of development that the coastal zone of the Black Sea could access in order t...

Design of a semi-autonomous boat for measurements of coastal sedimentation and erosion

Directory of Open Access Journals (Sweden)

D. Smith

2015-03-01

Full Text Available Measurement of sediment deposition and erosion in coastal areas is a challenge due to soft shifting sediments, but is critical to assessing loss or restoration of coastal sediments and wetlands. The aim of this project was to design and construct a semi-autonomous boat with water depth measuring capabilities. It was intended to map the depth of coastal wetlands to determine erosion rates and assess coastal restoration effects. Depth-measuring equipment was incorporated into an autonomous pontoon boat powered by solar panels. The propulsion system consisted of two paddlewheels and two-way motors to allow movement and positioning for measurements. Modifications included a lightweight, hard coating on the pontoons and powder-coating the frame to extend their usable life. A microcontroller controlled the boat and captured depth data from sensors and location data with a GPS system. The depth measuring system consisted of a pulley and counter system that completed each measurement in less than 45 seconds. This allowed the boat to take approximately 400 measurements per day. Net accuracy was approximately 3 cm in the tested configuration. The boat can continually measure the depth of specified areas in the wetlands; with this data, the change in depth can be monitored to see the effects of restoration projects.

Coastal knickpoints and the competition between fluvial and wave-driven erosion on rocky coastlines

Science.gov (United States)

Limber, Patrick; Barnard, Patrick

2018-01-01

Active margin coastlines are distinguished by rock erosion that acts in two different directions: waves erode the coast horizontally or landwards, a process that creates sea cliffs; and rivers and streams erode the landscape vertically via channel incision. The relative rates of each process exert a dominant control on coastline morphology. Using a model of river channel incision and sea-cliff retreat, we explore how terrestrial and marine erosion compete to shape coastal topography, and specifically what conditions encourage the development of coastal knickpoints (i.e., a river or stream channels that end at a raised sea-cliff edge). We then compare results to actual landscapes. Model results and observations show that coastal knickpoint development is strongly dependent on drainage basin area, where knickpoints typically occur in drainage basins smaller than 5 × 105–6 × 106 m2, as well as channel geometry and sea-cliff retreat rate. In our study area, coastal knickpoints with persistent flow (waterfalls) are uncommon and form only within a small morphological window when 1) drainage basin area is large enough to sustain steady stream discharge, but not large enough to out-compete sea-cliff formation, 2) sea-cliff retreat is rapid, and 3) channel concavity is low so that channel slopes at the coast are high. This particular geomorphic combination can sustain sea-cliff formation even when streams tap into larger drainage basins with greater discharge and more stream power, and provides an initial explanation of why persistent coastal waterfalls are, along many coastlines, relatively rare features.

Coastal knickpoints and the competition between fluvial and wave-driven erosion on rocky coastlines

Science.gov (United States)

Limber, Patrick W.; Barnard, Patrick L.

2018-04-01

Active margin coastlines are distinguished by rock erosion that acts in two different directions: waves erode the coast horizontally or landwards, a process that creates sea cliffs; and rivers and streams erode the landscape vertically via channel incision. The relative rates of each process exert a dominant control on coastline morphology. Using a model of river channel incision and sea-cliff retreat, we explore how terrestrial and marine erosion compete to shape coastal topography, and specifically what conditions encourage the development of coastal knickpoints (i.e., a river or stream channels that end at a raised sea-cliff edge). We then compare results to actual landscapes. Model results and observations show that coastal knickpoint development is strongly dependent on drainage basin area, where knickpoints typically occur in drainage basins smaller than 5 × 105-6 × 106 m2, as well as channel geometry and sea-cliff retreat rate. In our study area, coastal knickpoints with persistent flow (waterfalls) are uncommon and form only within a small morphological window when 1) drainage basin area is large enough to sustain steady stream discharge, but not large enough to out-compete sea-cliff formation, 2) sea-cliff retreat is rapid, and 3) channel concavity is low so that channel slopes at the coast are high. This particular geomorphic combination can sustain sea-cliff formation even when streams tap into larger drainage basins with greater discharge and more stream power, and provides an initial explanation of why persistent coastal waterfalls are, along many coastlines, relatively rare features.

Coastal erosion triggered by a shipwreck along the coast of Goa, India

Digital Repository Service at National Institute of Oceanography (India)

ManiMurali, R.; Babu, M.T.; Mascarenhas, A.; Choudhary, R.; Sudheesh, K.; Vethamony, P.

dunes and, as a consequence, has gradually become fragile due to severe erosion. Keywords: Coastal erosion, cyclone, remote sensing images, shipwreck. GOA is one of the most famous tourist coasts of the world. In general, the sea front of Goa... times due to the sudden boom of real estate sector, mushrooming of industries, inconsistent tourist flows, with a consequent impact on coastal ecosystems. Changes in the land-use/land-cover, geomorphology, ecology and sensitivity of coasts were...

Coastal erosion and mangrove progradation of Southern Thailand

NARCIS (Netherlands)

Thampanya, U.; Vermaat, J.E.; Sinsakul, S.; Panapitukkul, N.

2006-01-01

Approximately 60% of the southern Thai coastline used to be occupied by mangroves according to the first mangrove forest assessment in 1961. During the past three decades, these mangrove areas have been reduced to about 50% with less than 10% left on the east coast. Coastal erosion and accretion

Coastal erosion and beach nourishment in Scania as issues in Swedish coastal policy

NARCIS (Netherlands)

Bontje, L.E.; Frederiksson, Caroline; Wang, Zilin; Slinger, J.H.

2016-01-01

This paper discusses the dynamics of coastal policy change in Sweden, using erosion and beach nourishments as an example. The Multiple Stream Model is a theoretical model on agenda setting and policy change developed by the political scientist John Kingdon (1984, 2003). This paper applies Kingdon’s

Coastal erosion: Coast problem of the Colombian Caribbean; Erosion costera: Problema de la costa del Caribe Colombiano

Energy Technology Data Exchange (ETDEWEB)

Martinez, Jaime Orlando

1986-11-01

The erosion promoted by the sea, affects different sectors of the coast of the Colombian Caribbean. The erosion is particularly clear in the central and western sector of the coast. The coastal problem of Punta Sabanilla - Puerto Salgar - Puerto Colombia; Pueblo Nuevo - Lomarena; Manzanillo del Mar; La Boquilla; sector Tolu - Covenas and Arboletes areas are described. This discussion is presented comform to the data obtained in field and of the revision of maps, pictures and other documents related with the coast design. The coastal erosion is not only affecting to low areas conformed by beaches, but rather this phenomenon impacts on rocky cliffs of different elevation; it is the case of El Castillo and Punta Sabanilla to Barranquilla (west Part) sectors . The causes of the setback that it experiences the coast of the Colombian Caribbean are not known in clear form; however they can be contributing such factors as: the elevation of the sea level, phenomenon that has been checked in different costs of the world; equally it can be due to a decrease in the volume of silts contributed by the Magdalena River, inside the coastal area. A third factor would be related with the diapirism of mud, that possibly would be altering the conformation of the Caribbean littoral.

Coastal erosion and accretion in Pak Phanang, Thailand by GIS analysis of maps and satellite imagery

Directory of Open Access Journals (Sweden)

Sayedur Rahman Chowdhury

2013-12-01

Full Text Available Coastal erosion and accretion in Pak Phanang of southern Thailand between 1973 and 2003 was measured using multi-temporal topographic maps and Landsat satellite imageries. Within a GIS environment landward and seaward movements of shoreline was estimated by a transect-based analysis, and amounts of land accretion and erosion were estimated by a parcel-based geoprocessing. The whole longitudinal extent of the 58 kilometer coast was classified based on the erosion and accretion trends during this period using agglomerative hierarchical clustering approach. Erosion and accretion were found variable over time and space, and periodic reversal of status was also noticed in many places. Estimates of erosion were evaluated against field-survey based data, and found reasonably accurate where the rates were relatively great. Smoothing of shoreline datasets was found desirable as its impacts on the estimates remained within tolerable limits.

Erosion Pressure on the Danish Coasts

DEFF Research Database (Denmark)

Sørensen, Carlo Sass; Sørensen, Per; Kroon, Aart

Coastlines around the world are receding due to coastal erosion.With rising sea levels and a potential climatic deterioration due to climate change, erosion rates are likely to increase at many locations in the future.Together with the current preference of people to settle near or directly...... by the ocean, coastal erosion issues become increasingly more important to the human values at risk. Along many Danish coastlines, hard structures already act as coastal protection in the form of groins, breakwaters, revetments etc. These eroding coasts however still lack sand and where the public, in general......, neglects the need for sand replenishment i.e. in the form of repeated sand nourishments. Here we present a conceptual model and method for dividing coastal erosion into acute and chronic erosion pressure, respectively. We focus on the model use for management and climate change adaptation purposes...

Thermal erosion of a permafrost coastline: Improving process-based models using time-lapse photography

Science.gov (United States)

Wobus, C.; Anderson, R.; Overeem, I.; Matell, N.; Clow, G.; Urban, F.

2011-01-01

Coastal erosion rates locally exceeding 30 m y-1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where coastal erosion rates have averaged 10-15 m y-1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.

The influence of wave action on coastal erosion along Monwabisi ...

African Journals Online (AJOL)

Microsoft account

commonly recognised effect of this warming is the eustatic rise of sea level (Allen ... 100km of the coastline and could be affected by future sea-level rise (SLR)- ..... Douglas, BC 2000, 'Sea Level Rise Shown to Drive Coastal Erosion', Florida.

Demarcation of coastal vulnerability line along the Indian coast

Digital Repository Service at National Institute of Oceanography (India)

Ajai; Baba, M.; Unnikrishnan, A.S.; Rajawat, A.S.; Bhattacharya, S.; Ratheesh, R.; Kurian, N.P.; Hameed, S.; Sundar, D.

been considered. Changes along the shoreline are considered as net impact of dynamic coastal processes and are mapped using multidate satellite data. Vulnerability due to coastal erosion has been assessed based on rate of coastal erosion. Coastal...

Coastal erosion hazard and vulnerability using sig tools. Comparison between "La Barra town, Buenaventura, (Pacific Ocean of Colombia) and Providence - Santa Catalina islands (Colombian Caribbean Sea)

Science.gov (United States)

Coca-Domínguez, Oswaldo; Ricaurte-Villota, Constanza; Morales-Giraldo, David; Rangel-Buitrago, Nelson

2014-05-01

Analysis of hazards and vulnerability associated to coastal erosion along coastlines is a first issue in order to establish plans for adaptation to climate change in coastal areas. La Barra Town, Buenaventura (Pacific ocean of Colombia) and Providence - Santa Catalina Islands (Colombian Caribbean) were selected to develop a detailed analysis of coastal erosion hazard and vulnerability from different perspectives: i) physical (hazard) , ii) social , iii) conservation approach and iv) cultural heritage (Raizal). The analysis was made by a semi quantitative approximation method, applying variables associated with the intrinsic coastal zone properties (i.e. type of beach, exposure of the coast to waves, etc.). Coastal erosion data and associated variables as well land use; conservation and heritage data were used to carry out a further detailed analysis of the human - structural vulnerability and exposure to hazards. The data shows erosion rates close to -17 m yr-1 in La Barra Town (highlighting their critical condition and urgent relocation process), while in some sectors of Providence Island, such as Old Town, erosion rate was -5 m yr-1. The observed erosion process affects directly the land use and the local and regional economy. The differences between indexes and the structural and physical vulnerability as well the use of methodological variables are presented in the context of each region. In this work, all the information was worked using a GIS environment since this allows editing and updating the information continuously. The application of this methodology generates useful information in order to promote risk management as well prevention, mitigation and reduction plans. In both areas the adaptation must be a priority strategy to be considered, including relocation alternatives and sustainable protection with the support of studies of uses and future outlooks in the coast. The methodology is framed into the use of GIS tools and it highlights their benefits

The communication of the risk of coastal erosion in Portugal: a global problem, a local trouble

Directory of Open Access Journals (Sweden)

Eduardo BASTO

2014-07-01

Full Text Available In the past two decades a set of instruments has been devised by the Portuguese authorities to handle the issue of coastal erosion. We argue that this legal apparatus not only lacks the internal integration necessary for its effectiveness, but it also fails to recognise the ways in which the problem materialises in the everyday life of coastal areas. Through a case study in the village of Furadouro in Western Portugal, we demonstrate how this top-down implementation of policies does not promote a true communication of risks, in the sense that the problem of coastal erosion is not “put in common” across levels of governance.

An Extreme Event as a Game Changer in Coastal Erosion Management

DEFF Research Database (Denmark)

Sørensen, Carlo Sass; Drønen, Nils K.; Knudsen, Per

2016-01-01

of cyclone Xaver in December 2013 with severe coastal erosion led to collaboration between the involved municipalities to work on a coherent solution for the entire coastline that involves sand nourishments, renovation and optimization of hard protection structures, and the restoration of recreational values...

Erosion of Coastal Foredunes: A Review on the Effect of Dune Vegetation

Science.gov (United States)

2017-02-01

inhabited by vegetation (Figure 2).The collision regime occurs when the total storm water level exceeds the elevation of the dune toe but is lower than the...of Dune Vegetation by Duncan B. Bryant, Mary A. Bryant, and Alison S. Grzegorzewski PURPOSE: The purpose of this Coastal and Hydraulics...Engineering Technical Note (CHETN) is to identify the potential roles of vegetation in mitigating coastal dune erosion during storm events by presenting a

Coastal erosion vulnerability and risk assessment focusing in tourism beach use.

Science.gov (United States)

Alexandrakis, George

2016-04-01

It is well established that the global market for tourism services is a key source of economic growth. Especially among Mediterranean countries, the tourism sector is one of the principal sectors driving national economies. With the majority of the mass tourism activities concentrated around coastal areas, coastal erosion, inter alia, poses a significant threat to coastal economies that depend heavily on revenues from tourism. The economic implications of beach erosion were mainly focused in the cost of coastal protection measures, instead of the revenue losses from tourism. For this, the vulnerability of the coast to sea level rise and associated erosion, in terms of expected land loss and economic activity need to be identified. To achieve this, a joint environmental and economic evaluation approach of the problem can provide a managerial tool to mitigate the impact of beach erosion in tourism, through realistic cost-benefit scenarios for planning alternative protection measures. Such a multipurpose tool needs to consider social, economic and environmental factors, which relationships can be better understood when distributed and analyzed along the geographical space. The risk assessment is implemented through the estimation of the vulnerability and exposure variables of the coast in two scales. The larger scale estimates the vulnerability in a regional level, with the use environmental factors with the use of CVI. The exposure variable is estimated by the use of socioeconomic factors. Subsequently, a smaller scale focuses on highly vulnerable beaches with high social and economic value. The assessment of the natural processes to the environmental characteristics of the beach is estimated with the use of the Beach Vulnerability Index (BVI) method. As exposure variable, the value of beach width that is capitalized in revenues is implemented through a hedonic pricing model. In this econometric modelling, Beach Value is related with economic and environmental

Short and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region

Science.gov (United States)

Günther, F.; Overduin, P. P.; Sandakov, A. V.; Grosse, G.; Grigoriev, M. N.

2013-02-01

Permafrost coasts in the Arctic are susceptible to a variety of changing environmental factors all of which currently point to increasing coastal erosion rates and mass fluxes of sediment and carbon to the shallow arctic shelf seas. Rapid erosion along high yedoma coasts composed of Ice Complex permafrost deposits creates impressive coastal ice cliffs and inspired research for designing and implementing change detection studies for a long time, but continuous quantitative monitoring and a qualitative inventory of coastal thermo-erosion for large coastline segments is still lacking. Our goal is to use observations of thermo-erosion along the mainland coast of the Laptev Sea in eastern Siberia to understand how erosion rates depend on coastal geomorphology and the relative contributions of waterline and atmospheric drivers to coastal thermo-erosion over the past 4 decades and in the past few years. We compared multitemporal sets of orthorectified satellite imagery from 1965 to 2011 for three segments of coastline with a length of 73 to 95 km each and analyzed thermo-denudation (TD) along cliff top and thermo-abrasion (TA) along cliff bottom for two nested time periods: long-term rates (the past 39-43 yr) and short term rates (the past 1-3 yr). The Normalized Difference Thermo-erosion Index (NDTI) was used as a proxy that qualitatively describes the relative proportions of TD and TA. Mean annual erosion rates at all three sites were higher in recent years (-5.3 ± 1.31 m a-1) than over the long term mean (-2.2 ± 0.13 m a-1). The Mamontov Klyk coast exhibit primarily spatial variations of thermo-erosion, while intrasite-specific variations were strongest at the Buor Khaya coast, where slowest long-term rates around -0.5 ± 0.08 m a-1 were observed. The Oyogos Yar coast showed continuously rapid erosion up to -6.5 ± 0.19 m a-1. In general, variable characteristics of coastal thermo-erosion were observed not only between study sites and over time, but also within

An assessment of the radiological impact of coastal erosion of the UK Low-Level Waste Repository - 59137

International Nuclear Information System (INIS)

Sumerling, Trevor; Shevelan, John; Cummings, Richard; Fish, Paul; Towler, George; Penfold, James

2012-01-01

The UK Low Level Waste Repository Ltd submitted an Environmental Safety Case for the disposal of low-level waste to our regulator, the Environment Agency, on the 1 May 2011. This includes assessments of the long-term radiological safety of past and future disposals. A particular feature of the Low Level Waste Repository (LLWR) is that, because of its proximity to the coast, the site is vulnerable to coastal erosion. Our present understanding is that the site will be eroded on a timescale of a few hundred to a few thousand years, with consequent disruption of the repository, and dispersal of the wastes. We have undertaken a programme of scientific research and monitoring to characterise the evolution and function of the current coastal system that provides a basis for forecasting its future evolution. This has included modelling of contemporary hydrodynamics, geo-morphological mapping, repeat LiDAR and aerial photographic surveys to detect patterns and rates of change, coastal inspections and reconstructions of post-glacial (i.e. last 15, 000 years) sea levels and sediment budgets. Estimates of future sea-level rise have been derived from international sources and consideration given to the impact of such on the local coastline. Two alternative models of coastal recession have then been applied, one empirical and one physical-process based, taking account of the composition of Quaternary-age sediments between the coast and the site and uncertainties in future local sea level change. Comparison of the ranges of calculated times to site contact with sea-level rise indicate that the repository is most likely to be disrupted by undercutting of the engineered vaults and of the trenches. A novel and flexible radiological assessment model has been developed to analyse the impacts of the erosion of the repository and subsequent dispersal of wastes. The model represents the spatial layout of the site and distribution of radionuclides within the repository and is able to take

The social cost of coastal erosion. Using cultural theory to enrich the interpretation of stated preference data.

Science.gov (United States)

Kontogianni, A.; Tourkolias, C.; Vousdoukas, M.; Skourtos, M.

2012-04-01

Natural coastal processes are to a great extent modified by proximity to man-made structures. Engineered interventions, port facilities, housing and industrial infrastructure, all can increase the coastline fluctuations significantly relative to those along a long unobstructed coastline. As a consequence, coastlines are increasingly exposed to coastal erosion, a phenomenon defined as the encroachment of land by the sea after averaging over a period, which is sufficiently long to eliminate the impacts of weather, storm events and local sediment dynamics. In order to provide cost effective management of coastal erosion it is crucial to estimate both the benefits and costs associated with various management alternatives. The initiatives on Integrated Coastal Zone Manegment in Europe, but also the upcoming Marine Strategy Framwork Directive would benefit greatly from a proliferation of socioeconomic information to assist decision makers who must weigh the impacts of various types of coastal improvement and the cost of beach protection/restoration. In that spirit, the objective of the present research is to report the results of a survey undertaken in two resort beaches on the island of Lesvos (Greece), designed to estimate public preferences for avoiding coastal erosion. A mixed methodological approach is employed by combining an open-ended contingent valuation survey with cultural theory of risk perception. The empirical models to analyze individual choices of erosion control programs and the associated welfare measures are presented, followed by the discussion of model specification and estimation issues, and the results of the data analysis. Some concluding remarks are then presented. By choosing this approach we aim at improving our understanding of preference structure for avoiding public risk, accepted level of risk and perceptions thereof. The framework can also be used for assessing the social cost of extreme weather events such as storm surges in the coastal

Rill erosion rates in burned forests

Science.gov (United States)

Joseph W. Wagenbrenner; Peter R. Robichaud

2011-01-01

Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

Multivariate return periods of sea storms for coastal erosion risk assessment

Directory of Open Access Journals (Sweden)

S. Corbella

2012-08-01

Full Text Available The erosion of a beach depends on various storm characteristics. Ideally, the risk associated with a storm would be described by a single multivariate return period that is also representative of the erosion risk, i.e. a 100 yr multivariate storm return period would cause a 100 yr erosion return period. Unfortunately, a specific probability level may be associated with numerous combinations of storm characteristics. These combinations, despite having the same multivariate probability, may cause very different erosion outcomes. This paper explores this ambiguity problem in the context of copula based multivariate return periods and using a case study at Durban on the east coast of South Africa. Simulations were used to correlate multivariate return periods of historical events to return periods of estimated storm induced erosion volumes. In addition, the relationship of the most-likely design event (Salvadori et al., 2011 to coastal erosion was investigated. It was found that the multivariate return periods for wave height and duration had the highest correlation to erosion return periods. The most-likely design event was found to be an inadequate design method in its current form. We explore the inclusion of conditions based on the physical realizability of wave events and the use of multivariate linear regression to relate storm parameters to erosion computed from a process based model. Establishing a link between storm statistics and erosion consequences can resolve the ambiguity between multivariate storm return periods and associated erosion return periods.

Assessing the multidimensionality of coastal erosion risks: public participation and multicriteria analysis in a Mediterranean coastal system.

Science.gov (United States)

Roca, Elisabet; Gamboa, Gonzalo; Tàbara, J David

2008-04-01

The complex and multidimensional nature of coastal erosion risks makes it necessary to move away from single-perspective assessment and management methods that have conventionally predominated in coastal management. This article explores the suitability of participatory multicriteria analysis (MCA) for improving the integration of diverse expertises and values and enhancing the social-ecological robustness of the processes that lead to the definition of relevant policy options to deal with those risks. We test this approach in the Mediterranean coastal locality of Lido de Sète in France. Results show that the more adaptive alternatives such as "retreating the shoreline" were preferred by our selected stakeholders to those corresponding to "protecting the shoreline" and the business as usual proposals traditionally put forward by experts and policymakers on these matters. Participative MCA contributed to represent coastal multidimensionality, elicit and integrate different views and preferences, facilitated knowledge exchange, and allowed highlighting existing uncertainties.

LIDAR data to support coastal erosion analysis: the Conero study case

Science.gov (United States)

Calligaro, Simone; Sofia, Giulia; Guarnieri, Alberto; Tarolli, Paolo

2013-04-01

In the last decades, the topic of coastal erosion and the derived risk have been subject of a growing interest for public authorities and researchers. Recent major natural events, such as hurricanes, tsunamis, and sea level rising, called the attention of media and society, underlining serious concerns about such problems. In a high-density populated country such as Italy, where tourism is one of the major economic activities, the coastal erosion is really a critical issue. In April 2010, along a reach of the coast of Ventotene Island, two young students tragically died, killed by a rock fall. This event dramatically stressed public authorities about the effectiveness of structural and non-structural measures for the mitigation of such phenomena. It is clear that an improving of the actual knowledge about coastal erosion is needed, especially to monitor such events and to set alert systems. In the last few years, airborne LIDAR technology led to a dramatic increase in terrain information. Airborne LiDAR and Terrestrial Laser Scanner (TLS) derived high-resolution Digital Terrain Models (DTMs) have opened avenues for hydrologic and geomorphologic studies (Tarolli et al., 2009). In general, all the main surface processes signatures are correctly recognized using a DTM with cell sizes of 1 m. Having said that, some sub-meter grid sizes may be more suitable in those situations where the analysis of micro topography related to micro changes due to slope failures is critical for risk assessment, and the Terrestrial Laser Scanner (TLS) has been proven to be a useful tool for such detailed field survey. The acquired elevation data with TLS allow to derive a centimeters high quality DTMs. The possibility to detect in detail the slope failures signatures results in a better understanding and mapping of the erosion susceptibility, and of those areas where slope failures are more likely to happen. In addition, these information can be also considered as the basis to develop

Erosion reasons and rate on accumulative Polish dune coast caused by the January 2012 storm surge

Directory of Open Access Journals (Sweden)

Tomasz A. Łabuz

2014-03-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

High and Increasing Shoreline Erosion Rates of Thermokarst Lakes Set in Ice-Rich Permafrost Terrain of the Arctic Coastal Plain of Alaska

Science.gov (United States)

Bondurant, A. C.; Arp, C. D.; Jones, B. M.; Shur, Y.; Daanen, R. P.

2017-12-01

Thermokarst lakes are a dominant landform shaping landscapes and impacting permafrost on the Arctic Coastal Plain (ACP) of northern Alaska, a region of continuous permafrost. Here lakes cover greater than 20% of the landscape and drained lake basins cover an additional 50 to 60% of the landscape. The formation, expansion, and drainage of thaw lakes has been described by some researchers as part of a natural cycle that has reworked the ACP landscape during the Holocene. Yet the factors and processes controlling contemporary thermokarst lake expansion remain poorly described. This study focuses on the factors controlling expansion rates of thermokarst lakes in three ACP regions that vary in landscape history, ground-ice content, and lake morphology (i.e. size and depth), as well as evaluating changes through time. Through the use of historical aerial imagery, satellite imagery, and field observations, this study identifies the controlling factors at multiple spatial and temporal scales to better understand the processes relating to thermokarst lake expansion. Studies of 35 lakes across the ACP shows regional differences in expansion rate related to permafrost ice content ranging from an average expansion rate of 0.62 m/yr where ice content is highest ( 86%) to 0.16 m/yr where ice content is lowest (45%-71%). A subset of these lakes analyzed over multiple time periods show increasing rates of erosion, with average rates being 37% higher over the period 1979-2002 (0.73 m/yr) compared to 1948-1979 (0.53 m/yr). These increased rates of erosion have important implications for the regional hydrologic cycle and localized permafrost degradation. Predicting how thermokarst lakes will behave locally and on a landscape scale is increasingly important for managing habitat and water resources and informing models of land-climate interactions in the Arctic.

Short- and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region

Science.gov (United States)

Günther, F.; Overduin, P. P.; Sandakov, A. V.; Grosse, G.; Grigoriev, M. N.

2013-06-01

Permafrost coasts in the Arctic are susceptible to a variety of changing environmental factors all of which currently point to increasing coastal erosion rates and mass fluxes of sediment and carbon to the shallow arctic shelf seas. Rapid erosion along high yedoma coasts composed of Ice Complex permafrost deposits creates impressive coastal ice cliffs and inspired research for designing and implementing change detection studies for a long time, but continuous quantitative monitoring and a qualitative inventory of coastal thermo-erosion for large coastline segments is still lacking. Our goal is to use observations of thermo-erosion along the mainland coast of the Laptev Sea, in eastern Siberia, to understand how it depends on coastal geomorphology and the relative contributions of water level and atmospheric drivers. We compared multi-temporal sets of orthorectified satellite imagery from 1965 to 2011 for three segments of coastline ranging in length from 73 to 95 km and analyzed thermo-denudation (TD) along the cliff top and thermo-abrasion (TA) along the cliff bottom for two nested time periods: long-term rates (the past 39-43 yr) and short-term rates (the past 1-4 yr). The Normalized Difference Thermo-erosion Index (NDTI) was used as a proxy to qualitatively describe the relative proportions of TD and TA. Mean annual erosion rates at all three sites were higher in recent years (-5.3 ± 1.3 m a-1) than over the long-term mean (-2.2 ± 0.1 m a-1). The Mamontov Klyk coast exhibits primarily spatial variations of thermo-erosion, while intrasite-specific variations caused by local relief were strongest at the Buor Khaya coast, where the slowest long-term rates of around -0.5 ± 0.1 m a-1 were observed. The Oyogos Yar coast showed continuously rapid erosion up to -6.5 ± 0.2 m a-1. In general, variable characteristics of coastal thermo-erosion were observed not only between study sites and over time, but also within single coastal transects along the cliff profile

Monitoring Coastal Change after the Tsunami in Thailand

International Nuclear Information System (INIS)

Pantanahiran, W

2014-01-01

The tsunami on December 26, 2004 caused widespread devastation along the coast of Thailand, especially in Ban Nam Khem, Phang Nga province. This disaster claimed more than 941 lives, with 502 other people missing when the storm surge caught the residents of this area. The coastal geomorphology was impacted by this disaster. The objectives of the research were to study the effect of the tsunami on coastal change and the recovery of coastal areas. Six time-series datasets of aerial photographs and satellite images from 2002, 2004, 2005, 2006, 2009, and 2010 were compared using the Geographic Information System (GIS). The results showed the effect of the tsunami on the buildings in the area. Fifty-eight point sixty-three percent of the buildings in the urban area were destroyed by the tsunami and constructions was raised to 103.60% and 197.12% between 2004 and 2010, thus indicating the recovery of the local community. Geomorphological change in Ko Kho Khao (the island) was found after the tsunami disaster, including coastal erosion and coastal deposition. The balance of nature played a major role in controlling the erosion and deposition. The coastal deposits were the highest in 2005; however, deposition was not found in 2004. The erosion rate from 2002-2003 was the highest (48.10 meter per year) and higher than 2003-2004 (39.03 meters per year), 2004-2009 (15.64 meters per year) and 2009-2010 (29.49 meters per year). The coastal area was more severe eroded than the estuary area, and severe coastal erosion caused the loss of coastal area, approximately 0.28 ha. Severe coastal erosion has been repeatedly found since 2005 in the lower part of the area, and hard structures such as concrete seawalls might have been affected by coastal erosion. In addition, extrapolation of coastal erosion at the rate of 30 meters per year showed that the lower part of Ko Kho Khao should disappear in 2015

Natural and anthropogenic rates of soil erosion

Science.gov (United States)

Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natur...

Extreme coastal erosion enhanced by anomalous extratropical storm wave direction.

Science.gov (United States)

Harley, Mitchell D; Turner, Ian L; Kinsela, Michael A; Middleton, Jason H; Mumford, Peter J; Splinter, Kristen D; Phillips, Matthew S; Simmons, Joshua A; Hanslow, David J; Short, Andrew D

2017-07-20

Extratropical cyclones (ETCs) are the primary driver of large-scale episodic beach erosion along coastlines in temperate regions. However, key drivers of the magnitude and regional variability in rapid morphological changes caused by ETCs at the coast remain poorly understood. Here we analyze an unprecedented dataset of high-resolution regional-scale morphological response to an ETC that impacted southeast Australia, and evaluate the new observations within the context of an existing long-term coastal monitoring program. This ETC was characterized by moderate intensity (for this regional setting) deepwater wave heights, but an anomalous wave direction approximately 45 degrees more counter-clockwise than average. The magnitude of measured beach volume change was the largest in four decades at the long-term monitoring site and, at the regional scale, commensurate with that observed due to extreme North Atlantic hurricanes. Spatial variability in morphological response across the study region was predominantly controlled by alongshore gradients in storm wave energy flux and local coastline alignment relative to storm wave direction. We attribute the severity of coastal erosion observed due to this ETC primarily to its anomalous wave direction, and call for greater research on the impacts of changing storm wave directionality in addition to projected future changes in wave heights.

Natural and anthropogenic rates of soil erosion

Directory of Open Access Journals (Sweden)

Mark A. Nearing

2017-06-01

Full Text Available Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natural, non-cropped conditions have been documented to be less than 2 Mg ha−1 yr−1. On-site rates of erosion of lands under cultivation over large cropland areas, such as in the United States, have been documented to be on the order of 6 Mg ha−1 yr−1 or more. In northeastern China, lands that were brought into production during the last century are thought to have average rates of erosion over this large area of as much as 15 Mg ha−1 yr−1 or more. Broadly applied soil conservation practices, and in particular conservation tillage and no-till cropping, have been found to be effective in reducing rates of erosion, as was seen in the United States when the average rates of erosion on cropped lands decreased from on the order of 9 Mg ha−1 yr−1 to 6 or 7 Mg ha−1 yr−1 between 1982 and 2002, coincident with the widespread adoption of new conservation tillage and residue management practices. Taking cropped lands out of production and restoring them to perennial plant cover, as was done in areas of the United States under the Conservation Reserve Program, is thought to reduce average erosion rates to approximately 1 Mg ha−1 yr−1 or less on those lands.

Coastal erosion risk assessment using natural and human factors in different scales.

Science.gov (United States)

Alexandrakis, George; Kampanis, Nikolaos

2015-04-01

Climate change, including sea-level rise and increasing storms, raise the threats of coastal erosion. Mitigating and adapting to coastal erosion risks in areas of human interest, like urban areas, culture heritage sites, and areas of economic interest, present a major challenge for society. In this context, decision making needs to be based in reliable risk assessment that includes environmental, social and economic factors. By integrating coastal hazard and risk assessments maps into coastal management plans, risks in areas of interest can be reduced. To address this, the vulnerability of the coast to sea level rise and associated erosion, in terms of expected land loss and socioeconomic importance need to be identified. A holistic risk assessment based in environmental, socioeconomic and economics approach can provide managers information how to mitigate the impact of coastal erosion and plan protection measures. Such an approach needs to consider social, economic and environmental factors, which interactions can be better assessed when distributed and analysed along the geographical space. In this work, estimations of climate change impact to coastline are based on a combination of environmental and economic data analysed in a GIS database. The risk assessment is implemented through the estimation of the vulnerability and exposure variables of the coast in two scales. The larger scale estimates the vulnerability in a regional level, with the use environmental factors with the use of CVI. The exposure variable is estimated by the use of socioeconomic factors. Subsequently, a smaller scale focuses on highly vulnerable beaches with high social and economic value. The vulnerability assessment of the natural processes to the environmental characteristics of the beach is estimated with the use of the Beach Vulnerability Index. As exposure variable, the value of beach width that is capitalized in revenues is implemented through a hedonic pricing model. In this

Coastal dynamics studies for evaluation of hazard and vulnerability for coastal erosion. case study the town La Bocana, Buenaventura, colombian pacific

Science.gov (United States)

Coca-Domínguez, Oswaldo; Ricaurte-Villota, Constanza

2015-04-01

The analysis of the hazard and vulnerability in coastal areas caused for erosion is based on studies of coastal dynamics since that allows having a better information detail that is useful for decision-making in aspects like prevention, mitigation, disaster reduction and integrated risk management. The Town of La Bocana, located in Buenaventura (Colombian Pacific) was selected to carry out the threat assessment for coastal erosion based on three components: i) magnitude, ii) occurrence and iii) susceptibility. Vulnerability meanwhile, is also composed of three main components for its evaluation: i) exposure ii) fragility and iii) resilience, which in turn are evaluated in 6 dimensions of vulnerability: physical, social, economic, ecological, institutional and cultural. The hazard analysis performed used a semi-quantitative approach, and an index of variables such as type of geomorphological unit, type of beach, exposure of the surfing coast, occurrence, among others. Quantitative data of coastal retreat was measured through the use of DSAS (Digital Shoreline Analysis System) an application of ArcGIS, as well as the development of digital elevation models from the beach and 6 beach profiles strategically located on the coast obtained with GNSS technology. Sediment samples collected from these beaches, medium height and wave direction were used as complementary data. The information was integrated across the coast line into segments of 250 x 250 meters. 4 sectors are part of the coastal area of La Bocana: Pianguita, Vistahermosa, Donwtown and Shangay. 6 vulnerability dimensions units were taken from these population, as well as its density for exposure, wich was analyzed through a multi-array method that include variables such as, land use, population, type of structure, education, basic services, among others, to measure frailty, and their respective indicator of resilience. The hazard analysis results indicate that Vistahermosa is in very high threat, while

Erosion and its rate on an accumulative Polish dune coast: the effects of the January 2012 storm surge

Directory of Open Access Journals (Sweden)

Tomasz A. Łabuz

2014-01-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

STORMTOOLS: Coastal Environmental Risk Index (CERI

Directory of Open Access Journals (Sweden)

Malcolm L. Spaulding

2016-08-01

Full Text Available One of the challenges facing coastal zone managers and municipal planners is the development of an objective, quantitative assessment of the risk to structures, infrastructure, and public safety that coastal communities face from storm surge in the presence of changing climatic conditions, particularly sea level rise and coastal erosion. Here we use state of the art modeling tool (ADCIRC and STWAVE to predict storm surge and wave, combined with shoreline change maps (erosion, and damage functions to construct a Coastal Environmental Risk Index (CERI. Access to the state emergency data base (E-911 provides information on structure characteristics and the ability to perform analyses for individual structures. CERI has been designed as an on line Geographic Information System (GIS based tool, and hence is fully compatible with current flooding maps, including those from FEMA. The basic framework and associated GIS methods can be readily applied to any coastal area. The approach can be used by local and state planners to objectively evaluate different policy options for effectiveness and cost/benefit. In this study, CERI is applied to RI two communities; Charlestown representing a typical coastal barrier system directly exposed to ocean waves and high erosion rates, with predominantly low density single family residences and Warwick located within Narragansett Bay, with more limited wave exposure, lower erosion rates, and higher residential housing density. Results of these applications are highlighted herein.

Spatio-temporal variability in accretion and erosion of coastal foredunes in the Netherlands: regional climate and local topography.

Science.gov (United States)

Keijsers, Joep G S; Poortinga, Ate; Riksen, Michel J P M; Maroulis, Jerry

2014-01-01

Depending on the amount of aeolian sediment input and dune erosion, dune size and morphology change over time. Since coastal foredunes play an important role in the Dutch coastal defence, it is important to have good insight in the main factors that control these changes. In this paper the temporal variations in foredune erosion and accretion were studied in relation to proxies for aeolian transport potential and storminess using yearly elevation measurements from 1965 to 2012 for six sections of the Dutch coast. Longshore differences in the relative impacts of erosion and accretion were examined in relation to local beach width. The results show that temporal variability in foredune accretion and erosion is highest in narrow beach sections. Here, dune erosion alternates with accretion, with variability displaying strong correlations with yearly values of storminess (maximum sea levels). In wider beach sections, dune erosion is less frequent, with lower temporal variability and stronger correlations with time series of transport potential. In erosion dominated years, eroded volumes decrease from narrow to wider beaches. When accretion dominates, dune-volume changes are relatively constant alongshore. Dune erosion is therefore suggested to control spatial variability in dune-volume changes. On a scale of decades, the volume of foredunes tends to increase more on wider beaches. However, where widths exceed 200 to 300 m, this trend is no longer observed.

Accelerated relative sea-level rise and rapid coastal erosion: Testing a causal relationship for the Louisiana barrier islands

Science.gov (United States)

List, J.H.; Sallenger, A.H.; Hansen, M.E.; Jaffe, B.E.

1997-01-01

The role of relative sea-level rise as a cause for the rapid erosion of Louisiana's barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s. 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium Criterion this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus in terms of the Bruun approach relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

Processes of coastal bluff erosion in weakly lithified sands, Pacifica, California, USA

Science.gov (United States)

Collins, B.D.; Sitar, N.

2008-01-01

Coastal bluff erosion and landsliding are currently the major geomorphic processes sculpting much of the marine terrace dominated coastline of northern California. In this study, we identify the spatial and temporal processes responsible for erosion and landsliding in an area of weakly lithified sand coastal bluffs located south of San Francisco, California. Using the results of a five year observational study consisting of site visits, terrestrial lidar scanning, and development of empirical failure indices, we identify the lithologic and process controls that determine the failure mechanism and mode for coastal bluff retreat in this region and present concise descriptions of each process. Bluffs composed of weakly cemented sands (unconfined compressive strength - UCS between 5 and 30??kPa) fail principally due to oversteepening by wave action with maximum slope inclinations on the order of 65 at incipient failure. Periods of significant wave action were identified on the basis of an empirical wave run-up equation, predicting failure when wave run-up exceeds the seasonal average value and the bluff toe elevation. The empirical relationship was verified through recorded observations of failures. Bluffs composed of moderately cemented sands (UCS up to 400??kPa) fail due to precipitation-induced groundwater seepage, which leads to tensile strength reduction and fracture. An empirical rainfall threshold was also developed to predict failure on the basis of a 48-hour cumulative precipitation index but was found to be dependent on a time delay in groundwater seepage in some cases.

Large-scale coastal behaviour in relation to coastal zone management

NARCIS (Netherlands)

Stive, M.J.F.

1990-01-01

The development of coastal erosion management - addressing typical traditional erosion problems - towards coastal zone management addressing the evaluation of alternative solutions to guarantee a variety of coastal zone functions on their economic time scale - has necessitated the formulation of

Spatio-temporal variability in accretion and erosion of coastal foredunes in the Netherlands: regional climate and local topography

NARCIS (Netherlands)

Keijsers, J.G.S.; Poortinga, A.; Riksen, M.J.P.M.; Maroulis, J.

2014-01-01

Depending on the amount of aeolian sediment input and dune erosion, dune size and morphology change over time. Since coastal foredunes play an important role in the Dutch coastal defence, it is important to have good insight in the main factors that control these changes. In this paper the temporal

Erosion in the Beaches of Crete

Science.gov (United States)

Synolakis, C. E.; Foteinis, S.; Voukouvalas, V.; Kalligeris, N.

2009-04-01

In the past decade, erosion rates for the coastlines of Greece are rapidly increasing. Many beaches on the northern coast of the island have substantially retreated, while others have disappeared or will disappear within the present or the following decade if no action is taken. For the better understanding and visualization of the current situation, specific examples of rapid erosion are described and afterwards we speculate as to the causes. We infer that, as in other parts of the Mediterranean, the causes are anthropogenic and include removal of sand dunes to build roads, sand mining from beaches and rivers, permanent building construction within the active coastal zone, on or too close to shoreline, and poor design of coastal structures. The reason behind the rapid erosion of Greece coastlines is the complete lack of any semblance of coastal zone management and antiquated legislation. We conclude that unless urgent measures for the protection and even salvation of the beaches are taken and if the sand mining and dune removal does not stop, then several beaches will disappear within the present and the following decade.

Determining long-term regional erosion rates using impact craters

Science.gov (United States)

Hergarten, Stefan; Kenkmann, Thomas

2015-04-01

More than 300,000 impact craters have been found on Mars, while the surface of Moon's highlands is even saturated with craters. In contrast, only 184 impact craters have been confirmed on Earth so far with only 125 of them exposed at the surface. The spatial distribution of these impact craters is highly inhomogeneous. Beside the large variation in the age of the crust, consumption of craters by erosion and burial by sediments are the main actors being responsible for the quite small and inhomogeneous crater record. In this study we present a novel approach to infer long-term average erosion rates at regional scales from the terrestrial crater inventory. The basic idea behind this approach is a dynamic equilibrium between the production of new craters and their consumption by erosion. It is assumed that each crater remains detectable until the total erosion after the impact exceeds a characteristic depth depending on the crater's diameter. Combining this model with the terrestrial crater production rate, i.e., the number of craters per unit area and time as a function of their diameter, allows for a prediction of the expected number of craters in a given region as a function of the erosion rate. Using the real crater inventory, this relationship can be inverted to determine the regional long-term erosion rate and its statistical uncertainty. A limitation by the finite age of the crust can also be taken into account. Applying the method to the Colorado Plateau and the Deccan Traps, both being regions with a distinct geological history, yields erosion rates in excellent agreement with those obtained by other, more laborious methods. However, these rates are formally exposed to large statistical uncertainties due to the small number of impact craters. As higher crater densities are related to lower erosion rates, smaller statistical errors can be expected when large regions in old parts of the crust are considered. Very low long-term erosion rates of less than 4

Estimated erosion rate at the SRP burial ground

International Nuclear Information System (INIS)

Horton, J.H.; Wilhite, E.L.

1978-04-01

The rate of soil erosion at the Savannah River Plant (SRP) burial ground can be calculated by means of the universal soil loss equation. Erosion rates estimated by the equation are more suitable for long-term prediction than those which could be measured with a reasonable effort in field studies. The predicted erosion rate at the SRP burial ground ranges from 0.0007 cm/year under stable forest cover to 0.38 cm/year if farmed with cultivated crops. These values correspond to 170,000 and 320 years, respectively, to expose waste buried 4 ft deep

Quantification Of Erosion Rates Of Agriculturally Used Soils By Artificial

Science.gov (United States)

Jha, Abhinand

2010-05-01

0.0.1 1. Introduction to soil erosion measurement by radionuclides Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Studying this phenomenon would be one of the advancements in science. Soil erosion occurs worldwide and since the last two decades it has been a main topic of discussion all over the world. The use of environmental radionuclides such as 90Sr, 137Cs to study medium term soil erosion (40 yrs) started in the early 1990's. Using these new techniques better knowledge about erosion can be gained and this knowledge can be implemented for erosion risk management. The erosion and sedimentation study by using man-made and natural radioisotopes is a key technique, which has developed over the past 30 years. Fallout 137Cs and Cosmogenic 7Be are radionuclides that have been used to provide independent measurements of soil-erosion and sediment-deposition rates and patterns [1] [2] [3] [4]. Erosion measurements using radionuclides 137Cs, 7Be Caesium-137 from atmospheric nuclear-weapons tests in the 1950s and 1960s (Fig.1) is a unique tracer of erosion and sedimentation, since there are no natural sources of 137Cs. Unique events such as the Chernobyl accident in April 1986 caused regional dispersal of 137Cs that affects the total global deposition budget. This yearly pattern of fallout can be used to develop a chronology of deposition horizons in lakes, reservoirs, and floodplains. 137Cs can be easily measured by gamma spectroscopy. Using 137Cs is a fast and cheap method to study erosion-deposition processes compared to the traditional methods like silt bags. PIC Figure 1: Global 137Cs fallout (Modified from SAAS Bulletin 353, Part E, DDR, 1986) When 137Cs, 7Be reach the soil surface by wet and dry deposition, they are quickly and strongly adsorbed by ion exchange and are essentially non exchangeable in most environments. Each radionuclide is distributed differently in the soil because of differences in half-lives (30 yrs

Coastal Erosion Armoring 2005

Data.gov (United States)

California Natural Resource Agency — Coastal armoring along the coast of California, created to provide a database of all existing coastal armoring based on data available at the time of creation....

Regional shoreline change and coastal erosion hazards in Arctic Alaska

Science.gov (United States)

Gibbs, Ann E.; Richmond, Bruce M.; Erikson, Li H.; Harden, E. Lynne; Wallendorf, Louise

2011-01-01

Historical shoreline positions along the mainland Beaufort Sea coast of Alaska were digitized and analyzed to determine the long-term rate of change. Average shoreline change rates and ranges from 1947 to the mid-2000s were determined every 50 meters between Barrow and Demarcation Point, at the U.S.-Canadian border. Results show that shoreline change rates are highly variable along the coast, with an average regional shoreline change rate of-2.0 m/yr and localized rates of up to -19 m/yr. The highest erosion rates were observed at headlands, points, and associated with breached thermokarst lakes. Areas of accretion were limited, and generally associated with spit extension and minor beach accretion. In general, erosion rates increase from east to west, with overall higher rates east of Harrison Bay.

Testing the Control of Mineral Supply Rates on Chemical Erosion Rates in the Klamath Mountains

Science.gov (United States)

West, N.; Ferrier, K.

2016-12-01

The relationship between rates of chemical erosion and mineral supply is central to many problems in Earth science, including how tightly Earth's climate should be coupled to tectonics, how strongly nutrient supply to soils and streams depends on soil production, and how much lithology affects landscape evolution. Despite widespread interest in this relationship, there remains no consensus on how closely coupled chemical erosion rates should be to mineral supply rates. To address this, we have established a network of field sites in the Klamath Mountains along a latitudinal transect that spans an expected gradient in mineral supply rates associated with the geodynamic response to the migration of the Mendocino Triple Junction. Here, we present new measurements of regolith geochemistry and topographic analyses that will be compared with cosmogenic 10Be measurements to test hypotheses about supply-limited and kinetically-limited chemical erosion on granodioritic ridgetops. Previous studies in this area suggest a balance between rock uplift rates and basin wide erosion rates, implying the study ridgetops may have adjusted to an approximate steady state. Preliminary data are consistent with a decrease in chemical depletion fraction (CDF) with increasing ridgetop curvature. To the extent that ridgetop curvature reflects ridgetop erosion rates, this implies that chemical erosion rates at these sites are influenced by both mineral supply rates and dissolution kinetics.

Wildfires and post-fire erosion risk in a coastal area under severe anthropic pressure associated with the touristic fluxes

Science.gov (United States)

Canu, Annalisa; Arca, Bachisio; Pellizzaro, Grazia; Valeriano Pintus, Gian; Ferrara, Roberto; Duce, Pierpaolo

2017-04-01

In the last decades a rapid and intense development of the tourism industry led to an increasing of anthropic pressure on several coastal areas of Sardinia. This fact not only modified the coastal aesthetics, but has also generated an increase of risk for the environment. This phenomenon affected also the ancient structure of the landscape with a negative impact mainly caused by the following factors: land abandonment, wildfire occurrence, post-fire erosion, urbanization. These regional changes can be analyzed in detail by considering the geo-diachronic dynamics. The main objectives of this work were i) to perform a diachronic analysis of land use and land cover dynamics, ii) to analyse the recent dynamics of wildfires, and iii) to predict the soil erosion risk in relation to land use change occurred between the 1950s and the 2000s. The study was realized in a coastal area located in North-East Sardinia where the geo-historical processes were summarized and organized in a geographic information system that has been employed to examine the landscape variations at three different time steps: 1954, 1977 and 2000. In addition, different scenarios of wildfire propagation were simulated by FlamMap in order to estimate the spatial pattern of fire danger factors in the study area. Afterwards, maps of post-fire soil erosion were produced to identify the temporal and spatial variations of the erosion risk. The results show how the changes in land use and the significant and rapid increase of the residential areas affect the risk of both wildfires and post-fire soil erosion. The study reveals the capabilities of this type of approach and can be used by management agencies and policy makers e in sustainable landscape management planning. This approach can be extended to other regions of the Mediterranean basin characterized by complex interactions among landscape and anthropic factors affecting the environmental risk.

The June 2016 Australian East Coast Low: Importance of Wave Direction for Coastal Erosion Assessment

Directory of Open Access Journals (Sweden)

Thomas R. Mortlock

2017-02-01

Full Text Available In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.

Predicting the temporal relationship between soil cesium-137 and erosion rate

International Nuclear Information System (INIS)

Kachanoski, R.G.; De Jong, E.

1984-01-01

A model was developed that predicts the amount of 137 Cs remaining in soil as a function of time and erosion rate. The model accounts for atmospheric deposition, radioactive decay, tillage dilution, and erosion transport of 137 Cs, as well as seasonal differences in 137 Cs deposition and erosion rates. The model was used to estimate minimum resolution of erosion estimates based on detection limits and accuracy of 137 Cs measurement by gamma spectroscopy, as a function of time and erosion rate. The analysis showed that under Saskatchewan conditions, changes in 137 Cs at a given site can be used to estimate erosion rates between 0.5 and 10 kg m -2 yr -1 with reasonable precision, provided the sampling interval is at least 15 yr. The relationship of fraction of 137 Cs lost vs. erosion as predicted by the model was compared with other methods being used. The model was used to estimate erosion from selected Saskatchewan soils where 137 Cs levels were measured in 1966 and again in 1981. Erosion rates calculated with the model varied from 1 kg m -2 yr -1 for a sandy loam soil in continuous forage to 19 kg m -2 yr -1 for a similar soil in a crop-fallow rotation. Erosion estimates using the model were higher than those calculated by assuming that soil loss was directly proportional to 137 Cs loss, especially when 137 Cs loss was high

Erosi Pantai, Ekosistem Hutan Bakau dan Adaptasi Masyarakat Terhadap Bencana Kerusakan Pantai Di negara Tropis (Coastal Erosion, Mangrove Ecosystems and Community Adaptation to Coastal Disasters in Tropical Countries

Directory of Open Access Journals (Sweden)

Aji Ali Akbar

2017-05-01

Full Text Available ABSTRAK   Tulisan ini bertujuan untuk mengkaji terjadinya kerusakan lingkungan pantai di negara tropis dan sebagian negara subtropis akibat perilaku manusia. Perilaku manusia yang menyebabkan kerusakan lingkungan adalah memanfaatkan sumberdaya alam pesisir tanpa memperhatikan keberlanjutan sumber daya alam dan daya dukung lingkungannya. Kerusakan lingkungan pantai yang umum terjadi di negara tropis dan sebagian subtropis adalah erosi pantai dan degradasi ekosistem hutan bakau. Kerusakan lingkungan pantai ini akibat alih fungsi lahan menjadi jaringan jalan, permukiman, lahan pertanian/ perkebunan, pertambakan, dan pertambangan pasir. Kerusakan lingkungan pantai mempengaruhi kondisi sosial ekonomi masyarakat setempat seperti hilangnya badan jalan, permukiman, lahan pertanian, dan fasilitas umum akibat abrasi pantai. Upaya penanggulangan kerusakan lingkungan pantai sebagai bagian dari adaptasi manusia mempertahankan kehidupannya berupa pembangunan pemecah gelombang (breakwaters dan rehabilitasi ekosistem hutan bakau. Upaya penanggulangan bencana tersebut tentunya membutuhkan biaya yang besar dan waktu lama daripada upaya pencegahan. Oleh karena itu, perubahan pola pikir baik pemerintah dan masyarakat dalam memanfaatkan, mengelola dan melestarikan sumber daya alam perlu ditingkatkan melalui perbaikan informasi, ilmu pengetahuan, dan strategi perencanaan yang holistik. Kata kunci: erosi pantai, kerusakan ekosistem hutan bakau, alih fungsi lahan, pemecah gelombang, rehabilitasi ABSTRACT This paper aims to assess the coastal degradation in tropical and subtropical countries in part due to human behavior. Human behavior is causing coastal degradation is to utilize natural resources without regard to the sustainability of coastal natural resources and the carrying capacity of the environment. Degradation of coastal common in most tropical and subtropical countries are coastal erosion and degradation of mangrove ecosystems. This coastal degradation as a

Technologies for climate change adaptation. Coastal erosion and flooding

Energy Technology Data Exchange (ETDEWEB)

Zhu, X. (ed.) (UNEP Risoe Centre, Roskilde (Denmark)); Linham, M.M.; Nicholls, R.J. (Univ. of Southampton (United Kingdom))

2010-11-15

This guidebook is intended to be a practical tool for use by coastal zone managers in developing countries. The aim is to provide best practice guidance and assist these managers in assessing their evolving adaptation needs and help them to prepare action plans for adapting to climate change in the coastal zone. The guidebook first reviews the main physical and societal impacts of climate change in the coastal zone. It then considers the process of adaptation to erosion and flooding/inundation hazards where major impacts may occur and a range of adaptation technologies are best developed. Thirteen of these adaptation technologies are presented in this guide, representing examples of the protect, accommodate or (planned) retreat approaches to adaptation. While this does not represent an exhaustive list of the adaptation technologies that are available, these technologies are among those most widely used/considered in the coastal zone today. All the technologies considered are relevant to climate change adaptation and collectively, more widespread application is expected in the future under climate change and rising sea levels. For each adaptation technology the following issues are addressed: (1) definition and description; (2) technical advantages and disadvantages; (3) institutional and organisational requirements; (4) potential costs and opportunities; and (5) barriers to implementation; followed by a case study example. We have endeavoured to include developing country examples wherever possible, but as there is less activity and less documentation of developing world projects and some technologies are barely used in the developing world, this is not always possible. Knowledge and capacity building requirements and monitoring technologies are considered and contrasted across all 13 adaptation technologies. Finally, more detailed sources are indicated. Each adaptation technology has widely varying advantages and disadvantages. As such, selection of measures

High natural erosion rates are the backdrop for enhanced anthropogenic soil erosion in the Middle Hills of Nepal

Science.gov (United States)

West, A. J.; Arnold, M.; Aumaître, G.; Bourlès, D. L.; Keddadouche, K.; Bickle, M.; Ojha, T.

2014-08-01

Although agriculturally accelerated soil erosion is implicated in the unsustainable environmental degradation of mountain environments, such as in the Himalaya, the effects of land use can be difficult to quantify in many mountain settings because of the high and variable natural background rates of erosion. In this study, we present new long-term denudation rates, derived from cosmogenic 10Be analysis of quartz in river sediment from the Likhu Khola, a small agricultural river basin in the Middle Hills of central Nepal. Calculated long-term denudation rates, which reflect background natural erosion processes over 1000+ years prior to agricultural intensification, are similar to present-day sediment yields and to soil loss rates from terraces that are well-maintained. Similarity in short- and long-term catchment-wide erosion rates for the Likhu is consistent with data from elsewhere in the Nepal Middle Hills, but contrasts with the very large increases in short-term erosion rates seen in agricultural catchments in other steep mountain settings. Our results suggest that the large sediment fluxes exported from the Likhu and other Middle Hills rivers in the Himalaya are derived in large part from natural processes, rather than from soil erosion as a result of agricultural activity. Because of the high natural background rates, simple comparison of short- and long-term rates may not reveal unsustainable soil degradation, particularly if much of the catchment-scale erosion flux derives from mass wasting. Correcting for the mass wasting contribution in the Likhu implies minimum catchment-averaged soil production rates of ~0.25-0.35 mm yr-1. The deficit between these production rates and soil losses suggests that terraced agriculture in the Likhu may not be associated with a large systematic soil deficit, at least when terraces are well maintained, but that poorly managed terraces, forest and scrubland may lead to rapid depletion of soil resources.

Assessing storm erosion hazards

NARCIS (Netherlands)

Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

2017-01-01

The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

Contrasting Modern and 10Be- derived erosion rates for the Southern Betic Cordillera, Spain

Science.gov (United States)

Bellin, N.; Vanacker, V.; Kubik, P.

2012-04-01

In Europe, Southeast Spain was identified as one of the regions with major treat of desertification in the context of future land use and climate change. During the last years, significant progress has been made to understand spatial patterns of modern erosion rates in these semi-arid degraded environments. Numerous European projects have contributed to the collection of modern erosion data at different spatial scales for Southeast Spain. However, these data are rarely analysed in the context of long-term changes in vegetation, climate and human occupation. In this paper, we present Modern and Holocene denudation rates for small river basins (1 to 10 km2) located in the Spanish Betic Cordillera. Long-term erosion data were derived from cosmogenic nuclide analyses of river-borne sediment. Modern erosion data were quantified through analysis of sediment deposition volumes behind check dams, and represent average erosion rates over the last 10 to 40 years. Modern erosion rates are surprisingly low (mean erosion rate = 0.048 mm y-1; n=36). They indicate that the steep, sparsely vegetated hillslopes in the Betic Cordillera cannot directly be associated with high erosion rates. 10Be -derived erosion rates integrate over the last 37500 to 3500 years, and are roughly of the same magnitude. They range from 0.013 to 0.243 mm y-1 (mean denudation rate = 0.062 mm y-1 ± 0.054; n=20). Our data suggest that the modern erosion rates are similar to the long-term erosion rates in this area. This result is in contrast with the numerous reports on human-accelerated modern erosion rates for Southeast Spain. Interestingly, our new data on long-term erosion rates show a clear spatial pattern, with higher erosion rates in the Sierra Cabrera and lower erosion rates in Sierra de las Estancias, and Sierra Torrecilla. Preliminary geomorphometric analyses suggest that the spatial variation that we observe in long-term erosion rates is related to the gradient in uplift rates of the Betic

Investigating Coastal Processes and Hazards Along the Coastline of Ghana, West Africa (Invited)

Science.gov (United States)

Hapke, C. J.; Ashton, A. D.; Wiafe, G.; Addo, K. A.; Ababio, S.; Agyekum, K. A.; Lippmann, T. C.; Roelvink, J.

2010-12-01

As with many coastlines worldwide, erosion is a chronic issue along the Ghana coast. Erosion is presently impacting coastal infrastructure ranging from urban areas to small fishing villages, and threatening important cultural and historical resources in some locales. The Ghanaian coast displays significant geomorphological variability, ranging from rocky and bluffed shores to low-lying barrier beaches. Rates and trends of coastal change vary along the coast, interacting with physical oceanographic processes, alongshore sediment transport gradients, and anthropogenic disruptions of sediment supply. Little data are available for the systematic assessment of the relative importance of the various factors controlling coastal change, and thus the understanding of erosion threats and the response has been haphazard and inconsiderate of the system as a whole. Information on historical coastal change rates, alongshore geomorphic and geologic variation, sediment budgets, wave climates and other factors that shape the coast is limited. An enhanced understanding of basic coastal processes is critical as development pressures, including eco- and cultural tourism, and oil and gas exploration, continue to increase. An initiative is underway to develop a more comprehensive scientific understanding of coastal processes along the Ghana coastline. An international team of scientists, working in collaboration with researchers at the University of Ghana, are building the data- and knowledge-base required for a holistic and systematic assessment to understand coastal change and its driving forces. The approach includes regional analyses of shoreline change, field mapping of geology and geomorphology, short-term monitoring surveys, collection of geophysical data, deployment of a remote camera system, deployment of a directional wave buoy, and regional hydrodynamic modeling. These data and analyses will ultimately provide the foundation needed to make informed decisions on managing the

Coastal erosion's influencing factors include development, dams, wells, and climate change

International Nuclear Information System (INIS)

Aubrey, D.G.

1993-01-01

The demographic flight to the coast, begun in early civilization, continues unabated worldwide according to latest studies. The percentage of population living on the coast is expected to remain relatively constant over the next few decades, but the total numbers will increase as the population increases. Recent coastal battering by hurricanes and extratropical storms poses questions about coastal habitability and the real economics of coastal development. Repair costs are borne by private individuals as well as the public in various direct and indirect ways. As these costs escalate, it is fitting to ask what the future portends for storm and coastal-flood damage. It is known that development pressures will continue to increase along the coast, but what will happen concurrently to natural-hazard threats to this infrastructure? Though much emphasis has been placed on sea-level rise, the broader issue is climate change in general. Here, the author considers climate change in both its natural and anthropogenic perspectives. Without becoming mired in the debate about the greenhouse effect and human influence on climatic shifts, some of the broad classes of natural hazards that might accompany climate change are examined. There are several categories of possible global-change effects on coastal erosion. In the early 1980's, an Environmental Protection Agency (EPA) report postulated increases in global sea level up to 4 meters during the next 100 years. Though balanced somewhat by other, lower estimates of sea-level rise, this higher extreme grabbed public attention. During the next decade, scientists attempted to concur on a more reasonable estimate of global sea-level rise due to climate change. Recent credible estimates suggest that approximately 10 to 20 percent of EPA's earlier maximum estimate is most reasonable

Rainfall erosivity map for Ghana

International Nuclear Information System (INIS)

Oduro Afriyie, K.

1995-10-01

Monthly rainfall data, spanning over a period of more than thirty years, were used to compute rainfall erosivity indices for various stations in Ghana, using the Fournier index, c, defined as p 2 /P, where p is the rainfall amount in the wettest month and P is the annual rainfall amount. Values of the rainfall erosivity indices ranged from 24.5 mm at Sunyani in the mid-portion of Ghana to 180.9 mm at Axim in the south western coastal portion. The indices were used to construct a rainfall erosivity map for the country. The map revealed that Ghana may be broadly divided into five major erosion risk zones. The middle sector of Ghana is generally in the low erosion risk zone; the northern sector is in the moderate to severe erosion risk zone, while the coastal sector is in the severe to extreme severe erosion risk zone. (author). 11 refs, 1 fig., 1 tab

Enhancing rates of erosion and uplift through glacial perturbations

Science.gov (United States)

Norton, Kevin; Schlunegger, Fritz; Abbühl, Luca

2010-05-01

Research over the past decade has shown that the pattern of modern rock uplift in the Swiss Alps correlates with both long-term (thermochronometers) and short-term (cosmogenic nuclide-derived denudation rates, sediment loads, lake fills) measures of erosion. This correlation has been attributed alternately to isostatic causes (compensation to erosion and/or glacial unloading) and tectonic forces (ongoing collision and partial delamination). Of these potential driving forces, only isostatic compensation to erosion fits all available structural, geodetic, and flexural models. We explore this uplift-erosion relationship by analyzing river channel steepness for Alpine rivers. Zones of oversteepening, and hence enhanced stream power, are associated with glacial erosion and deposition during LGM and earlier glaciations, resulting in the focusing of erosion into the inner gorges which connect hanging tributary valleys to the main glacial trunk valley. These inner gorges are transient zones in which fluvial and hillslope processes are in the process of re-adjusting this glacially perturbed landscape. Bedrock properties also play a major role in the response time of these adjustments. Glacially generated knickzones are located within 5 km of the trunk stream in the Rhone valley where resistant lithologies dominate (gneiss), whereas the knickzones have migrated as much as 10 km or further in the less resistant rocks (buendnerschists) of the Rhine valley. We suggest that the rock uplift pattern is controlled by surface denudation as set by the glacial-interglacial history of the Alps. Rapid, focused erosion results in rapid rock uplift rates in the Central Swiss Alps, where glaciers were most active. An interesting ramification of this reasoning is that in the absence of glacial perturbation, both rock uplift rates and denudation rates would be substantially lower in this isostatically compensated mountain belt.

Slow Long-Term Erosion Rates of Banks Peninsula, New Zealand

Science.gov (United States)

Dudunake, T.; Nichols, K. K.; Pugsley, E.; Nelson, S.; Colton, J.

2017-12-01

Banks Peninsula, located south of Christchurch, New Zealand, is composed of a multi-aged complex of volcanic centers. The oldest, Lyttelton Volcano is 12 to 10 Ma, and 350 km3. The largest volcano, Akaroa Volcano, is 9 to 8 Ma and 1200 km3. Both of these volcanoes have large embayments (Lyttelton Harbour and Akaroa Harbour) that connect the central volcano (the location of the former volcanic summits) to the ocean. The other eruptive centers, Mt. Herbert ( 9.5 to 8 Ma) and Diamond Harbor (7 to 5.8 Ma), have not eroded to sea level. We used inferred original surfaces and present day topography to calculate the volume of rock eroded from river valleys draining the flanks of Lyttelton (n=11) and Akaroa (n=26) volcanoes and from the large embayments that penetrate the eroding Lyttelton (n=8) and Akaroa (n=25) volcanoes. We used the youngest age of the eruptions as the start of erosion (Lyttelton = 10 Ma and Akaroa = 8 Ma) to determine erosion rates. Preliminary data suggest average erosion rates of 8.2 ± 2.4 m/My (averaged over 10 Ma) on the flanks of Lyttelton Volcano and 12 ± 5.1 m/My (averaged over 8 Ma) on the flanks of Akaroa Volcano. Dating control and formation processes of Lyttelton Harbour and Akaroa Harbour are poorly constrained. The youngest lava flows, Diamond Harbor, are 5.7 Ma and flow into the Lyttelton Harbour embayment. Using endmembers of embayment age for Lyttelton Harbour (10 Ma to 5.7 Ma) the erosion rates range between 18 ± 5.8 m/My and 31 ± 10 m/My. Similarly, the hillslopes of Akaroa Harbour have slow erosion rates (based on endmember ages of 8 Ma and 5.7 Ma) and range between 22 ± 18 and 31 ± 25 m/My. Even the fastest erosion rates on Banks Peninsula are an order of magnitude slower than the erosion rates of other basalt volcanoes in the world's oceans. Using a similar methodology, Tahiti is eroding between 1200 and 2700 m/Ma (Hildenbrand et al., 2008). Other erosion rates, based on sediment yields and water chemistry for La Reunion (400

Coastal Erosion and Flooding Hazards on the North Sea Coast at Thyboron, Denmark

DEFF Research Database (Denmark)

Sørensen, Per; Sørensen, Carlo Sass; Nielsen, Peter

Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s coun...... counteracted the natural erosion in the upper profile on the North Sea coast where the alongshore sediment transport converges towards the channel and deposits up to 1 million m3/y on the flood tidal delta inside the fiord, Figure 1.......Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s...

Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

Science.gov (United States)

Moore, Laura J.; Griggs, Gary B.

2002-01-01

Quantification of cliff retreat rates for the southern half of Santa Cruz County, CA, USA, located within the Monterey Bay National Marine Sanctuary, using the softcopy/geographic information system (GIS) methodology results in average cliff retreat rates of 7–15 cm/yr between 1953 and 1994. The coastal dunes at the southern end of Santa Cruz County migrate seaward and landward through time and display net accretion between 1953 and 1994, which is partially due to development. In addition, three critically eroding segments of coastline with high average erosion rates ranging from 20 to 63 cm/yr are identified as erosion ‘hotspots’. These locations include: Opal Cliffs, Depot Hill and Manresa. Although cliff retreat is episodic, spatially variable at the scale of meters, and the factors affecting cliff retreat vary along the Santa Cruz County coastline, there is a compensation between factors affecting retreat such that over the long-term the coastline maintains a relatively smooth configuration. The softcopy/GIS methodology significantly reduces errors inherent in the calculation of retreat rates in high-relief areas (e.g. erosion rates generated in this study are generally correct to within 10 cm) by removing errors due to relief displacement. Although the resulting root mean squared error for erosion rates is relatively small, simple projections of past erosion rates are inadequate to provide predictions of future cliff position. Improved predictions can be made for individual coastal segments by using a mean erosion rate and the standard deviation as guides to future cliff behavior in combination with an understanding of processes acting along the coastal segments in question. This methodology can be applied on any high-relief coast where retreat rates can be measured.

Coastal erosion as a source of mercury into the marine environment along the Polish Baltic shore.

Science.gov (United States)

Bełdowska, Magdalena; Jędruch, Agnieszka; Łęczyński, Leszek; Saniewska, Dominika; Kwasigroch, Urszula

2016-08-01

The climate changes in recent years in the southern Baltic have been resulting in an increased frequency of natural extreme phenomena (i.e. storms, floods) and intensification of abrasion processes, which leads to introduction of large amounts of sedimentary deposits into the marine environment. The aim of this study was to determine the mercury load introduced to the Baltic Sea with deposits crumbling off the cliffs-parts of the coast that are the most exposed to abrasion. The studies were carried out close to five cliffs located on the Polish coast in the years 2011-2014. The results show that coastal erosion could be an important Hg source into the marine environment. This process is the third most important route, after riverine and precipitation input, by which Hg may enter the Gulf of Gdańsk. In the Hg budget in the gulf, the load caused by erosion (14.3 kg a(-1)) accounted for 80 % of the wet deposition and was 50 % higher than the amount of mercury introduced with dry deposition. Although the Hg concentration in the cliff deposits was similar to the natural background, due to their large mass, this problem could be significant. In addition, the preliminary studies on the impact of coastal erosion on the Hg level in the marine ecosystem have shown that this process may be one of the Hg sources into the trophic chain.

Spatio-Temporal Dynamics of a Coastal Island Using Geospatial Techniques: A Case in Hatiya Island, Bangladesh

Science.gov (United States)

Ramjan, S.; Mahmud, M. S.; Hossain, M. A.; Hasan, M.; Ashrafi, Z. M.

2016-12-01

Bangladesh is recognized for its high vulnerability to sea level rise (SLR). SLR directly and indirectly (by altering morphology of river estuary) accelerates erosion processes, washes out the loose materials of the coast and coastal islands. Hatiya, highly populated coastal island, located in Meghna river estuary is under severe threat of coastal erosion, which has not been quantified yet. The accurate mapping of the shoreline and coastal changes are very important for adopting conservation measures e.g. protection of human life, property and the natural environment. The objectives of the present study are to use remote sensing and Geographical Information System techniques to evaluate spatial and temporal changes in the shoreline and coastal land area of the Hatiya Island between the year of 1985 and 2016 from multi-temporal satellite images, i.e. assessing shifting of the shoreline position through digital shoreline analysis besides the erosion-accretion measurements. Study reveals that about 67 square kilometer areas has been lost between 1985 and 2016 which was about 17 percent of original area (1985). Erosion mainly took place in northern, north-western banks of the island. In these areas, the landward movement and rate of the shoreline were higher with a highest value of the net shoreline movement (NSM) around 6.2 km. Erosion rate is significant in exposed part of the island where tidal water pressure, shoreline configuration, loose bank materials and steep slope were observed. However, the accretion was noticed in recent years (2010-2016) in southern part of the island where slopes were gentle, perhaps due to backwash sediment deposition. As erosion process is prominent in this island, significant amounnt of usable land was lost. Therefore, local livelihood pattern has changed that has noticable effect on local economy. By quantifying the erosion-accretion rate, livelihood planning can be initiated in climatically threated vulnerable islands.

Measurement of erosion rate by absorption spectroscopy in a Hall thruster

International Nuclear Information System (INIS)

Yamamoto, Naoji; Yokota, Shigeru; Matsui, Makoto; Komurasaki, Kimiya; Arakawa, Yoshihiro

2005-01-01

The erosion rate of a Hall thruster was estimated with the objective of building a real-time erosion rate monitoring system using a 1 kW class anode layer type Hall thruster. This system aids the understanding of the tradeoff between lifetime and performance. To estimate the flux of the sputtered wall material, the number density of the sputtered iron was measured by laser absorption spectroscopy using an absorption line from ground atomic iron at 371.9935 nm. An ultravioletAl x In y Ga (1-x-y) N diode laser was used as the probe. The estimated number density of iron was 1.1x10 16 m -3 , which is reasonable when compared with that measured by duration erosion tests. The relation between estimated erosion rate and magnetic flux density also agreed with that measured by duration erosion tests

Thermomechanical Erosion Modelling of Baydaratskaya Bay, Russia with COSMOS

NARCIS (Netherlands)

Pearson, S.G.; Lubbad, R; Le, T.M.H.; Nairn, Rob

2016-01-01

Rapid coastal erosion threatens Arctic coastal infrastructure, including communities and industrial installations. Erosion of permafrost depends on numerous processes, including thermal and mechanical behaviour of frozen and unfrozen soil, nearshore hydrodynamics, atmospheric forcing, and the

Sea level driven marsh expansion in a coupled model of marsh erosion and migration

Science.gov (United States)

Kirwan, Matthew L.; Walters, David C.; Reay, William G.; Carr, Joel

2016-01-01

Coastal wetlands are among the most valuable ecosystems on Earth, where ecosystem services such as flood protection depend nonlinearly on wetland size and are threatened by sea level rise and coastal development. Here we propose a simple model of marsh migration into adjacent uplands and couple it with existing models of seaward edge erosion and vertical soil accretion to explore how ecosystem connectivity influences marsh size and response to sea level rise. We find that marsh loss is nearly inevitable where topographic and anthropogenic barriers limit migration. Where unconstrained by barriers, however, rates of marsh migration are much more sensitive to accelerated sea level rise than rates of edge erosion. This behavior suggests a counterintuitive, natural tendency for marsh expansion with sea level rise and emphasizes the disparity between coastal response to climate change with and without human intervention.

Coastal Engineering

NARCIS (Netherlands)

Van der Velden, E.T.J.M.

1989-01-01

Introduction, waves, sediment transport, littoral transport, lonshore sediment transport, onshore-offshore sediment transport, coastal changes, dune erosion and storm surges, sedimentation in channels and trenches, coastal engineering in practice.

Comparing Background and Recent Erosion Rates in Degraded Areas of Southeastern Brazil

Science.gov (United States)

Fernandes, N.; Bierman, P. R.; Sosa-Gonzalez, V.; Rood, D. H.; Fontes, R. L.; Santos, A. C.; Godoy, J. M.; Bhering, S.

2014-12-01

Soil erosion is a major problem in northwestern Rio de Janeiro State where, during the last three centuries, major land-use changes took place, associated with the replacement of the original rainforest by agriculture and grazing. The combination of steep hillslopes, erodible soils, sparse vegetation, natural and human-induced fires, as well as downslope ploughing, led to an increase in surface runoff and surface erosion on soil-mantled hillslopes; together, these actions and responses caused a decline in soil productivity. In order to estimate changes in erosion rates over time, we compared erosion rates measured at different spatial and temporal scales, both background (natural) and short-term (human-induced during last few decades). Background long-term erosion rates were measured using in-situ produced cosmogenic 10Be in the sand fraction quartz of active river channel sediment in four basins in the northwestern portion of Rio de Janeiro State. In these basins, average annual precipitation varies from 1,200 to 1,300 mm, while drainage areas vary from 15 to 7,200 km2. Short-term erosion rates were measured in one of these basins from fallout 210Pb in soil samples collected along a hillslope transect located in an abandoned agriculture field. In this transect, 190 undisturbed soil samples (three replicates) were collected from the surface to 0.50 m depth (5 cm vertical intervals) in six soil pits. 10Be average background, basin-wide, erosion rates in the area are ~ 13 m/My; over the last decades, time-integrated (210Pb) average hillslope erosion rates are around 1450 m/Myr, with maximum values at the steepest portion of convex hillslopes of about 2000 m/Myr. These results suggest that recent hillslope erosion rates are about 2 orders of magnitude above background rates of sediment generation integrated over many millennia. This unsustainable rate of soil loss has severely decreased soil productivity eventually leading to the abandonment of farming activities in

Reassessment of soil erosion on the Chinese loess plateau: were rates overestimated?

Science.gov (United States)

Zhao, Jianlin; Govers, Gerard

2014-05-01

Several studies have estimated regional soil erosion rates (rill and interrill erosion) on the Chinese loess plateau using an erosion model such as the RUSLE (e.g. Fu et al., 2011; Sun et al., 2013). However, the question may be asked whether such estimates are realistic: studies have shown that the use of models for large areas may lead to significant overestimations (Quinton et al., 2010). In this study, soil erosion rates on the Chinese loess plateau were reevaluated by using field measured soil erosion data from erosion plots (216 plots and 1380 plot years) in combination with a careful extrapolation procedure. Data analysis showed that the relationship between slope and erosion rate on arable land could be well described by erosion-slope relationships reported in the literature (Nearing, 1997). The increase of average erosion rate with slope length was clearly degressive, as could be expected from earlier research. However, for plots with permanent vegetation (grassland, shrub, forest) no relationship was found between erosion rates and slope gradient and/or slope length. This is important, as it implies that spatial variations of erosion on permanently vegetated areas cannot be modeled using topographical functions derived from observations on arable land. Application of relationships developed for arable land will lead to a significant overestimation of soil erosion rates. Based on our analysis we estimate the total soil erosion rate in the Chinese Loess plateau averages ca. 6.78 t ha-1 yr-1 for the whole loess plateau, resulting in a total sediment mobilisation of ca. 0.38 Gt yr-1. Erosion rates on arable land average ca. 15.10 t ha-1 yr-1. These estimates are 2 to 3 times lower than previously published estimates. The main reason why previous estimates are likely to be too high is that the values of (R)USLE parameters such as K, P and LS factor were overestimated. Overestimations of the K factor are due to the reliance of nomograph calculations, resulting

Coastal Hazards: Hurricanes, Tsunamis, Coastal Erosion.

Science.gov (United States)

Vandas, Steve

1998-01-01

Details an ocean-based lesson and provides background information on the designation of 1998 as the "Year of the Ocean" by the United Nations. Contains activities on the poster insert that can help raise student awareness of coastal-zone hazards. (DDR)

High natural erosion rates are the backdrop for present-day soil erosion in the agricultural Middle Hills of Nepal

Science.gov (United States)

West, A. J.; Arnold, M.; AumaItre, G.; Bourles, D. L.; Keddadouche, K.; Bickle, M.; Ojha, T.

2015-07-01

Although agriculturally accelerated soil erosion is implicated in the unsustainable environmental degradation of mountain environments, such as in the Himalaya, the effects of land use can be challenging to quantify in many mountain settings because of the high and variable natural background rates of erosion. In this study, we present new long-term denudation rates, derived from cosmogenic 10Be analysis of quartz in river sediment from the Likhu Khola, a small agricultural river basin in the Middle Hills of central Nepal. Calculated long-term denudation rates, which reflect background natural erosion processes over 1000+ years prior to agricultural intensification, are similar to present-day sediment yields and to soil loss rates from terraces that are well maintained. Similarity in short- and long-term catchment-wide erosion rates for the Likhu is consistent with data from elsewhere in the Nepal Middle Hills but contrasts with the very large increases in short-term erosion rates seen in agricultural catchments in other steep mountain settings. Our results suggest that the large sediment fluxes exported from the Likhu and other Middle Hills rivers in the Himalaya are derived in large part from natural processes, rather than from soil erosion as a result of agricultural activity. Catchment-scale erosional fluxes may be similar over short and long timescales if both are dominated by mass wasting sources such as gullies, landslides, and debris flows (e.g., as is evident in the landslide-dominated Khudi Khola of the Nepal High Himalaya, based on compiled data). As a consequence, simple comparison of catchment-scale fluxes will not necessarily pinpoint land use effects on soils where these are only a small part of the total erosion budget, unless rates of mass wasting are also considered. Estimates of the mass wasting contribution to erosion in the Likhu imply catchment-averaged soil production rates on the order of ~ 0.25-0.35 mm yr-1, though rates of mass wasting are

Bank erosion along the dam-regulated lower Roanoke River, North Carolina

Science.gov (United States)

Hupp, C.R.; Schenk, E.R.; Richter, J.M.; Peet, Robert K.; Townsend, Phil A.

2009-01-01

Dam construction and its impact on downstream fluvial processes may substantially alter ambient bank stability and erosion. Three high dams (completed between 1953 and 1963) were built along the Piedmont portion of the Roanoke River, North Carolina; just downstream the lower part of the river flows across largely unconsolidated Coastal Plain deposits. To document bank erosion rates along the lower Roanoke River, >700 bank-erosion pins were installed along 66 bank transects. Additionally, discrete measurements of channel bathymetry, turbidity, and presence or absence of mass wasting were documented along the entire study reach (153 km). A bank-erosion- floodplain-deposition sediment budget was estimated for the lower river. Bank toe erosion related to consistently high low-flow stages may play a large role in increased mid- and upper-bank erosion. Present bank-erosion rates are relatively high and are greatest along the middle reaches (mean 63 mm/yr) and on lower parts of the bank on all reaches. Erosion rates were likely higher along upstream reaches than present erosion rates, such that erosion-rate maxima have since migrated downstream. Mass wasting and turbidity also peak along the middle reaches; floodplain sedimentation systematically increases downstream in the study reach. The lower Roanoke River isnet depositional (on floodplain) with a surplus of ??2,800,000 m3yr. Results suggest that unmeasured erosion, particularly mass wasting, may partly explain this surplus and should be part of sediment budgets downstream of dams. ?? 2009 The Geological Society of America.

Coastal and Estuarine Mangrove Squeeze in the Mekong and Saigon Delta

Science.gov (United States)

Stive, M.

2016-02-01

Both in the Mekong and Saigon deltas coastal squeeze is a frequent and pregnant problem, which leads to amazingly alarmous coastal and estuarine erosion rates. From the landside the squeeze is due to encroaching dike relocations and agri- and aquacultures, from the sea side it is due to decreasing sediment sources and relative sea level rise. These multiple pressures at some locations, certainly away from the sediment sources (like Ca Mau) leads to unprecedentent erosion rates. Managed retreat may be a longer term solution, but this will require a new way of thinking. Sandy and silt nourishment strategies may be an innovative alternative, but will require underbuilding scientific and practical research.

Sedimentology and geomorphology analysis of coastal area along pantai penarik, terengganu before and during northeast monsoon season

Science.gov (United States)

Yusoff, Tengku Ahmad Imran Ku; Shaufi Sokiman, Mohamad

2017-10-01

This research is conducted to understand the sedimentology and morphological change before and during the northeast monsoon at the east coast of peninsular Malaysia. The increase in wind speed, wave energy and rainfall during the northeast monsoon are believed to causes the coastal erosion to increase during the season. Rapid development along the east coast area might disrupt the sediments distribution which can increase the coastal erosion rate every year. The understanding on the sediments distribution, erosion and deposition as well as the morphological change can help to figure out if the coastal erosion can affect the infrastructure in the future. The result of the study can show the necessity to perform mitigation or any required action toward the problem that might happen

Erosion and deposition in a field/forest system estimated using cesium-137 activity

International Nuclear Information System (INIS)

Lowrance, R.; McIntyre, S.; Lance, C.

1988-01-01

Soil erosion and deposition were estimated using Cs-137 activity within a 7.25-ha field/forest system in the southeastern coastal plain. Sol eroded from the field was deposited both in the riparian forest ecosystem and in downslope areas of the field. Total activity, depth to peak activity, and depth to zero activity increased downslope from field to stream. Erosion and deposition rates, estimated by changes in activity per unit area from a reference undisturbed forest site, showed that about twice as much total deposition had taken place as total erosion. Excess deposition was attributed to deposition from the upstream portions of the watershed. Erosion and deposition rates estimated with this method were about 63 and 256 Mg/ha/yr, respectively. Erosion and deposition rates estimated by two different calculation techniques were nearly identical. These rates were considerably higher than rates estimated in an earlier study. The rates may be overestimated because the differential rates of Cs-137 movement on clay particles were not considered. The riparian ecosystem acted as a very efficient sediment trap. 19 refs., 5 figs., 3 tabs

Quantification of short-term erosion rates using the cosmogenic radionuclide 7Be

International Nuclear Information System (INIS)

Jha, Abhinand

2012-12-01

The fallout radionuclides 137 Cs, 210 Pb ex are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the 7 Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The 7 Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of 7 Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Muencheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulselike fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10 -12 -10 -13 m 2 s -1 for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10 -13 m 2 s -1 . The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between -2 and 0.3±0.5 kg m -2 -2.0±1.4 kg m -2 respectively. The magnitude of erosion rates estimated

Erosion and erosion-corrosion

International Nuclear Information System (INIS)

Isomoto, Yoshinori

2008-01-01

It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

Testing the control of mineral supply rates on chemical erosion in the Klamath Mountains

Science.gov (United States)

West, N.; Ferrier, K.

2017-12-01

The relationship between rates of chemical erosion and mineral supply is central to many problems in Earth science, including the role of tectonics in the global carbon cycle, nutrient supply to soils and streams via soil production, and lithologic controls on landscape evolution. We aim to test the relationship between mineral supply rates and chemical erosion in the forested uplands of the Klamath mountains, along a latitudinal transect of granodioritic plutons that spans an expected gradient in mineral supply rates associated with the geodynamic response to the migration of the Mendocino Triple Junction. We present 10Be-derived erosion rates and Zr-derived chemical depletion factors, as well as bulk soil and rock geochemistry on 10 ridgetops along the transect to test hypotheses about supply-limited and kinetically-limited chemical erosion. Previous studies in this area, comparing basin-averaged erosion rates and modeled uplift rates, suggest this region may be adjusted to an approximate steady state. Our preliminary results suggest that chemical erosion at these sites is influenced by both mineral supply rates and dissolution kinetics.

Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

Science.gov (United States)

Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.

2016-12-01

Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment

ESTIMATION OF THE WANDA GLACIER (SOUTH SHETLANDS SEDIMENT EROSION RATE USING NUMERICAL MODELLING

Directory of Open Access Journals (Sweden)

Kátia Kellem Rosa

2013-09-01

Full Text Available Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands. This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the last decades. In this work, we examine basal sediment evacuation mechanisms by runoff and analyze glacial erosion processes occurring during subglacial transport. The glacial erosion rate at Wanda Glacier, estimated using a numerical model that consider sediment evacuated to outlet streams, ice flow velocity, ice thickness and glacier area, is 1.1 ton m yr-1.

The influence of basal-ice debris on patterns and rates of glacial erosion

Science.gov (United States)

Ugelvig, Sofie V.; Egholm, David L.

2018-05-01

Glaciers have played a key role for shaping much of Earth's high topography during the cold periods of the Late Cenozoic. However, despite of their distinct influence on landscapes, the mechanisms of glacial erosion, and the properties that determine their rate of operation, are still poorly understood. Theoretical models of subglacial erosion generally highlight the influence of basal sliding in setting the pace of erosion, but they also point to a strong influence of other subglacial properties, such as effective bed pressure and basal-ice debris concentration. The latter properties are, however, not easily measured in existing glaciers, and hence their influence cannot readily be confirmed by observations. In order to better connect theoretical models for erosion to measurable properties in glaciers, we used computational landscape evolution experiments to study the expected influence of basal-ice debris concentration for subglacial abrasion at the scale of glaciers. The computational experiments couple the two erosion processes of quarrying and abrasion, and furthermore integrate the flow of ice and transport of debris within the ice, thus allowing for the study of dynamic feedbacks between subglacial erosion and systematic glacier-scale variations in basal-ice debris concentration. The experiments explored several physics-based models for glacial erosion, in combination with different models for basal sliding to elucidate the relationship between sliding speed, erosion rate and basal-ice debris concentration. The results demonstrate how differences in debris concentration can explain large variations in measured rates. The experiments also provide a simple explanation for the observed dependence of glacier-averaged rate of erosion on glacier size: that large glacier uplands feed more debris into their lower-elevation parts, thereby strengthening their erosive power.

Soil Production and Erosion Rates and Processes in Mountainous Landscapes

Science.gov (United States)

Heimsath, A. M.; DiBiase, R. A.; Whipple, K. X.

2012-12-01

We focus here on high-relief, steeply sloped landscapes from the Nepal Himalaya to the San Gabriels of California that are typically thought to be at a critical threshold of soil cover. Observations reveal that, instead, there are significant areas mantled with soil that fit the conceptual framework of a physically mobile layer derived from the underlying parent material with some locally-derived organic content. The extent and persistence of such soils depends on the long-term balance between soil production and erosion despite the perceived discrepancy between high erosion and low soil production rates. We present cosmogenic Be-10-derived soil production and erosion rates that show that soil production increases with catchment-averaged erosion, suggesting a feedback that enhances soil-cover persistence, even in threshold landscapes. Soil production rates do decline systematically with increasing soil thickness, but hint at the potential for separate soil production functions for different erosional regimes. We also show that a process transistion to landslide-dominated erosion results in thinner, patchier soils and rockier topography, but find that there is no sudden transition to bedrock landscapes. Our landslide modeling is combined with a detailed quantification of bedrock exposure for these steep, mountainous landscapes. We also draw an important conclusion connecting the physical processes producing and transporting soil and the chemical processes weathering the parent material by measuring parent material strength across three different field settings. We observe that parent material strength increases with overlying soil thickness and, therefore, the weathered extent of the saprolite. Soil production rates, thus, decrease with increasing parent material competence. These observation highlight the importance of quantifying hillslope hydrologic processes where such multi-facted measurements are made.

Anthropogenic control on geomorphic process rates: can we slow down the erosion rates? (Geomorphology Outstanding Young Scientist Award & Penck Lecture)

Science.gov (United States)

Vanacker, V.

2012-04-01

The surface of the Earth is changing rapidly, largely in response to anthropogenic perturbation. Direct anthropogenic disturbance of natural environments may be much larger in many places than the (projected) indirect effects of climate change. There is now large evidence that humans have significantly altered geomorphic process rates, mainly through changes in vegetation composition, density and cover. While much attention has been given to the impact of vegetation degradation on geomorphic process rates, I suggest that the pathway of restoration is equally important to investigate. First, vegetation recovery after crop abandonment has a rapid and drastic impact on geomorphic process rates. Our data from degraded catchments in the tropical Andes show that erosion rates can be reduced by up to 100 times when increasing the protective vegetation cover. During vegetation restoration, the combined effects of the reduction in surface runoff, sediment production and hydrological connectivity are stronger than the individual effects together. Therefore, changes in erosion and sedimentation during restoration are not simply the reverse of those observed during degradation. Second, anthropogenic perturbation causes a profound but often temporary change in geomorphic process rates. Reconstruction of soil erosion rates in Spain shows us that modern erosion rates in well-vegetated areas are similar to long-term rates, despite evidence of strong pulses in historical erosion rates after vegetation clearance and agriculture. The soil vegetation system might be resilient to short pulses of accelerated erosion (and deposition), as there might exist a dynamic coupling between soil erosion and production also in degraded environments.

Integrating river incision rates over timescales in the Ecuadorian Andes: from uplift history to current erosion rates

Science.gov (United States)

Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; Tenorio, Gustavo

2013-04-01

River profile development is studied at different timescales, from the response to uplift over millions of years over steady state erosion rates over millennia to the response to a single event, such as a major landslide. At present, few attempts have been made to compare data obtained over various timescales. Therefore we do not know to what extent data and model results are compatible: do long-term river profile development models yield erosion rates that are compatible with information obtained over shorter time spans, both in terms of absolute rates and spatial patterns or not? Such comparisons could provide crucial insights into the nature of river development and allow us to assess the confidence we may have when predicting river response at different timescales (e.g. Kirchner et al., 2001). A major issue hampering such comparison is the uncertainty involved in the calibration of long-term river profile development models. Furthermore, calibration data on different timescales are rarely available for a specific region. In this research, we set up a river profile development model similar to the one used by Roberts & White (2010) and successfully calibrated it for the northern Ecuadorian Andes using detailed uplift and sedimentological data. Subsequently we used the calibrated model to simulate river profile development in the southern Ecuadorian Andes. The calibrated model allows to reconstruct the Andean uplift history in southern Ecuador, which is characterized by a very strong uplift phase during the last 5 My. Erosion rates derived from the modeled river incision rates were then compared with 10Be derived basin-wide erosion rates for a series of basins within the study area. We found that the model-inferred erosion rates for the last millennia are broadly compatible with the cosmogenic derived denudation rates, both in terms of absolute erosion rates as well as in terms of their spatial distribution. Hence, a relatively simple river profile development

In-situ real time measurements of net erosion rates of copper during hydrogen plasma exposure

Science.gov (United States)

Kesler, Leigh; Wright, Graham; Peterson, Ethan; Whyte, Dennis

2013-10-01

In order to properly understand the dynamics of net erosion/deposition in fusion reactors, such as tokamaks, a diagnostic measuring the real time rates of net erosion/deposition during plasma exposure is necessary. The DIONISOS experiment produces real time measurements of net erosion/deposition by using Rutherford backscattering spectroscopy (RBS) ion beam analysis simultaneously with plasma exposure from a helicon plasma source. This in-situ method improves on ex-situ weight loss measurements by allowing measurement of possible synergistic effects of high ion implantation rates and net erosion rate and by giving a real time response to changes in plasma parameters. Previous work has validated this new technique for measuring copper (Cu) erosion from helium (He) plasma ion bombardment. This technique is now extended to measure copper erosion due to deuterium and hydrogen plasma ion exposure. Targets used were a 1.5 μm Cu layer on an aluminum substrate. Cu layer thickness is tracked in real time using 1.2 MeV proton RBS. Measured erosion rates will be compared to results from literature and He erosion rates. Supported by US DoE award DE-SC00-02060.

Charge-exchange wall physical erosion rates for a proposed INTOR/FED limiter

International Nuclear Information System (INIS)

Heifetz, D.; Schmidt, J.; Ulrickson, M.; Post, D.

1983-01-01

We have analyzed power deposition and physical erosion rates on the first wall and limiter due to charge-exchange neutrals in a proposed pump limiter design for the INTOR/FED tokamak. Plasma conditions were modeled using the one-dimensional plasma transport code baldur. Neutral transport was modeled using a two-dimensional, multispecies Monte Carlo algorithm. No chemical erosion or wall redeposition processes were included. Two possible plasma discharges with different edge densities and temperatures were modeled, a regime with T/sub e/ approx.300 eV and napprox.5 x 10 12 cm - 3 , and a hotter, less dense edge regime produced with pellet fueling. We found that the erosion of the stainless steel vacuum vessel wall was highly localized in each case to the two points just beyond the limiter tips, and to the point directly across from the neutralizer plate, with peak erosion rates approx.2 cm/yr, assuming a 40% duty cycle. The erosion of a carbon limiter, neglecting redeposition and chemical erosion, varied in the two cases from 1.6--4 cm/yr, for the same duty cycle. The hotter, less dense discharge produced less sputtering. However achieving truly tolerable physical sputtering rates may require a very low edge temperature, plasma

Does vegetation prevent wave erosion of salt marsh edges?

Science.gov (United States)

Feagin, R A; Lozada-Bernard, S M; Ravens, T M; Möller, I; Yeager, K M; Baird, A H

2009-06-23

This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

Rate estimates for lateral bedrock erosion based on radiocarbon ages, Duck River, Tennessee

International Nuclear Information System (INIS)

Brakenridge, G.R.

1985-01-01

Rates of bedrock erosion in ingrown meandering rivers can be inferred from the location of buried relict flood-plain and river-bank surfaces, associated paleosols, and radiocarbon dates. Two independent methods are used to evaluate the long-term rates of limestone bedrock erosion by the Duck River. Radiocarbon dates on samples retrieved from buried Holocene flood-plain and bank surfaces indicate lateral migration of the river bank at average rates of 0.6-1.9 m/100 yr. Such rates agree with lateral bedrock cliff erosion rates of 0.5-1.4 m/100 yr, as determined from a comparison of late Pleistocene and modern bedrock cliff and terrace scarp positions. These results show that lateral bedrock erosion by this river could have occurred coevally with flood-plain and terrace formation and that the resulting evolution of valley meander bends carved into bedrock is similar in many respects to that of channel meanders cut into alluvium. 11 references, 5 figures

Evaluating Environment, Erosion and Sedimentation Aspects in Coastal Area to Determine Priority Handling (A Case Study in Jepara Regency, northern Central Java, Indonesia)

Science.gov (United States)

Wahyudi, S. I.; Adi, H. P.

2018-04-01

Many areas of the northern coastal in Central Java, Indonesia, have been suffering from damage. One of the areas is Jepara, which has been experiencing this kind of damage for 7.6 kilometres from total 72 kilometres long beach. All damages are mostly caused by coastal erosion, sedimentation, environment and tidal flooding. Several efforts have been done, such as replanting mangroves, building revetment and groins, but it still could not mitigated the coastal damage. The purposes of this study are to map the coastal damages, to analyze handling priority and to determine coastal protection model. The method used are by identifying and plotting the coastal damage on the map, assessing score of each variable, and determining the handling priority and suitable coastal protection model. There are five levels of coastal damage used in this study, namely as light damage, medium, heavy, very heavy, and extremely heavy. Based on the priority assessment of coastal damage, it needs to be followed up by designing in detail and implementing through soft structure for example mangrove, sand nourishes and hard structure, such as breakwater, groins and revetment.

Quantification of short-term erosion rates using the cosmogenic radionuclide {sup 7}Be

Energy Technology Data Exchange (ETDEWEB)

Jha, Abhinand

2012-12-15

The fallout radionuclides {sup 137}Cs, {sup 210}Pb{sub ex} are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the {sup 7}Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The {sup 7}Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of {sup 7}Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Muencheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulselike fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10{sup -12}-10{sup -13} m{sup 2} s{sup -1} for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10{sup -13} m{sup 2}s{sup -1}. The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between <0.001-4.7{+-}0.4 kg m{sup -2} and

ESTIMATION OF THE WANDA GLACIER (SOUTH SHETLANDS) SEDIMENT EROSION RATE USING NUMERICAL MODELLING

OpenAIRE

Kátia Kellem Rosa; Rosemary Vieira; Jefferson Cardia Simões

2013-01-01

Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands). This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the l...

Microlevel mapping of coastal geomorphology and coastal resources of Rameswaram island, India: A remote sensing and GIS perspective

Digital Repository Service at National Institute of Oceanography (India)

Nobi, E.P.; Shivaprasad, A.; Karikalan, R.; Dilipan, E.; Thangaradjou, T.; Sivakumar, K.

Coastal areas are facing serious threats from both manmade and natural disturbances; coastal erosion, sea-level variation, and cyclones are the major factors that alter the coastal topography and coastal resources of the island ecosystems...

Coastal defence solutions (approach of ComCoast)

NARCIS (Netherlands)

Verhagen, H.J.; Visser, P.J.

2007-01-01

Along the North Sea coast, water levels are rising and waves are intensifying due to climate change. The best scientific evidence suggests that both phenomena are likely to accelerate over the coming decades. In some North Sea coastal areas also land is sinking and tidal heights and rates of erosion

Coastal defence and societal activities in the coastal zone: Compatible or conflicting interests?

NARCIS (Netherlands)

van Vuren, Saskia; Kok, Matthijs; Jorissen, Richard E.

2004-01-01

World-wide coastal zones are subject to physical and societal changes. Due to climate change sea level is expected to rise and storm conditions may become more intensive. Both may lead to shore erosion intensification in the coastal zone. Moreover, the coastal zone is intensely used for societal

National Assessment of Shoreline Change: Part 1, Historical Shoreline Changes and Associated Coastal Land Loss Along the U.S. Gulf of Mexico

Science.gov (United States)

Morton, Robert A.; Miller, Tara L.; Moore, Laura J.

2004-01-01

EXECUTIVE SUMMARY Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. This report on states bordering the Gulf of Mexico (Florida, Alabama, Mississippi, Louisiana, and Texas) represents the first in a series that will eventually include the Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. The report summarizes the methods of analysis, interprets the results, provides explanations regarding the historical and present trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-2002. Long-term rates of change are calculated using all four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for the most recent period (1970s to lidar shoreline). The historical rates of change presented in this report represent past conditions and therefore are not

A 30000 yr record of erosion rates from cosmogenic 10Be in middle European river terraces

NARCIS (Netherlands)

Schaller, M.; Blanckenburg, von F.; Veldkamp, A.; Tebbens, L.A.; Hovius, N.; Kubik, P.W.

2002-01-01

Cosmogenic 10Be in river-borne quartz sand records a time-integrated erosion rate representative of an entire drainage basin. When sequestered in a terrace of known age, paleo-erosion rates may be recovered from the nuclide content of the terrace material. Paleo-erosion rates between 30 and 80

First results of the research project MIRAMAR, Innovative Methodologies for Coastal Environmental Monitoring and Analysis

Science.gov (United States)

Rovere, A.; Casella, E.; Vacchi, M.; Mucerino, L.; Pedroncini, A.; Ferrari, M.; Firpo, M.

2013-12-01

A large part of the Mediterranean coastlines are strongly affected by coastal erosion. This is mainly due to human impact, natural hazards and their mutual interaction. All along the Regione Liguria coastlines (Northwestern Mediterranean), significant problems of coastal erosion are reported since the '60s. In this study, we focus on the coastal area between Albenga and Savona, where dramatic coastal retreat of ~2 m y-1 has been inferred from comparison of historic maps and older aerial pictures. Beach monitoring is essential in order to understand the mechanisms of evolution of soft coasts, and the rates of erosion. Traditional beach monitoring techniques involve topographic and bathymetric surveys of the emerged and submerged beach, and/or aerial photos repeated in time and compared through geographical information systems. A major problem of this kind of approach is the high economic cost. This often leads to increase the time lag between successive monitoring campaigns to reduce survey costs, with the consequence of fragmenting the information available for coastal zone management. MIRAMar is a project funded by Regione Liguria through the PO CRO European Social Fund, and it has two main objectives: i) to study and develop an innovative technique, relatively low-cost, to monitor the evolution of the shoreline using low-altitude Unmanned Aerial Vehicle (UAV) photos; ii) to study the impact of different type of storm events on a vulnerable coastal tract subject to coastal erosion using also the data collected by the UAV instrument. To achieve these aims we use a drone with its hardware and software suit, traditional survey techniques (bathymetric surveys, topographic GPS surveys and GIS techniques) and we implement a numerical modeling chain (coupling hydrodynamic, wave and sand transport modules) in order to study the impact of different type of storm events on a vulnerable coastal tract subject to coastal erosion. Aerial picture of one of the beaches studied

The global coastline dataset: the observed relation between erosion and sea-level rise

Science.gov (United States)

Donchyts, G.; Baart, F.; Luijendijk, A.; Hagenaars, G.

2017-12-01

Erosion of sandy coasts is considered one of the key risks of sea-level rise. Because sandy coastlines of the world are often highly populated, erosive coastline trends result in risk to populations and infrastructure. Most of our understanding of the relation between sea-level rise and coastal erosion is based on local or regional observations and generalizations of numerical and physical experiments. Until recently there was no reliable global scale assessment of the location of sandy coasts and their rate of erosion and accretion. Here we present the global coastline dataset that covers erosion indicators on a local scale with global coverage. The dataset uses our global coastline transects grid defined with an alongshore spacing of 250 m and a cross shore length extending 1 km seaward and 1 km landward. This grid matches up with pre-existing local grids where available. We present the latest results on validation of coastal-erosion trends (based on optical satellites) and classification of sandy versus non-sandy coasts. We show the relation between sea-level rise (based both on tide-gauges and multi-mission satellite altimetry) and observed erosion trends over the last decades, taking into account broken-coastline trends (for example due to nourishments).An interactive web application presents the publicly-accessible results using a backend based on Google Earth Engine. It allows both researchers and stakeholders to use objective estimates of coastline trends, particularly when authoritative sources are not available.

The Major Cause of Observed Erosion Surge on the Beaches North ...

African Journals Online (AJOL)

Surges in coastal erosion north of Dar es Salaam city have been documented from 1977 to the early 1980s and around 1997/98. Analysis of the wind data shows that the documented increase in coastal erosion coincided with increased wind speeds. Extreme winds in excess of 10-11 m s-1 were experienced during ...

Erosion rates across space and timescales from a multi-proxy study of rivers of eastern Taiwan

Science.gov (United States)

Fellin, Maria Giuditta; Chen, Chia-Yu; Willett, Sean D.; Christl, Marcus; Chen, Yue-Gau

2017-10-01

We derive erosion rates from detrital zircon fission-track ages and cosmogenic nuclide concentrations from sediments from the modern rivers of eastern Taiwan in order to investigate how surface erosional processes vary in space and time across the young arc-continent collisional orogen of Taiwan. Taiwan is characterized by rapid rates of exhumation, a fluvial and landslide-dominated landscape, high seismicity, high relief and frequent typhoons. The obliquity between the convergence direction and the trend of the plate boundary provides a gradient in uplift and variations in longevity of orogenic activity with a young, immature orogen in the south, a mature orogen in central and northern Taiwan, and perhaps even the cessation of orogeny in the far north. The modern zircon fission-track detrital record is consistent with basement ages that show that much of the orogen is eroding at high rates with basin-wide mean zircon fission-track cooling ages as young as 0.9 Ma. The erosion rates derived from concentrations of cosmogenic nuclides (10Be) provide erosion rates averaged over much shorter timescales, but these two proxies provide estimates of erosion rates that are within error of each other across most of the collisional belt. Erosion rates are lowest in the immature zone of the orogen (Taiwan, and increase to values ≥ 4 km/Ma in central Taiwan. Geomorphic indices, in particular channel steepness, are also correlated with erosion rates, suggesting that fluvial erosion is the dominant exhumation process and that landscape evolution is reacting primarily to tectonic forcing, fast enough to keep the landscape in a state of quasi-equilibrium where erosion rates and rock uplift rates are nearly equal. We find no measurable effects due to rock erodibility or precipitation rate, but if these parameters co-vary with tectonic uplift rate, our data could not resolve the influence of each.

Coastal Vulnerability and risk assessment of infrastructures, natural and cultural heritage sites in Greece.

Science.gov (United States)

Alexandrakis, George; Kampanis, Nikolaos

2016-04-01

The majority of human activities are concentrated around coastal areas, making coastline retreat, a significant threat to coastal infrastructure, thus increasing protection cost and investment revenue losses. In this study the management of coastal areas in terms of protecting coastal infrastructures, cultural and environmental heritage sites, through risk assessment analysis is been made. The scope is to provide data for spatial planning for future developments in the coastal zone and the protection of existing ones. Also to determine the impact of coastal changes related to the loss of natural resources, agricultural land and beaches. The analysis is based on a multidisciplinary approach, combining environmental, spatial and economic data. This can be implemented by integrating the assessment of vulnerability of coasts, the spatial distribution and structural elements of coastal infrastructure (transport, tourism, and energy) and financial data by region, in a spatial database. The approach is based on coastal vulnerability estimations, considering sea level rise, land loss, extreme events, safety, adaptability and resilience of infrastructure and natural sites. It is based on coupling of environmental indicators and econometric models to determine the socio-economic impact in coastal infrastructure, cultural and environmental heritage sites. The indicators include variables like the coastal geomorphology; coastal slope; relative sea-level rise rate; shoreline erosion/accretion rate; mean tidal range and mean wave height. The anthropogenic factors include variables like settlements, sites of cultural heritage, transport networks, land uses, significance of infrastructure (e.g. military, power plans) and economic activities. The analysis in performed by a GIS application. The forcing variables are determined with the use of sub-indices related to coastal geomorphology, climate and wave variables and the socioeconomics of the coastal zone. The Greek coastline in

Development Of Rainfall Erosivity Map For Nigeria | Ogedengbe ...

African Journals Online (AJOL)

The indices were used to develop a rainfall erosivity map or Nigeria. The map reveals that Nigeria may be broadly divided into five major erosion risk zones. The south-western part is generally in the low erosion zone, with the exception of the coastal portion of Lagos, Ondo, Edo and Delta states. The south-east and central ...

Sediment contribution from coastal-cliff erosion into the Nile's littoral cell and its significance to cliff-retreat mitigation efforts

Science.gov (United States)

Katz, Oded; Mushkin, Amit; Crouvi, Onn; Alter, Samuel; Shemesh, Ran

2017-04-01

In 2013 the government of Israel initiated a national mitigation program aimed to prevent further collapse and retreat of the country's coastal cliffs, which occur along the northern termination of the Niles's littoral cell (NLC) in the eastern Mediterranean. The goals of this large-scale program are to protect infrastructure and property proximal to the cliff and to conduct long-term maintenance and monitoring of this highly dynamic and sensitive land-sea interface that spans 40 km of Israel's coast line. Here, we examine the possible impact of proposed cliff retreat mitigation efforts on long-shore sediment transport (LST) and coastal dynamics in the region. We used airborne LiDAR spanning a 9-year period between 2006 and 2015 to quantify the annual contribution of sediment eroded from a 20-km-long segment of Israel's coastal cliffs into the NLC. Our measurements reveal 282±85*103 m3 of sediment eroded from the cliff and delivered into the NLC during the studied period. Considering our study area comprises 50% of Israel's sea cliffs we infer an average contribution rate of 30,000-60,000 m^3/yr of cliff-derived sediment into the NLC prior to the planned broad-scale implementation of cliff-retreat mitigation measures. Previous studies report an average net LST flux of 80,000 - 90,000 m3 that reaches the northern termination of the NLC at Haifa Bay annually. Thus, our results suggest that Israel's actively eroding coastal cliffs are primary contributors (40-80%) to the LST budget along the northern termination of the NLC. It therefore appears that successful implementation of the coastal-cliff protection program along Israel's coastline will result in a significant sand deficit, which may drive LST in this part of the NLC out of its 'background' state. In the likely case that the energy/currents driving LST do not change, a possible outcome of this sediment deficit could be increased beach erosion along Israel's coast line to make up for the lost volumes of cliff

Determination of sedimentation, diffusion, and mixing rates in coastal sediments of the eastern Red Sea via natural and anthropogenic fallout radionuclides.

Science.gov (United States)

Al-Mur, Bandar A; Quicksall, Andrew N; Kaste, James M

2017-09-15

The Red Sea is a unique ecosystem with high biodiversity in one of the warmest regions of the world. In the last five decades, Red Sea coastal development has rapidly increased. Sediments from continental margins are delivered to depths by advection and diffusion-like processes which are difficult to quantify yet provide invaluable data to researchers. Beryllium-7, lead-210 and ceseium-137 were analyzed from sediment cores from the near-coast Red Sea near Jeddah, Saudi Arabia. The results of this work are the first estimates of diffusion, mixing, and sedimentation rates of the Red Sea coastal sediments. Maximum chemical diffusion and particle mixing rates range from 69.1 to 380cm -2 y -1 and 2.54 to 6.80cm -2 y -1 , respectively. Sedimentation rate is constrained to approximately 0.6cm/yr via multiple methods. These data provide baselines for tracking changes in various environmental problems including erosion, marine benthic ecosystem silting, and particle-bound contaminant delivery to the seafloor. Copyright © 2017. Published by Elsevier Ltd.

Experimental comparison of cavitation erosion rates of different steels used in hydraulic turbines

International Nuclear Information System (INIS)

Ton-That, L

2010-01-01

The prediction of cavitation erosion rates has an important role in order to evaluate the exact life of components in fluid machineries. Hydro-Quebec has studied this phenomenon for several years, in particular in hydraulic turbine runners, to try to understand the different degradation mechanisms related to this phenomenon. This paper presents part of this work. In this study, we carried out experimental erosion tests to compare different steels used in actual hydraulic turbine runners (carbon steels, austenitic and martensitic stainless steels) to high strength steels in terms of cavitation erosion resistance. The results for these different classes of steels are presented. The tests have been performed in a cavitating liquid jet apparatus according to the ASTM G134-95 standard to simulate the flow conditions. The mass loss has been followed during the exposure time. The maximum depth of erosion, the mean depth of erosion, and the mean depth erosion rate are determined. As a result we found that ASTM-A514 high strength steels present excellent cavitation erosion resistance properties. The cavitation eroded surface is followed by optical profilometry technique. Determination of mechanical properties and examinations of the eroded surfaces of the samples have also been carried out in order to identify the erosion mechanisms involved in the degradation of these kinds of materials.

National Assessment Of Shoreline Change: Part 2, Historical Shoreline Changes And Associated Coastal Land Loss Along The U.S. Southeast Atlantic Coast

Science.gov (United States)

Morton, Robert A.; Miller, Tara L.

2005-01-01

EXECUTIVE SUMMARY Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. This report on states comprising the Southeast Atlantic Coast (east Florida, Georgia, South Carolina, North Carolina) represents the second in a series that already includes the Gulf of Mexico and will eventually include the Northeast Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. The report summarizes the methods of analysis, interprets the results, provides explanations regarding the historical and present trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-2002. Long-term rates of change are calculated using four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for the most recent period (1970s to lidar shoreline). The historical rates of change presented in

Ecomorphodynamic Response of Foreshore Saltmarsh to the Implementation of Flood and Erosion Mitigation and Adaptation Structures in a Hypertidal Estuary: Minas Basin, Bay of Fundy, Canada.

Science.gov (United States)

Matheson, G.; van Proosdij, D.; Ross, C.

2017-12-01

Flood and erosion mitigations and adaptation structures are often implemented in anthropogenically modified coastal regions, such as dykelands, to protect against coastal hazards. If saltmarshes are to be incorporated into a coastal management plan as a source of coastal defence, it is paramount to understand how ecomorphodynamic feedbacks triggered by implementing these structures can impact saltmarshes. This study examines how these structures, in combination with natural drivers, have precipitated changes in foreshore saltmarsh erosion and progradation rates over varying spatial scales in the hypertidal Minas Basin, located in the upper Bay of Fundy, during the past 80 years. Foreshore change rates (in 25m segments) are obtained using empirical field measurements, geomatics techniques in a geographical information system (GIS), as well as imagery and digital surface models (DSMs) derived from an unmanned aerial vehicle (UAV). Furthermore, UAV DSMs were used to determine infill rates and short-term sediment budgets in saltmarsh borrow pits. Natural cyclical foreshore change rates are observed in the Minas Basin, but are often augmented by the presence of anthropogenic structures. Erosion and progradation rates in individual transects have been observed to be as much as -14.9m/yr and 20.1m/yr, respectively. In individual saltmarsh communities, average change rates have been observed to be as much -3.4m/yr and 2.1m/yr across the entire foreshore. Furthermore, results suggest that under specific environmental conditions some structures (e.g. kickers) work in tandem with saltmarshes to protect the upland by precipitating ecomorphodynamic feedbacks that promote saltmarsh progradation. Conversely, other structures (e.g. foreshore rocking) can exacerbate natural cycles of erosion, locally. Borrow pit studies reveal that although local suspended sediment concentrations, which can vary from 50mg/l to 50000mg/l, play an integral role in pit sedimentation, channel geometry

Evaluation of rate of swelling and erosion of verapamil (VRP) sustained-release matrix tablets.

Science.gov (United States)

Khamanga, Sandile M; Walker, Roderick B

2006-01-01

Tablets manufactured in-house were compared to a marketed sustained-release product of verapamil to investigate the rate of hydration, erosion, and drug-release mechanism by measuring the wet and subsequent dry weights of the products. Swelling and erosion rates depended on the polymer and granulating fluid used, which ultimately pointed to their permeability characteristics. Erosion rate of the marketed product was highest, which suggests that the gel layer that formed around these tablets was weak as opposed to the robust and resistant layers of test products. Anomalous and near zero-order transport mechanisms were dominant in tests and commercial product, respectively.

Effects of landforms on the erosion rate in a small watershed by the 137Cs tracing method

International Nuclear Information System (INIS)

Li Mian; Yao Wenyi; Li Zhanbin; Liu Puling; Shen Zhenzhou

2010-01-01

It's very important to analyze and evaluate quantitatively the effects of landforms on soil erosion for the prevention and treatment of soil loss in a small watershed. The objective of this study was to evaluate the effects of landform factors on erosion rate by the 137 Cs tracing method in a small watershed in the Purple Hilly Area of China. The erosion rates under different slope lengths, slope gradients and slope aspects were estimated in Xiangshuitan watershed in the Purple Hilly Area in Sichuan Basin by the 137 Cs tracing method. The results showed that the erosion rate decreased exponentially with downslope distance, and it increased with increasing slope gradient during the scope of 5 deg. - 16 deg. The slope aspect had great impact on the erosion rate, and the hillside on the sunny slope had larger erosion rate than that on the shady slope, particularly for the farmland.

COASTAL DYNAMICS OF SINGKAWANG, WEST KALIMANTAN

Directory of Open Access Journals (Sweden)

Yudi Darlan

2017-07-01

Full Text Available Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and steep hills. Granitic rocks and alluvium as a based rock of Singkawang coasts. Generally, Singkawang coasts was developed for coastal farms, fishery pond, and beach resorts, where most of these area have been eroded. Geological and physical oceanography condition are the aspects that build the characteristics of Singkawang coast. Human activities also play an important role in managing the equilibrium and dynamics of this coastal region. This research is to determine the dynamics and coastline changes of Singkawang coasts based on the characteristics of the coastal element and sediment. The high erosion was occurred at Semalagi–Cape Bajau. The Cape Bajau - Cape Banjar is relatively stable due to headlands of this coast is characterized by igneous rocks which resistant to the erosion. The Cape Banjar – South Coasts is very intensive erosion coast. Modern shorelines of the Singkawang coast might be as a shallow marine environment which were occurred thousands years ago (pre-Recent. The high of sedimentation process is generated by global sea level change, where was occurred at that time, and might be changed the area become part of the mainland coast of Singkawang. Keywords: coastal dynamics, erosion, sedimentation, Singkawang, West Kalimantan.

Climate adaptation and policy-induced inflation of coastal property value.

Science.gov (United States)

McNamara, Dylan E; Gopalakrishnan, Sathya; Smith, Martin D; Murray, A Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.

Coastal hazards: hurricanes, tsunamis, coastal erosion

Science.gov (United States)

Vandas, Stephen; Mersfelder, Lynne; Farrar, Frank; France, Rigoberto Guardado; Yajimovich, Oscar Efraín González; Muñoz, Aurora R.; Rivera, María del C.

1996-01-01

Oceans are the largest geographic feature on the surface of the Earth, covering approximately 70% of the planet's surface. As a result, oceans have a tremendous impact on the Earth, its climate, and its inhabitants. The coast or shoreline is the boundary between ocean environments and land habitats. By the year 2025, it is estimated that approximately two-thirds of the world's population will be living within 200 kilometers of a coast. In many ways, we treat the coast just like any other type of land area, as a safe and stable place to live and play. However, coastal environments are dynamic, and they constantly change in response to natural processes and to human activities.

Seasonal electrical resistivity surveys of a coastal bluff, Barter Island, North Slope Alaska

Science.gov (United States)

Swarzenski, Peter W.; Johnson, Cordell; Lorenson, Thomas; Conaway, Christopher H.; Gibbs, Ann E.; Erikson, Li; Richmond, Bruce M.; Waldrop, Mark P.

2016-01-01

Select coastal regions of the North Slope of Alaska are experiencing high erosion rates that can be attributed in part to recent warming trends and associated increased storm intensity and frequency. The upper sediment column of the coastal North Slope of Alaska can be described as continuous permafrost underlying a thin (typically less than 1–2 m) active layer that responds variably to seasonal thaw cycles. Assessing the temporal and spatial variability of the active layer and underlying permafrost is essential to better constrain how heightened erosion may impact material fluxes to the atmosphere and the coastal ocean, and how enhanced thaw cycles may impact the stability of the coastal bluffs. In this study, multi-channel electrical resistivity tomography (ERT) was used to image shallow subsurface features of a coastal bluff west of Kaktovik, on Barter Island, northeast Alaska. A comparison of a suite of paired resistivity surveys conducted in early and late summer 2014 provided detailed information on how the active layer and permafrost are impacted during the short Arctic summer. Such results are useful in the development of coastal resilience models that tie together fluvial, terrestrial, climatic, geologic, and oceanographic forcings on shoreline stability.

Covariation of climate and long-term erosion rates acrossa steep rainfall gradient on the Hawaiian island of Kaua'i

Science.gov (United States)

Ken Ferrier,; J. Taylor Perron,; Sujoy Mukhopadhyay,; Matt Rosener,; Stock, Jonathan; Slosberg, Michelle; Kimberly L. Huppert,

2013-01-01

Erosion of volcanic ocean islands creates dramatic landscapes, modulates Earth’s carbon cycle, and delivers sediment to coasts and reefs. Because many volcanic islands have large climate gradients and minimal variations in lithology and tectonic history, they are excellent natural laboratories for studying climatic effects on the evolution of topography. Despite concerns that modern sediment fluxes to island coasts may exceed long-term fluxes, little is known about how erosion rates and processes vary across island interiors, how erosion rates are influenced by the strong climate gradients on many islands, and how modern island erosion rates compare to long-term rates. Here, we present new measurements of erosion rates over 5 yr to 5 m.y. timescales on the Hawaiian island of Kaua‘i, across which mean annual precipitation ranges from 0.5 to 9.5 m/yr. Eroded rock volumes from basins across Kaua‘i indicate that million-year-scale erosion rates are correlated with modern mean annual precipitation and range from 8 to 335 t km–2 yr–1. In Kaua‘i’s Hanalei River basin, 3He concentrations in detrital olivines imply millennial-scale erosion rates of >126 to >390 t km–2 yr–1 from olivine-bearing hillslopes, while fluvial suspended sediment fluxes measured from 2004 to 2009 plus estimates of chemical and bed-load fluxes imply basin-averaged erosion rates of 545 ± 128 t km–2 yr–1. Mapping of landslide scars in satellite imagery of the Hanalei basin from 2004 and 2010 implies landslide-driven erosion rates of 30–47 t km–2 yr–1. These measurements imply that modern erosion rates in the Hanalei basin are no more than 2.3 ± 0.6 times faster than millennial-scale erosion rates, and, to the extent that modern precipitation patterns resemble long-term patterns, they are consistent with a link between precipitation rates and long-term erosion rates.

An assessment for the erosion rate of DEMO first wall

Science.gov (United States)

Tokar, M. Z.

2018-01-01

In a fusion reactor a significant fraction of plasma particles lost from the confined volume will reach the vessel wall. The recombination of these charged species, electrons and ions of hydrogen isotopes, is a source of neutral molecules and atoms, recycling back into the plasma. Here they participate, in particular, in charge-exchange (c-x) collisions with the plasma ions and, as a result, atoms of high energies with chaotically oriented velocities are generated. A significant fraction of these hot neutrals will hit the wall, leading, as well as the outflowing fuel and impurity ions, to its erosion, limiting the reactor operation time. The rate of the wall erosion in DEMO is assessed by applying a one-dimensional model which takes into account the transport of charged and neutral species across the flux surfaces in the main part of the scrape-off layer, beyond the X-point vicinity and divertor, and by considering the shift of the centers of flux surfaces, their elongation and triangularity. Atoms generated by c-x of recycling neutrals are modeled kinetically to define firmly their energy spectrum, being of particular importance for the erosion assessment. It is demonstrated the erosion rate of the DEMO wall armor of tungsten will have a pronounced ballooning character with a significant maximum of 0.3 mm per full power year at the low field side, decreasing with an increase in the anomalous perpendicular transport in the ‘far’ SOL or the plasma density at the separatrix.

Constraining local subglacial bedrock erosion rates with cosmogenic nuclides

Science.gov (United States)

Wirsig, Christian; Ivy-Ochs, Susan; Christl, Marcus; Reitner, Jürgen; Reindl, Martin; Bichler, Mathias; Vockenhuber, Christof; Akcar, Naki; Schlüchter, Christian

2014-05-01

The constant buildup of cosmogenic nuclides, most prominently 10Be, in exposed rock surfaces is routinely employed for dating various landforms such as landslides or glacial moraines. One fundamental assumption is that no cosmogenic nuclides were initially present in the rock, before the event to be dated. In the context of glacially formed landscapes it is commonly assumed that subglacial erosion of at least a few meters of bedrock during the period of ice coverage is sufficient to remove any previously accumulated nuclides, since the production of 10Be ceases at a depth of 2-3 m. Insufficient subglacial erosion leads to overestimation of surface exposure ages. If the time since the retreat of the glacier is known, however, a discordant concentration of cosmogenic nuclides delivers information about the depth of subglacial erosion. Here we present data from proglacial bedrock at two sites in the Alps. Goldbergkees in the Hohe Tauern National Park in Austria and Gruebengletscher in the Grimsel Pass area in Switzerland. Samples were taken inside as well as outside of the glaciers' Little Ice Age extent. Measured nuclide concentrations are analyzed with the help of a MATLAB model simulating periods of exposure or glacial cover of user-definable length and erosion rates.

Estimating the impact of seawater on the production of soil water-extractable organic carbon during coastal erosion.

Science.gov (United States)

Dou, Fugen; Ping, Chien-Lu; Guo, Laodong; Jorgenson, Torre

2008-01-01

The production of water-extractable organic carbon (WEOC) during arctic coastal erosion and permafrost degradation may contribute significantly to C fluxes under warming conditions, but it remains difficult to quantify. A tundra soil collected near Barrow, AK, was selected to evaluate the effects of soil pretreatments (oven drying vs. freeze drying) as well as extraction solutions (pure water vs. seawater) on WEOC yields. Both oven drying and freeze drying significantly increased WEOC release compared with the original moist soil samples; dried samples released, on average, 18% more WEOC than did original moist samples. Similar results were observed for the production of low-molecular-weight dissolved organic C. However, extractable OC released from different soil horizons exhibited differences in specific UV absorption, suggesting differences in WEOC quality. Furthermore, extractable OC yields were significantly less in samples extracted with seawater compared with those extracted with pure water, likely due to the effects of major ions on extractable OC flocculation. Compared with samples from the active horizons, upper permafrost samples released more WEOC, suggesting that continuously frozen samples were more sensitive than samples that had experienced more drying-wetting cycles in nature. Specific UV absorption of seawater-extracted OC was significantly lower than that of OC extracted using pure water, suggesting more aromatic or humic substances were flocculated during seawater extraction. Our results suggest that overestimation of total terrestrial WEOC input to the Arctic Ocean during coastal erosion could occur if estimations were based on WEOC extracted from dried soil samples using pure water.

15 CFR 923.25 - Shoreline erosion/mitigation planning.

Science.gov (United States)

2010-01-01

... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Shoreline erosion/mitigation planning... erosion/mitigation planning. (a) The management program must include a planning process for assessing the... planning process may be within the broader context of coastal hazard mitigation planning. (b) The basic...

Coastal sea-ice processes in Alaska and their relevance for sediment dynamics and coastal retreat (Invited)

Science.gov (United States)

Eicken, H.; Kapsch, M.; Johnson, M. A.; Weyapuk, W. U., Jr.

2009-12-01

Sea ice plays an important, complicated role in Arctic coastal sediment dynamics. It helps protect the shoreline from wave action and constrains coastal permafrost thaw; at the same time, sea ice is a highly effective sediment erosion and transport agent. For the coastline of (sub-)Arctic Alaska we have examined key processes that govern the role of sea ice as a geologic agent. Based on passive microwave satellite data for the time period 1979 to 2008 and augmented by field measurements and observations conducted by local sea-ice experts in coastal communities from 2006 onwards, we determined the onset of coastal ice spring break-up and fall freeze-up. These two events define the start and end of the open-water season during which the coast is rendered most vulnerable to thermal and dynamic processes promoting erosion. Satellite data show significant trends toward later fall freeze-up in many locations and moreover provide a picture of the statistical significance and variability of such trends in great spatio-temporal detail. Coastal ice observations suggest that important sea-ice processes (such as formation of ice berms) that precede freeze-up as detected by passive microwave data need to be taken into consideration in evaluating the vulnerability of the coastline and the specific threat of individual storms. Field observations, satellite data and local knowledge also highlight the substantial change in winter sea-ice regimes over the past two decades, with a much more mobile ice cover enhancing winter sediment transport. Ultimately, the shorter sea-ice season and the greater mobility and the lack of stability of winter coastal sea ice work in concert to increase the vulnerability of the coastline to erosion and flooding. At the same time, these changes provide a mechanism for effective redistribution and cross-shelf transport of sediments that prepares the stage for further erosive action in subsequent seasons.

Archaeological Site Vulnerability Modelling: The Influence of High Impact Storm Events on Models of Shoreline Erosion in the Western Canadian Arctic

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O’Rourke Michael J. E.

2017-01-01

Full Text Available Much of the Inuvialuit archaeological record is situated along shorelines of the western Canadian Arctic. These coastal sites are at substantial risk of damage due to a number of geomorphological processes at work in the region. The identification of threatened heritage remains is critical in the Mackenzie Delta, where landscape changes are taking place at an increasingly rapid pace. This paper outlines some preliminary observations from a research program directed toward identifying vulnerable archaeological remains within the Inuvialuit Settlement Region. Coastal erosion rates have been calculated for over 280 km of the Kugmallit Bay shoreline, extending along the eastern extent of Richards Island and neighbouring areas of the Tuktoyaktuk Peninsula. Helicopter surveys conducted during the 2014 field season confirmed that areas exposed to heavy erosive forces in the past continue to erode at alarming rates. Some of the calculated rates, however, have proven far too conservative. An extreme period of erosion at Toker Point in the autumn of 2013 has yielded a prime example of how increasingly volatile weather patterns can influence shoreline erosion models. It has also provided a case with which to demonstrate the value of using more recent, shorter time-interval imagery in assessing impacts to cultural landscapes.

Bank Erosion, Mass Wasting, Water Clarity, Bathymetry and a Sediment Budget Along the Dam-Regulated Lower Roanoke River, North Carolina

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Schenk, Edward R.; Hupp, Cliff R.; Richter, Jean M.; Kroes, Daniel E.

2010-01-01

Dam construction and its impact on downstream fluvial processes may substantially alter ambient bank stability, floodplain inundation patterns, and channel morphology. Most of the world's largest rivers have been dammed, which has prompted management efforts to mitigate dam effects. Three high dams (completed between 1953 and 1963) occur along the Piedmont portion of the Roanoke River, North Carolina; just downstream, the lower part of the river flows across largely unconsolidated Coastal Plain deposits. To document bank erosion rates along the lower Roanoke River, more than 700 bank erosion pins were installed along 124 bank transects. Additionally, discrete measurements of channel bathymetry, water clarity, and presence or absence of mass wasting were documented along the entire 153-kilometer-long study reach. Amounts of bank erosion in combination with prior estimates of floodplain deposition were used to develop a bank erosion and floodplain deposition sediment budget for the lower river. Present bank erosion rates are relatively high [mean 42 milimeters per year (mm/yr)] and are greatest along the middle reaches (mean 60 mm/yr) and on lower parts of the bank on all reaches. Erosion rates were likely higher along upstream reaches than present erosion rates such that erosion rate maxima have migrated downstream. Mass wasting and water clarity also peak along the middle reaches.

Climate Adaptation and Policy-Induced Inflation of Coastal Property Value

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McNamara, Dylan E.; Gopalakrishnan, Sathya; Smith, Martin D.; Murray, A. Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities. PMID:25806944

Climate adaptation and policy-induced inflation of coastal property value.

Directory of Open Access Journals (Sweden)

Dylan E McNamara

Full Text Available Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.

Coastal Ecosystem Assessment, Development and Creation of a Policy Tool using Unmanned Aerial Vehicles (UAVs) for: A Case Study of Western Puerto Rico Coastal Region

Science.gov (United States)

Munoz Barreto, J.; Pillich, J.; Aponte Bermúdez, L. D.; Torres Pagan, G.

2017-12-01

This project utilizes low-cost Unmanned Aerial Vehicles (UAVs) based systems for different applications, such as low-altitude (high resolution) aerial photogrammetry for aerial analysis of vegetation, reconstruction of beach topography and mapping coastal erosion to understand, and estimated ecosystem values. As part of this work, five testbeds coastal sites, designated as the Caribbean Littoral Aerial Surveillance System (CLASS), were established. The sites are distributed along western Puerto Rico coastline where population and industry (tourism) are very much clustered and dense along the coast. Over the past year, rapid post-storm deployment of UAV surveying has been successfully integrated into the CLASS sites, specifically at Rincon (Puerto Rico), where coastal erosion has raised the public and government concern over the past decades. A case study is presented here where we collected aerial photos before and after the swells caused by Hurricane Mathew (October 2016). We merged the point cloud obtained from the UAV photogrammetric assessment with topo-bathymetric data, to get a complete beach topography. Using the rectified and georeferenced UAV orthophotos, we identified the maximum wave runup for the pre-swell and post-swell events. Also, we used numerical modeling (X-Beach) to simulate the rate-of-change dynamics of the coastal zones and compare the model results to observed values (including multiple historic shoreline positions). In summary, our project has accomplished the first milestone which is the Development and Implementation of an Effective Shoreline Monitoring Program using UAVs. The activities of the monitoring program have enabled the collection of crucial data for coastal mapping along Puerto Rico's shorelines with emphasis on coastal erosion hot spots zones and ecosystem values. Our results highlight the potential of the synergy between UAVs, photogrammetry, and Geographic Information Systems to provide faster and low-cost reliable

Assessment of coastal erosion and quantification of land loss on Western Pacific atolls during the last 50 years

Science.gov (United States)

Taborosi, Danko; Zega, Mojca; Jenson, John W.

2010-05-01

The majority of islands in the tropical western Pacific are coral atolls. Most are inhabited by indigenous Micronesian populations. Local people have over the millennia developed coping strategies and response mechanisms to difficult natural conditions, including typhoons, erosion, giant swells, and flooding, as well as ensuing famines and epidemics. However, since 1990s residents of atolls in the region have been appealing for help. They indicate that their islands are being rapidly eroded along coastlines, land areas are becoming smaller, and taro patches and other vegetation are being damaged. Such concerns were corroborated by one sweeping assessment by South Pacific Applied Geoscience Commission in 1998, as well as various isolated field observations since. Evidence of recent coastal erosion is found locally on many islands, both on windward and leeward sides and ocean and lagoon facing shores. Examples include retreating modern beaches, exhumed beachrock, scouring and undercutting of vegetation, overhanging scarps, etc. In addition, a considerable number of uninhabited islets have been completely obliterated by storms in the recent past; unusually high tides and swells have swept over large populated islands, destroying homes and harming agriculture; and at least one atoll has been abandoned due to irrecoverable typhoon damage. Those problems have received much worldwide media coverage, in which they are generally presented as "sinking" of islands due to global climate change and accompanying sea level rise. In reality, modern atolls are now known to be artifacts of the Pacific mid-Holocene High-Stand, and no first-hand data are available from Pacific islands to discern what proportion of observed erosional phenomena are 1) due to local natural and anthropogenic coastal processes as opposed to global and regional changes, and 2) caused by continuous natural dynamics as opposed to episodic extreme events. It is clear that some islands are faring better than

Effects of landforms on the erosion rate in a small watershed by the {sup 137}Cs tracing method

Energy Technology Data Exchange (ETDEWEB)

Li Mian, E-mail: hnli-mian@163.co [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Shen Zhenzhou [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)

2010-05-15

It's very important to analyze and evaluate quantitatively the effects of landforms on soil erosion for the prevention and treatment of soil loss in a small watershed. The objective of this study was to evaluate the effects of landform factors on erosion rate by the {sup 137}Cs tracing method in a small watershed in the Purple Hilly Area of China. The erosion rates under different slope lengths, slope gradients and slope aspects were estimated in Xiangshuitan watershed in the Purple Hilly Area in Sichuan Basin by the {sup 137}Cs tracing method. The results showed that the erosion rate decreased exponentially with downslope distance, and it increased with increasing slope gradient during the scope of 5 deg. - 16 deg. The slope aspect had great impact on the erosion rate, and the hillside on the sunny slope had larger erosion rate than that on the shady slope, particularly for the farmland.

Modeling the fluid/soil interface erosion in the Hole Erosion Test

Directory of Open Access Journals (Sweden)

Kissi B.

2012-07-01

Full Text Available Soil erosion is a complex phenomenon which yields at its final stage to insidious fluid leakages under the hydraulic infrastructures known as piping and which are the main cause of their rupture. The Hole Erosion Test is commonly used to quantify the rate of piping erosion. In this work, The Hole Erosion Test is modelled by using Fluent software package. The aim is to predict the erosion rate of soil during the hole erosion test. The renormalization group theory – based k–ε turbulence model equations are used. This modelling makes it possible describing the effect of the clay concentration in flowing water on erosion. Unlike the usual one dimensional models, the proposed modelling shows that erosion is not uniform erosion along the hole length. In particular, the concentration of clay is found to increase noticeably the erosion rate.

Living Shorelines: Coastal Resilience with a Blue Carbon Benefit.

Science.gov (United States)

Davis, Jenny L; Currin, Carolyn A; O'Brien, Colleen; Raffenburg, Craig; Davis, Amanda

2015-01-01

Living shorelines are a type of estuarine shoreline erosion control that incorporates native vegetation and preserves native habitats. Because they provide the ecosystem services associated with natural coastal wetlands while also increasing shoreline resilience, living shorelines are part of the natural and hybrid infrastructure approach to coastal resiliency. Marshes created as living shorelines are typically narrow (erosion control and habitat for estuarine organisms has been documented but their capacity for carbon sequestration has not. We measured carbon sequestration rates in living shorelines and sandy transplanted Spartina alterniflora marshes in the Newport River Estuary, North Carolina. The marshes sampled here range in age from 12 to 38 years and represent a continuum of soil development. Carbon sequestration rates ranged from 58 to 283 g C m-2 yr-1 and decreased with marsh age. The pattern of lower sequestration rates in older marshes is hypothesized to be the result of a relative enrichment of labile organic matter in younger sites and illustrates the importance of choosing mature marshes for determination of long-term carbon sequestration potential. The data presented here are within the range of published carbon sequestration rates for S. alterniflora marshes and suggest that wide-scale use of the living shoreline approach to shoreline management may come with a substantial carbon benefit.

Sand mining impacts on long-term dune erosion in southern Monterey Bay

Science.gov (United States)

Thornton, E.B.; Sallenger, Abby; Sesto, Juan Conforto; Egley, L.; McGee, Timothy; Parsons, Rost

2006-01-01

Southern Monterey Bay was the most intensively mined shoreline (with sand removed directly from the surf zone) in the U.S. during the period from 1906 until 1990, when the mines were closed following hypotheses that the mining caused coastal erosion. It is estimated that the yearly averaged amount of mined sand between 1940 and 1984 was 128,000 m3/yr, which is approximately 50% of the yearly average dune volume loss during this period. To assess the impact of sand mining, erosion rates along an 18 km range of shoreline during the times of intensive sand mining (1940–1990) are compared with the rates after sand mining ceased (1990–2004). Most of the shoreline is composed of unconsolidated sand with extensive sand dunes rising up to a height of 46 m, vulnerable to the erosive forces of storm waves. Erosion is defined here as a recession of the top edge of the dune. Recession was determined using stereo-photogrammetry, and LIDAR and GPS surveys. Long-term erosion rates vary from about 0.5 m/yr at Monterey to 1.5 m/yr in the middle of the range, and then decrease northward. Erosion events are episodic and occur when storm waves and high tides coincide, allowing swash to undercut the dune and resulting in permanent recession. Erosion appears to be correlated with the occurrence of El Niños. The calculated volume loss of the dune in southern Monterey Bay during the 1997–98 El Niño winter was 1,820,000 m3, which is almost seven times the historical annual mean dune erosion of 270,000 m3/yr. The alongshore variation in recession rates appears to be a function of the alongshore gradient in mean wave energy and depletions by sand mining. After cessation of sand mining in 1990, the erosion rates decreased at locations in the southern end of the bay but have not significantly changed at other locations.

An evolving research agenda for human-coastal systems

Science.gov (United States)

Lazarus, Eli D.; Ellis, Michael A.; Brad Murray, A.; Hall, Damon M.

2016-03-01

Within the broad discourses of environmental change, sustainability science, and anthropogenic Earth-surface systems, a focused body of work involves the coupled economic and physical dynamics of developed shorelines. Rapid rates of change in coastal environments, from wetlands and deltas to inlets and dune systems, help researchers recognize, observe, and investigate coupling in natural (non-human) morphodynamics and biomorphodynamics. This same intrinsic quality of fast-paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities. In many coastal communities, beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies, including beach replenishment, groynes, revetments, and seawalls. As cycles of erosion and mitigation iterate, coastline change and economically driven interventions become mutually linked. Emergent dynamics of two-way economic-physical coupling is a recent research discovery. Having established a strong theoretical basis, research into coupled human-coastal systems has passed its early proof-of-concept phase. This paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human-coastal systems: (1) codifying salient individual and social behaviors of decision-making in ways that capture societal actions across a range of scales (thus engaging economics, social science, and policy disciplines); (2) quantifying anthropogenic effects on alongshore and cross-shore sediment pathways and long-term landscape evolution in coastal zones through time, including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices (e.g., construction of buildings and artificial dunes, bulldozer removal of overwash after major storms); and (3) reciprocal knowledge and data exchange between researchers in coastal

Types and Functions of Coastal Structures

DEFF Research Database (Denmark)

Burcharth, H. F.; A. Hughes, Steven

2003-01-01

Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives include sheltering of harbour basins and harbour entrances against waves, stabilization of navigation channels at inlets, and protection...

Comparing erosion rates in burnt forests and agricultural fields for a mountain catchment in NW Iberia

Science.gov (United States)

Nunes, João Pedro; Marisa Santos, Juliana; Bernard-Jannin, Léonard; Keizer, Jan Jacob

2013-04-01

A large part of northwestern Iberia is nowadays covered by commercial forest plantations of eucalypts and maritime pines, which have partly replaced traditional agricultural land-uses. The humid Mediterranean climate, with mild wet winters and warm dry summers, creates favorable conditions for the occurrence of frequent and recurrent forest fires. Erosion rates in recently burnt areas have been the subject of numerous studies; however, there is still a lack of information on their relevance when compared with agricultural erosion rates, impairing a comprehensive assessment of the role of forests for soil protection. This study focuses on Macieira de Alcoba, head-water catchment in the Caramulo Mountain Range, north-central Portugal, with a mixture of agricultural fields (mostly a rotation between winter pastures and summer cereals) on the lower slopes and forest plantations (mostly eucalypts) on the upper slopes. Agricultural erosion in this catchment has been monitored since 2010; a forest fire in 2011 presented an opportunity to compare post-fire and agricultural erosion rates at nearby sites with comparable soil and climatic conditions. Erosion rates were monitored between 2010 and 2013 by repeated surveys of visible erosion features and, in particular, by mapping and measuring rills and gullies after important rainfall events. During the 2011/2012 hydrological year, erosion rates in the burnt forest were two orders of magnitude above those in agricultural fields, amounting to 17.6 and. 0.1 Mg ha-1, respectively. Rills were widespread in the burnt area, while in the agricultural area they were limited to a small number of fields with higher slope; these particular fields experienced an erosion rate of 2.3 Mg ha-1, still one order of magnitude lower than at the burnt forest site. The timing of the erosion features was also quite distinct for the burnt area and the agricultural fields. During the first nine months after the fire, rill formation was not observed in

Toward a community coastal sediment transport modeling system: the second workshop

Science.gov (United States)

Sherwood, Christopher R.; Harris, Courtney K.; Geyer, W. Rockwell; Butman, Bradford

2002-01-01

Models for transport and the long-term fate of particles in coastal waters are essential for a variety of applications related to commerce, defense, public health, and the quality of the marine environment. Examples include: analysis of waste disposal and transport and the fate of contaminated materials; evaluation of burial rates for naval mines or archaeological artifacts; prediction of water-column optical properties; analysis of transport and the fate of biological particles; prediction of coastal flooding and coastal erosion; evaluation of impacts of sea-level or wave-climate changes and coastal development; planning for construction and maintenance of navigable waterways; evaluation of habitat for commercial fisheries; evaluation of impacts of natural or anthropogenic changes in coastal conditions on recreational activities; and design of intakes and outfalls for sewage treatment, cooling systems, and desalination plants.

Assessing soil erosion rates for a large catchment in the Central Highlands of Vietnam using fallout radionuclides

International Nuclear Information System (INIS)

Phan Son Hai; Nguyen Thanh Binh; Nguyen Minh Dao; Nguyen Thi Huong Lan; Nguyen Thi Mui; Le Xuan Thang; Phan Quang Trung; Trinh Cong Tu; Tran Tien Dung

2014-01-01

Fallout radionuclides Be-7 and Cs-137 were applied to assess soil erosion rates for a 270.5 km 2 catchment with a variety of slope (from 0 o to more than 45 o , crops or vegetation (natural forest, artificial forest, perennial crops, annual crops) and a variety of tillage and soil conservation measures. Soil erosion rates were estimated at 90 areas within the catchment. Each sampling area has at least one feature of the slope, rainfall, crops, farming practice different from others. Soil erosion rates in this region depend significantly on the slope, crops and farming techniques. Averaging over crops, soil erosion rates by slopes 0 - 5 o , 5 - 15 o , 15 - 25 o and 25 - 35 o are 5.0, 12.8, 18.9 and 21.3 t.ha -1 .y -1 , respectively. Forest land has the least soil erosion rates, ranging between 0.5 t.ha -1 .y -1 and 14 t.ha -1 .y -1 depending on the slope. Annual crops land has the highest soil erosion rates, ranging between 6 t.ha -1 .y -1 and 42 t.ha -1 .y -1 when slope varies from < 5 o to 32 o . Perennial crop land has soil erosion rates in the range of 5 t.ha -1 .y -1 and 39 t.ha -1 .y -1 . In areas with the same slope, the soil erosion rate is the highest for cashew plantations, lower for mulberry field and the lowest for tea or coffee plantations. Soil erosion has resulted in losing a significant quantity of plant nutrients such as OM, N, P 2 O 5 and K 2 O every year. Generally, lost nutrient quantities due to soil erosion are proportional to erosion rates. Some areas of annual crop land lost a large amount of nutrients every year, up to 1435 kg OM, 79 kg N, 54 kg P 2 O 5 and 36 kg K 2 O. Similarly, perennial crop lands in this region could lost up to 1736 kg OM, 91 kg N, 66 kg P 2 O 5 and 40 kg K 2 O every year. Owing to soil erosion, the catchment has lost about 211200 tons of surface soil per year during last 50 years, corresponding to the rate of 7.8 t.ha -1 .y -1 . This amount of eroded soil was deposited in drainage of the catchment and in reservoirs

Quantifying modern erosion rates and river-sediment contamination in the Bolivian Andes

Science.gov (United States)

Vezzoli, Giovanni; Ghielmi, Giacomo; Mondaca, Gonzalo; Resentini, Alberto; Villarroel, Elena Katia; Padoan, Marta; Gentile, Paolo

2013-08-01

We use petrographic, mineralogical and geochemical data on modern river sediments of the Tupiza basin in the Bolivian Andes to investigate the relationships among human activity, heavy-metal contamination of sediments and modern erosion rates in mountain fluvial systems. Forward mixing model was used to quantify the relative contributions from each main tributary to total sediment load of the Tupiza River. The absolute sediment load was estimated by using the Pacific Southwest Inter Agency Committee model (PSIAC, 1968) after two years of geological field surveys (2009; 2010), together with data obtained from the Instituto Nacional del Agua public authority (INA, 2007), and suspended-load data from Aalto et al. (2006). Our results indicate that the sediment yield in the drainage basin is 910 ± 752 ton/km2year and the mean erosion rate is 0.40 ± 0.33 mm/year. These values compare well with erosion rates measured by Insel et al. (2010) using 10Be cosmogenic radionuclide concentrations in Bolivian river sediments. More than 40% of the Tupiza river load is produced in the upper part of the catchment, where highly tectonized and weathered rocks are exposed and coupled with sporadic land cover and intense human activity (mines). In the Rio Chilco basin strong erosion of upland valleys produce an increase of erosion (˜10 mm/year) and the influx of large amounts of sediment by mass wasting processes. The main floodplain of the Tupiza catchment represents a significant storage site for the heavy metals (˜657 ton/year). Fluvial sediments contain zinc, lead, vanadium, chromium, arsenic and nickel. Since the residence time of these contaminants in the alluvial plain may be more than 100 years, they may represent a potential source of pollution for human health.

Increase in the rate and uniformity of coastline erosion in Arctic Alaska

Science.gov (United States)

Jones, Benjamin M.; Arp, C.D.; Jorgenson, M.T.; Hinkel, Kenneth M.; Schmutz, J.A.; Flint, P.L.

2009-01-01

Analysis of a 60 km segment of the Alaskan Beaufort Sea coast using a time-series of aerial photography revealed that mean annual erosion rates increased from 6.8 m a-1 (1955 to 1979), to 8.7 m a-1 (1979 to 2002), to 13.6 m a-1 (2002 to 2007). We also observed that spatial patterns of erosion have become more uniform across shoreline types with different degrees of ice-richness. Further, during the remainder of the 2007 ice-free season 25 m of erosion occurred locally, in the absence of a westerly storm event. Concurrent arctic changes potentially responsible for this shift in the rate and pattern of land loss include declining sea ice extent, increasing summertime sea surface temperature, rising sea-level, and increases in storm power and corresponding wave action. Taken together, these factors may be leading to a new regime of ocean-land interactions that are repositioning and reshaping the Arctic coastline. Copyright 2009 by the American Geophysical Union.

Spatial Patterns of Long-Term Erosion Rates Beneath the Marine West Antarctic Ice Sheet: Insights into the Physics of Continental Scale Glacial Erosion from a Comparison with the Ice-Velocity Field

Science.gov (United States)

Howat, I. M.; Tulaczyk, S.; Mac Gregor, K.; Joughin, I.

2001-12-01

As part of the effort to build quantitative models of glacial erosion and sedimentation, it is particularly important to construct scaled relations between erosion, transport, and sedimentation rates and appropriate glaciological variables (e.g., ice velocity). Recent acquisition of bed topography and ice velocity data for the marine West Antarctic Ice Sheet (WAIS)[Joughin et al., 1999; Lythe et al., in press] provides an unprecedented opportunity to investigate continental-scale patterns of glacial erosion and their relationship to the ice velocity field. Utilizing this data, we construct a map of estimated long-term erosion rates beneath the WAIS. In order to calculate long-term erosion rates from the available data, we assume that: (1) the ice sheet has been present for ~5 mill. years, (2) the initial topography beneath the WAIS was that of a typical ( ~200 m.b.s.l.) continental shelf, and (3) the present topography is near local isostatic equilibrium (Airy type). The map of long-term erosion rates constructed in this fashion shows an intriguing pattern of relatively high rates (of the order of 0.1 mm/yr) concentrated beneath modern ice stream tributaries (ice velocity ~100 m/yr), but much lower erosion rates (of the order of 0.01 mm/yr) beneath both the modern fast-moving ice streams ( ~400 m/yr.) and the slow-moving parts of the ice sheet ( ~10 m/yr). This lack of clear correlation between the estimated erosion rates and ice velocity is somewhat unexpected given that both observational and theoretical studies have shown that bedrock erosion rates beneath mountain glaciers can often be calculated by multiplying the basal sliding velocity by a constant (typically of the order of ~10^-4)(Humphrey and Raymond, 1993 and Mac Gregor et al., 2000). We obtain an improved match between estimated erosion rates and bed topography by calculating erosion rates using horizontal gradients within the ice velocity field rather than the magnitude of ice velocity, as consistent

Establishment of the relationship between 137Cs loss and soil erosion rates

International Nuclear Information System (INIS)

Phan Son Hai

2003-01-01

The key stages involved in the use of 137 Cs in soil erosion assessment is presented. The method have been successfully applied in pilot scale. These main stages can be summarized as follows: 1/ selection of reference sites next to the study site and establishment of a reference fallout inventory for the study site; 2/measurement of the current spatial distribution of 137 Cs inventory; 3/ evaluation of the pattern of 137 Cs redistribution at the study site; 4/ development of a calibration relationship between 137 CS loss and gain and rate of soil erosion; 5/ estimation of soil redistribution rates using the calibration relationship. (PSH)

Estimating the erosion and deposition rates in a small watershed by the 137Cs tracing method

International Nuclear Information System (INIS)

Li Mian; Li Zhanbin; Yao Wenyi; Liu Puling

2009-01-01

Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the 137 Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The 137 Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed

Coastal protection policy in the Netherlands

NARCIS (Netherlands)

Verhagen, H.J.

1990-01-01

The 350 km long Dutch coast along the North Sea is characterized by alternating coastal stretches of accretion and erosion resp. resulting in seaward and landward displacement retreats of the shoreline. Places of accretion and erosion also vary in time. Behind the dunes are low lying polders (very

Determination of Redistribution of Erosion/Deposition Rate in Cultivated Area Using 137Cs Technique

International Nuclear Information System (INIS)

Nita Suhartini; Syamsul Abbas RAS; Barokah A; Ali Arman L

2004-01-01

The aim of the research is to determine the rate of redistribution of erosion/deposition in cultivated area. The application of 137 Cs technique was carried out at cultivated area in Bojong - Ciawi, with slope less than 10 o and slope length of about 2 km. A reference site was selected at the top of the slope, and this site is flat, open and covered with grass. Two sites in the cultivated area were selected as study site namely LU-I ( 15 x 25 ) m with the distance of 1000 m from the top, and LU-II (17.5 x 20) m with the distance of 1300 m from the top. Sampling of soil at reference site was done by using scraper (20 x 50) cm, while sampling at study site by using core sampling (di = 7 cm). Soil samples were brought to the laboratorium for preparation and analysis of 137 Cs content. Preparation are including of drying, weighing the total dry, sieving and crushing. Analysis of 137 Cs content was done using multi channel analyzer (MCA) that connected to high purity germanium (HPGe), at 661 keV, and the minimum counting time of 16 hours. To estimate the erosion/deposit rate, two mathematical model were used, namely Proportional Model (PM) and Mass Balance Model 1 (MBM1). The result for application of 137 Cs technique showed that MBM1 gives somewhat higher value for deposit rate and somewhat lower value for erosion than PM. Land use - I (LU-I) of Bojong - Ciawi was suffering from erosion with the erosion rate from 1 t/(ha.y) to 13 t/(ha.y), and LU-II has deposit rate from 1 t/(ha.y) to 50 t/(ha.y). (author)

CHANGE ANALYSIS ON SOIL EROSION OF FUJIAN PROVINCE FROM 1990 TO 2015

OpenAIRE

X. Q. Wang; S. J. Zeng; X. G. Chen; J. L. Lin; S. M. Chen

2017-01-01

Soil erosion is one of major environment problems in the world, and China is one of the most serious soil erosion country. In this paper, Fujian province was used as a study area for its typical red soil region. Based on USLE model, the soil erosion modulus in 1990 and 2015 were calculated and turned to soil erosion intensity. The soil erosion distribution trend in Fujian province was decrease from south-east coastal zone to north-west inland region. In soil erosion areas, the main e...

Bank erosion of navigation canals in the western and central Gulf of Mexico

Science.gov (United States)

Thatcher, Cindy A.; Hartley, Stephen B.; Wilson, Scott A.

2011-01-01

Erosion of navigation canal banks is a direct cause of land loss, but there has been little quantitative analysis to determine why certain major canals exhibit faster widening rates (indicative of erosion) than others in the coastal zones of Texas, Louisiana, Mississippi, and Alabama. We hypothesize that navigation canals exhibit varying rates of erosion based on soil properties of the embankment substrate, vegetation type, geologic region (derived from digital versions of state geologic maps), and the presence or absence of canal bank armaments (that is, rock rip-rap, concrete bulkheads, or other shoreline protection structures). The first objective of this project was to map the shoreline position and substrate along both banks of the navigation canals, which were digitized from 3 different time periods of aerial photography spanning the years of 1978/79 to 2005/06. The second objective was to quantify the erosion rates of the navigation canals in the study area and to determine whether differences in erosion rates are related to embankment substrate, vegetation type, geologic region, or soil type. To measure changes in shoreline position over time, transects spaced at 50-m (164-ft) intervals were intersected with shorelines from all three time periods, and an annual rate of change was calculated for each transect. Mean annual rates of shoreline change ranged from 1.75 m/year (5.74 ft/year) on the west side of the Atchafalaya River, La., where there was shoreline advancement or canal narrowing, to -3.29 m/year (-10.79 ft/year) on the south side of the Theodore Ship Channel, Ala., where there was shoreline retreat or erosion. Statistical analysis indicated that there were significant differences in shoreline retreat rates according to geologic region and marsh vegetation type, and a weak relationship with soil organic content. This information can be used to better estimate future land loss rates associated with navigation canals and to prioritize the location of

Shipborne LiDAR system for coastal change monitoring

Science.gov (United States)

Kim, chang hwan; Park, chang hong; Kim, hyun wook; hyuck Kim, won; Lee, myoung hoon; Park, hyeon yeong

2016-04-01

Coastal areas, used as human utilization areas like leisure space, medical care, ports and power plants, etc., are regions that are continuously changing and interconnected with oceans and land and the sea level has risen by about 8cm (1.9mm / yr) due to global warming from 1964 year to 2006 year in Korea. Coastal erosion due to sea-level rise has caused the problem of marine ecosystems and loss of tourism resources, etc. Regular monitoring of coastal erosion is essential at key locations with such volatility. But the survey method of land mobile LiDAR (light detection and ranging) system has much time consuming and many restrictions. For effective monitoring beach erosion, KIOST (Korea Institute of Ocean Science & Technology) has constructed a shipborne mobile LiDAR system. The shipborne mobile LiDAR system comprised a land mobile LiDAR (RIEGL LMS-420i), an INS (inertial navigation system, MAGUS Inertial+), a RTKGPS (LEICA GS15 GS25), and a fixed platform. The shipborne mobile LiDAR system is much more effective than a land mobile LiDAR system in the measuring of fore shore areas without shadow zone. Because the vessel with the shipborne mobile LiDAR system is continuously moved along the shoreline, it is possible to efficiently survey a large area in a relatively short time. Effective monitoring of the changes using the constructed shipborne mobile LiDAR system for seriously eroded coastal areas will be able to contribute to coastal erosion management and response.

Rainfall erosivity in subtropical catchments and implications for erosion and particle-bound contaminant transfer: a case-study of the Fukushima region

Science.gov (United States)

Laceby, J. P.; Chartin, C.; Evrard, O.; Onda, Y.; Garcia-Sanchez, L.; Cerdan, O.

2015-07-01

The Fukushima Dai-ichi nuclear power plant (FDNPP) accident in March 2011 resulted in a significant fallout of radiocesium over the Fukushima region. After reaching the soil surface, radiocesium is almost irreversibly bound to fine soil particles. Thereafter, rainfall and snow melt run-off events transfer particle-bound radiocesium downstream. Erosion models, such as the Universal Soil Loss Equation (USLE), depict a proportional relationship between rainfall and soil erosion. As radiocesium is tightly bound to fine soil and sediment particles, characterizing the rainfall regime of the fallout-impacted region is fundamental to modelling and predicting radiocesium migration. Accordingly, monthly and annual rainfall data from ~ 60 meteorological stations within a 100 km radius of the FDNPP were analysed. Monthly rainfall erosivity maps were developed for the Fukushima coastal catchments illustrating the spatial heterogeneity of rainfall erosivity in the region. The mean average rainfall in the Fukushima region was 1387 mm yr-1 (σ 230) with the mean rainfall erosivity being 2785 MJ mm ha-1 yr-1 (σ 1359). The results indicate that the majority of rainfall (60 %) and rainfall erosivity (86 %) occurs between June and October. During the year, rainfall erosivity evolves positively from northwest to southeast in the eastern part of the prefecture, whereas a positive gradient from north to south occurs in July and August, the most erosive months of the year. During the typhoon season, the coastal plain and eastern mountainous areas of the Fukushima prefecture, including a large part of the contamination plume, are most impacted by erosive events. Understanding these rainfall patterns, particularly their spatial and temporal variation, is fundamental to managing soil and particle-bound radiocesium transfers in the Fukushima region. Moreover, understanding the impact of typhoons is important for managing sediment transfers in subtropical regions impacted by cyclonic activity.

Centennial- to millennial-scale hard rock erosion rates deduced from luminescence-depth profiles

NARCIS (Netherlands)

Sohbati, Reza; Liu, Jinfeng; Jain, Mayank; Murray, Andrew; Egholm, David; Paris, Richard; Guralnik, Benny

2018-01-01

The measurement of erosion and weathering rates in different geomorphic settings and over diverse temporal and spatial scales is fundamental to the quantification of rates and patterns of earth surface processes. A knowledge of the rates of these surface processes helps one to decipher their

Linking rapid erosion of the Mekong River delta to human activities.

Science.gov (United States)

Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic 10Be

Science.gov (United States)

Pupim, Fabiano do Nascimento; Bierman, Paul R.; Assine, Mario Luis; Rood, Dylan H.; Silva, Aguinaldo; Merino, Eder Renato

2015-04-01

The importance of Earth's low sloping areas in regard to global erosion and sediment fluxes has been widely and vigorously debated. It is a crucial area of research to elucidate geologically meaningful rates of land-surface change and thus the speed of element cycling on Earth. However, there are large portions of Earth where erosion rates have not been well or extensively measured, for example, the tropical lowlands. The Cuiabana lowlands are an extensive low-altitude and low-relief dissected metamorphic terrain situated in the Upper Paraguay river basin, central-west Brazil. Besides exposures of highly variable dissected metamorphic rocks, flat residual lateritic caps related to a Late Cenozoic planation surface dominate interfluves of the Cuiabana lowlands. The timescale over which the lowlands evolved and the planation surface developed, and the rate at which they have been modified by erosion, are poorly known. Here, we present measurements of in situ produced cosmogenic 10Be in outcropping metamorphic bedrock and clastic-lateritic caps to quantify rates of erosion of the surface and associated landforms in order to better understand the Quaternary landscape evolution of these lowlands. Overall, slow erosion rates (mean 10 m/Ma) suggest a stable tectonic environment in these lowlands. Erosion rates vary widely between different lithologies (range 0.57 to 28.3 m/Ma) consistent with differential erosion driving regional landform evolution. The lowest erosion rates are associated with the low-relief area (irregular plains), where clastic-laterite (mean 0.67 m/Ma) and quartzite (mean 2.6 m/Ma) crop out, whereas the highest erosion rates are associated with dissection of residual hills, dominated by metasandstone (mean 11.6 m/Ma) and phyllite (mean 27.6 m/Ma). These data imply that the Cuiabana lowland is comprised of two dominant landform sets with distinct and different dynamics. Because the planation surface (mostly lowlands) is lowering and losing mass more

Effect of Impact Angle on the Erosion Rate of Coherent Granular Soil, with a Chernozemic Soil as an Example

Science.gov (United States)

Larionov, G. A.; Bushueva, O. G.; Gorobets, A. V.; Dobrovol'skaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Kobylchenko Kuksina, L. V.; Litvin, L. F.; Sudnitsyn, I. I.

2018-02-01

It has been shown in experiments in a hydraulic flume with a knee-shaped bend that the rate of soil erosion more than doubles at the flow impact angles to the channel side from 0° to 50°. At higher channel bends, the experiment could not be performed because of backwater. Results of erosion by water stream approaching the sample surface at angles between 2° and 90° are reported. It has been found that the maximum erosion rate is observed at flow impact angles of about 45°, and the minimum rate at 90°. The minimum soil erosion rate is five times lower than the maximum erosion rate. This is due to the difference in the rate of free water penetration into the upper soil layer, and the impact of the hydrodynamic pressure, which is maximum at the impact angle of 90°. The penetration of water into the interaggregate space results in the breaking of bonds between aggregates, which is the main condition for the capture of particles by the flow.

Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

Directory of Open Access Journals (Sweden)

C. D. O'Dowd

2007-01-01

Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

Evolving Landscapes: the Effect of Genetic Variation on Salt Marsh Erosion

Science.gov (United States)

Bernik, B. M.; Blum, M. J.

2014-12-01

Ecogeomorphic studies have demonstrated that biota can exert influence over geomorphic processes, such as sediment transport, which in turn have biotic consequences and generate complex feedbacks. However, little attention has been paid to the potential for feedback to arise from evolutionary processes as population genetic composition changes in response to changing physical landscapes. In coastal ecosystems experiencing land loss, for example, shoreline erosion entails reduced plant survival and reproduction, and thereby represents a geomorphic response with inherent consequences for evolutionary fitness. To get at this topic, we examined the effect of genetic variation in the saltmarsh grass Spartina alterniflora, a renowned ecosystem engineer, on rates of shoreline erosion. Field transplantation studies and controlled greenhouse experiments were conducted to compare different genotypes from both wild and cultivated populations. Plant traits, soil properties, accretion/subsidence, and rates of land loss were measured. We found significant differences in rates of erosion between field plots occupied by different genotypes. Differences in erosion corresponded to variation in soil properties including critical shear stress and subsidence. Plant traits that differed across genotypes included belowground biomass, root tensile strength, and C:N ratios. Our results demonstrate the importance of genetic variation to salt marsh functioning, elucidating the relationship between evolutionary processes and ecogeomorphic dynamics in these systems. Because evolutionary processes can occur on ecological timescales, the direction and strength of ecogeomorphic feedbacks may be more dynamic than previously accounted for.

An index-based method to assess risks of climate-related hazards in coastal zones: The case of Tetouan

Science.gov (United States)

Satta, Alessio; Snoussi, Maria; Puddu, Manuela; Flayou, Latifa; Hout, Radouane

2016-06-01

The regional risk assessment carried out within the ClimVar & ICZM Project identified the coastal zone of Tetouan as a hotspot of the Mediterranean Moroccan coast and so it was chosen for the application of the Multi-Scale Coastal Risk Index for Local Scale (CRI-LS). The local scale approach provides a useful tool for local coastal planning and management by exploring the effects and the extensions of the hazards and combining hazard, vulnerability and exposure variables in order to identify areas where the risk is relatively high. The coast of Tetouan is one of the coastal areas that have been most rapidly and densely urbanized in Morocco and it is characterized by an erosive shoreline. Local authorities are facing the complex task of balancing development and managing coastal risks, especially coastal erosion and flooding, and then be prepared to the unavoidable impacts of climate change. The first phase of the application of the CRI-LS methodology to Tetouan consisted of defining the coastal hazard zone, which results from the overlaying of the erosion hazard zone and the flooding hazard zone. Nineteen variables were chosen to describe the Hazards, Vulnerability and Exposure factors. The scores corresponding to each variable were calculated and the weights assigned through an expert judgement elicitation. The resulting values are hosted in a geographic information system (GIS) platform that enables the individual variables and aggregated risk scores to be color-coded and mapped across the coastal hazard zone. The results indicated that 10% and 27% of investigated littoral fall under respectively very high and high vulnerability because of combination of high erosion rates with high capital land use. The risk map showed that some areas, especially the flood plains of Restinga, Smir and Martil-Alila, with distances over 5 km from the coast, are characterized by high levels of risk due to the low topography of the flood plains and to the high values of exposure

Constraining Quaternary ice covers and erosion rates using cosmogenic 26Al/10Be nuclide concentrations

Science.gov (United States)

Knudsen, Mads Faurschou; Egholm, David Lundbek

2018-02-01

Paired cosmogenic nuclides are often used to constrain the exposure/burial history of landforms repeatedly covered by ice during the Quaternary, including tors, high-elevation surfaces, and steep alpine summits in the circum-Arctic regions. The approach generally exploits the different production rates and half-lives of 10Be and 26Al to infer past exposure/burial histories. However, the two-stage minimum-limiting exposure and burial model regularly used to interpret the nuclides ignores the effect of variable erosion rates, which potentially may bias the interpretation. In this study, we use a Monte Carlo model approach to investigate systematically how the exposure/burial and erosion history, including variable erosion and the timing of erosion events, influence concentrations of 10Be and 26Al. The results show that low 26Al/10Be ratios are not uniquely associated with prolonged burial under ice, but may as well reflect ice covers that were limited to the coldest part of the late Pleistocene combined with recent exhumation of the sample, e.g. due to glacial plucking during the last glacial period. As an example, we simulate published 26Al/10Be data from Svalbard and show that it is possible that the steep alpine summits experienced ice-free conditions during large parts of the late Pleistocene and varying amounts of glacial erosion. This scenario, which contrasts with the original interpretation of more-or-less continuous burial under non-erosive ice over the last ∼1 Myr, thus challenge the conventional interpretation of such data. On the other hand, high 26Al/10Be ratios do not necessarily reflect limited burial under ice, which is the common interpretation of high ratios. In fact, high 26Al/10Be ratios may also reflect extensive burial under ice, combined with a change from burial under erosive ice, which brought the sample close to the surface, to burial under non-erosive ice at some point during the mid-Pleistocene. Importantly, by allowing for variable

Predicting severe winter coastal storm damage

International Nuclear Information System (INIS)

Hondula, David M; Dolan, Robert

2010-01-01

Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'-such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989-are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the losses along the North

Predicting severe winter coastal storm damage

Energy Technology Data Exchange (ETDEWEB)

Hondula, David M; Dolan, Robert, E-mail: hondula@virginia.edu [Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22903 (United States)

2010-07-15

Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'-such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989-are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the

Predicting severe winter coastal storm damage

Science.gov (United States)

Hondula, David M.; Dolan, Robert

2010-07-01

Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'—such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989—are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the losses along the

A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

Science.gov (United States)

Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

2016-01-01

Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

Science.gov (United States)

Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

2016-01-05

Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

Estimating the erosion and deposition rates in a small watershed by the {sup 137}Cs tracing method

Energy Technology Data Exchange (ETDEWEB)

Li Mian [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)], E-mail: hnli-mian@163.com; Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China)

2009-02-15

Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the {sup 137}Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The {sup 137}Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed.

Thresholds of sea-level rise rate and sea-level acceleration rate in a vulnerable coastal wetland

Science.gov (United States)

Wu, W.; Biber, P.; Bethel, M.

2017-12-01

Feedback among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold help address the key challenge in ecology - nonlinear response of ecosystems to environmental change, and promote communication between ecologists and policy makers. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to the enhanced anthropogenic forces. We developed a mechanistic model to simulate wetland change and derived the SLR thresholds for Grand Bay, MS, a micro-tidal estuary with limited upland freshwater and sediment input in the northern Gulf of Mexico. The new SLR acceleration rate threshold complements the threshold of SLR rate and can help explain the temporal lag before the rapid decline of wetland area becomes evident after the SLR rate threshold is exceeded. Deriving these two thresholds depends on the temporal scale, the interaction of SLR with other environmental factors, and landscape metrics, which have not been fully accounted for before this study. The derived SLR rate thresholds range from 7.3 mm/yr to 11.9 mm/yr. The thresholds of SLR acceleration rate are 3.02×10-4 m/yr2 and 9.62×10-5 m/yr2 for 2050 and 2100 respectively. Based on the thresholds developed, predicted SLR that will adversely impact the coastal wetlands in Grand Bay by 2100 will fall within the likely range of SLR under a high warming scenario (RCP8.5), and beyond the very likely range under a low warming scenario (RCP2.6 or 3), highlighting the need to avoid the high warming scenario in the future if these marshes are to be preserved.

Satellite observation of bio-optical indicators related to North-Western Black Sea coastal zone changes

Science.gov (United States)

Zoran, Maria

Satellite remote sensing provides a means for locating, identifying and mapping certain coastal zone features and assessing of spatio-temporal changes.The Romanian coastal zone of the Black Sea is a mosaic of complex, interacting ecosystems, exposed to dramatic changes due to natural and anthropogenic causes (increase in the nutrient and pollutant load of rivers input, industrial and municipal wastewater pollution along the coast, and dumping on the open sea). This study focuses on the assessment of coastal zone land cover changes based on the fusion of satellite remote sensing data.The evaluation of coastal zone landscapes is based upon different sub-functions which refer to landscape features such as water, soil, land-use, buildings, groundwater, biotope types. Mixed pixels result when the sensor's instantaneous field-of-view includes more than one land cover class on the ground. Based on different satellite data (Landsat TM, ETM, SAR ERS, IKONOS, Quickbird, and MODIS) was performed object recognition for North-Western Black Sea coastal zone. Preliminary results show significant coastline position changes of North Western Black Sea during the period of 1987-2007 and urban growth of Constantza town. Also the change in the position of the coastline is examined and linked to the urban expansion in order to determine if the changes are natural or anthropogenic. A distinction is made between landfill/sedimentation processes on the one hand and dredging/erosion processes on the other. Waves play an important role for shoreline configuration. Wave pattern could induce erosion and sedimentation. A quasi-linear model was used to model the rate of shoreline change. The vectors of shoreline were used to compare with wave spectra model in order to examine the accuracy of the coastal erosion model. The shoreline rate modeled from vectors data of SAR ERS-1 has a good correlation with a quasi-linear model. Wave refraction patterns are a good index for shoreline erosion. A coast

Nutrient and Organic Carbon Losses, Enrichment Rate, and Cost of Water Erosion

Directory of Open Access Journals (Sweden)

Ildegardis Bertol

Full Text Available ABSTRACT Soil erosion from water causes loss of nutrients and organic carbon, enriches the environment outside the erosion site, and results in costs. The no-tillage system generates increased nutrient and C content in the topsoil and, although it controls erosion, it can produce a more enriched runoff than in the conventional tillage system. This study was conducted in a Humic Cambisol in natural rainfall from 1997 to 2012 to quantify the contents and total losses of nutrients and organic C in soil runoff, and to calculate the enrichment rates and the cost of these losses. The treatments evaluated were: a soil with a crop, consisting of conventional tillage with one plowing + two harrowings (CT, minimum tillage with one chisel plowing + one harrowing (MT, and no tillage (NT; and b bare soil: one plowing + two harrowings (BS. In CT, MT, and NT, black oat, soybean, vetch, corn, turnip, and black beans were cultivated. Over the 15 years, 15.5 Mg ha-1 of limestone, 525 kg ha-1 of N (urea, 1,302 kg ha-1 of P2O5 (triple superphosphate, and 1,075 kg ha-1 of K2O (potassium chloride were used in the soil. The P, K, Ca, Mg, and organic C contents in the soil were determined and also the P, K, Ca, and Mg sediments in the runoff water. From these contents, the total losses, the enrichment rates (ER, and financial losses were calculated. The NT increased the P, K, and organic C contents in the topsoil. The nutrients and organic C content in the runoff from NT was greater than from CT, showing that NT was not a fully conservationist practice for soil. The linear model y = a + bx fit the data within the level of significance (p≤0.01 when the values of P, K, and organic C in the sediments from erosion were related to those values in the soil surface layer. The nutrient and organic C contents were higher in the sediments from erosion than in the soil where the erosion originated, generating values of ER>1 for P, K, and organic C. The value of the total losses

Developing an Erosion Rate Map for Myanmar Using USLE, GIS and Remote Sensing

Science.gov (United States)

Emtehani, Sobhan; Rutten, Martine

2017-04-01

Predicting erosion and estimating sediment loads in rivers are of major tasks in water resources system planning and management. In Myanmar erosion and collapse of river banks is common during the rainy season and riverine communities are frequently forced to relocate as their homes are dangerously close to the disintegrating river banks (Mann 2013). Myanmar is one of climatically most diverse countries located in Southeast Asia, where sheet, rill, and gully erosion affect crop yields as well as livelihood strategies of many people (Htwe, Brinkmann et al. 2015). In Myanmar, soil erosion measurement and monitoring approaches are increasingly important for land management planning to effectively avoid erosion and soil degradation, but such monitoring is limited by the availability of data and budgetary constraints. Therefore, spatial modeling approaches using GIS and remote sensing techniques play an important role for rapid risk assessments (Htwe 2016). In this study ''Model Builder'' tool in ArcGIS was used to create a model which generates an erosion rate map using Universal Soil Loss Equation (USLE). USLE is the product of five factors: rainfall erosivity factor (R), soil erodibility factor (K), slope length and steepness factor (LS), crop management factor (C), and support practice factor (P). Input data files for this model were acquired from online open source databases. Precipitation data was downloaded from Tropical Rainfall Measuring Mission (TRMM) for calculation of R factor. The resolution of TRMM data is very coarse (0.25 degree × 0.25 degree), therefore it was spatially downscaled by developing a relation between TRMM and Normalized Difference Vegetation Index (NDVI) using regression analysis method. Soil maps depicting percentages of sand, clay and silt were obtained from soilgrids website for calculation of K factor. Digital Elevation Model (DEM) with resolution of 90 meters was taken from Shuttle Radar Topography Mission (SRTM) for calculation of LS

Automatic Detection of Decadal Shoreline Change on Northern Coastal of Gresik, East Java - Indonesia

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Fuad, M. A. Z.; A, M. Fais D.

2017-12-01

The Coastal zone is a dynamic region that has high environmental and economic values. This present research focuses on the analyzing the rate of shoreline change using multi-temporal Landsat Imagery and Digital Shoreline Analysis Systems (DSAS) along the northern part of Gresik coastal area, East Java Indonesia. Five village were selected for analysis; Campurejo, Dalegan, Prupuh, Ngemboh, and Banyuurip. Erosion and Accretion were observed and detected on Multi-temporal satellite Images along the area of interest from 1972 - 2016. Landsat Images were radiometrically and geometrically corrected before using for analysis. Coastline delineation for each Landsat image was performed by MNDWI method before digitized for quantitative shoreline change analysis. DSAS was performed for quantitative analysis of Net Shoreline Movement (NSM) and End Point Rate (EPR). The results indicate that in the study area accretion and abrasion was occurred, but overall abrasion was dominated than accretion. The remarkable shoreline changes were observed in the entire region. The highest abrasion area was occurred in Ngemboh village. From 1972 to 2016, coastline was retreat 242.56 meter to the land and the rate of movement was -5.54m/yr. In contrast, Campurejo area was relatively stable due to the introduction of manmade structure, i.e. Jetty and Groin. The Shoreline movement and the rate of movement in this area were -6.11m and -0.12 m/yr respectively. The research represents an important step in understanding the dynamics of coastal area in this area. By identification and analysis of coastline evolution, the stake holder could perform a scenario for reducing the risk of coastal erosion and minimize the social and economic lost.

Holocene Evolution of Incised Coastal Channels on the Isle of Wight, UK: Interpretation via Numerical Simulation.

Science.gov (United States)

Leyland, J.; Darby, S. E.

2006-12-01

Incised coastal channels are found in numerous locations around the world where the shoreline morphology consists of cliffs. The incised coastal channels found on the Isle of Wight, UK, are known locally as `Chines' and debouche (up to 45m) through the soft cliffs of the south west coast, maintaining steep side walls subject to deep-seated mass wasting. These canyons offer sheltered locations and bare substrate, providing habitat for plant (Philonotis marchica, Anthoceros punctatos) and invertebrate (Psen atratinus, Baris analis, Melitaea cinxi) species of international importance. The base level of the Chines is highly dynamic, with episodes of sea cliff erosion causing the rejuvenation of the channel network. Consequently a key factor in Chine evolution is the relative balance between rates of cliff retreat and headwards incision caused by knickpoint migration. Specifically, there is concern that if contemporary coastal retreat rates are higher than the corresponding rates of knickpoint recession, there will be long-term a reduction in the overall extent of the Chines and their associated habitats. In an attempt to provide a long-term context for these issues, in this poster we explore the Holocene erosional history of the Chines using a numerical landscape evolution model. The model includes a stochastic cliff recession function that controls the position of the outlet boundary. Knickpoint recession rates are simulated using a detachment-limited channel erosion law wherein erosion rate is a power function of drainage area and stream gradient with model parameters defined using empirically- derived data. Simulations are undertaken for a range of imposed boundary conditions representing different scenarios of long-term cliff retreat forced by Holocene sea-level rise, plausible scenarios corresponding to cases where simulated and observed Chine and landscape forms match. The study provides an example of how a landscape evolution model could be used to reconstruct

Simulating CRN derived erosion rates in a transient Andean catchment using the TTLEM model

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Campforts, Benjamin; Vanacker, Veerle; Herman, Frédéric; Schwanghart, Wolfgang; Tenrorio Poma, Gustavo; Govers, Gerard

2017-04-01

Assessing the impact of mountain building and erosion on the earth surface is key to reconstruct and predict terrestrial landscape evolution. Landscape evolution models (LEMs) are an essential tool in this research effort as they allow to integrate our growing understanding of physical processes governing erosion and transport of mass across the surface. The recent development of several LEMs opens up new areas of research in landscape evolution. Here, we want to seize this opportunity by answering a fundamental research question: does a model designed to simulate landscape evolution over geological timescales allows to simulate spatially varying erosion rates at a millennial timescale? We selected the highly transient Paute catchment in the Southeastern Ecuadorian Andes as a study area. We found that our model (TTLEM) is capable to better explain the spatial patterns of ca. 30 Cosmogenic Radio Nuclide (CRN) derived catchment wide erosion rates in comparison to a classical, statistical approach. Thus, the use of process-based landscape evolution models may not only be of great help to understand long-term landscape evolution but also in understanding spatial and temporal variations in sediment fluxes at the millennial time scale.

Economic and social demands for coastal protection

NARCIS (Netherlands)

Polome, Philippe; Marzetti, S.; van der Veen, A.

2005-01-01

The purpose of this paper is to present methods and examples of economic valuation in the framework of cost–benefit analysis of coastal defense schemes. We summarize the concepts of value in economics and their application to coastal erosion defense. We describe the results of an original benefit

Geophysical monitoring of coastal erosion and cliff retreat of ...

African Journals Online (AJOL)

Monitoring of the coastal zone is necessary to assess its vulnerability and help formulate coastal management plans. A predetermined stretch of beach along the northern rim of False Bay known locally as Monwabisi Beach was chosen to compare different monitoring techniques and from the data acquired, see if accurate ...

Assessment of Damage and Adaptation Strategies for Structures and Infrastructure from Storm Surge and Sea Level Rise for a Coastal Community in Rhode Island, United States

Directory of Open Access Journals (Sweden)

Christopher Small

2016-10-01

Full Text Available This paper presents an evaluation of inundation, erosion, and wave damage for a coastal community in Rhode Island, USA. A methodology called the Coastal Environmental Risk Index (CERI was used that incorporates levels of inundation including sea level rise, wave heights using STWAVE, and detailed information about individual structures from an E911 database. This information was input into damage functions developed by the U.S. Army Corps of Engineers following Hurricane Sandy. Damage from erosion was evaluated separately from local published erosion rates. Using CERI, two different adaptation strategies were evaluated that included a combination of dune restoration, protective berms, and a tide gate. A total of 151 out of 708 structures were estimated to be protected from inundation and wave action by the combined measures. More importantly, the use of CERI allowed for the assessment of the impact of different adaptation strategies on both individual structures and an entire community in a Geographical Information Systems (GIS environment. This tool shows promise for use by coastal managers to assess damage and mitigate risk to coastal communities.

Erosion-corrosion synergistics in the low erosion regime

International Nuclear Information System (INIS)

Corey, R.G.; Sethi, V.K.

1986-01-01

Many engineering alloys display good high temperature corrosion resistance. However, when they are used in corrosive environments where they are subjected to erosion also, the corrosion resistance has been adversely affected. The phenomenon known as erosion-corrosion is complex and requires detailed investigation of how the erosion and corrosion kinetics interact and compete. At the Kentucky Center for Energy Research Laboratory, an erosion-corrosion tester was used to perform erosion-oxidation tests on 2 1/4 Cr-1 Mo steel at 500-600 0 C using alumina abrasive at low velocities. The erosion-oxidation rate data and morphology of exposed surfaces are consistent with oxide chipping and fracturing being the mode of material loss

Impacts of the post-fire erosion processes compared with the agricultural erosion rates for a mountain catchment in NW Iberia

Science.gov (United States)

Marisa Santos, Juliana; Nunes, João Pedro; Bernard-Jannin, Léonard; Gonzalez Pelayo, Oscar; Keizer, Jan Jacob

2014-05-01

after forest fires. The last forest fire in August 2011 burned 10% of the total area in the north-west part of the catchment. Post-fire management operations 9 month after the fire (clear-cutting and deep plowing operations) and after plantation of "Quercus robur" left the soil exposed, and relatively mild rainstorms led to large amounts of soil loss, including a large amount of rills and other erosion features. This constituted an opportunity to compare these erosion rates with the ones observed in agricultural fields for similar edapho-climatic conditions, and also observe distinct timing of erosion occurrence which was linked with different periods when soils are exposed. This communication presents the assessment of the impact of this fire on soil erosion rates, where results indicate that soil losses after soil preparation for forest replanting might be equivalent, in long-term, to soil losses in agricultural fields.

Numerical simulation of mud erosion rate in sand-mud alternate layer and comparison with experiment

Science.gov (United States)

Yoshida, T.; Yamaguchi, T.; Oyama, H.; Sato, T.

2015-12-01

For gas production from methane hydrates in sand-mud alternate layers, depressurization method is expected as feasible. After methane hydrate is dissociated, gas and water flow in pore space. There is a concern about the erosion of mud surface and it may result in flow blockage that disturbs the gas production. As a part of a Japanese National hydrate research program (MH21, funded by METI), we developed a numerical simulation of water-induced mud erosion in pore-scale sand-mud domains to model such mud erosion. The size of which is of the order of 100 micro meter. Water flow is simulated using a lattice Boltzmann method (LBM) and mud surface is treated as solid boundary with arbitrary shape, which changes with time. Periodic boundary condition is adopted at the domain boundaries, except for the surface of mud layers and the upper side. Shear stress acting on the mud surface is calculated using a momentum-exchange method. Mud layer is eroded when the shear stress exceeds a threshold coined a critical shear stress. In this study, we compared the simulated mud erosion rate with experimental data acquired from an experiment using artificial sand-mud core. As a result, the simulated erosion rate agrees well with that of the experiment.

Estimation of water erosion rates using RUSLE3D in Alicante province (Spain)

OpenAIRE

Garcia Rodríguez, Jose Luis; Giménez Suárez, Martín Cruz; Arraiza Bermudez-Cañete, Maria Paz

2015-01-01

The purpose of this study was the estimation of current and potential water erosion rates in Alicante Province using RUSLE3D (Revised Universal Soil Loss Equation-3D) model with Geographical Information System (GIS) support by request from the Valencia Waste Energy Use. RUSLE3D uses a new methodology for topographic factor estimation (LS factor) based on the impact of flow convergence allowing better assessment of sediment distribution detached by water erosion. In RUSLE3D equation, the effec...

Drivers of coastal shoreline change: case study of hon dat coast, Kien Giang, Vietnam.

Science.gov (United States)

Nguyen, Hai-Hoa; McAlpine, Clive; Pullar, David; Leisz, Stephen Joseph; Galina, Gramotnev

2015-05-01

Coastal shorelines are naturally dynamic, shifting in response to coastal geomorphological processes. Globally, land use change associated with coastal urban development and growing human population pressures is accelerating coastal shoreline change. In southern Vietnam, coastal erosion currently is posing considerable risks to shoreline land use and coastal inhabitants. The aim of this paper is to quantify historical shoreline changes along the Hon Dat coast between 1995 and 2009, and to document the relationships between coastal mangrove composition, width and density, and rates of shoreline change. The generalized linear mixed-effects models were used to quantify the major biophysical and land-use factors influencing shoreline change rates. Most significant drivers of the rates of change are cutting of mangroves, the dominant mangrove genus, changes in adjacent shoreline land use, changes of shoreline land cover, and width of fringing mangroves. We suggest that a possible and inexpensive strategy for robust mangrove shoreline defense is direct mangrove planting to promote mangrove density with the presence of breakwater structures. In the shorter term, construction of coastal barriers such as fence-structured melaleuca poles in combination with mangrove restoration schemes could help retain coastal sediments and increase the elevation of the accretion zone, thereby helping to stabilize eroding fringe shorelines. It also is recommended that implementation of a system of payments for mangrove ecosystem services and the stronger regulation of mangrove cutting and unsustainable land-use change to strengthen the effectiveness of mangrove conservation programs and coastal land-use management.

Drivers of Coastal Shoreline Change: Case Study of Hon Dat Coast, Kien Giang, Vietnam

Science.gov (United States)

Nguyen, Hai-Hoa; McAlpine, Clive; Pullar, David; Leisz, Stephen Joseph; Galina, Gramotnev

2015-05-01

Coastal shorelines are naturally dynamic, shifting in response to coastal geomorphological processes. Globally, land use change associated with coastal urban development and growing human population pressures is accelerating coastal shoreline change. In southern Vietnam, coastal erosion currently is posing considerable risks to shoreline land use and coastal inhabitants. The aim of this paper is to quantify historical shoreline changes along the Hon Dat coast between 1995 and 2009, and to document the relationships between coastal mangrove composition, width and density, and rates of shoreline change. The generalized linear mixed-effects models were used to quantify the major biophysical and land-use factors influencing shoreline change rates. Most significant drivers of the rates of change are cutting of mangroves, the dominant mangrove genus, changes in adjacent shoreline land use, changes of shoreline land cover, and width of fringing mangroves. We suggest that a possible and inexpensive strategy for robust mangrove shoreline defense is direct mangrove planting to promote mangrove density with the presence of breakwater structures. In the shorter term, construction of coastal barriers such as fence-structured melaleuca poles in combination with mangrove restoration schemes could help retain coastal sediments and increase the elevation of the accretion zone, thereby helping to stabilize eroding fringe shorelines. It also is recommended that implementation of a system of payments for mangrove ecosystem services and the stronger regulation of mangrove cutting and unsustainable land-use change to strengthen the effectiveness of mangrove conservation programs and coastal land-use management.

Understanding erosion rates in the Himalayan orogen: A case study from the Arun Valley

Science.gov (United States)

Olen, Stephanie M.; Bookhagen, Bodo; Hoffmann, Bernd; Sachse, Dirk; Adhikari, D. P.; Strecker, Manfred R.

2015-10-01

Understanding the rates and pattern of erosion is a key aspect of deciphering the impacts of climate and tectonics on landscape evolution. Denudation rates derived from terrestrial cosmogenic nuclides (TCNs) are commonly used to quantify erosion and bridge tectonic (Myr) and climatic (up to several kiloyears) time scales. However, how the processes of erosion in active orogens are ultimately reflected in 10Be TCN samples remains a topic of discussion. We investigate this problem in the Arun Valley of eastern Nepal with 34 new 10Be-derived catchment-mean denudation rates. The Arun Valley is characterized by steep north-south gradients in topography and climate. Locally, denudation rates increase northward, from <0.2 mm yr-1 to ~1.5 mm yr-1 in tributary samples, while main stem samples appear to increase downstream from ~0.2 mm yr-1 at the border with Tibet to 0.91 mm yr-1 in the foreland. Denudation rates most strongly correlate with normalized channel steepness (R2 = 0.67), which has been commonly interpreted to indicate tectonic activity. Significant downstream decrease of 10Be concentration in the main stem Arun suggests that upstream sediment grains are fining to the point that they are operationally excluded from the processed sample. This results in 10Be concentrations and denudation rates that do not uniformly represent the upstream catchment area. We observe strong impacts on 10Be concentrations from local, nonfluvial geomorphic processes, such as glaciation and landsliding coinciding with areas of peak rainfall rates, pointing toward climatic modulation of predominantly tectonically driven denudation rates.

Influence of liquid temperature and flow rate on enamel erosion and surface softening.

Science.gov (United States)

Eisenburger, M; Addy, M

2003-11-01

Enamel erosion and softening are based on chemical processes which could be influenced by many factors including temperature and acid flow rate. Knowledge of the influence of these variables could have relevance to research experiments and clinical outcomes. Both parameters were investigated using an ultrasonication and profilometry method to assess erosion depth and surface softening of enamel. The influence of temperature was studied by eroding polished human enamel samples at 4, 20, 35 or 50 degrees C for 2 h. Secondly, different liquid flow conditions were established by varying acid agitation. Additionally, a slow laminar flow and a jet of citric acid, to simulate drinking through a straw, were applied to specimens. Erosion depth increased significantly with acid temperature from 11.0 microm at 4 degrees C to 35.8 microm at 50 degrees C. Surface softening increased much more slowly and plateaued at 2.9 microm to 3.5 microm after 35 degrees C. A strong dependence of erosion on liquid flow was revealed. In unstirred conditions only 8.6 microm erosion occurred, which increased to 22.2 microm with slow stirring and 40.9 microm with fast stirring. Surface softening did not increase correspondingly with its largest extent at slow stirring at 3.4 microm.The implication of these data are: first, the conditions for erosion experiments in vitro or in situ need to be specified for reliable comparisons between studies. Secondly, erosion of teeth by soft drinks are likely to be influenced both by the temperature of the drink and individual drinking habits.

Ultrasonic Measurement of Erosion/corrosion Rates in Industrial Piping Systems

Science.gov (United States)

Sinclair, A. N.; Safavi, V.; Honarvar, F.

2011-06-01

Industrial piping systems that carry aggressive corrosion or erosion agents may suffer from a gradual wall thickness reduction that eventually threatens pipe integrity. Thinning rates could be estimated from the very small change in wall thickness values measured by conventional ultrasound over a time span of at least a few months. However, measurements performed over shorter time spans would yield no useful information—minor signal distortions originating from grain noise and ultrasonic equipment imperfections prevent a meaningful estimate of the minuscule reduction in echo travel time. Using a Model-Based Estimation (MBE) technique, a signal processing scheme has been developed that enables the echo signals from the pipe wall to be separated from the noise. This was implemented in a laboratory experimental program, featuring accelerated erosion/corrosion on the inner wall of a test pipe. The result was a reduction in the uncertainty in the wall thinning rate by a factor of four. This improvement enables a more rapid response by system operators to a change in plant conditions that could pose a pipe integrity problem. It also enables a rapid evaluation of the effectiveness of new corrosion inhibiting agents under plant operating conditions.

Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

Science.gov (United States)

Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.

2009-12-01

In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy

Organic carbon sedimentation rates in Asian mangrove coastal ecosystems estimated by 210PB chronology

International Nuclear Information System (INIS)

Tateda, Y.; Wattayakorn, G.; Nhan, D.D.; Kasuya, Y.

2004-01-01

Organic carbon balance estimation of mangrove coastal ecosystem is important for understanding of Asian coastal carbon budget/flux calculation in global carbon cycle modelling which is powerful tool for the prediction of future greenhouse gas effect and evaluation of countermeasure preference. Especially, the organic carbon accumulation rate in mangrove ecosystem was reported to be important sink of carbon as well as that in boreal peat accumulation. For the estimation of 10 3 years scale organic carbon accumulation rates in mangrove coastal ecosystems, 14 C was used as long term chronological tracer, being useful in pristine mangrove forest reserve area. While in case of mangrove plantation of in coastal area, the 210 Pb is suitable for the estimation of decades scale estimation by its half-life. Though it has possibility of bio-/physical- turbation effect in applying 210 Pb chronology that is offset in case of 10 3 years scale estimation, especially in Asian mangrove ecosystem where the anthropogenic physical turbation by coastal fishery is vigorous.In this paper, we studied the organic carbon and 210 Pb accumulation rates in subtropical mangrove coastal ecosystems in Japan, Vietnam and Thailand with 7 Be analyses to make sure the negligible effect of above turbation effects on organic carbon accumulation. We finally concluded that 210 Pb was applicable to estimate organic carbon accumulation rates in these ecosystems even though the physical-/bio-turbation is expected. The measured organic carbon accumulation rates using 210 Pb in mangrove coastal ecosystems of Japan, Vietnam and Thailand were 0.067 4.0 t-C ha -1 y -1 . (author)

Bangladesh’s dynamic coastal regions and sea-level rise

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Hugh Brammer

2014-01-01

Full Text Available The physical geography of Bangladesh’s coastal area is more diverse and dynamic than is generally recognised. Failure to recognise this has led to serious misconceptions about the potential impacts of a rising sea-level on Bangladesh with global warming. This situation has been aggravated by accounts giving incorrect information on current rates of coastal erosion and land subsidence. This paper describes physical conditions within individual physiographic regions in Bangladesh’s coastal area based on ground-surveyed information, and it reviews possible area-specific mitigation measures to counter predicted rates of sea-level rise in the 21st century. Two important conclusions are drawn: the adoption of appropriate measures based on knowledge of the physical geography of potentially-affected areas could significantly reduce the currently-predicted displacement of many millions of people; and the impacts of a slowly-rising sea-level are currently much less than those generated by rapidly increasing population pressure on Bangladesh’s available land and water resources and by exposure to existing environmental hazards, and the latter problems need priority attention.

Modeling erosion of unsaturated compacted bentonite by groundwater flow; pinhole erosion test case

International Nuclear Information System (INIS)

Laurila, T.; Sane, P.; Olin, M.; Koskinen, K.

2012-01-01

swelling rate to erosion rate. Expressing eroded mass as a function of time as M(t) ∝ tβ. we note that for non-swelling material the wall shear -based erosion model gives β = 0,5. We find this limit in our model by suppressing swelling, and we observe that β increases when ratio of swelling to erosion increases, approaching values β ≅ 1 for strong swelling. It follows that the long term erosion of backfill and buffer materials are expected to differ, with erosion rates in the more compact buffer dropping slower. The result also suggests that the lower the initial erosion, the longer one can expect that rate to be maintained. We solve the model in cylindrically symmetric coordinates using COMSOL Multiphysics software, and fit parameters to match pinhole experiments on MX-80 bentonite with different salinities of the water inflow. Significant scatter within the experimental data makes it difficult to definitively validate models. Figure 1 shows erosion behavior in the model at the limit of vanishing swelling, and contrasts it to the highly-swelling case. Observations from the pinhole experiments, as well as from down-scaled piping erosion tests, show that erosion rates in buffer material don't drop significantly in time, suggesting a consistent with high swelling. In the larger piping erosion tests a seemingly steady state in the erosion rate is reached for an extended amount of time. The effects of scatter are reduced using statistical analysis of this state. An important experimental finding of unsaturated erosion is that larger salinities lead to larger erosion rates, in contrast to saturated erosion where the opposite has been observed. We expect this effect to be due to the processes of saturation, suction and permeability. Future work aims to model the dominant processes in this effect, as pertains to Posiva reference conditions for the Olkiluoto site, without going to the full complexity of (T)HM modeling, such as the Barcelona expansible model

Quantifying Soil Erosion and Deposition Rates in Tea Plantation Area, Cameron Highlands, Malaysia Using 137Cs

International Nuclear Information System (INIS)

Zaini Hamzah; Che Yasmin Amirudin; Ahmad Saat; Ahmad Saat; Ab Khalik Wood

2014-01-01

The soil erosion and deposition in the hilly area is a great concern for the planters. In this study, the tea plantation was chosen to quantify the rates of soil erosion and deposition for it will provide information on the improvement of soil conditions and cost reduction of fertilizer consumption. The aims of this research are to determine the rate of soil erosion and deposition using environmental radionuclide, 137 Cs. Soil profile samples were collected by using scrapper plate and two cores soil sample were collected in the undisturbed forests area nearby. The 137 Cs activity concentration was measured using low background coaxial hyper pure germanium detector gamma spectrometer based on 137 Cs gamma energy peak at 661.66 keV. The highest erosion rate using Proportional Models and Mass Balance Model 1 was found in point HE top area which is 52.39 t ha -1 yr -1 and 95.53 t ha -1 yr -1 respectively while the lowest at location HF top which is 4.78 t ha -1 yr -1 and 4.97 t ha -1 yr -1 . The deposition rate was higher in HF center which is 216.82 t ha -1 yr -1 and 97.51 t ha -1 yr -1 and the lowest at HE center which is 0.05 t ha -1 yr -1 for both models used. (author)

Erosion and its rate on an accumulative Polish dune coast: the effects of the January 2012 storm surge

OpenAIRE

Łabuz, Tomasz A.

2014-01-01

The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves at...

The Influence of Cultivation System on Distribution Profile Of 137cs and Erosion / Deposition Rate

Directory of Open Access Journals (Sweden)

Nita Suhartini

2016-05-01

Full Text Available 137Cs radiogenic content in the soil can be used to estimate the rate of erosion and deposition in an area occurring since 1950’s, by comparing the content of the 137Cs in observed site with those in a stable reference site. This experiment aimed to investigate the influence of cultivation type on distribution profile of 137Cs and distribution of erosion and deposition rate in cultivated area. A study site was small cultivated area with slope steepness <10o and length 2 km located in Bojong – Ciawi. For this purpose, the top of a slope was chosen for reference site and three plot sites were selected namely Land Use I that using simple cultivation, Land Use II that using simple cultivation with ridge and furrow, and Land Use III using machine cultivation. The results showed that cultivation could make a movement of 137Cs to the deeper layer and ridges and furrows cultivation system could minimized an erosion process. The net erosion and deposition for land Use I, II and III were -25 t/ha/yr , 24 t/ha/yr and -58 t/ha/yr, respectively.

Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex

International Nuclear Information System (INIS)

Benmansour, M.; Mabit, L.; Nouira, A.; Moussadek, R.; Bouksirate, H.; Duchemin, M.; Benkdad, A.

2013-01-01

In Morocco land degradation – mainly caused by soil erosion – is one of the most serious agroenvironmental threats encountered. However, only limited data are available on the actual magnitude of soil erosion. The study site investigated was an agricultural field located in Marchouch (6°42′ W, 33° 47′ N) at 68 km south east from Rabat. This work demonstrates the potential of the combined use of 137 Cs, 210 Pb ex as radioisotopic soil tracers to estimate mid and long term erosion and deposition rates under Mediterranean agricultural areas. The net soil erosion rates obtained were comparable, 14.3 t ha −1 yr −1 and 12.1 ha −1 yr −1 for 137 Cs and 210 Pb ex respectively, resulting in a similar sediment delivery ratio of about 92%. Soil redistribution patterns of the study field were established using a simple spatialisation approach. The resulting maps generated by the use of both radionuclides were similar, indicating that the soil erosion processes has not changed significantly over the last 100 years. Over the previous 10 year period, the additional results provided by the test of the prediction model RUSLE 2 provided results of the same order of magnitude. Based on the 137 Cs dataset established, the contribution of the tillage erosion impact has been evaluated with the Mass Balance Model 3 and compared to the result obtained with the Mass Balance Model 2. The findings highlighted that water erosion is the leading process in this Moroccan cultivated field, tillage erosion under the experimental condition being the main translocation process within the site without a significant and major impact on the net erosion. - Highlights: ► Net erosion rates estimated by 137 Cs and 210 Pb ex techniques were found comparable. ► The water erosion is the leading process in this Moroccan cultivated field. ► Soil erosion process has not changed significantly over the last 100 years. ► The prediction model RUSLE 2 provided results of the same order of

Small crater modification on Meridiani Planum and implications for erosion rates and climate change on Mars

Science.gov (United States)

Golombek, M.P.; Warner, N.H.; Ganti, V.; Lamb, M.P.; Parker, T.J.; Fergason, Robin L.; Sullivan, R.

2014-01-01

A morphometric and morphologic catalog of ~100 small craters imaged by the Opportunity rover over the 33.5 km traverse between Eagle and Endeavour craters on Meridiani Planum shows craters in six stages of degradation that range from fresh and blocky to eroded and shallow depressions ringed by planed off rim blocks. The age of each morphologic class from Mars over ~100 Myr and 3 Gyr timescales from the Amazonian and Hesperian are of order <0.01 m/Myr, which is 3–4 orders of magnitude slower than typical terrestrial rates. Erosion rates during the Middle-Late Noachian averaged over ~250 Myr, and ~700 Myr intervals are around 1 m/Myr, comparable to slow terrestrial erosion rates calculated over similar timescales. This argues for a wet climate before ~3 Ga in which liquid water was the erosional agent, followed by a dry environment dominated by slow eolian erosion.

Living Shorelines: Coastal Resilience with a Blue Carbon Benefit.

Directory of Open Access Journals (Sweden)

Jenny L Davis

Full Text Available Living shorelines are a type of estuarine shoreline erosion control that incorporates native vegetation and preserves native habitats. Because they provide the ecosystem services associated with natural coastal wetlands while also increasing shoreline resilience, living shorelines are part of the natural and hybrid infrastructure approach to coastal resiliency. Marshes created as living shorelines are typically narrow (< 30 m fringing marshes with sandy substrates that are well flushed by tides. These characteristics distinguish living shorelines from the larger meadow marshes in which most of the current knowledge about created marshes was developed. The value of living shorelines for providing both erosion control and habitat for estuarine organisms has been documented but their capacity for carbon sequestration has not. We measured carbon sequestration rates in living shorelines and sandy transplanted Spartina alterniflora marshes in the Newport River Estuary, North Carolina. The marshes sampled here range in age from 12 to 38 years and represent a continuum of soil development. Carbon sequestration rates ranged from 58 to 283 g C m-2 yr-1 and decreased with marsh age. The pattern of lower sequestration rates in older marshes is hypothesized to be the result of a relative enrichment of labile organic matter in younger sites and illustrates the importance of choosing mature marshes for determination of long-term carbon sequestration potential. The data presented here are within the range of published carbon sequestration rates for S. alterniflora marshes and suggest that wide-scale use of the living shoreline approach to shoreline management may come with a substantial carbon benefit.

External dose rates in coastal urban environments in Brazil

International Nuclear Information System (INIS)

Souza, E.M.; Rochedo, E.R.R.; Conti, C.C.

2015-01-01

A long term activity aiming on assessing the exposure of the Brazilian population to natural background radiation is being developed at IRD/CNEN. Several research groups within IRD work in this activity, although mostly as a parallel work associated to main research lines followed by researches of the institution. One main activity is related to the raise of external gamma dose rates throughout the country. The objective of this work is to present results from recent surveys performed as part of the emergency preparedness for radiological emergencies during major public events in Brazil, such as the the World Youth Day, held in Rio de Janeiro in 2013, and the Confederations Cup and the FIFA World Cup soccer games, in 2013 and 2014, respectively. In this work, only the recent (2014) coastal urban environments measurements were included. Average kerma rates for Fortaleza is 80 ± 23 nGy/h, for Vitoria is 96 ± 33 nGy/h and for Angra dos Reis is 147 ± 16 nGy/h. These results are then compared to previous results on other coastal urban towns (Rio de Janeiro, Niterói and Salvador), and with the high background coastal area of Guarapari town. (authors)

Building Blocks: A Quantitative Approach for Evaluating Coastal Vulnerability

Directory of Open Access Journals (Sweden)

Komali Kantamaneni

2017-11-01

Full Text Available Climate change and associated factors such as global and regional sea-level rise; the upsurge in high-intensity flooding events; and coastal erosion are pulse and press disturbances that threaten to increase landslides in coastal regions. Under these circumstances; a rigorous framework is required to evaluate coastal vulnerability in order to plan for future climate change scenarios. A vast majority of coastal vulnerability assessments across the globe are evaluated at the macro level (city scale but not at the micro level (small town scale; particularly in the United Kingdom (UK. In order to fill this vital research gap; the current study established a coastal vulnerability index termed here as the Micro Town Coastal Vulnerability Index (MTCVI and then applied it to Barton-on-Sea; which is a small coastal town of the Hampshire region; England; UK. MTCVI was evaluated for Barton-on-Sea coastal vulnerability by integrating both novel and existing parameters. Results suggest that the entire shoreline frontage (2 km exhibits very high coastal vulnerability and is prone to various coastal hazards such as landslides; erosion; and wave intrusion. This suggests that Barton-on-Sea coastal amenities will require a substantial improvement in shoreline protection measures. In this study; GIS (geographic information system coastal vulnerability and landslide maps were generated; and these maps can be used by the local authorities; district councils; coastal engineers; and planners to improve and design coastal management strategies under the climate change scenarios. Meanwhile; the methodology used in this study could also be applied to any other suitable location in the world depending on the availability of the data.

Implementation of remote sensing data in research of coastal dynamics at the Baydaratskaya Bay, Kara Sea

Science.gov (United States)

Kuznetsov, D. E.; Belova, N.; Noskov, A.; Ogorodov, S.

2011-12-01

The development of Arctic coastal regions is now in progress due to significant amount of hydrocarbon deposits discovered. In high latitudes, natural hazards such as coastal erosion and thermoerosion, deflation, linear erosion and thermal denudation, ice gouging can make petroleum production and transport unprofitable. A prominent feature of Kara Sea, as well as other Arctic seas, is the development of coast in permafrost conditions. Despite the long ice period (up to 9 months), during the ice free period coastal dynamics are very intensive. If pipeline landfall site occurs at a shore section with high retreat rate (1 - 3m/year and higher), danger of pipeline damage due to exposure, line sagging and mechanical deformations becomes high. Protective measures may appear inefficient, since shore sections with active coastal erosion are subject not only to bluff retreat, but also to nearshore zone and coastal slope erosion. Exposed pipeline sections also get in danger of sea ice effect. For correct definition of coastal dynamics setting we use dual approach. The first part is perennial instrumental monitoring of shore morphology, relying on system of benchmarks used for repeated measures, together with in-field geomorphologic expertise. Measures include direct observations and geodetic leveling onshore and echosounding offshore. Being the most precise method, direct measurements are expensive. The other drawback is that they can't give an overview of long-span tendencies of coastal evolution for prolonged shore sections, which is essential for shore deformation forecast complying with lifetime of structures (usually 30 to 50 years). This is where the importance of the 2nd part, analysis of the different time remote sensing data, becomes decisive. Most important sources of remote sensing data include Corona imagery from 1960s - 70s, aerial photos of different times (but most of them are inaccessible for Russian Arctic coast), Landsat imagery (covering a long time span

State of the Art in the Design of Coastal Structures

DEFF Research Database (Denmark)

Burcharth, H. F.

1997-01-01

Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives are sheltering of harbour basins and entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes ...

State of the Art in the Design of Coastal Structures

DEFF Research Database (Denmark)

Burcharth, Hans F.

1998-01-01

Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives are sheltering of harbour basins and entrances against waves, stabilization of navigation channels at inlets and protection of water intakes a...

Application of the 137Cs determination to evaluate the erosion rates in cultivated soils in the west part of Cuba

International Nuclear Information System (INIS)

Gil Castillo, Reinaldo; Peralta Vital, Jose Luis; Carrazana Gonzalez, Jorge; Riverol Rosquet, Mario; Penna Valenti, Fermin; Cabrera Calcedo, Eduardo

2004-01-01

The paper shows the experience in the application of 137Cs technique to estimate the erosion rates in cultivated soils (Ultisol) in the west part of the country, and the validation of the technique results by comparison against the results from traditional methods (watershed segments). The proportional, the simplified balance of mass and the balance of mass models were used to calculate the erosion rates, for three segments. In the evaluated area, have been obtained erosion rates from 3.5 to 7.1 t/ha/y for the segment I, from 5.17 to 10.3 t/ha/y for the segment III and from 2.3 to 17 t/ha/y for the segment IX. The conclusions are, the 137Cs technique is reliable for the estimation of erosion rates in the evaluated soil and the mass balance model obtained the nearest values to the estimated by watershed segments

Hydrogeological And Geotechnical Investigations Of Gully Erosion ...

African Journals Online (AJOL)

Consequently, hydrogeological and geotechnical studies of gully erosion sites were carried out in order to provide information on the genesis and continual expansion of gullies in the area. The results indicate that gullies are located in the upper aquifer of the Benin Formation (Coastal Plain Sands). The estimated hydraulic ...

A Climate Change Adaptation Strategy for Management of Coastal Marsh Systems

Science.gov (United States)

Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, includin...

Soil erosion and sediment fluxes analysis: a watershed study of the Ni Reservoir, Spotsylvania County, VA, USA.

Science.gov (United States)

Pope, Ian C; Odhiambo, Ben K

2014-03-01

Anthropogenic forces that alter the physical landscape are known to cause significant soil erosion, which has negative impact on surface water bodies, such as rivers, lakes/reservoirs, and coastal zones, and thus sediment control has become one of the central aspects of catchment management planning. The revised universal soil loss equation empirical model, erosion pins, and isotopic sediment core analyses were used to evaluate watershed erosion, stream bank erosion, and reservoir sediment accumulation rates for Ni Reservoir, in central Virginia. Land-use and land cover seems to be dominant control in watershed soil erosion, with barren land and human-disturbed areas contributing the most sediment, and forest and herbaceous areas contributing the least. Results show a 7 % increase in human development from 2001 (14 %) to 2009 (21.6 %), corresponding to an increase in soil loss of 0.82 Mg ha(-1) year(-1) in the same time period. (210)Pb-based sediment accumulation rates at three locations in Ni Reservoir were 1.020, 0.364, and 0.543 g cm(-2) year(-1) respectively, indicating that sediment accumulation and distribution in the reservoir is influenced by reservoir configuration and significant contributions from bedload. All three locations indicate an increase in modern sediment accumulation rates. Erosion pin results show variability in stream bank erosion with values ranging from 4.7 to 11.3 cm year(-1). These results indicate that urban growth and the decline in vegetative cover has increased sediment fluxes from the watershed and poses a significant threat to the long-term sustainability of the Ni Reservoir as urbanization continues to increase.

Erosion problems in Alexandroupolis coastline, North-Eastern Greece

Science.gov (United States)

Xeidakis, G. S.; Delimani, P.; Skias, S.

2007-12-01

This paper deals with the coastal erosion processes and the related problems around the city of Alexandroupolis, NE Aegean Sea, N. Greece. The area is very fast developing, as the city is an important port and a summer resort center in SE Balkans, and will become soon a transportation and energy center, as well. The coastline under study exhibits an east west orientation and has a length of more than 50 km. The spatial distribution and the characteristics of the changes in the shoreline were studied by comparing old and new air photographs and topographic maps, as well as through repeated series of field observations and local measurements regarding the erosion process. From these studies it was concluded that the greater stretch of the western part of the coast, under consideration, is of moderate to high relief, with a considerable participation of coastal cliffs. It consists of conglomerates of varying granulometry and consistency and is under moderate to severe erosion process. The erosion phenomena in the western part of the coast may be attributed, primarily, to strong S, SW winds, blowing in the area and to trapping of sediments by Alexandroupolis’ port breakwaters; the port stops or/and diverts the sediments to the open sea; and to the east to west longshore sea current, prevailing in the area. The eastern stretch of the coast is a plain area, formed by sandy silty sediments; being a part of the river Evros’ Delta, it is under deposition and accretes seawards. The majority of the coasts under consideration are classified as coasts of high wave energy potential. Hard structures, as shore protection measures, have been constructed in some places, but they were proved, in rather short time-period, ineffective and suffered extensive failures. Thus, it is argued that for a long-term cost-effective tackling of the various erosion problems on any stretch, priority must be given to soft engineering measures; although, certain hard measures, carefully selected

Modulation of the erosion rate of an uplifting landscape by long-term climate change: An experimental investigation

Science.gov (United States)

Moussirou, Bérangé; Bonnet, Stéphane

2018-02-01

Whether or not climatic variations play a major role in setting the erosion rate of continental landscapes is a key factor in demonstrating the influence of climate on the tectonic evolution of mountain belts and understanding how clastic deposits preserved in sedimentary basins may record climatic variations. Here, we investigate how a change in precipitation influences the erosional dynamics of laboratory-scale landscapes that evolved under a combination of uplift and rainfall forcings. We consider here the impact of a decrease in the precipitation rate of finite duration on the erosive response of a landscape forced by a constant uplift and initially at a steady state (SS1). We performed several experiments with the same amplitude but different durations of precipitation decrease (Tp). We observe that the decrease in precipitation induces a phase of surface uplift of landscapes to a new steady state condition (SS2); however, the details of the uplift histories (timing, rate) differ between the experiments according to Tp. We also observe a decrease in the erosion rate induced by the precipitation change; however, the timing and amplitude of this decrease vary according to Tp, defining a delayed and damped erosion signal. Our data show that the landscape response to precipitation change is dictated by a critical water-to-rock ratio (ratio of precipitation over uplift) that likely corresponds to a geomorphic threshold. Our study suggests that variations in precipitation that occur at a geological time scale (> 106 years) may have a weak impact on the erosion of landscapes and on the delivery of siliciclastic material to large rivers and sedimentary basins.

The Coastal Hazard Wheel system for coastal multi-hazard assessment & management in a changing climate

DEFF Research Database (Denmark)

Appelquist, Lars Rosendahl; Halsnæs, Kirsten

2015-01-01

This paper presents the complete Coastal Hazard Wheel (CHW) system, developed for multi-hazard-assessment and multi-hazard-management of coastal areas worldwide under a changing climate. The system is designed as a low-tech tool that can be used in areas with limited data availability...... screening and management. The system is developed to assess the main coastal hazards in a single process and covers the hazards of ecosystem disruption, gradual inundation, salt water intrusion, erosion and flooding. The system was initially presented in 2012 and based on a range of test......-applications and feedback from coastal experts, the system has been further refined and developed into a complete hazard management tool. This paper therefore covers the coastal classification system used by the CHW, a standardized assessment procedure for implementation of multi-hazard-assessments, technical guidance...

Thresholds of sea-level rise rate and sea-level rise acceleration rate in a vulnerable coastal wetland.

Science.gov (United States)

Wu, Wei; Biber, Patrick; Bethel, Matthew

2017-12-01

Feedbacks among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold helps address key challenges in ecology-nonlinear response of ecosystems to environmental change, promotes communication between ecologists and resource managers, and facilitates decision-making in climate change policies. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to enhanced anthropogenic forces. Deriving these two thresholds depends on the temporal scale, the interaction of SLR with other environmental factors, and landscape metrics, which have not been fully accounted for before this study. We chose a representative marine-dominated estuary in the northern Gulf of Mexico, Grand Bay in Mississippi, to test the concept of SLR thresholds. We developed a mechanistic model to simulate wetland change and then derived the SLR thresholds for Grand Bay. The model results show that the threshold of SLR rate in Grand Bay is 11.9 mm/year for 2050, and it drops to 8.4 mm/year for 2100 using total wetland area as a landscape metric. The corresponding SLR acceleration rate thresholds are 3.02 × 10 -4  m/year 2 and 9.62 × 10 -5  m/year 2 for 2050 and 2100, respectively. The newly developed SLR acceleration rate threshold can help quantify the temporal lag before the rapid decline in wetland area becomes evident after the SLR rate threshold is exceeded, and cumulative SLR a wetland can adapt to under the SLR acceleration scenarios. Based on the thresholds, SLR that will adversely impact the coastal wetlands in Grand Bay by 2100 will fall within the likely range of SLR under a high warming scenario (RCP8.5), highlighting the need to avoid RCP8.5 to preserve these marshes.

Change Analysis on Soil Erosion of Fujian Province from 1990 TO 2015

Science.gov (United States)

Wang, X. Q.; Zeng, S. J.; Chen, X. G.; Lin, J. L.; Chen, S. M.

2017-09-01

Soil erosion is one of major environment problems in the world, and China is one of the most serious soil erosion country. In this paper, Fujian province was used as a study area for its typical red soil region. Based on USLE model, the soil erosion modulus in 1990 and 2015 were calculated and turned to soil erosion intensity. The soil erosion distribution trend in Fujian province was decrease from south-east coastal zone to north-west inland region. In soil erosion areas, the main erosion type was light level with about 80 %, and the soil erosion levels above serious type were mainly sporadic distribution with less than 10 %. The soil erosion improved for the past 25 years. The areas of different erosion types all decreased, and the total erosion area reduced by 26.59 %. The improvement area mainly located in north-east, south and west region. The aggravation area mainly located in the north and some middle hilly regions. The impact of human activities is more significant for erosion control.

Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

Science.gov (United States)

Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

2013-11-01

This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands

Science.gov (United States)

Braun, Jean; Gemignani, Lorenzo; van der Beek, Peter

2018-03-01

One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo-Siang-Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo-Siang-Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i.e., from the predicted distribution of surface ages within each catchment and from the relative contribution of any given catchment to the

Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands

Directory of Open Access Journals (Sweden)

J. Braun

2018-03-01

Full Text Available One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo–Siang–Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo–Siang–Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i.e., from the predicted distribution of surface ages within each catchment and from the relative contribution of

Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

Science.gov (United States)

Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

2018-04-01

Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

Remote sensing and aerial photography for delineation and management of coastal ecosystems

Digital Repository Service at National Institute of Oceanography (India)

Jagtap, T.G.

sensing data. may provide necessary information to the planners and researchers. interested in the 11 .. coastal ecosystems. Mismanagement or lack of management of coastal zones may result in the loss of marine ecosystems, influencing erosion and the sea..., topographic maps and other resources. The effective management and research of coastal zones, require information on coastal landforms, wetlands, shoreline changes, sediment and current pattern, which can easily be obtained from the satellite data. Coastal...

Using remote sensing to inform integrated coastal zone management

CSIR Research Space (South Africa)

Roberts, W

2010-06-01

Full Text Available TO INFORM INTERGRATED COASTAL ZONE MANAGEMENT GISSA Western Cape Regional Meeting Wesley Roberts & Melanie Luck-Vogel 2 June 2010 CSIR NRE Ecosystems Earth Observation Group What is Integrated Coastal Zone Management? Integrated coastal management... D1D1 B a n d 1 Band 2 Quick theory of CVA Magnitude Direction ( ) ( )22 xaxbyaybM ?+?= Quadrant 1 (++) Accretion Quadrant 2 (-+) Quadrant 4 (+-) Quadrant 3 (--) Erosion CVA Results & Conclusions ? Change in image time series...

Protection from erosion following wildfire

Science.gov (United States)

Peter R. Robichaud; William J. Elliot

2006-01-01

Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for...

Soil Erosion and Agricultural Sustainability

Science.gov (United States)

Montgomery, D. R.

2009-04-01

Data drawn from a global compilation of studies support the long articulated contention that erosion rates from conventionally plowed agricultural fields greatly exceed rates of soil production, erosion under native vegetation, and long-term geological erosion. Whereas data compiled from around the world show that soil erosion under conventional agriculture exceeds both rates of soil production and geological erosion rates by up to several orders of magnitude, similar global distributions of soil production and geological erosion rates suggest an approximate balance. Net soil erosion rates in conventionally plowed fields on the order of 1 mm/yr can erode typical hillslope soil profiles over centuries to millennia, time-scales comparable to the longevity of major civilizations. Well-documented episodes of soil loss associated with agricultural activities date back to the introduction of erosive agricultural methods in regions around the world, and stratigraphic records of accelerated anthropogenic soil erosion have been recovered from lake, fluvial, and colluvial stratigraphy, as well as truncation of soil stratigraphy (such as truncated A horizons). A broad convergence in the results from studies based on various approaches employed to study ancient soil loss and rates of downstream sedimentation implies that widespread soil loss has accompanied human agricultural intensification in examples drawn from around the world. While a broad range of factors, including climate variability and society-specific social and economic contexts — such as wars or colonial relationships — all naturally influence the longevity of human societies, the ongoing loss of topsoil inferred from studies of soil erosion rates in conventional agricultural systems has obvious long-term implications for agricultural sustainability. Consequently, modern agriculture — and therefore global society — faces a fundamental question over the upcoming centuries. Can an agricultural system

Buffer erosion in dilute groundwater

International Nuclear Information System (INIS)

Schatz, T.; Kanerva, N.; Martikainen, J.; Sane, P.; Olin, M.; Seppaelae, A.; Koskinen, K.

2013-08-01

One scenario of interest for repository safety assessment involves the loss of bentonite buffer material in contact with dilute groundwater flowing through a transmissive fracture interface. In order to examine the extrusion/erosion behavior of bentonite buffer material under such circumstances, a series of experiments were performed in a flow-through, 1 mm aperture, artificial fracture system. These experiments covered a range of solution chemistry (salt concentration and composition), material composition (sodium montmorillonite and admixtures with calcium montmorillonite), and flow velocity conditions. No erosion was observed for sodium montmorillonite against solution compositions from 0.5 g/L to 10 g/L NaCl. No erosion was observed for 50/50 calcium/sodium montmorillonite against 0.5 g/L NaCl. Erosion was observed for both sodium montmorillonite and 50/50 calcium/sodium montmorillonite against solution compositions ≤ 0.25 g/L NaCl. The calculated erosion rates for the tests with the highest levels of measured erosion, i.e., the tests run under the most dilute conditions (ionic strength (IS) < ∼1 mM), were well-correlated to flow velocity, whereas the calculated erosion rates for the tests with lower levels of measured erosion, i.e., the tests run under somewhat less dilute conditions (∼1 mM < IS < ∼4 mM), were not similarly correlated indicating that material and solution composition can significantly affect erosion rates. In every experiment, both erosive and non-erosive, emplaced buffer material extruded into the fracture and was observed to be impermeable to water flowing in the fracture effectively forming an extended diffusive barrier around the intersecting fracture/buffer interface. Additionally, a model which was developed previously to predict the rate of erosion of bentonite buffer material in low ionic strength water in rock fracture environments was applied to three different cases: sodium montmorillonite expansion in a vertical tube, a

Divertor erosion in DIII-D

International Nuclear Information System (INIS)

Whyte, D.G.; Bastasz, R.; Wampler, W.R.; Brooks, J.N.; West, W.P.; Wong, C.P.C.

1998-05-01

Net erosion rates of carbon target plates have been measured in situ for the DIII-D lower divertor. The principal method of obtaining this data is the DiMES sample probe. Recent experiments have focused on erosion at the outer strike-point of two divertor plasma conditions: (1) attached (Te > 40 eV) ELMing plasmas and (2) detached (Te 10 cm/year, even with incident heat flux 2 . In this case, measurements and modeling agree for both gross and net carbon erosion, showing the near-surface transport and redeposition of the carbon is well understood and that effective sputtering yields are > 10%. In ELM-free discharges, this erosion rate can account for the rate of carbon accumulation in the core plasma. Divertor plasma detachment eliminates physical sputtering, while spectroscopically measured chemical erosion yields are also found to be low (Y(C/D + ) ≤ 2.0 x 10 -3 ). This leads to suppression of net erosion at the outer strike-point, which becomes a region of net redeposition (∼ 4 cm/year). The private flux wall is measured to be a region of net redeposition with dense, high neutral pressure, attached divertor plasmas. Leading edges intercepting parallel heat flux (∼ 50 MW/m 2 ) have very high net erosion rates (∼ 10 microm/s) at the OSP of an attached plasma. Leading edge erosion, and subsequent carbon redeposition, caused by tile gaps can account for half of the deuterium codeposition in the DIII-D divertor

Decadal-scale coastal cliff retreat in southern and central California

Science.gov (United States)

Young, Adam P.

2018-01-01

Airborne LiDAR data collected in 1998 and 2009-2010 were used to measure coastal cliff erosion and retreat between the Mexico/California border and Bodega Head, California. Cliff erosion was detected along 44% of the 595 km of shoreline evaluated, while the remaining cliffs were relatively stable. The mean cliff top retreat rate was 0.12 m/yr, while mean retreat averaged over the entire cliff face was 0.04 m/yr. The maximum cliff top and face retreat rates were 4.2 and 3.8 m/yr, respectively. Historical ( 1930s to 1998) and recent retreat rates were significantly inversely correlated for areas with large historical or recent cliff retreat, such that locations with elevated historical retreat had low levels of recent retreat and locations with elevated recent retreat were preceded by low rates of historical retreat. The strength of this inverse correlation increased with cliff change magnitudes up to r2 of 0.91 for cliff top retreat rates > 2.9 m/yr. Mean recent retreat rates were 52-83% lower than mean historical retreat rates. Although beaches can protect cliffs against wave-driven erosion, cliffs fronted by beaches retreated 49% more than cliffs without beaches. On average, unarmored cliff faces retreated 0.05 m/yr between 1998 and 2009-2010, about three times faster than artificially armored cliffs. Alongshore metrics of wave-cliff impact, precipitation, and cliff hardness were generally not well correlated with recent cliff changes. A cliff hazard metric is used to detect cliff steepening and areas prone to future cliff top failures.

Centennial- to millennial-scale hard rock erosion rates deduced from luminescence-depth profiles

DEFF Research Database (Denmark)

Sohbati, Reza; Liu, Jinfeng; Jain, Mayank

2018-01-01

to quantify hard rock erosion rates at centennial to millennial timescales. Here we propose a novel technique, based on the solar bleaching of luminescence signals with depth into rock surfaces, to bridge this analytical gap. We apply our technique to glacial and landslide boulders in the Eastern Pamirs...

Effects of oil on the rate and trajectory of Louisiana marsh shoreline erosion

International Nuclear Information System (INIS)

McClenachan, Giovanna; Eugene Turner, R; Tweel, Andrew W

2013-01-01

Oil can have long-term detrimental effects on marsh plant health, both above- and belowground. However, there are few data available that quantify the accelerated rate of erosion that oil may cause to marshes and the trajectory of change. Between November 2010 and August 2012, we collected data on shoreline erosion, soil strength, per cent cover of Spartina alterniflora, and marsh edge overhang at 30 closely spaced low oil and high oil sites in Bay Batiste, Louisiana. Surface oil samples were taken one meter into the marsh in February 2011. All high oiled sites in Bay Batiste were contaminated with Macondo 252 oil (oil from the Deepwater Horizon oil spill, 20 April–15 July 2010). The results suggest that there is a threshold where soil parameters change dramatically with a relatively small increase in oil concentration in the soil. Heavy oiling weakens the soil, creating a deeper undercut of the upper 50 cm of the marsh edge, and causing an accelerated rate of erosion that cascades along the shoreline. Our results demonstrate that it could take at least 2 yr to document the effects heavy oiling has had on the marsh shoreline. The presence of aboveground vegetation alone may not be an appropriate indicator of recovery. (letter)

The impact of watershed management on coastal morphology: A case study using an integrated approach and numerical modeling

Science.gov (United States)

Samaras, Achilleas G.; Koutitas, Christopher G.

2014-04-01

Coastal morphology evolves as the combined result of both natural- and human- induced factors that cover a wide range of spatial and temporal scales of effect. Areas in the vicinity of natural stream mouths are of special interest, as the direct connection with the upstream watershed extends the search for drivers of morphological evolution from the coastal area to the inland as well. Although the impact of changes in watersheds on the coastal sediment budget is well established, references that study concurrently the two fields and the quantification of their connection are scarce. In the present work, the impact of land-use changes in a watershed on coastal erosion is studied for a selected site in North Greece. Applications are based on an integrated approach to quantify the impact of watershed management on coastal morphology through numerical modeling. The watershed model SWAT and a shoreline evolution model developed by the authors (PELNCON-M) are used, evaluating with the latter the performance of the three longshore sediment transport rate formulae included in the model formulation. Results document the impact of crop abandonment on coastal erosion (agricultural land decrease from 23.3% to 5.1% is accompanied by the retreat of ~ 35 m in the vicinity of the stream mouth) and show the effect of sediment transport formula selection on the evolution of coastal morphology. Analysis denotes the relative importance of the parameters involved in the dynamics of watershed-coast systems, and - through the detailed description of a case study - is deemed to provide useful insights for researchers and policy-makers involved in their study.

Comparison of soil erosion and deposition rates using radiocesium, RUSLE, and buried soils in dolines in East Tennessee

International Nuclear Information System (INIS)

Turnage, K.M.; Lee, S.Y.; Foss, J.E.; Kim, K.H.; Larsen, I.L.

1997-01-01

Three dolines (sinkholes), each representing different land uses (crop, grass, and forest) in a karst area in East Tennesse, were selected to determine soil erosional and depositional rates. Three methods were used to estimate the rates: fallout radiocesium ( 137 Cs) redistribution, buried surface soil horizons (Ab horizon), and the revised universal soil loss equation (RUSLE). When 137 Cs redistribution was examined, the average soil erosion rates were calculated to be 27 t ha -1 yr -1 at the cropland, 3 t ha -1 yr -1 at the grassland, and 2 t ha -1 yr -1 at the forest. By comparison, cropland erosion rate of 2.6 t ha -1 yr -1 , a grassland rate of 0.6 t ha -1 yr -1 , and a forest rate of 0.2 t ha -1 yr -1 were estimated by RUSLE. The 137 Cs method expressed higher rates than RUSLE because RUSLE tends to overestimate low erosion rates and does not account for deposition. The buried surface horizons method resulted in deposition rates that were 8 t ha -1 yr -1 (during 480 yr) at the cropland, 12 t ha -1 yr -1 (during 980 yr) at the grassland, and 4 t ha -1 yr -1 (during 101 yr) at the forest site. By examining 137 Cs redistribution, soil deposition rates were found to be 23 t ha -1 yr -1 at the cropland, 20 t ha -1 yr -1 at the grassland, and 16 t ha -1 yr -1 at the forest site. The variability in deposition rates was accounted for by temporal differences; 137 Cs expressed deposition during the last 38 yr, whereas Ab horizons represented deposition during hundreds of years. In most cases, land used affected both erosion and deposition rates - the highest rates of soil redistribution usually representing the cropland and the lowest, the forest. When this was not true, differences in the rates were attributed to differences in the size, shape, and closure of the dolines. (orig.)

Divertor erosion in DIII-D

International Nuclear Information System (INIS)

Whyte, D.G.; Bastasz, R.; Wampler, W.R.; Brooks, J.N.; West, W.P.; Wong, C.P.C.; Buzhinskij, O.I.; Opimach, I.V.

1998-08-01

Net erosion rates of carbon target plates have been measured in situ for the DIII-D lower divertor. The principal method of obtaining this data is the DiMES sample probe. Recent experiments have focused on erosion at the outer strike-point (OSP) of two divertor plasma conditions: attached (T e > 40 eV) ELMing plasmas, and detached (T e 2 . In this case, measurements and modeling agree for both gross and net carbon erosion, showing the near-surface transport and redeposition of the carbon is well understood. In the attached cases, physical sputtering (with enhancement from self-sputtering and oblique incidence) is dominant, and the effective sputtering yield, Y, is greater than 10%. In ELM-free discharges, the total OSP net erosion rate is equal to the rate of carbon accumulation in the core plasma. For the detached divertor cases, the cold incident plasma eliminates physical sputtering. Attempts to measure chemically eroded hydrocarbon molecules spectroscopically indicate an upper limit of Y ≤ 0.1% for the chemical sputtering yield. Net erosion is suppressed at the outer strike-point, which becomes a region of net redeposition (∼ 4 cm/exposure-year). The private flux wall is measured to be a region of net redeposition with dense, high neutral pressure, attached divertor plasmas. Leading edges intercepting parallel heat flux (∼ 50 MW/m 2 ) have very high net erosion rates at the OSP of an attached plasma (∼ 10 microm/s > 1,000x erosion rate of aligned surfaces). Leading edge erosion, and subsequent carbon redeposition, caused by tile gaps can account for half of the deuterium codeposition in the DIII-D divertor

Erosion of the Mekong delta: the role of human activities

Science.gov (United States)

Anthony, E.; Dussouillez, P.; Goichot, M.; Brunier, G.; Dolique, F.; Nguyen, V.; Loisel, H.; Mangin, A.; Vantrepotte, V.

2013-12-01

River deltas are threatened by dams, dykes, flow channelling, and aggregate extraction. These activities outweigh climate change and sea-level rise in causing delta vulnerability1, and will aggravate the impacts to be expected from these effects2. We show here from analysis of: (1) delta channel morphology and sediment budgets, and (2) satellite imagery, that the Mekong delta, considered as the world's third largest, and hitherto strongly prograding, is now in a phase of large-scale erosion. We discuss the mechanistic links involved in erosion and the way these are related to human activities. High-resolution (2.5 m) SPOT 5 images for the years 2003, 2007, 2011/12 covering 405 km of the delta shoreline show an overall retreat rate of over 8 m a year. 75% of the analysed shoreline, i.e., the muddy western sector, is now retreating at rates exceeding 50 m a year in places. The sandy river-mouth sector maintains a semblance of stability, but with strong variations. We attribute erosion to a cascade of morphosedimentary changes linked to sediment mining from the deltaic channels and upstream dam interception. We estimated from Meris satellite imagery an annual 5% decrease in surface suspended concentrations exiting at the mouths of the Mekong over the period 2003-2011 that may reflect increased trapping of mud behind dams in China. We also infer modification of river-mouth and coastal mud storage patterns resulting from a loss of ca. 200 million m3 of delta channel sediments between 1998 and 2008 from aggregate extraction. Dykes have been shown to result in increased channel flow velocities during the high-discharge monsoon season, favouring further channel deepening3. Stronger river-mouth outflow velocities during this season may be leading to export of a greater proportion of mud far offshore of the coastal longshore transport corridor that ensured mud supply to, and past progradation of, the muddy western coast. In contrast, greater seawater penetration in the

Impact of human interventions and coastal processes along the Nile Delta coast, Egypt during the past

Directory of Open Access Journals (Sweden)

Elham M. Ali

2016-03-01

Full Text Available The coastal zone of the Nile Delta lodges highly populated cities (e.g. Alexandria, Port Said together with small towns and villages. It represents the major industrial, agricultural, and economic resource of the country. The area has been subjected to extensive and excessive unplanned developmental projects to foster the economic status of the local communities that, however, negatively impacted both land use and land cover characteristics. Satellite images were processed to identify the dominant land use/cover classes (from 1990 to 2014 and GIS techniques spatially analyzed and quantified the rate of changes. Five dominant classes were identified and their changes monitored against the unprecedented human activities. Results demonstrated a significant rate of land forms transformation within the last 25 years, in favor of developing of fish farming (+13% and urban (+22%. Such development of these land use classes was unfortunately at the expense of the agricultural land (−15%, coastal dune and barren land (−13% and water bodies (−7%. In addition, the coastal processes have made significant changes in the shoreline creating areas of erosion (maximum of 24–36 m/year and others of accretion (a total accreted area of 3.14 km2 with an overall retreat of 2.7 km2 along the shoreline. The expected changes in climate and sea level rise will worsen the erosion rate and the general status of the coastal zone. Based on the IPCC scenarios (i.e. the 59 cm sea level rise by the end of this century and the proposed land subsidence (2.5 mm/year, one fifth of the Nile Delta will be seriously vulnerable to inundation.

Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion

Science.gov (United States)

This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA...

The use of spatial empirical models to estimate soil erosion in arid ecosystems.

Science.gov (United States)

Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

2017-02-01

The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

Implementation of coastal erosion management in the Netherlands

NARCIS (Netherlands)

Mulder, J.P.M. P.M.; Hommes, Saskia; Horstman, Erik

2011-01-01

The Netherlands is a low-lying country, in which 9 million people are living below sea level and 70% of the gross domestic product is being earned in areas below sea level. Therefore, protection against flooding is traditionally the primary focus of coastal policy in the Netherlands. Analysis shows

Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex.

Science.gov (United States)

Benmansour, M; Mabit, L; Nouira, A; Moussadek, R; Bouksirate, H; Duchemin, M; Benkdad, A

2013-01-01

In Morocco land degradation - mainly caused by soil erosion - is one of the most serious agroenvironmental threats encountered. However, only limited data are available on the actual magnitude of soil erosion. The study site investigated was an agricultural field located in Marchouch (6°42' W, 33° 47' N) at 68 km south east from Rabat. This work demonstrates the potential of the combined use of (137)Cs, (210)Pb(ex) as radioisotopic soil tracers to estimate mid and long term erosion and deposition rates under Mediterranean agricultural areas. The net soil erosion rates obtained were comparable, 14.3 t ha(-1) yr(-1) and 12.1 ha(-1) yr(-1) for (137)Cs and (210)Pb(ex) respectively, resulting in a similar sediment delivery ratio of about 92%. Soil redistribution patterns of the study field were established using a simple spatialisation approach. The resulting maps generated by the use of both radionuclides were similar, indicating that the soil erosion processes has not changed significantly over the last 100 years. Over the previous 10 year period, the additional results provided by the test of the prediction model RUSLE 2 provided results of the same order of magnitude. Based on the (137)Cs dataset established, the contribution of the tillage erosion impact has been evaluated with the Mass Balance Model 3 and compared to the result obtained with the Mass Balance Model 2. The findings highlighted that water erosion is the leading process in this Moroccan cultivated field, tillage erosion under the experimental condition being the main translocation process within the site without a significant and major impact on the net erosion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Soil erosion and sedimentation rates in a small eutrophic lake in southern Chile estimated by 210Pb isotope analysis

International Nuclear Information System (INIS)

Cisternas, M.; Urrutia, R.; Araneda, A.; Debels, P.; Rios, F.

1999-01-01

The purpose of this research is to study the effects of historical land use patterns on soil erosion within the San Pedro Lake watershed (Concepcion, VIII Region, Chile). To this end, a geochronological reconstruction of the last 50 years was accomplished by 210 Pb isotope and photo-interpretation analysis through the use of GIS. The erosion rate has varied from 0.40 t ha -1 y -1 in 1955 to 0.86 t ha -1 y -1 in 1994. The decrease in native forest was closely coupled with the increase in exotic forestry. The Total Change, meaning the land use change without considering each typology, shows a constant trend indicating a greater degree of anthropogenic intervention. As opposed to the expected, there is no relationship between land use typologies and erosion rates, however it is possible to recognise some degree of dependency between Total Change and erosion values. It is concluded that over the last 50 years the soil erosion processes in the San Pedro Lake watershed may have been more regulated more by land use changes than by land use typologies themselves. (author)

Determining the rates and drivers of headwall erosion within glaciated catchments in the NW Himalaya

Science.gov (United States)

Orr, E.; Owen, L. A.; Saha, S.; Caffee, M. W.

2017-12-01

Rates of headwall erosion are defined for fourteen glaciated catchments in the NW Himalaya by measuring 10Be terrestrial cosmogenic nuclide concentrations in supraglacial debris. The investigated catchments are located throughout three broad climatic zones, which include the Lesser Himalaya (rainfall >1000 mm a-1), Greater Himalaya (500-1000 mm a-1) and Transhimalaya (arid catchments that are occupied by sub-polar glaciers, suggesting that there are additional controls upon periglacial domain landscape change. Other factors and catchment-specific dynamics influencing these landscapes include, temperature, surface processes, topography, valley morphology, geologic setting and glacial history. Defining rates of headwall erosion is one of the first steps to understanding the nature of sediment production and transfer within high-altitude glaciated catchments, and highlights the importance of periglacial rockfall processes in landscape evolution.

Quantification of risks to coastal areas and development: wave run-up and erosion

CSIR Research Space (South Africa)

Theron, A

2010-09-01

Full Text Available In support of the effective implementation of the Integrated Coastal Management Act (Act No 24 of 2008), a review is presented of coastal hazard assessment methods. In particular the ICM Act legislates the establishment or change of coastal setback...

In-situ buildup of cosmogenic isotopes at the earth's surface: measurement of erosion rates and exposure times

International Nuclear Information System (INIS)

Fifield, L.K.; Allan, G.L.; Stone, J.O.H.; Evans, J.M.; Cresswell, R.G.; Ophel, T.R.

1993-01-01

Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes 10 Be (t 1/2 = 1.5Ma), 26 Al (0.7Ma) and 36 Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on 36 Cl. The accumulation of cosmogenic 36 Cl in calcite (CaCO 3 ) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of 36 Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of 36 Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of 36 Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs

The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

Science.gov (United States)

Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.

2017-01-01

Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10− 4σT− 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the − 1.5 power of tensile strength.

Scenario Studies on Effects of Soil Infiltration Rates, Land Slope, and Furrow Irrigation Characteristics on Furrow Irrigation-Induced Erosion.

Science.gov (United States)

Dibal, Jibrin M; Ramalan, A A; Mudiare, O J; Igbadun, H E

2014-01-01

Furrow irrigation proceeds under several soil-water-furrow hydraulics interaction dynamics. The soil erosion consequences from such interactions in furrow irrigation in Samaru had remained uncertain. A furrow irrigation-induced erosion (FIIE) model was used to simulate the potential severity of soil erosion in irrigated furrows due to interactive effects of infiltration rates, land slope, and some furrow irrigation characteristics under different scenarios. The furrow irrigation characteristics considered were furrow lengths, widths, and stream sizes. The model itself was developed using the dimensional analysis approach. The scenarios studied were the interactive effects of furrow lengths, furrow widths, and slopes steepness; infiltration rates and furrow lengths; and stream sizes, furrow lengths, and slopes steepness on potential furrow irrigation-induced erosion, respectively. The severity of FIIE was found to relate somewhat linearly with slope and stream size, and inversely with furrow lengths and furrow width. The worst soil erosion (378.05 t/ha/yr) was found as a result of the interactive effects of 0.65 m furrow width, 50 m furrow length, and 0.25% slope steepness; and the least soil erosion (0.013 t/ha/yr) was induced by the combined effects of 0.5 l/s, 200 m furrow length, and 0.05% slope steepness. Evidently considering longer furrows in furrow irrigation designs would be a better alternative of averting excessive FIIE.

Limited impact of beach nourishment on macrofaunal recruitment/settlement in a site of community interest in coastal area of the Adriatic Sea (Mediterranean Sea).

Science.gov (United States)

Danovaro, Roberto; Nepote, Ettore; Martire, Marco Lo; Ciotti, Claudia; De Grandis, Gianluca; Corinaldesi, Cinzia; Carugati, Laura; Cerrano, Carlo; Pica, Daniela; Di Camillo, Cristina Gioia; Dell'Anno, Antonio

2018-03-01

Beach nourishment is a widely utilized solution to counteract the erosion of shorelines, and there is an active discussion on its possible consequences on coastal marine assemblages. We investigated the impact caused by a small-scale beach nourishment carried out in the Western Adriatic Sea on macrofaunal recruitment and post-settlement events. Artificial substrates were deployed in proximity of nourished and non-manipulated beaches and turbidity and sedimentation rates were measured. Our results indicate that sedimentation rates in the impacted site showed a different temporal change compared to the control sites, suggesting potential modifications due to the beach nourishment. The impact site was characterized by subtle changes in terms of polychaete abundance and community structure when compared to controls, possibly due to beach nourishment, although the role of other factors cannot be ruled out. We conclude that small-scale beach nourishments appear to be an eco-sustainable approach to contrast coastal erosion. Copyright © 2018. Published by Elsevier Ltd.

The role of bathymetry, wave obliquity and coastal curvature in dune erosion prediction

NARCIS (Netherlands)

Den Heijer, C.

2013-01-01

This study aims at reducing uncertainty in dune erosion predictions, in particular at complex dune coasts, in order to improve the assessment method for dune safety against flooding. To that end, state-of-the-art process-based dune erosion models are employed to further investigate issues

Effects of disturbance on vegetation by sand accretion and erosion across coastal dune habitats on a barrier island.

Science.gov (United States)

Miller, Thomas E

2015-01-12

Coastal geomorphology and vegetation are expected to be particularly sensitive to climate change, because of disturbances caused by sea-level rise and increased storm frequency. Dunes have critical reciprocal interactions with vegetation; dunes create habitats for plants, while plants help to build dunes and promote geomorphological stability. These interactions are also greatly affected by disturbances associated with sand movement, either in accretion (dune building) or in erosion. The magnitude and intensity of disturbances are expected to vary with habitat, from the more exposed and less stable foredunes, to low-lying and flood-prone interdunes, to the protected and older backdunes. Permanent plots were established at three different spatial scales on St George Island, FL, USA, where the vegetation and dune elevation were quantified annually from 2011 to 2013. Change in elevation, either through accretion or erosion, was used as a measure of year-to-year disturbance over the 2 years of the study. At the scale of different dune habitats, foredunes were found to have the greatest disturbance, while interdunes had the least. Elevation and habitat (i.e. foredune, interdune, backdune) were significantly correlated with plant community composition. Generalized linear models conducted within each habitat show that the change in elevation (disturbance) is also significantly correlated with the plant community, but only within foredunes and interdunes. The importance of disturbance in exposed foredunes was expected and was found to be related to an increasing abundance of a dominant species (Uniola paniculata) in eroding areas. The significant effect of disturbance in the relatively stable interdunes was surprising, and may be due to the importance of flooding associated with small changes in elevation in these low-lying areas. Overall, this study documents changes in the plant community associated with elevation, and demonstrates that the foredune and interdune

Connecting large-scale coastal behaviour with coastal management of the Rhône delta

Science.gov (United States)

Sabatier, François; Samat, Olivier; Ullmann, Albin; Suanez, Serge

2009-06-01

The aim of this paper is to connect the Large Scale Coastal Behaviour (LSCB) of the Rhône delta (shoreface sediment budget, river sediment input to the beaches, climatic change) with the impact and efficiency of hard engineering coastal structures. The analysis of the 1895 to 1974 bathymetric maps as well as 2D modelling of the effect of wave blocking on longshore transport allows us to draw up a conceptual model of the LSCB of the Rhône delta. The river sand input, settled in the mouth area (prodeltaic lobe), favours the advance of adjacent beaches. There is however a very weak alongshore sand feeding of the non-adjacent beaches farther off the mouth. After a mouth shift, the prodelta is eroded by aggressive waves and the sand is moved alongshore to build spits. This conceptual model suggests that there is a "timeshift" between the input of river sediments to the sea and the build up of a beach (nonadjacent to the mouth). Nowadays, as the river channels are controlled by dykes and human interventions, a river shift is not possible. It thus appears unlikely that the river sediments can supply the beaches of the Rhône delta coast. Under these conditions, we must expect that the problems of erosion will continue at Saintes-Maries-de-la-Mer and on the Faraman shore, in areas with chronic erosion where the shoreline retreat has been partially stopped by hard engineering practices in the 1980s. Therefore, these artificially stabilised sectors remain potentially under threat because of profile steepening and downdrift erosion evidenced in this paper by bathymetric profile measurements. In the long-term (1905 to 2003), the temporal analysis of the storm surges and the sea level show very weak but reliable increasing trends. Thus, these climatic agents will be more aggressive on the beaches and on the coastal structures calling their efficiency into question. We also evidence that the hard engineering structures were built in a favourable climatic context during the

On researching erosion-corrosion wear in pipelines: the rate and residual lifetime estimation

International Nuclear Information System (INIS)

Baranenko, V.I.; Yanchenko, Yu.A.; Gulina, O.M.; Dokukin, D.A.

2010-01-01

To base the normative document on calculation of pipelines erosive-corrosive wear (ECW) rate and residual lifetime this research of ECW regularities for pearlitic steel NPP pipelines was performed. The estimates of control data treatment statistical procedures efficiency were presented. The influence of the scheme of piping control on the ECW rate and residual lifetime estimation results was demonstrated. The simplified scheme is valid only in case of complete information. It's usage under data uncertainties leads to essential residual lifetime overstating [ru

The comparison of various approach to evaluation erosion risks and design control erosion measures

Science.gov (United States)

Kapicka, Jiri

2015-04-01

In the present is in the Czech Republic one methodology how to compute and compare erosion risks. This methodology contain also method to design erosion control measures. The base of this methodology is Universal Soil Loss Equation (USLE) and their result long-term average annual rate of erosion (G). This methodology is used for landscape planners. Data and statistics from database of erosion events in the Czech Republic shows that many troubles and damages are from local episodes of erosion events. An extent of these events and theirs impact are conditional to local precipitation events, current plant phase and soil conditions. These erosion events can do troubles and damages on agriculture land, municipally property and hydro components and even in a location is from point of view long-term average annual rate of erosion in good conditions. Other way how to compute and compare erosion risks is episodes approach. In this paper is presented the compare of various approach to compute erosion risks. The comparison was computed to locality from database of erosion events on agricultural land in the Czech Republic where have been records two erosion events. The study area is a simple agriculture land without any barriers that can have high influence to water flow and soil sediment transport. The computation of erosion risks (for all methodology) was based on laboratory analysis of soil samples which was sampled on study area. Results of the methodology USLE, MUSLE and results from mathematical model Erosion 3D have been compared. Variances of the results in space distribution of the places with highest soil erosion where compared and discussed. Other part presents variances of design control erosion measures where their design was done on based different methodology. The results shows variance of computed erosion risks which was done by different methodology. These variances can start discussion about different approach how compute and evaluate erosion risks in areas

Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

Energy Technology Data Exchange (ETDEWEB)

Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

2017-04-01

Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

STUDY OF RAINFALL RATES AND EROSIVE PROCESSES AT THE URBAN AREA OF SÃO LUÍS – MA

Directory of Open Access Journals (Sweden)

Antonio José Teixeira Guerra

2005-05-01

Full Text Available The study of the rain rates is here highlighted, in order to understand the mechanisms that generate the starting point of the erosive processes. The precipitation varies spatially not only in local and regional levels, due to mechanisms that generate rains, but also in short distances, due to the control of local variations, such as winds and constructions. In this way, the precipitations should be measured in different points of the study area, depending on the interest of the study and scale of analysis.The erosive process caused by rainfall covers almost the whole terrestrial surface, especially in tropical areas where the total rainfall is higher than in other regions of the planet. Besides that, the rain only falls on specific seasons in several areas, which worsens the erosion. The process tends to accelerate as the deforestation for wood exploitation and/or agricultural production takes place, once the soils become unprotected without the vegetal cover, so that the rains affect the surface of the grounds directly (GUERRA, 1999.This work presents the results of the monitoring of erosive processes along more than three years of studies at the urban area of São Luís City, relating rainfall rates to gullies evolution, an important instrument for the control and recovery of large-scale erosive processes.

Eco-engineered coastal defense integrated with sustainable aquatic food production in Bangladesh (ECOBAS)

NARCIS (Netherlands)

Tangelder, M.; Ysebaert, T.; Chowdhury, Shah; Reinhard, A.J.; Doorn, F.; Hossain, M.; Smaal, A.C.

2015-01-01

The objective of the ECOBAS project is to provide the coastal people of Bangladesh with an alternative approach for adaptation to coastal erosion and flooding. By using the concept of “eco-engineering” the natural resistance of shellfish reefs against hydrodynamic forces reduces human vulnerability

A simplified 137Cs transport model for estimating erosion rates in undisturbed soil

International Nuclear Information System (INIS)

Zhang Xinbao; Long Yi; He Xiubin; Fu Jiexiong; Zhang Yunqi

2008-01-01

137 Cs is an artificial radionuclide with a half-life of 30.12 years which released into the environment as a result of atmospheric testing of thermo-nuclear weapons primarily during the period of 1950s-1970s with the maximum rate of 137 Cs fallout from atmosphere in 1963. 137 Cs fallout is strongly and rapidly adsorbed by fine particles in the surface horizons of the soil, when it falls down on the ground mostly with precipitation. Its subsequent redistribution is associated with movements of the soil or sediment particles. The 137 Cs nuclide tracing technique has been used for assessment of soil losses for both undisturbed and cultivated soils. For undisturbed soils, a simple profile-shape model was developed in 1990 to describe the 137 Cs depth distribution in profile, where the maximum 137 Cs occurs in the surface horizon and it exponentially decreases with depth. The model implied that the total 137 Cs fallout amount deposited on the earth surface in 1963 and the 137 Cs profile shape has not changed with time. The model has been widely used for assessment of soil losses on undisturbed land. However, temporal variations of 137 Cs depth distribution in undisturbed soils after its deposition on the ground due to downward transport processes are not considered in the previous simple profile-shape model. Thus, the soil losses are overestimated by the model. On the base of the erosion assessment model developed by Walling, D.E., He, Q. [1999. Improved models for estimating soil erosion rates from cesium-137 measurements. Journal of Environmental Quality 28, 611-622], we discuss the 137 Cs transport process in the eroded soil profile and make some simplification to the model, develop a method to estimate the soil erosion rate more expediently. To compare the soil erosion rates calculated by the simple profile-shape model and the simple transport model, the soil losses related to different 137 Cs loss proportions of the reference inventory at the Kaixian site of the

Using "1"3"7Cs measurements to estimate soil erosion rates in the Pčinja and South Morava River Basins, southeastern Serbia

International Nuclear Information System (INIS)

Petrović, Jelena; Dragović, Snežana; Dragović, Ranko; Đorđević, Milan; Đokić, Mrđan; Zlatković, Bojan; Walling, Desmond

2016-01-01

The need for reliable assessments of soil erosion rates in Serbia has directed attention to the potential for using "1"3"7Cs measurements to derive estimates of soil redistribution rates. Since, to date, this approach has not been applied in southeastern Serbia, a reconnaissance study was undertaken to confirm its viability. The need to take account of the occurrence of substantial Chernobyl fallout was seen as a potential problem. Samples for "1"3"7Cs measurement were collected from a zone of uncultivated soils in the watersheds of Pčinja and South Morava Rivers, an area with known high soil erosion rates. Two theoretical conversion models, the profile distribution (PD) model and diffusion and migration (D&M) model were used to derive estimates of soil erosion and deposition rates from the "1"3"7Cs measurements. The estimates of soil redistribution rates derived by using the PD and D&M models were found to differ substantially and this difference was ascribed to the assumptions of the simpler PD model that cause it to overestimate rates of soil loss. The results provided by the D&M model were judged to more reliable. - Highlights: • The "1"3"7Cs measurements are employed to estimate the soil erosion and deposition rates in southeastern Serbia. • Estimates of annual soil loss by profile distribution (PD) and diffusion and migration (D&M) models differ significantly. • Differences were ascribed to the assumptions of the simpler PD model which cause it to overestimate rates of soil loss. • The study confirmed the potential for using "1"3"7Cs measurements to estimate soil erosion rates in Serbia.

The contribution of mulches to control high soil erosion rates in vineyards in Eastern Spain

Science.gov (United States)

Cerdà, Artemi; Jordán, Antonio; Zavala, Lorena; José Marqués, María; Novara, Agata

2014-05-01

Soil erosion take place in degraded ecosystem where the lack of vegetation, drought, erodible parent material and deforestation take place (Borelli et al., 2013; Haregeweyn et al., 2013; Zhao et al., 2013). Agriculture management developed new landscapes (Ore and Bruins, 2012) and use to trigger non-sustainable soil erosion rates (Zema et al., 2012). High erosion rates were measured in agriculture land (Cerdà et al., 2009), but it is also possible to develop managements that will control the soil and water losses, such as organic amendments (Marqués et al., 2005), plant cover (Marqués et al., 2007) and geotextiles (Giménez Morera et al., 2010). The most successful management to restore the structural stability and the biological activity of the agriculture soil has been the organic mulches (García Orenes et al; 2009; 2010; 2012). The straw mulch is also very successful on bare fire affected soil (Robichaud et al., 2013a; 2013b), which also contributes to a more stable soil moisture content (García-Moreno et al., 2013). The objective of this research is to determine the impact of two mulches: wheat straw and chipped branches, on the soil erosion rates in a rainfed vineyard in Eastern Spain. The research site is located in the Les Alcusses Valley within the Moixent municipality. The Mean annual temperature is 13 ºC, and the mean annual rainfall 455 mm. Soil are sandy loam, and are developed at the foot-slope of a Cretaceous limestone range, the Serra Grossa range. The soils use to be ploughed and the features of soil erosion are found after each thunderstorm. Rills are removed by ploughing. Thirty rainfall simulation experiments were carried out in summer 2011 during the summer drought period. The simulated rainfall lasted during 1 hour at a 45 mmh-1 intensity on 1 m2 plots (Cerdà and Doerr, 2010; Cerdà and Jurgensen 2011). Ten experiments were carried out on the control plots (ploughed), 10 on straw mulch covered plots, and 10 on chipped branches covered

Delta lobe degradation and hurricane impacts governing large-scale coastal behavior, South-central Louisiana, USA

Science.gov (United States)

Miner, M.D.; Kulp, M.A.; FitzGerald, D.M.; Flocks, J.G.; Weathers, H.D.

2009-01-01

A large deficit in the coastal sediment budget, high rates of relative sea-level rise (???0.9 cm/year), and storm-induced current and wave erosion are forcing barrier shoreface retreat along the periphery of the Mississippi River delta plain. Additionally, conversion of interior wetlands to open water has increased the bay tidal prism, resulting in degradation of barrier islands due to inlet widening, formation of new inlets, and sediment sequestration at ebb-tidal deltas. Single-beam bathymetric surveys along a 165-km stretch of south-central Louisiana barrier coast, from Raccoon Point in Terrebonne Parish to Sandy Point in Plaquemines Parish, were conducted in 2006. These data, combined with historical bathymetry from three time periods (dating to the 1880s), provide a series of digital elevation models that were used to calculate sediment volumetric changes and determine long-term erosional-depositional trends. Dominant patterns during the 125-year period include (1) erosion of ???1.6????????109 m3 from the shoreface, forcing up to 3 km of shoreface retreat, (2) sediment deposition in coastal bights and at ebb-tidal deltas, and (3) a combined increase in tidal inlet cross-sectional area from ???41,400 m2 to ???139,500 m 2. Bathymetric and shoreline change datasets separated by shorter time periods (sub-annual) demonstrate that these long-term trends are driven by processes associated with major hurricane impacts, and that rates of shoreface erosion are an order of magnitude greater during active hurricane seasons compared to long-term trends. ?? 2009 Springer-Verlag.

Centennial-scale human alterations, unintended natural-system responses, and event-driven mitigation within a coupled fluvial-coastal system: Lessons for collective management and long-term coastal change planning

Science.gov (United States)

Hein, C. J.; Hoagland, P.; Huang, J. C.; Canuel, E. A.; Fitzsimons, G.; Rosen, P.; Shi, W.; Fallon, A. R.; Shawler, J. L.

2017-12-01

On decadal to millennial timescales, human modifications of linked riparian and coastal landscapes have altered the natural transport of sediments to the coast, causing time-varying sediment fluxes to estuaries, wetlands, and beaches. This study explored the role of historical changes in land use and river/coastal engineering on patterns of coastal erosion in the coupled system comprising the Merrimack River and the Plum Island barrier beach (northern Massachusetts, USA). Recreational values of the beach, attendant impacts on the local housing market, human perceptions of future beach utilization, and collective management options were investigated. Key historical changes included the installation of dams to benefit industry and control flooding in the early 19th century; river-mouth jetties to maintain navigation and allow for the residential development of a more stable barrier in the early 20th century; and the progressive hardening of the shoreline in response to multi-decadal cyclical erosion and house losses throughout the latter 20th and 21st centuries. The tools of sedimentology, shoreline-change analysis, historic documentation, population surveys, and economic modeling were used to examine these changes and the dynamic linked responses of the natural system and human populations. We found cascading effects of human alterations to the river that changed sediment fluxes to the coastal zone, driving a need for mitigation over centennial timescales. More recently, multidecadal erosion-accretion cycles of the beach have had little impact on the housing market, which is instead more responsive to public shoreline stabilization efforts in response to short-term (sustainable management of coupled fluvial-coastal systems.

Communicating Coastal Risk Analysis in an Age of Climate Change

Science.gov (United States)

2011-10-01

extratropical storm systems); the geometry and geomorphology of the area (regional and local bathymetry and topography, including rivers, marshes, and...at risk from coastal hazards including storm surge inundation, precipitation driven flooding, waves, and coastal erosion. This population segment...will likely be exposed to increased risk as impacts of a changing climate are felt through elevated sea levels and potentially increased storm

Experimental study of the cavitation erosion in centrifugal pump impeller

International Nuclear Information System (INIS)

Rayan, M.A.

1985-01-01

Research on cavitation damage scale effects show that the damage rate is increased with size and velocity. It seems that for constant velocity there is no clear trend for the variation of erosion with cavitation number. Research on the time effects on damage rate show similarity between cavitation and impingement erosion. The cumulative weight loss versus time curve is of a ''S'' shaped type characterized by an incubation period followed by a period of increasing erosion rate, then a maximum erosion rate, and finally a period of decreasing erosion rate. The objective of this investigation is to present a prototype cavitation erosion experiment in order to clarify the time dependency of the erosive wear

Hydrological and Oceanographic Considerations for Integrated Coastal Zone Management in Southern Belize.

Science.gov (United States)

Heyman; Kjerfve

1999-09-01

/ The objectives of this study are to: (1) characterize the meteorology and hydrology of the Maya Mountain-Marine Area Transect in southern Belize, (2) employ a simple water balance model to examine the discharge rates of seven watersheds to Port Honduras, (3) test the validity of the hydrological model, (4) explore the implications of potential landscape and hydrological alterations, and (5) examine the value of protected areas. The southern coastal portion of the study area is classified as wet tropical forest and the remainder as moist tropical forest. Rainfall is 3000-4000 mm annually. Resulting annual freshwater discharge directly into Port Honduras is calculated at 2.5 x 10(9) m3, a volume equal to the basin. During the rainy season, June-September, 84% of the annual discharge occurs, which causes the bay to become brackish. Port Honduras serves as an important nursery ground for many species of commercially important fish and shellfish. The removal of forest cover in the uplands, as a result of agriculture, aquaculture, and village development, is likely to significantly accelerate erosion. Increased erosion would reduce soil fertility in the uplands and negatively affect mangrove, seagrass, and coral reef productivity in the receiving coastal embayment. Alternatively, the conservation of an existing protected areas corridor, linking the Maya Mountains to the Caribbean Sea, is likely to enhance regional sustainable economic development. This study aims to support environmental management at the scale of the "ecoscape"-a sensible ecological unit of linked watersheds and coastal and marine environments.KEY WORDS: Ecosystem management; Coastal zone management; Belize; Hydrologyhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n2p229.html

Dynamic revetments for coastal erosion in Oregon : final report.

Science.gov (United States)

2005-08-01

Gravel beaches have long been recognized as one of the most efficient forms of "natural" coastal protection, and have been suggested as a form of shore protection. "Cobble berms," "dynamic revetments" or "rubble beaches" involve the construction of a...

Coastal Adaptation: The Case of Ocean Beach, San Francisco

Science.gov (United States)

Cheong, S.

2012-12-01

Coastal erosion, storms, sea-level rise, and tsunamis all lead to inundation that puts people and communities at risk. Adapting to these coastal hazards has gained increasing attention with climate change. Instead of promoting one particular strategy such as seawalls or defending against one type of hazard, scholars and practitioners encourage a combination of existing methods and strategies to promote synergistic effects. The recently published Intergovernmental Panel on Climate Change (IPCC) Special Report on climate extremes reflects this trend in the integration of disaster risk management and climate change adaptation. This paper focuses on the roles, compatibilities, and synergies of three coastal adaptation options - engineering, vegetation, and policy - in the case of Ocean Beach in San Francisco. Traditionally engineering approach and ecosystem conservation often have stood in opposition as hard shoreline structures destroy coastal habitats, worsen coastal erosion, divert ocean currents, and prevent the natural migration of shores. A natural migration of shores without structure translates into the abandonment of properties in the coastal zone, and is at odds with property rights and development. For example, policies of relocation, retreat, and insurance may not be popular given the concerns of infrastructure and coastal access. As such, engineering, natural defense, and policy can be more conflictual than complementary. Nonetheless, all these responses are used in combination in many locations. Complementarities and compatibilities, therefore, must be assessed when considering the necessity of engineering responses, natural defense capabilities, and policy options. In this light, the question is how to resolve the problem of mixed responses and short- and long-term interests and values, identify compatibilities, and generate synergies. In the case of Ocean Beach, recent erosions that endangered San Francisco's wastewater treatment system acted as major

Using (137)Cs measurements to estimate soil erosion rates in the Pčinja and South Morava River Basins, southeastern Serbia.

Science.gov (United States)

Petrović, Jelena; Dragović, Snežana; Dragović, Ranko; Đorđević, Milan; Đokić, Mrđan; Zlatković, Bojan; Walling, Desmond

2016-07-01

The need for reliable assessments of soil erosion rates in Serbia has directed attention to the potential for using (137)Cs measurements to derive estimates of soil redistribution rates. Since, to date, this approach has not been applied in southeastern Serbia, a reconnaissance study was undertaken to confirm its viability. The need to take account of the occurrence of substantial Chernobyl fallout was seen as a potential problem. Samples for (137)Cs measurement were collected from a zone of uncultivated soils in the watersheds of Pčinja and South Morava Rivers, an area with known high soil erosion rates. Two theoretical conversion models, the profile distribution (PD) model and diffusion and migration (D&M) model were used to derive estimates of soil erosion and deposition rates from the (137)Cs measurements. The estimates of soil redistribution rates derived by using the PD and D&M models were found to differ substantially and this difference was ascribed to the assumptions of the simpler PD model that cause it to overestimate rates of soil loss. The results provided by the D&M model were judged to more reliable. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling soil erosion in a watershed

OpenAIRE

Lanuza, R.

1999-01-01

Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in aerial scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level; identify the location of erosion prone areas; and analyze the impact of landuse changes on soil erosion. The general methodology of desktop modeling or soil erosion at watershe...

Spatial bedrock erosion distribution in a natural gorge

Science.gov (United States)

Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

2015-12-01

Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half

In-situ buildup of cosmogenic isotopes at the earth`s surface: measurement of erosion rates and exposure times

Energy Technology Data Exchange (ETDEWEB)

Fifield, L K; Allan, G L; Stone, J O.H.; Evans, J M; Cresswell, R G; Ophel, T R [Australian National Univ., Canberra, ACT (Australia)

1994-12-31

Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes {sup 10}Be (t{sub 1/2} = 1.5Ma), {sup 26}Al (0.7Ma) and {sup 36}Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on {sup 36}Cl. The accumulation of cosmogenic {sup 36}Cl in calcite (CaCO{sub 3}) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of {sup 36}Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of {sup 36}Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of {sup 36}Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs.

In-situ buildup of cosmogenic isotopes at the earth`s surface: measurement of erosion rates and exposure times

Energy Technology Data Exchange (ETDEWEB)

Fifield, L.K.; Allan, G.L.; Stone, J.O.H.; Evans, J.M.; Cresswell, R.G.; Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia)

1993-12-31

Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes {sup 10}Be (t{sub 1/2} = 1.5Ma), {sup 26}Al (0.7Ma) and {sup 36}Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on {sup 36}Cl. The accumulation of cosmogenic {sup 36}Cl in calcite (CaCO{sub 3}) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of {sup 36}Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of {sup 36}Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of {sup 36}Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs.

Nile Delta exhibited a spatial reversal in the rates of shoreline retreat on the Rosetta promontory comparing pre- and post-beach protection

Science.gov (United States)

Ghoneim, Eman; Mashaly, Jehan; Gamble, Douglas; Halls, Joanne; AbuBakr, Mostafa

2015-01-01

The coastline of the Nile Delta experienced accelerated erosion since the construction of the Aswan High Dam in 1964 and, consequently, the entrapment of a large amount of river sediments behind it. The coastline of the Rosetta promontory showed the highest erosion in the Delta with an average retreat rate of 137.4 m year- 1. In 1991, in an effort to mitigate sediment loss, a 4.85 km long seawall was built on the outer margin of the promontory. For additional beach protection, 15 groins were constructed along the eastern and western sides of the seawall in 2003 and 2005. To quantify erosion and accretion patterns along the Rosetta promontory, 11 Landsat images acquired at unequal intervals during a 40 year time span (1972 and 2012) were analyzed. The positions of shorelines were automatically extracted from satellite imagery and compared with three very high resolution QuickBird and WorldView2 images for data validation. Analysis of the rates of shoreline change revealed that the construction of the seawall was largely successful in halting the recession along the tip of the promontory, which lost 10.8 km2 prior to coastal protection. Conversely, the construction of the 15 groins has negatively affected the coastal morphology of the promontory and caused a reversal from accretion to fast erosion along the promontory leeside, where some segments of the shoreline have undergone as much as 30.8 m year- 1 of erosion. Without hard structures, the tip of the Rosetta promontory would have retreated 2.3 km by 2013 and lost 7.2 km2 of land. About 10% of this land is deltaic fertile cultivated farms. Moreover, without additional protection the sides of the promontory will lose about 1.3 km2 of land and the coastline would recede at an average rate of 200 m by 2020. Unless action is taken, coastal erosion, enhanced by rising sea level, will steadily eat away the Nile Delta at an alarming rate. The successful demonstration of the advocated procedures in this study could be

Application of the Coastal Hazard Wheel methodology for coastal multi-hazard assessment and management in the state of Djibouti

DEFF Research Database (Denmark)

Appelquist, Lars Rosendahl; Balstrøm, Thomas

2014-01-01

coastal classification system that incorporates the main static and dynamic parameters determining the characteristics of a coastal environment. The methodology provides information on the hazards of ecosystem disruption, gradual inundation, salt water intrusion, erosion and flooding and can be used...... to support management decisions at local, regional and national level, in areas with limited access to geophysical data. The assessment for Djibouti applies a geographic information system (GIS) to develop a range of national hazard maps along with relevant hazard statistics and is showcasing the procedure......This paper presents the application of a new methodology for coastal multi-hazard assessment and management in a changing global climate on the state of Djibouti. The methodology termed the Coastal Hazard Wheel (CHW) is developed for worldwide application and is based on a specially designed...

Soil movements and surface erosion rates on rocky slopes in the mountain areas of the karst region of Southwest China

Science.gov (United States)

Zhang, X. B.; Bai, X. Y.; Long, Y.

2012-04-01

The karst region of Southwest China with an area of 54 × 104 km2 is one of the largest karst areas in the world and experiences subtropical climate. Hill-depressions are common landforms in the mountain areas of this region. Downslope soil movement on the ground by surface water erosion and soil sinking into underground holes by creeping or pipe erosion are mayor types of soil movements on rocky carbonate slopes. The 137Cs technique was used to date the sediment deposits in six karst depressions, to estimate average surface erosion rates on slopes from their catchments. The estimates of soil loss rates obtained from this study evidenced considerable variability. A value of 1.0 t km-2 year-1 was obtained for a catchment under original dense karst forest, but the erosion rates ranged between 19.3 t km-2 year-1 and 48.7 t km-2 year-1 in four catchments under secondary forest or grasses, where the original forest cover had been removed in the Ming and Qing dynasties, several hundred years ago. The highest rate of 1643 t km-2 year-1 was obtained for a catchment underlain by clayey carbonate rocks, where the soil cover was thicker and more extensive than in the other catchments and extensive land reclamation for cultivation had occurred during the period 1979-1981, immediately after the Cultural Revolution.

Fundamental study on cavitation erosion in liquid metal. Effect of liquid parameter on cavitation erosion in liquid metals (Joint research)

International Nuclear Information System (INIS)

Hattori, Shuji; Kurachi, Hiroaki; Inoue, Fumitaka; Watashi, Katsumi; Tsukimori, Kazuyuki; Yada, Hiroki; Hashimoto, Takashi

2009-02-01

Cavitation erosion, which possibly occurs on the surfaces of fluid machineries and components contacting flowing liquid and causes sponge-like damage on the material surface, is important problem, since it may become the cause of performance deduction, life shortening, noise, vibration of mechanical components and moreover failure of machine. Research on cavitation erosion in liquid metal is very important to confirm the safety of fast breeder reactor using sodium coolant and to avoid serious damage of the target vessel of spallation neutron source containing liquid-mercury. But the research on cavitation erosion in liquid metal has been hardly performed because of its specially in comparison with that in water. In this study, a cavitation erosion test apparatus was developed to carry out the erosion tests in low-temperature liquid metals. Cavitation erosion tests were carried out in liquid lead-bismuth alloy and in deionized water. We discuss the effect of liquid parameters and temperature effects on the erosion rate. We reach to the following conclusions. The erosion rate was evaluated in terms of a relative temperature which was defind as the percentage between freezing and boiling points. At 14degC relative temperature, the erosion rate is 10 times in lead-bismuth alloy, and 2 to 5 times in sodium, compared with that in deionized water. At 14degC relative temperature, the erosion rate can be evaluated in terms of the following parameter. 1 / (1/ρ L /C L +1/ρ S C S )√ρ L . Where ρ is the material density and c is the velocity of sound, L and S denote liquid and solid. In the relative temperature between 14 and 30degC, the temperature dependence on the erosion rate is due to the increase in vapor pressure. (author)

Renewed soil erosion and remobilisation of radioactive sediment in Fukushima coastal rivers after the 2013 typhoons.

Science.gov (United States)

Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Lepage, Hugo; Cerdan, Olivier; Lefèvre, Irène; Ayrault, Sophie

2014-04-03

Summer typhoons and spring snowmelt led to the riverine spread of continental Fukushima fallout to the coastal plains of Northeastern Japan and the Pacific Ocean. Four fieldwork campaigns based on measurement of radioactive dose rates in fine riverine sediment that has recently deposited on channel bed-sand were conducted between November 2011 and May 2013 to document the spread of fallout by rivers. After a progressive decrease in the fresh riverine sediment doses rates between 2011 and early spring in 2013, a fifth campaign conducted in November 2013 showed that they started to increase again after the occurrence of violent typhoons. We show that this increase in dose rates was mostly due to remobilization of contaminated material that was temporarily stored in river channels or, more importantly, in dam reservoirs of the region during the typhoons. In addition, supply of particles from freshly eroded soils in autumn 2013 was the most important in areas where decontamination works are under progress. Our results underline the need to monitor the impact of decontamination works and dam releases in the region, as they may provide a continuous source of radioactive contamination to the coastal plains and the Pacific Ocean during the coming years.

Erosion characteristics and horizontal variability for small erosion depths in the Sacramento-San Joaquin River Delta, California, USA

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Schoellhamer, David H.; Manning, Andrew J.; Work, Paul A.

2017-01-01

Erodibility of cohesive sediment in the Sacramento-San Joaquin River Delta (Delta) was investigated with an erosion microcosm. Erosion depths in the Delta and in the microcosm were estimated to be about one floc diameter over a range of shear stresses and times comparable to half of a typical tidal cycle. Using the conventional assumption of horizontally homogeneous bed sediment, data from 27 of 34 microcosm experiments indicate that the erosion rate coefficient increased as eroded mass increased, contrary to theory. We believe that small erosion depths, erosion rate coefficient deviation from theory, and visual observation of horizontally varying biota and texture at the sediment surface indicate that erosion cannot solely be a function of depth but must also vary horizontally. We test this hypothesis by developing a simple numerical model that includes horizontal heterogeneity, use it to develop an artificial time series of suspended-sediment concentration (SSC) in an erosion microcosm, then analyze that time series assuming horizontal homogeneity. A shear vane was used to estimate that the horizontal standard deviation of critical shear stress was about 30% of the mean value at a site in the Delta. The numerical model of the erosion microcosm included a normal distribution of initial critical shear stress, a linear increase in critical shear stress with eroded mass, an exponential decrease of erosion rate coefficient with eroded mass, and a stepped increase in applied shear stress. The maximum SSC for each step increased gradually, thus confounding identification of a single well-defined critical shear stress as encountered with the empirical data. Analysis of the artificial SSC time series with the assumption of a homogeneous bed reproduced the original profile of critical shear stress, but the erosion rate coefficient increased with eroded mass, similar to the empirical data. Thus, the numerical experiment confirms the small-depth erosion hypothesis. A linear

Assessment of Coastal Vulnerability Through the Use of GIS Tools in South Sicily (Italy)

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Anfuso, Giorgio; Martínez Del Pozo, José Ángel

2009-03-01

This study assessed coastal erosion vulnerability along a 90-km sector, which included both erosional and accretionary beaches, and different levels of human occupation. Two aerial photogrammetric flights were used to reconstruct coastal evolution between 1977 and 1999. During this period, extensive accretion was recorded updrift of human structures at harbors and ports, e.g., Scoglitti (105.6 m), Donnalucata (52.8 m), and Pozzallo (94.6 m). Conversely, erosion was recorded in downdrift areas, with maximum values at Modica Stream mouth (63.8 m) and Point Castellazzo (35.2 m). Assessments were subsequently divided into four categories ranging from “high erosion” to “accretion.” Several sources were examined to assess human activities and land use. The latter was mapped and divided into four categories, ranging from “very high” to “no capital” land use. Subsequently, coastal erosion vulnerability was assessed by combining land use categories with recorded coastline behavior. Results showed “very high” to “high” vulnerability along 5.8% and 16.6%, respectively, of the littoral, while 20.9% and 56.7%, respectively, was found to exhibit “medium” and “low/very low” vulnerability. A very good agreement between predicted coastal vulnerability and coastal trend had been observed over recent years. Furthermore, several human structures and activities are located within the “imminent collapse zone (ICZ)” which reached maximum values of 17.5 m at Modica Stream and 13.5 m at Point Braccetto.

Using Shoreline Video Assessment for coastal planning and restoration in the context of climate change in Kien Giang, Vietnam

Science.gov (United States)

Van Cuong, Chu; Russell, Michael; Brown, Sharon; Dart, Peter

2015-06-01

Kien Giang, bordering Cambodia in the Mekong River Delta, is one of the two most vulnerable provinces in the region to coastal erosion and flooding. Coastal protection can conflict with current land use and economic development activities. The conditions of the mangrove forest and mainland coastline of the Kien Giang province were assessed using the Shoreline Video Assessment Method (SVAM) backed up with information from satellite images. Half of the 206 km Kien Giang coastline has been eroded or is being eroded. Protective mangrove forests naturally occurred in 74% of the coastline but have been under threat from illegal cutting, erosion and coastal retreat. Accurate information on the state of the coastline and mangrove forest health provided invaluable data for developing a new coastal rehabilitation plan to guard against future sea level rise. In contrast to the current boundary management of land and natural resources, this plan divided the provincial coastline into 19 sections based on the landscape condition and exposure to erosion. Priority strategic actions for erosion management, mangrove restoration and sustainable livelihood development for local communities for each section of coast were developed based on an integrated cross sectoral approach and practical experience in the Conservation and Development of the Kien Giang Biosphere Reserve Project.

Quantifying thresholds for significant dune erosion along the Sefton Coast, Northwest England

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Esteves, Luciana S.; Brown, Jennifer M.; Williams, Jon J.; Lymbery, Graham

2012-03-01

Field and model hindcast data are used to establish a critical dune erosion threshold for the Sefton Coast (NW England). Events are classified as causing significant erosion if they result in: (a) a mean dune retreat along the entire study area of > 2 m; (b) a dune retreat of ≥ 5 m along a coastal segment ≥ 2 km in length; and (c) an eroded area ≥ 20,000 m2. For the period 1996 to 2008, individual storms were characterised using hindcast results from a POLCOMS-WAM model and measured data from the Liverpool Bay Coastal Observatory. Results show that combined extreme surge levels (> 1.5 m) and wave heights (> 4 m), or tidal water levels above 9.0 m Chart Datum (CD), do not always result in significant dune erosion. Evidence suggests that erosion is more likely to occur when wave heights are > 2.6 m, peak water level is > 10.2 m CD at Liverpool and when consecutive tidal cycles provide 10 h or more of water levels above 9.4 m CD. However, lower water levels and wave heights, and shorter events of sustained water levels, can cause significant erosion in the summer. While the return period for events giving rise to the most severe erosion in the winter is > 50 years, significant erosion in the summer can be caused by events with return periods dune toe elevation c. 30 cm. Although the study shows it might be possible to characterise objectively storm events based on oceanographic conditions, the resultant morphological change at the coast is demonstrated to depend on the time and duration of events, and on other variables which are not so easy to quantify. Further investigation is needed to understand the influence of alongshore and seasonal variability in beach/dune morphology in determining the response to the hydrodynamic and meteorological conditions causing significant erosion. Improved monitoring pre- and post-storm of changes in beach/dune morphology is required to develop reliable proxies that can be used to establish early warning systems to mitigate the

Rates and probable causes of freshwater tidal marsh failure, Potomac River Estuary, Northern Virginia, USA

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Litwin, Ronald J.; Smoot, Joseph P.; Pavich, Milan J.; Markewich, Helaine Walsh; Oberg, Erik T.; Steury, Brent W.; Helwig, Ben; Santucci, Vincent L.; Sanders, Geoffrey

2013-01-01

Dyke Marsh, a distal tidal marsh along the Potomac River estuary, is diminishing rapidly in areal extent. This study documents Dyke Marsh erosion rates from the early-1860s to the present during pre-mining, mining, and post-mining phases. From the late-1930s to the mid-1970s, Dyke Marsh and the adjacent shallow riverbottom were mined for gravel, resulting in a ~55 % initial loss of area. Marsh loss continued during the post-mining phase (1976–2012). Causes of post-mining loss were unknown, but were thought to include Potomac River flooding. Post-mining areal-erosion rates increased from 0.138 ha yr−1 (~0.37 ac yr−1) to 0.516 ha yr−1(~1.67 ac yr−1), and shoreline-erosion rates increased from 0.76 m yr−1 (~2.5 ft yr−1) to 2.60 m yr−1 (~8.5 ft yr−1). Results suggest the accelerating post-mining erosion reflects a process-driven feedback loop, enabled by the marsh's severely-altered geomorphic and hydrologic baseline system; the primary post-mining degradation process is wave-induced erosion from northbound cyclonic storms. Dyke Marsh erosion rates are now comparable to, or exceed, rates for proximal coastal marshes in the same region. Persistent and accelerated erosion of marshland long after cessation of mining illustrates the long-term, and potentially devastating, effects that temporally-restricted, anthropogenic destabilization can have on estuarine marsh systems.

Definition of tolerable soil erosion values

Directory of Open Access Journals (Sweden)

G. Sparovek

1997-09-01

Full Text Available Although the criteria for defining erosion tolerance are well established, the limits generally used are not consistent with natural, economical and technological conditions. Rates greater than soil formation can be accepted only until a minimum of soil depth is reached, provided that they are not associated with environmental hazard or productivity losses. A sequence of equations is presented to calculate erosion tolerance rates through time. The selection of equation parameters permits the definition of erosion tolerance rates in agreement with environmental, social and technical needs. The soil depth change that is related to irreversible soil degradation can be calculated. The definition of soil erosion tolerance according to these equations can be used as a guideline for sustainable land use planning and is compatible with expert systems.

Sediment budget for Murder Creek, Georgia, USA, from Pu239+240 - determined soil erosion rates

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Stubblefield, A. P.; Matissoff, G.; Ketterer, M. E.; Whiting, P. J.

2005-12-01

Soil inventories of the radionuclides Cs137 and Pb210 have been used in a variety of environments as indicators for erosion and depositional processes. Development of sediment budgets for entire watersheds from radionuclide data has been somewhat constrained because limited sample numbers may not adequately characterize the wide range of geomorphic conditions and land uses found in heterogeneous environments. The measurement of Pu239+240 shows great potential for developing quantitative watershed sediment budgets. With inductively-coupled plasma mass spectrometry, hundreds of samples may be processed in dramatically shorter times than the gamma spectrometry method used for Cs137 or alpha spectrometry method used for Pb210. We collected surface soil samples from Murder Creek in the Piedmont region of Georgia, USA, to compare Pu239+240 inventories with Cs137 and Pb210 inventories for a range of land uses in a predominantly forested watershed. Excellent correlations were found for radionuclide inventories (r2 =0.88, n = 38) and high resolution (4 mm) depth profiles. The second objective was to generate a sediment budget using the full Pu239+240 dataset (n = 309). Average Pu239+240 inventories were 70.0 Bq/m2 for hardwood forest, 60.0 Bq/m2 for pine plantation, 65.1 Bq/m2 for pine forest, 66.7 Bq/m2 for row crop agriculture and 67.9 Bq/m2 for pasture. The sediment budget will be constructed by converting inventories into site-specific erosion rates. Erosion rates will be scaled up to the watershed scale using GIS coverages of land use, soil, slope, and slope position. Results will be compared with Murder Creek sediment budgets in the scientific literature generated from RUSLE erosion modeling, USGS monitoring networks and reservoir sedimentation.

Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

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Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

2014-01-01

Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

Ecological site‐based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands.

Science.gov (United States)

Webb, Nicholas P; Herrick, Jeffrey E; Duniway, Michael C

Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation, or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explored how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting, and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass–succulent states across the ecological sites at the plot scale (0.25 ha). We identified vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area could be effectively controlled when bare ground cover was 100 cm in length was less than ∼35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the

Detecting Anthropogenic Disturbance on Weathering and Erosion Processes

Science.gov (United States)

Vanacker, V.; Schoonejans, J.; Bellin, N.; Ameijeiras-Mariño, Y.; Opfergelt, S.; Christl, M.

2014-12-01

Anthropogenic disturbance of natural vegetation can profoundly alter the physical, chemical and biological processes within soils. Rapid removal of topsoil during intense farming can result in an imbalance between soil production through chemical weathering and physical erosion, with direct implications on local biogeochemical cycling. However, the feedback mechanisms between soil erosion, chemical weathering and biogeochemical cycling in response to anthropogenic forcing are not yet fully understood. In this paper, we analyze dynamic soil properties for a rapidly changing anthropogenic landscape in the Spanish Betic Cordillera; and focus on the coupling between physical erosion, soil production and soil chemical weathering. Modern erosion rates were quantified through analysis of sediment deposition volumes behind check dams, and represent catchment-average erosion rates over the last 10 to 50 years. Soil production rates are derived from in-situ produced 10Be nuclide concentrations, and represent long-term flux rates. In each catchment, soil chemical weathering intensities were calculated for two soil-regolith profiles. Although Southeast Spain is commonly reported as the European region that is most affected by land degradation, modern erosion rates are low (140 t ha-1 yr-1). About 50 % of the catchments are losing soils at a rate of less than 60 t km-2 yr-1. Our data show that modern erosion rates are roughly of the same magnitude as the long-term or cosmogenically-derived erosion rates in the Betic Cordillera. Soils developed on weathered metamorphic rocks have no well-developed profile characteristics, and are generally thin and stony. Nevertheless, soil chemical weathering intensities are high; and question the occurrence of past soil truncation.

Coastal vulnerability across the Pacific dominated by El Niño-Southern Oscillation

Science.gov (United States)

Barnard, Patrick L.; Short, Andrew D.; Harley, Mitchell D.; Splinter, Kristen D.; Vitousek, Sean; Turner, Ian L.; Allan, Jonathan; Banno, Masayuki; Bryan, Karin R.; Doria, André; Hansen, Jeff E.; Kato, Shigeru; Kuriyama, Yoshiaki; Randall-Goodwin, Evan; Ruggiero, Peter; Walker, Ian J.; Heathfield, Derek K.

2015-01-01

To predict future coastal hazards, it is important to quantify any links between climate drivers and spatial patterns of coastal change. However, most studies of future coastal vulnerability do not account for the dynamic components of coastal water levels during storms, notably wave-driven processes, storm surges and seasonal water level anomalies, although these components can add metres to water levels during extreme events. Here we synthesize multi-decadal, co-located data assimilated between 1979 and 2012 that describe wave climate, local water levels and coastal change for 48 beaches throughout the Pacific Ocean basin. We find that observed coastal erosion across the Pacific varies most closely with El Niño/Southern Oscillation, with a smaller influence from the Southern Annular Mode and the Pacific North American pattern. In the northern and southern Pacific Ocean, regional wave and water level anomalies are significantly correlated to a suite of climate indices, particularly during boreal winter; conditions in the northeast Pacific Ocean are often opposite to those in the western and southern Pacific. We conclude that, if projections for an increasing frequency of extreme El Niño and La Niña events over the twenty-first century are confirmed, then populated regions on opposite sides of the Pacific Ocean basin could be alternately exposed to extreme coastal erosion and flooding, independent of sea-level rise.

Sediment and Cavitation Erosion Studies through Dam Tunnels

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Muhammad Abid

2016-01-01

Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

Effect of mechanical properties on erosion resistance of ductile materials

Science.gov (United States)

Levin, Boris Feliksovih

Solid particle erosion (SPE) resistance of ductile Fe, Ni, and Co-based alloys as well as commercially pure Ni and Cu was studied. A model for SPE behavior of ductile materials is presented. The model incorporates the mechanical properties of the materials at the deformation conditions associated with SPE process, as well as the evolution of these properties during the erosion induced deformation. An erosion parameter was formulated based on consideration of the energy loss during erosion, and incorporates the material's hardness and toughness at high strain rates. The erosion model predicts that materials combining high hardness and toughness can exhibit good erosion resistance. To measure mechanical properties of materials, high strain rate compression tests using Hopkinson bar technique were conducted at strain rates similar to those during erosion. From these tests, failure strength and strain during erosion were estimated and used to calculate toughness of the materials. The proposed erosion parameter shows good correlation with experimentally measured erosion rates for all tested materials. To analyze subsurface deformation during erosion, microhardness and nanoindentation tests were performed on the cross-sections of the eroded materials and the size of the plastically deformed zone and the increase in materials hardness due to erosion were determined. A nanoindentation method was developed to estimate the restitution coefficient within plastically deformed regions of the eroded samples which provides a measure of the rebounding ability of a material during particle impact. An increase in hardness near the eroded surface led to an increase in restitution coefficient. Also, the stress rates imposed below the eroded surface were comparable to those measured during high strain-rate compression tests (10sp3-10sp4 ssp{-1}). A new parameter, "area under the microhardness curve" was developed that represents the ability of a material to absorb impact energy. By

A study of erosion rates on salt diapir surfaces in the Zagros Mountains, SE Iran

Czech Academy of Sciences Publication Activity Database

Bruthans, J.; Asadi, N.; Filippi, Michal; Wilhelm, Z.; Zare, M.

2008-01-01

Roč. 53, č. 5 (2008), s. 1079-1089 ISSN 0943-0105 R&D Projects: GA AV ČR(CZ) KJB301110501 Institutional research plan: CEZ:AV0Z30130516 Keywords : salt diapir * weathering residuum * erosion rate Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.026, year: 2008

DEFORMATION EFFECTS OF DAMS ON COASTAL REGIONS USING SENTINEL-1 IW TOPS TIME SERIES: THE WEST LESVOS, GREECE CASE

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K. Karamvasis

2017-11-01

Full Text Available Coastal zones are vulnerable to erosion and loss by level sea rise. Subsidence caused by the reduction of fluvial sediments in coastal zones found close to dams, is another important deformation factor. Quantification of the deformation rate of coastal region is essential for natural and anthropogenic activities. The study utilizes Interferometric SAR (Synthetic Aperture Radar techniques and exploits the archive of Sentinel-1 TOPS data for the period 2014–2016. The freely available, wide ground coverage (250 × 170 km and small temporal resolution Sentinel-1 TOPS datasets are promising for coastal applications. Persistent Scatterer Interferometry (PSI methodologies are considered state-of-the-art remote sensing approaches for land deformation monitoring. The selected PSI method is the Small Baseline Subset (SBAS multitemporal InSAR technique. The study area of this study is the coastal zone of west region of Lesvos Island, Greece. The main characteristic of the area is the reduction of the fluvial sediment supply from the coastal drainage basins due to construction of dams and the abstraction of riverine sediments. The study demonstrates the potentials of the SBAS method for measuring and mapping the dynamic changes in coastal topography in terms of subsidence rates and discusses its advantages and limitations. The results show that natural and rural environments appear to have diverse ground deformation patterns.

Monitoring the change of coastal zones from space

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Cazenave, A. A.; Le Cozannet, G.; Benveniste, J.; Woodworth, P. L.

2017-12-01

The world's coastal zones, where an important fraction of the world population is currently living, are under serious threat because of coastal erosion, cyclones, storms, and salinization of estuaries and coastal aquifers. In the future, these hazards are expected to increase due to the combined effects of sea level rise, climate change, human activities and population increase. The response of coastal environments to natural and anthropogenic forcing factors (including climate change) depends on the characteristics of the forcing agents, as well as on the internal properties of the coastal systems, that remain poorly known and mostly un-surveyed at global scale. To better understand changes affecting coastal zones and to provide useful information to decision makers, various types of observations with global coverage need to be collected and analysed. Observations from space appear as an important complement to existing in situ observing systems (e.g., regional tide gauge networks). In this presentation, we discuss the benefit of systematic coastal monitoring from space, addressing both observations of forcing agents and of the coastal response. We highlight the need for a global coastal sea level data set based on retracked nadir altimetry missions and new SAR technology.

Using 7Be to document soil erosion on the weed plots

International Nuclear Information System (INIS)

Zhang Bo; Zhang Fengbao; Yang Mingyi

2013-01-01

Be tracing technology was applied to document soil erosion on the bare plot and weed plot, and compae soil erosion rate with the calculated rate. Results indicated that vegetation cover had obvious effect on the estimate of soil erosion rate on the weed plot using 7 Be measurement. Therefore, a factor of vegetation had been introduced into the Walling's model of converting 7 Be activity to soil erosion rate for estimating soil erosion rate on the weed slope surface. It was found that the soil erosion rates calculated by modified model were well close to the measured values on the weed plot, which illustrated that the modified model could be well used to estimate the rates of soil loss on the weed slope surface. These findings provide effective means for further study on the relationship between vegetation cover and soil erosion. (authors)

Effects of Bank Vegetation and Incision on Erosion Rates in an Urban Stream

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Emily Arnold

2018-04-01

Full Text Available Changing land-use associated with urbanization has resulted in shifts in riparian assemblages, stream hydraulics, and sediment dynamics leading to the degradation of waterways. To combat degradation, restoration and management of riparian zones is becoming increasingly common. However, the relationship between flora, especially the influence of invasive species, on sediment dynamics is poorly understood. Bank erosion and turbidity were monitored in the Tookany Creek and its tributary Mill Run in the greater Philadelphia, PA region. To evaluate the influence of the invasive species Reynoutria japonica (Japanese knotweed on erosion, reaches were chosen based on their riparian vegetation and degree of incision. Bank pins and turbidity loggers were used to estimate sediment erosion. Erosion calculations based on bank pins suggest greater erosion in reaches dominated by knotweed than those dominated by trees. For a 9.5-month monitoring period, there was 29 cm more erosion on banks that were also incised, and 9 cm more erosion in banks with little incision. Turbidity responses to storm events were also higher (77 vs. 54 NTU (nephelometric turbidity unit in reaches with knotweed, although this increase was found when the reach dominated by knotweed was also incised. Thus, this study linked knotweed to increased erosion using multiple methods.

Dynamics of soil organic carbon and microbial biomass carbon in relation to water erosion and tillage erosion.

Science.gov (United States)

Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su

2013-01-01

Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the (137)Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of (137)Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. (137)Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion.

Extreme oceanographic forcing and coastal response due to the 2015-2016 El Niño.

Science.gov (United States)

Barnard, Patrick L; Hoover, Daniel; Hubbard, David M; Snyder, Alex; Ludka, Bonnie C; Allan, Jonathan; Kaminsky, George M; Ruggiero, Peter; Gallien, Timu W; Gabel, Laura; McCandless, Diana; Weiner, Heather M; Cohn, Nicholas; Anderson, Dylan L; Serafin, Katherine A

2017-02-14

The El Niño-Southern Oscillation is the dominant mode of interannual climate variability across the Pacific Ocean basin, with influence on the global climate. The two end members of the cycle, El Niño and La Niña, force anomalous oceanographic conditions and coastal response along the Pacific margin, exposing many heavily populated regions to increased coastal flooding and erosion hazards. However, a quantitative record of coastal impacts is spatially limited and temporally restricted to only the most recent events. Here we report on the oceanographic forcing and coastal response of the 2015-2016 El Niño, one of the strongest of the last 145 years. We show that winter wave energy equalled or exceeded measured historical maxima across the US West Coast, corresponding to anomalously large beach erosion across the region. Shorelines in many areas retreated beyond previously measured landward extremes, particularly along the sediment-starved California coast.

Intercomparison of techniques for estimation of sedimentation rate in the Sabah and Sarawak coastal waters

International Nuclear Information System (INIS)

Zal U'yun Wan Mahmood; Zaharudin Ahmad; Abdul Kadir Ishak; Che Abd Rahim Mohamed

2011-01-01

A total of eight sediment cores with 50 cm length were taken in the Sabah and Sarawak coastal waters using a gravity corer in 2004 to estimate sedimentation rates using four mathematical models of CIC, Shukla-CIC, CRS and ADE. The average of sedimentation rate ranged from 0.24 to 0.48 cm year -1 , which is calculated based on the vertical profile of 210 Pbex in sediment core. The finding also showed that the sedimentation rates derived from four models were generally shown in good agreement with similar or comparable value at some stations. However, based on statistical analysis of paired sample t-test indicated that CIC model was the most accurate, reliable and suitable technique to determine the sedimentation rate in the coastal area. (author)

Decreasing soil erosion rates with evolving land-use techniques in a central European catchment

Science.gov (United States)

Larsen, Annegret; Heckmann, Tobias; Hans-Rudolf, Bork; Alexander, Fuelling

2015-04-01

Agricultural societies around the world have caused accelerated soil erosion. Soil erosion and a decrease in soil fertility may also have caused the abandonment of entire landscapes and the collapse of civilizations. In central Europe, Medieval land-use is thought to have lead to the largest loss of top soil in history, which in turn lead to a malnutrition of the population and abandonment of agricultural land. However, this might be only part of the picture, as people are also able to adapt to changing environmental conditions, including the type of land-use they adopt. Within a catchment in the central European mountain belt, we were able to distinguish the evolution between three main types of land-use techniques between ~ 900 AD and 1950 AD: horticulture, agriculture and shifting cultivation. We were able to relate these techniques with different soil erosion rates, which differ by an order of magnitude, ranging from 0.83 ± 0.09 mm/yr to 1.62 ± 0.17 mm/yr. Using high-resolution surface data and chrono-stratigraphical methods in combination with soil charcoal analysis, we were able to reconstruct past land-use techniques on a local scale. This illustrates that less erosive and more sustainable techniques were developed through time, and hypothesize that people were able to adapt to the less favorable environmental conditions by changing the cultivation techniques. Although cultural adaptation to changing environmental conditions has been extensively discussed, this study is able to quantitatively demonstrate improved soil management with evolving land-use in central Europe.

Tectonic controls of Holocene erosion in a glaciated orogen

OpenAIRE

Adams, Byron A.; Ehlers, Todd A.

2018-01-01

Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 new 10Be and ...

Towards quantifying long-term erosion rates in the Campine Basin, NE Belgium

Science.gov (United States)

Beerten, Koen; Vanacker, Veerle

2016-04-01

The Campine Basin, NE Belgium, is situated between the uplifting Ardennes Massif and rapidly subsiding Roer Valley Graben. It contains a thick series of marine, estuarine and continental Neogene and Quaternary sediments, locally more than 300 m. As a result of relief inversion during the Quaternary, the Campine Plateau is nowadays a distinct morphological feature in this basin. Its surface elevation dips from 100 m in the south to 30 m in the north over a distance of about 60 km, which is the result of differential uplift. The Campine Plateau is covered by Early and Middle Pleistocene erosion-resistant fluvial sediments from the Rhine and Meuse and can thus be regarded as a fluvial terrace. The age of deposition and time of abandonment of the terrace have not yet been resolved by direct numerical dating. In this study, we apply the cosmogenic radionuclide (CRN) profiling technique that, in ideal circumstances, allows one to constrain the exposure age, burial age and amount of post-depositional erosion of the landform. Samples were taken from a 3.5 m deep cross-section in coarse river sands that were deposited by the river Rhine, and now situated at an altitude of about 50 m (a.s.l.). Nine of them were prepared for CRN measurements according to state-of-the-art techniques. The in-situ 10Be concentration of the samples was determined using accelerator mass spectrometry (ETH, Zurich). The in-situ 10Be concentrations are 1.5x10e5 atoms/g for the uppermost sample (at 0.3 m depth) and 0.9x10e5 at/g for the lowermost sample (at 3.1 m depth), yielding an estimated 0.6x10e5 at/g of radionuclide accumulation following sediment deposition. Using forward modelling, we solved for the exposure duration and erosion rate that best fit the measured in-situ 10Be depth profile data, nuclide inheritance and their associated analytical uncertainties. Model optimisation is here based on the sum of chi-squared between the measured and modelled 10Be concentrations. When taking previous

Assessing Rainfall Erosivity with Artificial Neural Networks for the Ribeira Valley, Brazil

Directory of Open Access Journals (Sweden)

Reginald B. Silva

2010-01-01

Full Text Available Soil loss is one of the main causes of pauperization and alteration of agricultural soil properties. Various empirical models (e.g., USLE are used to predict soil losses from climate variables which in general have to be derived from spatial interpolation of point measurements. Alternatively, Artificial Neural Networks may be used as a powerful option to obtain site-specific climate data from independent factors. This study aimed to develop an artificial neural network to estimate rainfall erosivity in the Ribeira Valley and Coastal region of the State of São Paulo. In the development of the Artificial Neural Networks the input variables were latitude, longitude, and annual rainfall and a mathematical equation of the activation function for use in the study area as the output variable. It was found among other things that the Artificial Neural Networks can be used in the interpolation of rainfall erosivity values for the Ribeira Valley and Coastal region of the State of São Paulo to a satisfactory degree of precision in the estimation of erosion. The equation performance has been demonstrated by comparison with the mathematical equation of the activation function adjusted to the specific conditions of the study area.

Use of a mobile terrestrial laser system to quantify the impact of rigid coastal protective structures on sandy beaches, Quebec, Canada

Science.gov (United States)

Van-Wierts, S.; Bernatchez, P.

2012-04-01

Coastal erosion is an important issue within the St-Lawrence estuary and gulf, especially in zones of unconsolidated material. Wide beaches are important coastal environments; they act as a buffer against breaking waves by absorbing and dissipating their energy, thus reducing the rate of coastal erosion. They also offer protection to humans and nearby ecosystems, providing habitat for plants, animals and lifeforms such as algae and microfauna. Conventional methods, such as aerial photograph analysis, fail to adequately quantify the morphosedimentary behavior of beaches at the scale of a hydrosedimentary cells. The lack of reliable and quantitative data leads to considerable errors of overestimation and underestimation of sediment budgets. To address these gaps and to minimize acquisition costs posed by airborne LiDAR survey, a mobile terrestrial LiDAR has been set up to acquire topographic data of the coastal zone. The acquisition system includes a LiDAR sensor, a high precision navigation system (GPS-INS) and a video camera. Comparison of LiDAR data with 1050 DGPS control points shows a vertical mean absolute error of 0.1 m in beach areas. The extracted data is used to calculate sediment volumes, widths, slopes, and a sediment budget index. A high accuracy coastal characterization is achieved through the integration of laser data and video. The main objective of this first project using this system is to quantify the impact of rigid coastal protective structures on sediment budget and beach morphology. Results show that the average sediment volume of beaches located before a rock armour barrier (12 m3/m) were three times narrower than for natural beaches (35,5 m3/m). Natural beaches were also found to have twice the width (25.4 m) of the beaches bordering inhabited areas (12.7 m). The development of sediment budget index for beach areas is an excellent proxy to quickly identify deficit areas and therefore the coastal segments most at risk of erosion. The obtained

Proceedings of the 79th Meeting of the Coastal Engineering Research Board, 6-10 June 2005 (Anchorage, AK)

Science.gov (United States)

2006-09-29

integrated Coastal Community Vulnerability and Adaptation Program focused on improving the resilience of coastal communities to natural hazards and...in sharp contrast to the situation of a coastal community facing a serious erosion threat. The nature of the problem may be pretty clear, but the...products to improve the preparedness of communities, businesses, and government entities. As described in Section 8 of S.50, this Coastal

Coastal sediment elevation change following anthropogenic mangrove clearing

Science.gov (United States)

Hayden, Heather L.; Granek, Elise F.

2015-11-01

Coastal mangrove forests along tropical shorelines serve as an important interface between land and sea. They provide a physical buffer protecting the coastline from erosion and act as sediment "traps" catching terrestrial sediment, thus preventing smothering of subtidal coral reefs. Coastal development that removes mangrove habitat may impact adjacent nearshore coral reefs through sedimentation and nutrient loading. We examined differences in sediment elevation change between patches of open-coast intact and anthropogenically cleared red mangroves (Rhizophora mangle) on the east side of Turneffe Atoll, Belize, to quantify changes following mangrove clearing. Samples were collected over a 24 month period at five study sites, each containing paired intact (+mangrove) and cleared (-mangrove) plots. Five sediment elevation pins were deployed in each plot: behind areas cleared of mangroves (-mangrove) and behind adjacent intact mangroves (+mangrove). Sediment elevation increased at intact mangrove sites (M = +3.83 mm, SE = 0.95) whereas cleared mangrove areas suffered elevation loss (M = -7.30 mm, SE = 3.38). Mangroves inshore of partial or continuous gaps in the adjacent fringing reefs had higher rates of elevation loss (M = -15.05 mm) than mangroves inshore of continuous fringing reefs (M = -1.90 mm). Our findings provide information on potential effects of mangrove clearing and the role of offshore habitat characteristics on coastal sediment trapping and maintenance of sediment elevation by mangroves. With implications for coastline capacity to adjust to sea level rise, these findings are relevant to management of coastal fringing mangrove forests across the Caribbean.

Spatial and temporal assessment of back-barrier erosion on Cumberland Island National Seashore, Georgia, 2011–2013

Science.gov (United States)

Calhoun, Daniel L.; Riley, Jeffrey W.

2016-07-15

Much research has been conducted to better understand erosion and accretion processes for the seaward zones of coastal barrier islands; however, at Cumberland Island National Seashore, Georgia, the greater management concern is the effect that erosion is having on the resources of the island’s western shoreline, or the back barrier. Catastrophic slumping and regular rates of erosion greater than 1 meter per year threaten important habitat, historical and pre-historical resources, and modern infrastructure on the island. Prior research has helped National Park Service (NPS) staff identify the most severe and vulnerable areas, but in order to develop effective management actions, information is needed on what forces and conditions cause erosion. To this end, the U.S. Geological Survey, in cooperation with the NPS, conducted two longitudinal surveys, one each at the beginning and end of the approximately year-long monitoring period from late 2011 to early 2013, along five selected segments of the back barrier of the Cumberland Island National Seashore. Monitoring stations were constructed at four of these locations that had previously been identified as erosional hotspots. The magnitude of erosion at each location was quantified to determine the relative influence of causative agents. Results indicate that erosion is, in general, highly variable within and among these segments of the Cumberland Island National Seashore’s back barrier. Observed erosion ranged from a maximum of 2.5 meters of bluff-line retreat to some areas that exhibited no net erosion over the 1-year study period. In terms of timing of erosion, three of the four sites were primarily affected by punctuated erosional events that were coincident with above-average high tides and elevated wind speeds. The fourth site exhibited steady, low-magnitude retreat throughout the study period. While it is difficult to precisely subscribe certain amounts of erosion to specific agents, this study provides

Coastal zones : shifting shores, sharing adaptation strategies for coastal environments

Energy Technology Data Exchange (ETDEWEB)

Hay, J.E. [Waikato Univ. (New Zealand); Morneau, F.; Savard, J.P. [Ouranos, Montreal, PQ (Canada); Madruga, R.P. [Centre of Investigation on the Global Economy (Cuba); Leslie, K.R. [Caribbean Community Climate Change Centre (Belize); Agricole, W. [Ministry of Environment and Natural Resources (Seychelles); Burkett, V. [United States Geological Survey (United States)

2006-07-01

A parallel event to the eleventh Conference of Parties (COP) to the United Nations Framework Convention of Climate Change was held to demonstrate examples of adaptation from around the world in the areas of food security, water resources, coastal zones, and communities/infrastructure. Panels on each theme presented examples from developing countries, countries in economic transition, and developed countries. These 4 themes were chosen because both mitigation and adaptation are essential to meeting the challenge of climate change. The objective of the event was to improve the knowledge of Canada's vulnerabilities to climate change, identify ways to minimize the negative effects of future impacts, and explore opportunities that take advantage of any positive impacts. This third session focused on how coastal communities are adapting to climate change in such places as Quebec, the Caribbean, and small Island States. It also presented the example of how a developed country became vulnerable to Hurricane Katrina which hit the coastal zone in the United States Gulf of Mexico. The presentations addressed the challenges facing coastal communities along with progress in risk assessment and adaptation both globally and in the Pacific. Examples of coastal erosion in Quebec resulting from climate change were presented along with climate change and variability impacts over the coastal zones of Seychelles. Cuba's vulnerability and adaptation to climate change was discussed together with an integrated operational approach to climate change, adaptation, biodiversity and land utilization in the Caribbean region. The lessons learned from around the world emphasize that adaptation is needed to reduce unavoidable risks posed by climate change and to better prepare for the changes ahead. refs., tabs., figs.

The use of 137Cs to establish longer-term soil erosion rates on footpaths in the UK.

Science.gov (United States)

Rodway-Dyer, S J; Walling, D E

2010-10-01

There is increasing awareness of the damage caused to valuable and often unique sensitive habitats by people pressure as degradation causes a loss of plant species, disturbance to wildlife, on-site and off-site impacts of soil movement and loss, and visual destruction of pristine environments. This research developed a new perspective on the problem of recreational induced environmental degradation by assessing the physical aspects of soil erosion using the fallout radionuclide caesium-137 ((137)Cs). Temporal sampling problems have not successfully been overcome by traditional research methods monitoring footpath erosion and, to date, the (137)Cs technique has not been used to estimate longer-term soil erosion in regard to sensitive recreational habitats. The research was based on-sites within Dartmoor National Park (DNP) and the South West Coast Path (SWCP) in south-west England. (137)Cs inventories were reduced on the paths relative to the reference inventory (control), indicating loss of soil from the path areas. The Profile Distribution Model estimated longer-term erosion rates (ca. 40 years) based on the (137)Cs data and showed that the combined mean soil loss for all the sites on 'paths' was 1.41 kg m(-2) yr(-1) whereas the combined 'off path' soil loss was 0.79 kg m(-2) yr(-1), where natural (non-recreational) soil redistribution processes occur. Recreational pressure was shown to increase erosion in the long-term, as greater soil erosion occurred on the paths, especially where there was higher visitor pressure. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Rate and cost of soil erosion in Monkayo, Compostela Valley Province Philippines

Directory of Open Access Journals (Sweden)

Sunshine G. Paulin

2016-01-01

Full Text Available Soil erosion is a major agricultural and environmental problem in the Philippines that is primarily caused by rainfall under upland, subsistence rainfed farming. The study sought to compare the degree of erosion as influenced by different upland tillage systems using soil erosion plots and MUSLE model, and estimate the cost of soil erosion in Monkayo, Compostela Valley. The erosion plots were laid on a 31.45 percent slope with a seasonal rainfall intensity of 2,314 mm. Corn (Zea mays L. planted through conventional tillage generated a mean soil loss of 2.64 t/ha/cropping, which is higher than the reduced tillage with a mean of 1.20 t/ha/cropping. The weighted on-site soil loss was 12 percent lower than the obtained soil erosion using the modified Universal Soil Loss Equation that is 2.97 t/ha. The study developed equations to estimate soil loss (t/ha per seasonal rainfall on three tillage systems using linear regression analysis which are: (1 E= -0.0031+0.0003R, (2 E= -0.0406+0.0011R, and (3 E=0.2249+0.0034R in corn grown on undisturbed land with natural vegetation, corn grown on bare soil through dibble method and corn planted through conventional planting system, respectively. On-site cost of erosion ranged from Php 1,473.42/ha/cropping to Php 1,938.81/ha/cropping. The amount of soil eroded can be attributed to the higher erositivity of rains, higher erodibility of the soil surface, and the poor soil cover.

Pressure and velocity dependence of flow-type cavitation erosion

CSIR Research Space (South Africa)

Auret, JG

1993-12-01

Full Text Available Previous results on the influence of water pressure and velocity on flow-type cavitations erosion, i.e. an increase in erosion rate with increasing velocity and peaking of erosion rate as a function of pressure, were confirmed by measurements with a...

Development of a Climate Change Adaptation Strategy for Management of Coastal Marsh Systems in Southern New England USA

Science.gov (United States)

Sea level rise is accelerating throughout the U.S. Northeast causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat ...

Development of a Climate-Change Adaptation Strategy for Management of Coastal Marsh Systems in Southern New England USA

Science.gov (United States)

Sea level rise is accelerating throughout the U.S. Northeast causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat ...

Review of denudation processes and quantification of weathering and erosion rates at a 0.1 to 1 Ma time scale

Energy Technology Data Exchange (ETDEWEB)

Olvmo, Mats (Univ. of Goeteborg, Goeteborg (Sweden). Dept. of Earth Sciences)

2010-06-15

The Forsmark and Laxemar areas are quite similar from a geomorphological point of view. Both sites are situated within intact parts of the Sub-Cambrian Peneplain with extremely low relief. The peneplain is considered to be intact at both sites, i.e. the present relief is quite close to the original surface of this old denudation surface. The total amount of glacial erosion up to present is estimated to be relatively low at both sites (less than 10 m on average), but may have been quite important for stripping of old regolith, especially along fracture zones. This is most obvious in the vicinity of the Forsmark site where the dissected coastline 15 km south of the site is interpreted as a result of glacial erosion along old fracture zones. Therefore, from a strict glacial erosion perspective the Laxemar site is somewhat better than Forsmark. However, given the presented long-term denudation up to present, the expected amount of glacial erosion during a future glacial cycle, if similar to the last glacial cycle, is probably very limited for both sites, in the order of 2-5 m. Excluding glacial erosion, the long-term denudation rates of the two sites is fairly low as a consequence of the very low relief and the proximity to base level. The figures estimated for the long term denudation rates are in agreement with reports of denudation rates in shield areas and lie within the range 0 to 10 m/Ma for both sites. A scenario with a five-fold increase of relief that could be the effect of tectonic uplift, in a time perspective considerably longer than the coming 100,000 years, does not significantly change the picture. Even if the local relief is raised to above 100 m at both sites the estimated non-glacial denudation is very low. However, it should be noted that the effect of a relief change on the glacial system is not included in the calculations. Again, such a change on the pattern of glacial erosion would be more pronounced in the Forsmark area, since the coastline is

Review of denudation processes and quantification of weathering and erosion rates at a 0.1 to 1 Ma time scale

International Nuclear Information System (INIS)

Olvmo, Mats

2010-06-01

The Forsmark and Laxemar areas are quite similar from a geomorphological point of view. Both sites are situated within intact parts of the Sub-Cambrian Peneplain with extremely low relief. The peneplain is considered to be intact at both sites, i.e. the present relief is quite close to the original surface of this old denudation surface. The total amount of glacial erosion up to present is estimated to be relatively low at both sites (less than 10 m on average), but may have been quite important for stripping of old regolith, especially along fracture zones. This is most obvious in the vicinity of the Forsmark site where the dissected coastline 15 km south of the site is interpreted as a result of glacial erosion along old fracture zones. Therefore, from a strict glacial erosion perspective the Laxemar site is somewhat better than Forsmark. However, given the presented long-term denudation up to present, the expected amount of glacial erosion during a future glacial cycle, if similar to the last glacial cycle, is probably very limited for both sites, in the order of 2-5 m. Excluding glacial erosion, the long-term denudation rates of the two sites is fairly low as a consequence of the very low relief and the proximity to base level. The figures estimated for the long term denudation rates are in agreement with reports of denudation rates in shield areas and lie within the range 0 to 10 m/Ma for both sites. A scenario with a five-fold increase of relief that could be the effect of tectonic uplift, in a time perspective considerably longer than the coming 100,000 years, does not significantly change the picture. Even if the local relief is raised to above 100 m at both sites the estimated non-glacial denudation is very low. However, it should be noted that the effect of a relief change on the glacial system is not included in the calculations. Again, such a change on the pattern of glacial erosion would be more pronounced in the Forsmark area, since the coastline is

Understanding Reef Flat Sediment Regimes and Hydrodynamics can Inform Erosion Mitigation on Land

Directory of Open Access Journals (Sweden)

Lida Tenkova Teneva

2016-01-01

Full Text Available Coral reefs worldwide are affected by excessive sediment and nutrient delivery from adjacent watersheds. Land cover and land use changes contribute to reef ecosystem degradation, which in turn, diminish many ecosystem services, including coastal protection, recreation, and food provisioning. The objectives of this work were to understand the role of coastal oceanic and biophysical processes in mediating the effects of sedimentation in shallow reef environments, and to assess the efficacy of land-based sediment remediation in the coastal areas near Maunalei reef, Lāna’i Island, Hawai’i. To the best of our knowledge, this was the first study of sediment dynamics on an east-facing (i.e., facing the trade winds reef in the Hawaiian Islands. We developed ridge-to-reef monitoring systems at two paired stream bed-to-reef sites, where one of the reef sites was adjacent to a community stream sediment remediation project. We found that the two reef sites were characterized by different processes that affected the sediment removal rates; the two sites were also exposed to different amounts of sediment runoff. The community stream sediment remediation project appeared to keep at least 77 tonnes of sediment off the reef flat in one wet season. We found that resuspension of sediments on this reef was similar to that on north-facing and south-facing reefs that also are exposed to the trade winds. We posit that sites with slower sediment removal rates due to slower current velocities or high resuspension rates will require more-robust sediment capture systems on land to reduce sediment input rates and maximize potential for reef health recovery. This suggests that interventions such as local sediment remediation and watershed restoration may mitigate sediment delivery to coral reefs, but these interventions are more likely to be effective if they account for how adjacent coastal oceanographic processes distribute, accumulate, or advect sediment away from

Saliva composition in three selected groups with normal stimulated salivary flow rates, but yet major differences in caries experience and dental erosion.

Science.gov (United States)

Bardow, Allan; Lykkeaa, Joan; Qvist, Vibeke; Ekstrand, Kim; Twetman, Svante; Fiehn, Niels-Erik

2014-08-01

It was hypothesized that, by comparing matched subjects with major differences in these dental diseases, but yet normal saliva flow rates, it would be possible to obtain data on the effect of saliva composition on dental disease isolated from the effect of the flow rate. Thus, the aim of the study was to compare the major physicochemical characteristics of stimulated whole saliva in three groups of 85 subjects, each with normal saliva flow rates and at least 24 remaining teeth. A group with very little dental disease (healthy), a group with dental erosion (erosion) and a group with very high caries experience (caries) were chosen. Furthermore, the aim was to determine whether differences among groups could also be found on an individual level. Although it was not possible to retrieve three groups whose members were completely identical, the present study points in the direction that, on a group level, subjects with very little dental disease seemed to have a more favorable physicochemical saliva composition with respect to higher calcium, phosphate, bicarbonate, pH, degree of saturation with respect to hydroxyapatite and a lower critical pH (p dental erosion (p dental caries and erosion in single individuals.

Application of the Coastal Hazard Wheel methodology for coastal multi-hazard assessment and management in the state of Djibouti

Directory of Open Access Journals (Sweden)

Lars Rosendahl Appelquist

2014-01-01

Full Text Available This paper presents the application of a new methodology for coastal multi-hazard assessment and management in a changing global climate on the state of Djibouti. The methodology termed the Coastal Hazard Wheel (CHW is developed for worldwide application and is based on a specially designed coastal classification system that incorporates the main static and dynamic parameters determining the characteristics of a coastal environment. The methodology provides information on the hazards of ecosystem disruption, gradual inundation, salt water intrusion, erosion and flooding and can be used to support management decisions at local, regional and national level, in areas with limited access to geophysical data. The assessment for Djibouti applies a geographic information system (GIS to develop a range of national hazard maps along with relevant hazard statistics and is showcasing the procedure for applying the CHW methodology for national hazard assessments. The assessment shows that the coastline of Djibouti is characterized by extensive stretches with high or very high hazards of ecosystem disruption, mainly related to coral reefs and mangrove forests, while large sections along the coastlines of especially northern and southern Djibouti have high hazard levels for gradual inundation. The hazard of salt water intrusion is moderate along most of Djibouti’s coastline, although groundwater availability is considered to be very sensitive to human ground water extraction. High or very high erosion hazards are associated with Djibouti’s sedimentary plains, estuaries and river mouths, while very high flooding hazards are associated with the dry river mouths.

PENGKLASTERAN EROSI DI SUB DAS NGRANCAH KULONROGO (Soil Erosion Rates Clustering of Ngrancah Sub Watershed, Kulon Progo

Directory of Open Access Journals (Sweden)

Ambar Kusumandari

2012-03-01

Full Text Available ABSTRAK Penelitian ini dilakukan di Sub DAS Ngrancah yang merupakan daerah tangkapan air Waduk Sermo. Luas wilayah penelitian ini sekitar 2.200 ha. Mayoritas lahan di Sub DAS Ngrancah tergolong kritis yang ditunjukkan oleh tingginya tingkat erosi. Dengan demikian, wilayah ini sangat mendesak untuk dapat dikelola dengan benar agar degradasi lahan dapat dihambat. Untuk memprediksi erosi, diterapkan Model USLE, dengan rumus: A = RKLSCP. Wilayah studi dapat dipilahkan menjadi 77 unit lahan. Sampel tanah diambil dari seluruh unit lahan, demikian pula pengamatan lereng, vegetasi, dan penerapan konservasi tanah. Untuk menganalisis data digunakan analisis kluster. Hasil penelitian menunjukkan bahwa tingkat erosi bervariasi dari yang paling rendah sebesar 2,54 ton/ha/th sampai dengan yang tertinggi sebesar 489,30 ton/ha/th. Sekitar 68% wilayah studi termasuk dalam kelas erosi sedang dan sekitar 15% wilayah studi termasuk dalam kelas erosi tinggi. Pengklasteran unit lahan secara statistik menunjukkan bahwa pada jarak klaster terpendek terbentuk 8 klaster tingkat erosi. Uji diskriminan menunjukkan bahwa faktor K (erodibilitas dan P (praktek konservasi tanah dan air merupakan faktor yang paling dominan untuk terbentuknya klaster-klaster tersebut. Hasil penelitian ini diharapkan bermanfaat dalam merancang teknik konservasi tanah dan air untuk menangani erosi di Sub DAS Ngrancah. ABSTRACT The research was carried out at Ngrancah Sub Watershed which is located at the upper area of Sermo Dam and covers an area of almost 2.200 hectares.  The area is mostly critical showed by the high rates of erosion, so, it is  urgently required to manage properly in order to combat  land degradation. In this research, to study the erosion rates of the area, the USLE method was used, i.e. A = RxKxLSxCxP. The area was devided into 77 land units and the soil samples were taken from each land units as well as the observation of slopes, vegetation and soil conservation practices

Coral reefs for coastal protection: A new methodological approach and engineering case study in Grenada.

Science.gov (United States)

Reguero, Borja G; Beck, Michael W; Agostini, Vera N; Kramer, Philip; Hancock, Boze

2018-03-15

Coastal communities in tropical environments are at increasing risk from both environmental degradation and climate change and require urgent local adaptation action. Evidences show coral reefs play a critical role in wave attenuation but relatively little direct connection has been drawn between these effects and impacts on shorelines. Reefs are rarely assessed for their coastal protection service and thus not managed for their infrastructure benefits, while widespread damage and degradation continues. This paper presents a systematic approach to assess the protective role of coral reefs and to examine solutions based on the reef's influence on wave propagation patterns. Portions of the shoreline of Grenville Bay, Grenada, have seen acute shoreline erosion and coastal flooding. This paper (i) analyzes the historical changes in the shoreline and the local marine, (ii) assess the role of coral reefs in shoreline positioning through a shoreline equilibrium model first applied to coral reef environments, and (iii) design and begin implementation of a reef-based solution to reduce erosion and flooding. Coastline changes in the bay over the past 6 decades are analyzed from bathymetry and benthic surveys, historical imagery, historical wave and sea level data and modeling of wave dynamics. The analysis shows that, at present, the healthy and well-developed coral reefs system in the southern bay keeps the shoreline in equilibrium and stable, whereas reef degradation in the northern bay is linked with severe coastal erosion. A comparison of wave energy modeling for past bathymetry indicates that degradation of the coral reefs better explains erosion than changes in climate and historical sea level rise. Using this knowledge on how reefs affect the hydrodynamics, a reef restoration solution is designed and studied to ameliorate the coastal erosion and flooding. A characteristic design provides a modular design that can meet specific engineering, ecological and

The influence of engineering design considerations on species recruitment and succession on coastal defence structures

OpenAIRE

Jackson, Juliette Elizabeth

2015-01-01

Engineering design considerations of artificial coastal structures were tested to resemble as far as possible the nearest natural equivalent habitat, ecologically valuable rocky shores, as a potential management option. Coastal areas around the world attract urbanisation but these transitional areas between sea and land are inherently vulnerable to risk of flooding and erosion. Thus hard structures are often built in sensitive coastal environments to defend assets such as property and infrast...

The interaction of prehistoric human settlement, sea level change and tectonic uplift of the Coastal Range, eastern Taiwan

Science.gov (United States)

Yang, H.; Chen, W. S.

2017-12-01

The late Cenozoic mountain belt of Taiwan, resulting from the collision between the Eurasian and Philippine Sea plates, is known for its rapid tectonic uplift. As postglacial sea level rose ca. 15,000 yr ago, the eastern coast of Taiwan, due to the rapid tectonic uplift rate, displayed a totally different scenario comparing with most of the coastal plains around the world. At the beginning of postglacial era, the sea level rising rate was greater than the tectonic uplift rate which induced the original piedmont alluvial fan or coastal plain to be overwhelmed by sea water rapidly. Around 13.5 ka, the tectonic uplift rate caught up with the sea level rising and broad wave-cut platform formed. The approximation of tectonic uplift and sea level rising rates was lasting from 13.5 to 5ka, but shoreline progradation may have been enhanced by increased slope erosion which resulted in the alluvial fan forming at the later time of this period. As soon as the eustasy stabilized, the landmass continued to uplift which might have enhanced the river incising and wave erosion rapidly. Therefore the topographic expression along the eastern fringing of Coastal Range forms extended alluvial-fan, stream, and marine terraces and are covered by late Holocene colluvium and marine deposits. 88 archaeological sites were chosen in this study based on surface survey where the archaeological chronology of cultural stage is established primarily through examining pottery series and associated manual excavation. It is interesting that most of the archaeological sites were located on the alluvial fan although the Holocene marine terraces have formed after 5ka. There are no clear evidences to support a shore-oriented settlement, but the abundant alluvial depositional structures observed from the overlaying formation reveals the stream depositional system was still active at this time. If the Neolithic people wanted to come to the "new born" coastal region for the abundant ocean resources, they

Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño

Science.gov (United States)

Barnard, Patrick; Hoover, Daniel J.; Hubbard, David M.; Snyder, Alexander; Ludka, Bonnie C.; Allan, Jonathan; Kaminsky, George M.; Ruggiero,; Gallien, Timu W.; Gabel, Laura; McCandless, Diana; Weiner, Heather M.; Cohn, Nicholas; Anderson, Dylan L.; Serafin, Katherine A.

2017-01-01

The El Niño-Southern Oscillation is the dominant mode of interannual climate variability across the Pacific Ocean basin, with influence on the global climate. The two end members of the cycle, El Niño and La Niña, force anomalous oceanographic conditions and coastal response along the Pacific margin, exposing many heavily populated regions to increased coastal flooding and erosion hazards. However, a quantitative record of coastal impacts is spatially limited and temporally restricted to only the most recent events. Here we report on the oceanographic forcing and coastal response of the 2015–2016 El Niño, one of the strongest of the last 145 years. We show that winter wave energy equalled or exceeded measured historical maxima across the US West Coast, corresponding to anomalously large beach erosion across the region. Shorelines in many areas retreated beyond previously measured landward extremes, particularly along the sediment-starved California coast.

Molybdenum erosion measurements in Alcator C-Mod

Energy Technology Data Exchange (ETDEWEB)

Wampler, W.R. [Sandia National Labs., Albuquerque, NM (United States); LaBombard, B.; Lipshultz, B.; Pappas, D.; Pitcher, C.S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); McCracken, G.M. [JET Joint Undertaking, Abingdon (United Kingdom)

1998-05-01

Erosion of molybdenum was measured on a set of 21 tiles after a run campaign of 1,090 shots in the Alcator C-Mod tokamak. The net erosion of molybdenum, was determined from changes in the depth of a thin chromium marker layer measured by Rutherford backscattering. Net Mo erosion was found to be approximately 150 nm near the outer divertor strike point, and much less everywhere else. Gross erosion rates by sputtering were estimated using ion energies and fluxes obtained from Langmuir probe measurements of edge-plasma conditions. Predicted net erosion using calculated gross erosion with prompt redeposition and measured net erosion agree within a factor of 3. Sputtering by boron and molybdenum impurities dominates erosion.

Shoreline change due to coastal structures of power plants

International Nuclear Information System (INIS)

Kang, K. S.; Lee, T. S.; Kim, Y. I.

2001-01-01

Characteristics of shoreline change at the coastal area near power plant were analyzed. For a nuclear power plant located in the east coast of Korean peninsula, remote-sensing data, i.e.airborne images and satellite images are acquired and shoreline data were extracted. Recession and davance of shoreline due to coastal structures of powder plant and land reclamation was showed. 1-line numerical shoreline change model was established for simulating the response of shoreline to construction of coastal structures. The model uses curvilinear coordinates that follow the shoreline and is capable of handling the formation of tombolos as well as the growth of salients in the vicinity of coastal structures. The model predicted significant erosion of beach in case breakwaters were extended. Offshore breakwaters were suggested as a countermeasure to shoreline change

SSEM: A model for simulating runoff and erosion of saline-sodic soil slopes under coastal reclamation

Science.gov (United States)

Liu, Dongdong; She, Dongli

2018-06-01

Current physically based erosion models do not carefully consider the dynamic variations of soil properties during rainfall and are unable to simulate saline-sodic soil slope erosion processes. The aim of this work was to build upon a complete model framework, SSEM, to simulate runoff and erosion processes for saline-sodic soils by coupling dynamic saturated hydraulic conductivity Ks and soil erodibility Kτ. Sixty rainfall simulation rainfall experiments (2 soil textures × 5 sodicity levels × 2 slope gradients × 3 duplicates) provided data for model calibration and validation. SSEM worked very well for simulating the runoff and erosion processes of saline-sodic silty clay. The runoff and erosion processes of saline-sodic silt loam were more complex than those of non-saline soils or soils with higher clay contents; thus, SSEM did not perform very well for some validation events. We further examined the model performances of four concepts: Dynamic Ks and Kτ (Case 1, SSEM), Dynamic Ks and Constant Kτ (Case 2), Constant Ks and Dynamic Kτ (Case 3) and Constant Ks and Constant Kτ (Case 4). The results demonstrated that the model, which considers dynamic variations in soil saturated hydraulic conductivity and soil erodibility, can provide more reasonable runoff and erosion prediction results for saline-sodic soils.

Intensified coastal development behind nourished beaches

Science.gov (United States)

Armstrong, Scott; Lazarus, Eli; Limber, Patrick; Goldstein, Evan; Thorpe, Curtis; Ballinger, Rhoda

2016-04-01

Population density, housing development, and property values in coastal counties along the U.S. Atlantic and Gulf Coasts continue to rise despite increasing hazard from storm impacts. Since the 1970s, beach nourishment, which involves importing sand to deliberately widen an eroding beach, has been the main strategy in the U.S. for protecting coastal properties from erosion and flooding hazards. Paradoxically, investment in hazard protection may intensify development. Here, we examine the housing stock of all existing shorefront single-family homes in Florida - a microcosm of U.S. coastal hazards and development - to quantitatively compare development in nourishing and non-nourishing towns. We find that nourishing towns now account for more than half of Florida's coastline, and that houses in nourishing towns are larger and more numerous. Even as the mean size of single-family homes nationwide has grown steadily since 1970, Florida's shorefront stock has exceeded the national average by 34%, and in nourishing towns by 45%. This emergent disparity between nourishing and non-nourishing towns in Florida demonstrates a pattern of intensifying coastal risk, and is likely representative of a dominant trend in coastal development more generally. These data lend empirical support to the hypothesis that US coastal development and hazard mitigation through beach nourishment have become dynamically coupled.

Mapping soil erosion risk in Serra de Grândola (Portugal)

Science.gov (United States)

Neto Paixão, H. M.; Granja Martins, F. M.; Zavala, L. M.; Jordán, A.; Bellinfante, N.

2012-04-01

Geomorphological processes can pose environmental risks to people and economical activities. Information and a better knowledge of the genesis of these processes is important for environmental planning, since it allows to model, quantify and classify risks, what can mitigate the threats. The objective of this research is to assess the soil erosion risk in Serra de Grândola, which is a north-south oriented mountain ridge with an altitude of 383 m, located in southwest of Alentejo (southern Portugal). The study area is 675 km2, including the councils of Grândola, Santiago do Cacém and Sines. The process for mapping of erosive status was based on the guidelines for measuring and mapping the processes of erosion of coastal areas of the Mediterranean proposed by PAP/RAC (1997), developed and later modified by other authors in different areas. This method is based on the application of a geographic information system that integrates different types of spatial information inserted into a digital terrain model and in their derivative models. Erosive status are classified using information from soil erodibility, slope, land use and vegetation cover. The rainfall erosivity map was obtained using the modified Fournier index, calculated from the mean monthly rainfall, as recorded in 30 meteorological stations with influence in the study area. Finally, the soil erosion risk map was designed by ovelaying the erosive status map and the rainfall erosivity map.

The global coastal hazards data base

International Nuclear Information System (INIS)

Gornitz, V.; White, T.W.

1989-01-01

A rise of sea level between 0.5 and 1.5 m, caused by predicted climate warming in the next century, could jeopardize low-lying radioactive waste disposal sites near the coast, due to permanent and episodic inundation, increased shoreline retreat, and changes in the water table. The effects of global sea level rise on the shoreline will not be spatially uniform. Therefore, site selection will depend on assessment of these differential vulnerabilities, in order to avoid high-risk coasts. The coastal hazards data base described here could provide an appropriate framework. The coastal hazards data base integrates relevant topographic, geologic, geomorphologic, erosional and subsidence information in a Geographic Information System (GIS), to identify high-risk shorelines characterized by low coastal relief, an erodible substrate, present and past evidence of subsidence, extensive shoreline retreat, and high wave/tide energies. Data for seven variables relating to inundation and erosion hazards are incorporated into the ORNL ARC/INFO Geographic Information System (GIS). Data compilation has been completed for the US and is being extended to North America, and ultimately the world. A coastal vulnerability index (CVI) has been designed to flag high risk coastal segments. 17 refs., 2 figs., 2 tabs

Validating an erosion model using the environmental radionuclide 210Pb in the Lake Wollumboola catchment, southwestern NSW, Australia

International Nuclear Information System (INIS)

Simms, A.; Woodroffe, C.; Jones, B.G.; Heijnis, H.; Harrison, J.; Brooke, B.

2005-01-01

Soil erosion is a key limitation to achieving sustainable land use and effective soil management, and is the major source of sediment to Australian water bodies resulting in degradation of water quality. Sediment delivery is an important constraint on the sustainable management of coastal lakes along the south coast of New South Wales. Assessment and mitigation of sediment input is a major issue for the sustainable management of water bodies such as coastal lakes and soil erosion caused by rainfall and runoff is of particular concern. In this paper we examine the application of 210 Pb analyses of sediment samples to test the extent to which a modified version of the Universal Soil Loss Equation for Australian conditions (OxMUSCLE) is valid. The model is applied to Lake Wollumboola to estimate sediment yield from the catchment into its terminal lake, which is a saline coastal lake 172 km south of Sydney. 14 refs., 1 fig., 1 tab

[US Geological Survey research in radioactive waste disposal, fiscal year 1980:] Tectonics, seismicity, volcanism, and erosion rates in the southern Great Basin

International Nuclear Information System (INIS)

Carr, W.J.; Rogers, A.M.

1982-01-01

The objective is to assess the potential for faulting, damaging earthquakes, recurrence of volcanism, and local acceleration of erosion in parts of the southern Great Basin. The following approaches are being used: (1) investigating the rate, intensity, and distribution of faulting during approximately the last 25 m.y., with emphasis on the last 10 m.y.; (2) monitoring and interpreting present seismicity; (3) studying the history of volcanism; and (4) evaluating past rates of erosion and deposition. Progress is reported

Quantifying the erosion processes and land-uses which dominate fine sediment supply to Moreton Bay, Southeast Queensland, Australia

International Nuclear Information System (INIS)

Wallbrink, Peter J.

2004-01-01

In this paper, the contributions from the three major erosion sources in the catchments of Moreton Bay are quantified, specifically for the 137 Cs and 226 Ra were measured on the <10 μm fraction of eroding soils from these areas and then compared to concentrations on the same size fraction on deposited sediments within the rivers. A mixing model was then used to calculate the contributions from the different sources to the sediments. The contributions in the Brisbane and Logan catchments were found to be subsoil erosion (∼66±10%); sheet erosion from cultivated lands 33±10% and sheet erosion of uncultivated land 1±10%. Surface and subsoil erosion contributions from the coastal catchments were found to be variable

Sand transport, erosion and granular electrification

DEFF Research Database (Denmark)

Merrison, J.P.

2012-01-01

is expanding our current understanding and outline the areas of advancement needed in the future. Presentation is made of current models for wind driven detachment/entrainment and the transport rates of sand and dust, including the effects of contact induced grain electrification. This ubiquitous phenomenon...... can affect grain transport through the generation of intense electric fields and processes of electrostatic assembly. Importantly the transport of sand is characterized by saltation, which is known to be an active process for erosion and therefore a source for dust and sand formation. Using novel...... erosion simulation techniques the link between grain transport rates and erosion rates has been quantified. Furthermore this can be linked to production rates for dust and has been associated with chemical and mineral alteration through a process of mechanical activation of fractured surfaces. This work...

High rate of vaginal erosions associated with the mentor ObTape.

Science.gov (United States)

Yamada, Brian S; Govier, Fred E; Stefanovic, Ksenija B; Kobashi, Kathleen C

2006-08-01

The transobturator tape method is a newer surgical technique for the treatment of stress urinary incontinence. Limited data exist related to complications with this approach or the types of mesh products used. We report our experience with vaginal erosions associated with the Mentor ObTape and American Medical Systems Monarc transobturator slings. Beginning in December 2003 selected female patients with anatomic urinary incontinence were prospectively followed after placement of the Mentor ObTape. Beginning in January 2004 we also began using the American Medical Systems Monarc in similar patients. Patients were admitted overnight after surgery, discharged on oral antibiotics, and seen in the clinic at 6 weeks postoperatively. A total of 67 patients have undergone placement of the Mentor ObTape and 9 of those patients (13.4%) have had vaginal extrusions of the sling. Eight patients reported a history of persistent vaginal discharge. One patient presented initially to an outside facility with a left thigh abscess tracking to the left inguinal incision site. Each patient was taken back to the operating room for mesh removal. A total of 56 patients have undergone placement of the AMS Monarc and none have had any vaginal erosions. Our high rate of vaginal extrusion using the ObTape has led us to discontinue the use of this product in our institution. Continued followup of all of these patients will be of critical importance.

THE INFLUENCE OF CONVERSION MODEL CHOICE FOR EROSION RATE ESTIMATION AND THE SENSITIVITY OF THE RESULTS TO CHANGES IN THE MODEL PARAMETER

Directory of Open Access Journals (Sweden)

Nita Suhartini

2010-06-01

Full Text Available A study of soil erosion rates had been done on a slightly and long slope of cultivated area in Ciawi - Bogor, using 137Cs technique. The objective of the present study was to evaluate the applicability of the 137Cs technique in obtaining spatially distributed information of soil redistribution at small catchment. This paper reports the result of the choice of conversion model for erosion rate estimates and the sensitive of the changes in the model parameter. For this purpose, small site was selected, namely landuse I (LU-I. The top of a slope was chosen as a reference site. The erosion/deposit rate of individual sampling points was estimated using the conversion models, namely Proportional Model (PM, Mass Balance Model 1 (MBM1 and Mass Balance Model 2 (MBM2. A comparison of the conversion models showed that the lowest value is obtained by the PM. The MBM1 gave values closer to MBM2, but MBM2 gave a reliable values. In this study, a sensitivity analysis suggest that the conversion models are sensitive to changes in parameters that depend on the site conditions, but insensitive to changes in  parameters that interact to the onset of 137Cs fallout input.   Keywords: soil erosion, environmental radioisotope, cesium

Using geochemical fingerprinting to track the dispersion of radioactive contamination along coastal catchments of the Fukushima Prefecture

Science.gov (United States)

Lepage, Hugo; Laceby, J. Patrick; Evrard, Olivier; Onda, Yuichi; Caroline, Chartin; Lefèvre, Irène; Bonté, Philippe; Ayrault, Sophie

2015-04-01

Several coastal catchments located in the vicinity of the Fukushima Dai-Ichi Power Plant were impacted contaminated fallout in March 2011. Following the accident, typhoons and snowmelt runoff events transfer radiocesium contamination through the coastal floodplains and ultimately to the Pacific Ocean. Therefore it is important to understand the location and relative contribution of different erosion sources in order to manage radiocesium transfer within these coastal catchments and the cumulative export of radiocesium to the Pacific Ocean. Here we present a sediment fingerprinting approach to determine the relative contributions of sediment from different soil types to sediment transported throughout two coastal riverine systems. The sediment fingerprinting technique presented utilizes differences in the elemental geochemistry of the distinct soil types to determine their relative contributions to sediment sampled in riverine systems. This research is important as it furthers our understanding of dominant erosion sources in the region which will help with ongoing decontamination and monitoring efforts pertaining to the management of fallout radiocesium migration in the region.

Soil erosion in Slovene Istria

Directory of Open Access Journals (Sweden)

Matjaž Mikoš

2009-12-01

Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

Multi-hazards coastal vulnerability assessment of Goa, India, using geospatial techniques.

Digital Repository Service at National Institute of Oceanography (India)

Kunte, P.D.; Jauhari, N.; Mehrotra, U.; Kotha, M.; Hursthouse, A.S.; Gagnon, A.S.

that are the most and least vulnerable to erosion, flooding and inundation of coastal lands, and that the inclusion of socio-economic parameters influences the overall assessment of vulnerability. This study provides information aimed at increasing awareness amongst...

Intensified coastal development in beach-nourishment zones

Science.gov (United States)

Lazarus, E.; Armstrong, S.; Limber, P. W.; Goldstein, E. B.; Ballinger, R.

2016-12-01

Population density, housing development, and property values in coastal counties along the U.S. Atlantic and Gulf Coasts continue to rise despite increasing hazard from storm impacts. Beach nourishment, a method for mitigating coastal storm damage or chronic erosion by deliberately replacing sand on an eroded beach, has been the leading form of coastal protection in the U.S. since the 1970s. However, investment in hazard protection can have the unintended consequence of encouraging development in places especially vulnerable to damage. To quantitatively compare development in nourishing and non-nourishing zones, we examine the parcel-scale housing stock of all shorefront single-family homes in the state of Florida. We find that houses in nourishing zones are significantly larger and more numerous than in non-nourishing zones. Florida represents both an advanced case of coastal risk and an exemplar of ubiquitous, fundamental challenges in coastal management. The predominance of larger homes in nourishing zones indicates a positive feedback between nourishment and development that is compounding coastal risk in zones already characterized by high vulnerability. We offer that this phenomenon represents a variant of Jevons' paradox, a theoretical argument from environmental economics in which more efficient use of a resource spurs an increase in its consumption. Here, we suggest reductions in coastal risk through hazard protection are ultimately offset or reversed by increased coastal development.

Extremely low long-term erosion rates around the Gamburtsev Mountains in interior East Antarctica

Science.gov (United States)

Cox, S. E.; Thomson, S. N.; Reiners, P. W.; Hemming, S. R.; van de Flierdt, T.

2010-11-01

The high elevation and rugged relief (>3 km) of the Gamburtsev Subglacial Mountains (GSM) have long been considered enigmatic. Orogenesis normally occurs near plate boundaries, not cratonic interiors, and large-scale tectonic activity last occurred in East Antarctica during the Pan-African (480-600 Ma). We sampled detrital apatite from Eocene sands in Prydz Bay at the terminus of the Lambert Graben, which drained a large pre-glacial basin including the northern Gamburtsev Mountains. Apatite fission-track and (U-Th)/He cooling ages constrain bedrock erosion rates throughout the catchment. We double-dated apatites to resolve individual cooling histories. Erosion was very slow, averaging 0.01-0.02 km/Myr for >250 Myr, supporting the preservation of high elevation in interior East Antarctica since at least the cessation of Permian rifting. Long-term topographic preservation lends credence to postulated high-elevation mountain ice caps in East Antarctica since at least the Cretaceous and to the idea that cold-based glaciation can preserve tectonically inactive topography.

Coastal Community Group for Coastal Resilient in Timbulsloko Village, Sayung, Demak Regency, Indonesia

Science.gov (United States)

Purnaweni, Hartuti; Kismartini; Hadi, Sudharto P.; Soraya, Ike

2018-02-01

Coastal areas are very dynamic and fragile environment, demanding for policies to preserve these areas as materialized in the Resilient Coastal Development Program (PKPT) by the Indonesian government. Amongst the targeted area was Timbulsloko Village in Sayung District, Demak Regency, which coastal areas is severely damaged by erosion. This article analyzed the development of the Coastal Community Group (CCG) related to the PKPT program in Timbulsloko village, especially in how the group is empowered to increase the community's resilient in facing the disaster. This study, applied an analytical descriptive method, used the development of the CCG as phenomenon. Primary data was collected through observation and in-depth interviews with stakeholders, accompanying the secondary data. The result shows that the PKPT funding was mostly spent on infrastructure development and used for project management, not for optimizing local economic empowerment. After the completion of the PKPT, there are no actions or following programs to keep the physical results constructed by the CCG. Accordingly, the orientation towards the CCG building capacity for Timbulsloko community's ecological resilience had not been optimally implemented. This study recommended a "putting the last first" policy approach to preparing the local community. The government must play a stronger role in encouraging a self-help local group for strong human development

Interactive effects of vegetation and sediment properties on erosion of salt marshes in the Northern Adriatic Sea.

Science.gov (United States)

Lo, V B; Bouma, T J; van Belzen, J; Van Colen, C; Airoldi, L

2017-10-01

We investigated how lateral erosion control, measured by novel photogrammetry techniques, is modified by the presence of Spartina spp. vegetation, sediment grain size, and the nutrient status of salt marshes across 230 km of the Italian Northern Adriatic coastline. Spartina spp. vegetation reduced erosion across our study sites. The effect was more pronounced in sandy soils, where erosion was reduced by 80% compared to 17% in silty soils. Erosion resistance was also enhanced by Spartina spp. root biomass. In the absence of vegetation, erosion resistance was enhanced by silt content, with mean erosion 72% lower in silty vs. sandy soils. We found no relevant relationships with nutrient status, likely due to overall high nutrient concentrations and low C:N ratios across all sites. Our results contribute to quantifying coastal protection ecosystem services provided by salt marshes in both sandy and silty sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rainfall erosivity in the Fukushima Prefecture: implications for radiocesium mobilization and migration

Science.gov (United States)

Laceby, J. Patrick; Chartin, Caroline; Degan, Francesca; Onda, Yuichi; Evrard, Olivier; Cerdan, Olivier; Ayrault, Sophie

2015-04-01

The Fukushima Dai-ichi nuclear power plant (FDNPP) accident in March 2011 led to the fallout of predominantly radiocesium (137Cs and 134Cs) on soils of the Fukushima Prefecture. This radiocesium was primarily fixated to fine soil particles. Subsequently, rainfall and snow melt run-off events result in significant quantities of radiocesium being eroded and transported throughout the coastal catchments and ultimately exported to the Pacific Ocean. Erosion models, such as the Universal Soil Loss Equation (USLE), relate rainfall directly to soil erosion in that an increase in rainfall one month will directly result in a proportional increase in sediment generation. Understanding the rainfall regime of the region is therefore fundamental to modelling and predicting long-term radiocesium export. Here, we analyze rainfall data for ~40 stations within a 100 km radius of the FDNPP. First we present general information on the rainfall regime in the region based on monthly and annual rainfall totals. Second we present general information on rainfall erosivity, the R-factor of the USLE equation and its relationship to the general rainfall data. Third we examine rainfall trends over the last 100 years at several of the rainfall stations to understand temporal trends and whether ~20 years of data is sufficient to calculate the R-factor for USLE models. Fourth we present monthly R-factor maps for the Fukushima coastal catchments impacted by the FDNPP accident. The variability of the rainfall in the region, particularly during the typhoon season, is likely resulting in a similar variability in the transfer and migration of radiocesium throughout the coastal catchments of the Fukushima Prefecture. Characterizing the region's rainfall variability is fundamental to modelling sediment and the concomitant radiocesium migration and transfer throughout these catchments and ultimately to the Pacific Ocean.

Testing model parameters for wave‐induced dune erosion using observations from Hurricane Sandy

Science.gov (United States)

Overbeck, Jacquelyn R.; Long, Joseph W.; Stockdon, Hilary F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave‐impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision‐making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Testing model parameters for wave-induced dune erosion using observations from Hurricane Sandy

Science.gov (United States)

Overbeck, J. R.; Long, J. W.; Stockdon, H. F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave-impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision-making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Experiments on Erosion of Mud from the Danish Wadden Sea

DEFF Research Database (Denmark)

Johansen, C.; Larsen, Torben; Petersen, O.

1994-01-01

Experiments on erosion and consolidation of natural cohesive sediments from the harbour of Esbjerg located in the Danish Watten Sea were conducted using a rotating annular flume. The objective of the paper is to describe the erosion rate of deposited beds and relate the erosion rate...

The barley straw residues avoid high erosion rates in persimmon plantations. Eastern Spain

Science.gov (United States)

Cerdà, Artemi; González Pelayo, Óscar; Giménez-Morera, Antonio; Jordán, Antonio; Novara, Agata; Pereira, Paulo; Mataix-Solera, Jorge

2015-04-01

World persimmon production is 4 Millions tones and China produce more than 80 % of the total world yield. Korea and Japan are the second and the third producers respectively with 0.4 and 0.2 millions tones, and all three Asian countries concentrate more than 95 % of the world production. Spain produce less than 0.1 million tones but there is a sudden increase in new plantations due to the high prices and the new marked developed in Europe, Brazil and Arabic countries. The new chemically managed and highly mechanized plantations in Eastern Spain are using high doses of herbicides and the lack of vegetation is triggering high erosion rates. This paper aims to contribute with information about the soil losses on this new persimmon plantations and to develop strategies to reduce the soil and water losses. A 15 years old plantation of persimmon (Dyospirus lotus) was selected in Eastern Spain (Canals Municipality, La Costera District) to measure the soil losses on No-Tillage bare (herbicide treatments) management and on barley straw covered plots. The straw cover was applied 3 days before the expereriments at at doses that cover more than 50 % of the soil surface using 75 gr of straw per m2. Rainfall simulations under 55 mm h-1 rainfall intensity during one hour on 0.25 m2 plots were carried out on plots paired plots: bare and covered with straw. The measurements were carried out during July 2014 on paired plots, under very dry soil moisture contents ranging from 4.65 to 7.87 %. The results show that the 3% cover of vegetation of the control plots moved to more than 60% due to the application of the straw. This induced a delayed ponding (from 60 to 309 seconds) and surface runoff (from 262 to 815 seconds) and runoff outlet (418 to 1221 seconds). The runoff coefficients moved from 60 % in the control plots to 29 % in the straw covered and the runoff sediment concentration was dramatically reduced from 11 to 1 g l-1. The total soil losses were higher that 1 Kg per plot in

Low-canopy seagrass beds still provide important coastal protection services

NARCIS (Netherlands)

Christianen, M.J.A.; van Belzen, J.; Herman, P.M.J.; van Katwijk, M.M.; Lamers, L.P.M.; Bouma, T.J.

2013-01-01

One of the most frequently quoted ecosystem services of seagrass meadows is their value for coastal protection. Many studies emphasize the role of above-ground shoots in attenuating waves, enhancing sedimentation and preventing erosion. This raises the question if short-leaved, low density (grazed)

Corneal erosions, bacterial contamination of contact lenses, and microbial keratitis.

Science.gov (United States)

Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua

2010-11-01

To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.

The influence of material hardness on liquid droplet impingement erosion

International Nuclear Information System (INIS)

Fujisawa, Nobuyuki; Yamagata, Takayuki; Takano, Shotaro; Saito, Kengo; Morita, Ryo; Fujiwara, Kazutoshi; Inada, Fumio

2015-01-01

Highlights: • Liquid droplet impingement erosion is studied for various metal materials. • Average power dependency on droplet velocity is found as 7. • Power dependency on Vickers hardness is found as −4.5. • An empirical formula is constructed for erosion rates of metal materials. • Predicted erosion rate is well correlated with experiment within a factor of 1.5. - Abstract: This paper describes the experimental study on the liquid droplet impingement erosion of metal materials to understand the influence of material hardness on the erosion rate. The experiment is carried out using a water spray jet apparatus with a condition of relatively thin liquid film thickness. The metal materials tested are pure aluminum, aluminum alloy, brass, mild steel, carbon steel and stainless steel. The liquid droplets considered are 30 ± 5 μm in volume average diameter of water, which is the same order of droplet diameter in the actual pipeline in nuclear/fossil power plants. In order to understand the influence of material hardness on the liquid droplet impingement erosion, the scanning electron microscope (SEM) observation on the eroded surface and the measurement of erosion rate are carried out in the terminal stage of erosion. The experimental results indicate that the erosion rates are expressed by the droplet velocity, volume flux, Vickers hardness and the liquid film thickness, which are fundamentals of the liquid droplet impingement erosion. The empirical formula shows that the power index for droplet velocity dependency is found to be 7 with a scattering from 5 to 9 depending on the materials, while the power index for Vickers hardness dependency is found as −4.5

The influence of material hardness on liquid droplet impingement erosion

Energy Technology Data Exchange (ETDEWEB)

Fujisawa, Nobuyuki, E-mail: fujisawa@eng.niigata-u.ac.jp [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Yamagata, Takayuki, E-mail: yamagata@eng.niigata-u.ac.jp [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Takano, Shotaro; Saito, Kengo [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Morita, Ryo; Fujiwara, Kazutoshi; Inada, Fumio [Central Research Institute of Electric Power Industry, 2-11-1, Iwatokita, Komae, Tokyo 201-8511 (Japan)

2015-07-15

Highlights: • Liquid droplet impingement erosion is studied for various metal materials. • Average power dependency on droplet velocity is found as 7. • Power dependency on Vickers hardness is found as −4.5. • An empirical formula is constructed for erosion rates of metal materials. • Predicted erosion rate is well correlated with experiment within a factor of 1.5. - Abstract: This paper describes the experimental study on the liquid droplet impingement erosion of metal materials to understand the influence of material hardness on the erosion rate. The experiment is carried out using a water spray jet apparatus with a condition of relatively thin liquid film thickness. The metal materials tested are pure aluminum, aluminum alloy, brass, mild steel, carbon steel and stainless steel. The liquid droplets considered are 30 ± 5 μm in volume average diameter of water, which is the same order of droplet diameter in the actual pipeline in nuclear/fossil power plants. In order to understand the influence of material hardness on the liquid droplet impingement erosion, the scanning electron microscope (SEM) observation on the eroded surface and the measurement of erosion rate are carried out in the terminal stage of erosion. The experimental results indicate that the erosion rates are expressed by the droplet velocity, volume flux, Vickers hardness and the liquid film thickness, which are fundamentals of the liquid droplet impingement erosion. The empirical formula shows that the power index for droplet velocity dependency is found to be 7 with a scattering from 5 to 9 depending on the materials, while the power index for Vickers hardness dependency is found as −4.5.

Trends and causes of historical wetland loss in coastal Louisiana

Science.gov (United States)

Bernier, Julie

2013-01-01

Wetland losses in the northern Gulf Coast region of the United States are so extensive that they represent critical concerns to government environmental agencies and natural resource managers. In Louisiana, almost 3,000 square kilometers (km2) of low-lying wetlands converted to open water between 1956 and 2004, and billions of dollars in State and Federal funding have been allocated for coastal restoration projects intended to compensate for some of those wetland losses. Recent research at the St. Petersburg Coastal and Marine Science Center (SPCMSC) focused on understanding the physical processes and human activities that contributed to historical wetland loss in coastal Louisiana and the spatial and temporal trends of that loss. The physical processes (land-surface subsidence and sediment erosion) responsible for historical wetland loss were quantified by comparing marsh-surface elevations, water depths, and vertical displacements of stratigraphic contacts at 10 study areas in the Mississippi River delta plain and 6 sites at Sabine National Wildlife Refuge (SNWR) in the western chenier plain. The timing and extent of land loss at the study areas was determined by comparing historical maps, aerial photographs, and satellite imagery; the temporal and spatial trends of those losses were compared with historical subsidence rates and hydrocarbon production trends.

IN SITU MEASUREMENT OF BEDROCK EROSION

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D. H. Rieke-Zapp

2012-07-01

Full Text Available While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are – if at all available – based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest

In Situ Measurement of Bedrock Erosion

Science.gov (United States)

Rieke-Zapp, D. H.; Beer, A.; Turowski, J. M.; Campana, L.

2012-07-01

While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are - if at all available - based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ) and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest generation of compact

Extent of Cropland and Related Soil Erosion Risk in Rwanda

Directory of Open Access Journals (Sweden)

Fidele Karamage

2016-06-01

Full Text Available Land conversion to cropland is one of the major causes of severe soil erosion in Africa. This study assesses the current cropland extent and the related soil erosion risk in Rwanda, a country that experienced the most rapid population growth and cropland expansion in Africa over the last decade. The land cover land use (LCLU map of Rwanda in 2015 was developed using Landsat-8 imagery. Based on the obtained LCLU map and the spatial datasets of precipitation, soil properties and elevation, the soil erosion rate of Rwanda was assessed at 30-m spatial resolution, using the Revised Universal Soil Loss Equation (RUSLE model. According to the results, the mean soil erosion rate was 250 t·ha−1·a−1 over the entire country, with a total soil loss rate of approximately 595 million tons per year. The mean soil erosion rate over cropland, which occupied 56% of the national land area, was estimated at 421 t·ha−1·a−1 and was responsible for about 95% of the national soil loss. About 24% of the croplands in Rwanda had a soil erosion rate larger than 300 t·ha−1·a−1, indicating their unsuitability for cultivation. With a mean soil erosion rate of 1642 t·ha−1·a−1, these unsuitable croplands were responsible for 90% of the national soil loss. Most of the unsuitable croplands are distributed in the Congo Nile Ridge, Volcanic Range mountain areas in the west and the Buberuka highlands in the north, regions characterized by steep slopes (>30% and strong rainfall. Soil conservation practices, such as the terracing cultivation method, are paramount to preserve the soil. According to our assessment, terracing alone could reduce the mean cropland soil erosion rate and the national soil loss by 79% and 75%, respectively. After terracing, only a small proportion of 7.6% of the current croplands would still be exposed to extreme soil erosion with a rate >300 t·ha−1·a−1. These irremediable cropland areas should be returned to mountain forest to

Rates of Dinitrogen Fixation and the Abundance of Diazotrophs in North American Coastal Waters Between Cape Hatteras and Georges Bank

Science.gov (United States)

Mulholland, M.R.; Bernhardt, P. W.; Blanco-Garcia, J. L.; Mannino, A.; Hyde, K.; Mondragon, E.; Turk, K.; Moisander, P. H.; Zehr, J. P.

2012-01-01

We coupled dinitrogen (N2) fixation rate estimates with molecular biological methods to determine the activity and abundance of diazotrophs in coastal waters along the temperate North American Mid-Atlantic continental shelf during multiple seasons and cruises. Volumetric rates of N2 fixation were as high as 49.8 nmol N L(sup -1) d(sup -1) and areal rates as high as 837.9 micromol N m(sup -2) d(sup -1) in our study area. Our results suggest that N2 fixation occurs at high rates in coastal shelf waters that were previously thought to be unimportant sites of N2 fixation and so were excluded from calculations of pelagic marine N2 fixation. Unicellular N2-fixing group A cyanobacteria were the most abundant diazotrophs in the Atlantic coastal waters and their abundance was comparable to, or higher than, that measured in oceanic regimes where they were discovered. High rates of N2 fixation and the high abundance of diazotrophs along the North American Mid-Atlantic continental shelf highlight the need to revise marine N budgets to include coastal N2 fixation. Integrating areal rates of N2 fixation over the continental shelf area between Cape Hatteras and Nova Scotia, the estimated N2 fixation in this temperate shelf system is about 0.02 Tmol N yr(sup -1), the amount previously calculated for the entire North Atlantic continental shelf. Additional studies should provide spatially, temporally, and seasonally resolved rate estimates from coastal systems to better constrain N inputs via N2 fixation from the neritic zone.

The Abudance Of Makrozoobenthos On Different Break Water In Semarang And Demak Coastal Area

Science.gov (United States)

Kristiningsih, A.; Sugianto, D. N.; Munasik; Pribadi, R.; Suprijanto, J.

2018-02-01

The coast of Semarang and Demak has suffered some damage to its coastal areas. This damage is caused by natural factors and also human activities. There are number of mitigation methods such as hard, soft and hybrid that available for mitigation erosion. In Semarang and Demak coastal area using hard and hybrid option as their mitigation erotion. Breakwater is one of the way beach structure that often used as mitigation erosion di coastal area. Breakwater will cause sediment deposits that will become the living place of various organisms such as makrozoobenthos. The aim of this research is compare the abudance of makrozoobenthos in different type breakwater in Semarang and Demak coastal area.This research held on December 2016 - January 2017 in five different location with different breakwater type. Hard structure in Mangkang (West Semarang), Morosari (Demak district) and Tambak Lorok (North Semarang) and the hybrid engineering in Morosari 2 (Demak district) and Timbulsloko (Demak district). The method used in this study is descriptive comparative. Makrozoobenthos has been found in each station and the highest indeks is in hybrid engineering location. Polychaeta is a genus that dominates at every location because muddy sand is its main habitat.

Solid particle erosion of polymers and composites

Science.gov (United States)

Friedrich, K.; Almajid, A. A.

2014-05-01

After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

Using cosmogenic isotopes to measure basin-scale rates of erosion

International Nuclear Information System (INIS)

Bierman, P.R.; Steig, E.

1992-01-01

The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as 36 Cl, 26 Al, and 10 Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont

Erosion products in disruption simulation experiments

International Nuclear Information System (INIS)

Safronov, V.; Arkhipov, N.; Bakhtin, V.; Barsuk, V.; Kurkin, S.; Mironova, E.; Toporkov, D.; Vasenin, S.; Zhitlukhin, A.; Arkhipov, I.; Werle, H.; Wuerz, H.

1998-01-01

Erosion of divertor materials under tokamak disruption event presents a serious problem of ITER technology. Erosion restricts the divertor lifetime and leads to production of redeposited layers of the material retaining large amount of tritium, which is a major safety issue for future fusion reactor. Since ITER disruptive heat loads are not achievable in existing tokamaks, material erosion is studied in special simulation experiments. Till now the simulation experiments have focused mainly on investigation of shielding effect and measurement of erosion rate. In the present work the properties of eroded and redeposited graphite are studied under condition typical for hard ITER disruption. (author)

Nourishment of perched sand dunes and the issue of erosion control in the Great Lakes

Science.gov (United States)