Gully catchments as a sediment sink, not just a source: Results from a long-term (~12 500 year) sediment budget

2015 ◽  
Vol 41 (4) ◽  
pp. 486-498 ◽  
Author(s):  
Annegret Larsen ◽  
Tobias Heckmann ◽  
Joshua R. Larsen ◽  
Hans-Rudolf Bork
Keyword(s):  
Sediment Budget

Influence of ground ice and permafrost on coastal evolution, Richards Island, Beaufort Sea coast, N.W.T.

1996 ◽  
Vol 33 (5) ◽  
pp. 664-675 ◽  
Author(s):  
Scott R. Dallimore ◽  
Stephen A. Wolfe ◽  
Steven M. Solomon
Keyword(s):  
Coastal Erosion ◽  
Sediment Budget ◽  
Storm Event ◽  
Ground Ice ◽  
Coastal Evolution ◽  
Thermal Erosion ◽  
Ice Wedge ◽  
Mechanical Erosion ◽  
Sea Coast

A long-term sediment budget (1947−1985) for northern Richards Island shows that, when ground ice and offshore erosion are accounted for, there is a near balance between headland erosion and coastal deposition. Excess ice constitutes about 20% of the total volume of eroded material from the headlands, with massive ground ice contributing nearly 9% and segregated ice lenses and ice wedges making up the remainder. Coastal response to major storms in 1987 and 1993 suggests that erosion is episodic, with short periods of intense disruption followed by readjustment of cliff profiles. Processes characteristic of this environment include mechanical erosion of ice-bonded sediments creating unstable erosional niches, mechanical failure of niches along ice-wedge planes, and longer term thermal erosion of ice-bonded sediments. Where ice contents are high, localized thaw slumps initiated by coastal erosion may retreat at rates substantially higher than those observed at other sections of the coast. Cliff-top retreat rates may be out of phase with storm-event chronology.

scholarly journals Erosion assessment in the middle Kali Gandaki (Nepal): A sediment budget approach

2013 ◽  
Vol 46 ◽  
Author(s):  
Monique Fort ◽  
Etienne Cossart
Keyword(s):  
Drainage Basin ◽  
Sediment Budget ◽  
Mountain Range ◽  
Primary Concern ◽  
Stream Power ◽  
Sediment Budgets ◽  
Relative Chronology ◽  
Wide Range ◽  
History Of

Active mountains supply the largest sediment fluxes experienced on earth. At mountain range scale, remote sensing approaches, sediments provenance or stream power law analyses, collectively provide rough long-term estimates of total erosion. Erosion is indeed controlled by rock uplift and climate, hence by a wide range of processes (detachment, transport and deposition), all operating within drainage basin units, yet with time and spatial patterns that are quite complex at local scale. We focus on the Kali Gandaki valley, along the gorge section across the Higher Himalaya (e.g. from Kagbeni down to Tatopani). Along this reach, we identify sediment sources, stores and sinks, and consider hillslope int eractions with valley floor, in particular valley damming at short and longer time scales, and their impact on sediment budgets and fluxes. A detailed sediment budget is presented, constrained by available dates and/or relative chronology, ranging from several 10 kyr to a few decades. Obtained results span over two orders of magnitude that can best be explained by the type and magnitude of erosional processes involved. We show that if large landslides contribute significantly to the denudation history of active mountain range, more frequent medium to small scales landslides are in fact of primary concern for Himalayan population.

West Sole Pipeline Stabilisation

2005 ◽  
Author(s):  
Z. Chen ◽  
Eamon Sheehan
Keyword(s):  
Negative Impact ◽  
Optimal Solution ◽  
Sediment Budget ◽  
Gas Field ◽  
Critical Position ◽  
Coastal Evolution ◽  
Sea Bed ◽  
Pipeline Failure ◽  
The Uk

The BP West Sole gas field is located in Block 48/6 in the UK sector of the southern North Sea, about 70 km off the Holderness coast. Production from the gas field is exported to a shore terminal at Easington by two pipelines. Both pipelines were trenched at installation. Pipeline surveys over the last few years show that both pipelines are substantially exposed at the shore approach and inshore sections. This has occurred in part due to the retreat of the cliffs in Easington and subsequent lowering of the sea bed level and also the migration of sand from around the pipelines leaving them largely unburied and sitting on the local clay abrasion platform. It has been concluded that both pipelines require stabilisation sooner rather than later to reduce the risk of pipeline failure. Pipeline stabilisation options need to take account of the environment in which they have been placed. Easington is at a critical position along the Holderness coast. All net sediment transport from the Holderness coastline passes through this section. Any interruption to this movement could result in a change to the adjacent coast. Maintenance of the sediment budget is important to a wider area of the East coast of England. Stabilisation options must not reduce the net amount of sediment moving southwards past Dimlington and must not result in any long term negative impact on the coastal evolution. This paper outlines consultancy required and problems process regarding the geomorphological issues in getting acceptance from government and non-government bodies. A methodology has been developed that allows quantification of impacts of different options on the sediment budget and on the long-term coastal evolution (see also Chen et al 1998, 2001 and 2002). Application of this method aimed at providing understanding and information which is considered to be important in the process of selecting an optimal solution for the pipeline stabilisation in such an environmental sensitive coast.

scholarly journals Estimation of Background Erosion Rate at Janghang Beach due to the Construction of Geum Estuary Tidal Barrier in Korea

2020 ◽  
Vol 8 (8) ◽  
pp. 551
Author(s):  
Sahong Lee ◽  
Jung Lyul Lee
Keyword(s):  
Coastal Erosion ◽  
Sediment Budget ◽  
Coastal Development ◽  
Coastal Sediment ◽  
Littoral Cell ◽  
Watershed Development ◽  
Open Sea ◽  
Sediment Loss ◽  
The Future

In this study, a reduction in sediment budget due to the development of a river watershed, resulting in coastal erosion, was reviewed, and the rate of background erosion was calculated through an examination of the loss of coastal sediment into the open sea. The west coast of the Korean peninsula is severely impacted by the intercept of inflowing sediments from rivers, owing to the watershed development. However, the effects have not fully propagated into the entire coastal area, and thus, the long-term coastal erosion remains insignificant. However, a serious and irrevocable disaster may occur once the coastal erosion begins. Therefore, an analysis of the coastal erosion resulting from changes in the sediment budget, due to the development of the watershed, was conducted on Janghang Songrim Beach. A littoral cell of the Geum River was selected for a quantitative analysis of the decrease in the sediment budget from the watershed development. The rate of coastal sediment loss offshore, which reflects the characteristics of the Janghang Songrim Beach, and the future rate of coastal erosion were calculated. Then, the results were verified by employing geometrically corrected satellite photographs from previous years. This will enable us to predict the time of coastal erosion in the future due to a reduction in the sediment budget and watershed development, and prepare for future disasters resulting from the coastal erosion. Based on research into the components constituting the coastal development, the present study presents theoretical formulae allowing the prediction of the sediment budget and providing a practical contribution to the prevention of coastal erosion, for which additional reliable studies need to be conducted.

scholarly journals BEACH RESTORATION IN THE TARRAGONA COAST (SPAIN); SAND MANAGEMENT DURING THE LAST 25 YEARS AND FUTURE PLANS

2018 ◽  
pp. 20
Author(s):  
Jordi Galofré ◽  
José A. Jiménez ◽  
Herminia I. Valdemoro
Keyword(s):  
Adaptation Strategy ◽  
Management Plan ◽  
Sediment Budget ◽  
General Context ◽  
River Sand ◽  
Protection Measure ◽  
Shoreline Evolution ◽  
Nw Mediterranean ◽  
Transport Patterns

Erosion is the dominant behavior along worldwide coastlines. Although many factors can locally influence processes governing coastline evolution some common factors can be identified. Thus, the sediment budget has largely been modified in most of developed coasts, with river sand supplies being drastically reduced due to human influence in drainage basins. On the other hand, coastal segmentation due to infrastructures alters sediment transport patterns and induces and/or accelerates coastline erosion. Within this general context, artificial nourishment has been one of the most used coastal engineering measure by mimicking the role played by river sediment supplies to compensate local erosion problems. Since nourishment is not acting on the origin of the problems, erosive processes will continue to control shoreline evolution. Thus, the evolution of beach fills will be controlled by the sediment budget within the coastal cell where works have been done and, this will determine required sediment volumes to maintain the future shoreline. Within this context, we present data on long-term (25 years) shoreline evolution and nourishment operations in the Tarragona coast (Spain, NW Mediterranean). The main aim of the work is to analyze the coastal stability and the effects of beach fills along the coast taking into account the type of the coastal cell where works have been implemented. Once this has been evaluated, the sustainability of an adaptation strategy based on the use of this protection measure to cope with climate change induced scenarios is also assessed to propose a long- term sediment management plan.

scholarly journals Spatio-temporal dynamics of sediment transfer systems in landslide-prone alpine catchments

2019 ◽  
Author(s):  
François Clapuyt ◽  
Veerle Vanacker ◽  
Fritz Schlunegger ◽  
Marcus Christl ◽  
Kristof Van Oost
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Landscape Evolution ◽  
Sediment Budget ◽  
Spatial And Temporal Scales ◽  
Sediment Fluxes ◽  
Downstream Distance ◽  
Denudation Rates ◽  
Decadal Scale

Abstract. Tectonic and geomorphic processes drive landscape evolution over different spatial and temporal scales. In mountainous environments, river incision sets the pace of landscape evolution, and hillslopes respond to channel incision by e.g. gully retreat, bank erosion and landslides. Sediment produced during stochastic landslide events leads to mobilisation of soil and regolith on the slopes that can later be transported by gravity and water to the river network. Quantifying sediment storage and conveyance requires an integrated approach accounting for different space and time scales. To better understand mechanisms and spatial and temporal scales of geomorphic connectivity in mountainous environments, we characterised the sediment cascade of the Entle River catchment located in the foothills of the Central Swiss Alps. We quantified sediment fluxes over annual, decadal and millennial time scales using respectively UAV-SfM techniques, classic photogrammetry and in situ produced cosmogenic radionuclides. At the annual scale (2013–2015), the sediment budget of the Schimbrig earthflow is roughly in equilibrium, despite the fact that we measured intense sediment redistribution on the hillslopes. At the decadal scale (1962–1998), Schwab et al. (2008) reported episodes of sediment export that were not directly related to increased geomorphic activity on the hillslopes. At the millennial scale, catchment-wide denudation rates show a positive relationship with downstream distance or drainage area, when ignoring landslide-affected catchments. The latter are characterised by a negative relationship between denudation rates and downstream distance, along with high variability in denudation rates. The high denudation rates that we measured in the earthflow-affected Schimbrig catchment are illustrative for its high rates of geomorphic activity in comparison to adjacent areas. Our data show that the elevated denudation rates of the landslide-affected catchments are not necessary traceable when analyzing long-term sediment fluxes of the wider geographic area, as the landslide-affected catchments are often only a small fraction of the total catchment. The multi-temporal assessment of sediment fluxes indicates that (1) landslides can provide local sediment pulses, and mobilise material that becomes available for further mobilisation and transport when hillslopes and channels are connected. (2) Connection and disconnection cycles occur at decadal time scale. (3) Phases of high geomorphic activity at the catchment scale are episodic over thousands of years. Consequently, one single landslide has not necessarily an impact on the long-term sediment budget of first-order catchments. Rather, it is the cumulated effect of multiple landslides which are intermittently connected to the channel network at the decadal scale that may regulate sediment fluxes at the regional scale over the millennial time scale.

scholarly journals Single Extreme Strong Sequence Can Offset Decades of Shoreline Retreat by Sea-level Rise

2021 ◽  
Author(s):  
Mitchell Harley ◽  
Gerd Masselink ◽  
Amaia Ruiz de Alegría-Arzaburu ◽  
Nieves Valiente ◽  
Tim Scott
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Sediment Budget ◽  
Positive Contribution ◽  
Volume Changes ◽  
Shoreline Retreat ◽  
Quantitative Understanding ◽  
The Uk

Abstract Extreme storms cause extensive beach-dune erosion and are universally considered to enhance coastal erosion due to sea-level rise (SLR). However, extreme storms can also have a positive contribution to the nearshore sediment budget by exchanging sediment between the lower and upper shoreface and/or between adjacent headlands, potentially mitigating adverse SLR impacts. Here we use three high-resolution morphological datasets of extreme storm-recovery sequences from Australia, the UK and Mexico to quantify the nearshore sediment budget and relate these episodic volume changes to long-term coastal forecasts. We show that sediment gains over the upper shoreface and beach were very significant (58-140 m3/m) and sufficient to offset decades of predicted shoreline retreat due to SLR, even for an upper SSP5-8.5 scenario. It is evident that increased confidence in shoreline predictions due to SLR relies fundamentally on robust quantitative understanding of the sediment budget, in particular any long-term contribution of sediment transport from outside the nearshore region.

scholarly journals Sediment Budget and Sediment Trap efficiency of Baglihar Hydroelectric project Reservoir – a calibrated model for prediction of longevity of the Dam

2021 ◽  
Vol 38 (1) ◽  
pp. 65-74
Author(s):  
Romesh Kumar ◽  
AHSAN UL HAQ ◽  
G M Bhat ◽  
Yudhbir Singh ◽  
Javid Ahmed Dar
Keyword(s):  
Sediment Trap ◽  
Empirical Relationship ◽  
Field Investigation ◽  
Sediment Budget ◽  
Hydropower Project ◽  
Trap Efficiency ◽  
Hydroelectric Project ◽  
Reservoir Volume ◽  
Total Sediment

 The field investigation of the reservoir area of Baglihar Hydropower project shows that the sediment budget to the reservoir is controlled by fragile rock type like shales, sandstones, phyllites and slates, soil characteristics, steep hill slopes, rainfall and landslides. The rocks are highly weathered, fissile and micaceous in nature and very sensitive to water absorption.  The analysed sediments are characterised by dominance of sands, silts and clays with lower values of plasticity (14.3PL), liquidity (23.5 LL), cohesion (118) and shear strength (202 Kpa). The slope wash deposits are highly susceptible to landslides and slope failures and directly contribute to the sediment budget in the reservoir. In addition tributaries of Chenab River also bring sediments in the reservoir from the catchment area. The empirical relationship for estimating the long-term reservoir trap efficiency for large storage based on correlation between the relative reservoir size and trap efficiency was simulated in 3D model which shows that the annual sediment trap efficiency of the Baglihar reservoir is of 0.39%. The extrapolation of the calculated values shows that the total sediment load shall increase by 11% in the next 30 years and 20% in the next 50 years and correspondingly 40% in the next 100 years that shall induce corresponding decrease in the reservoir volume over the time.  By applying flushing schemes, life span of the reservoir can be extended. It is estimated that after 100 years the reservoir shall lose ~35.6% storage volume. On further extrapolation, the trap efficiency will decrease from 25.5% after 30 years to 23% after 100 years. The estimated trap efficiency of Baglihar reservoir is 60%, which is greater than that based on numerical results, showing a significant overestimation.

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