scholarly journals Tides modulate crevasse opening prior to a major calving event at Bowdoin Glacier, Northwest Greenland

2019 ◽  
Vol 66 (255) ◽  
pp. 113-123 ◽  
Author(s):  
Eef van Dongen ◽  
Guillaume Jouvet ◽  
Andrea Walter ◽  
Joe Todd ◽  
Thomas Zwinger ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
Sea Water ◽  
Cyclic Fatigue ◽  
Tidal Amplitude ◽  
Ice Flow ◽  
Tidewater Glaciers ◽  
Water Level Variations ◽  
Key Driver

AbstractRetreat of calving glaciers worldwide has contributed substantially to sea-level rise in recent decades. Mass loss by calving contributes significantly to the uncertainty of sea-level rise projections. At Bowdoin Glacier, Northwest Greenland, most calving occurs by a few large events resulting from kilometre-scale fractures forming parallel to the calving front. High-resolution terrestrial radar interferometry data of such an event reveal that crevasse opening is fastest at low tide and accelerates during the final 36 h before calving. Using the ice flow model Elmer/Ice, we identify the crevasse water level as a key driver of modelled opening rates. Sea water-level variations in the range of local tidal amplitude (1 m) can reproduce observed opening rate fluctuations, provided crevasse water level is at least 4 m above the low-tide sea level. The accelerated opening rates within the final 36 h before calving can be modelled by additional meltwater input into the crevasse, enhanced ice cliff undercutting by submarine melt, ice damage increase due to tidal cyclic fatigue, crevasse deepening or a combination of these processes. Our results highlight the influence of surface meltwater and tides on crevasse opening leading to major calving events at grounded tidewater glaciers such as Bowdoin.

A 3D full-Stokes model of Store Glacier, Greenland, with coupling of ice flow, subglacial hydrology, submarine melting and calving

2020 ◽  
Author(s):  
Samuel Cook ◽  
Poul Christoffersen ◽  
Joe Todd ◽  
Donald Slater ◽  
Nolwenn Chauché ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Water Pressure ◽  
Drainage System ◽  
Greenland Ice Sheet ◽  
Pressure System ◽  
Ice Flow ◽  
Tidewater Glaciers ◽  
Iceberg Calving ◽  
Subglacial Drainage

<p>Tidewater glaciers are complex systems, which present numerous modelling challenges with regards to integrating a multitude of environmental processes spanning different timescales. At the same time, an accurate representation of these systems in models is critical to being able to effectively predict the evolution of the Greenland Ice Sheet and the resulting sea-level rise. In this study, we present results from numerical simulations of Store Glacier in West Greenland that couple ice flow modelled by Elmer/Ice with subglacial hydrology modelled by GlaDS and submarine melting represented with a simple plume model forced by hydrographic observations. The simulations capture the seasonal evolution of the subglacial drainage system and the glacier’s response, and also include the influence of plume-induced ice front melting on calving and buttressing from ice melange present in winter and spring.</p><p>Through running the model for a 6-year period from 2012 to 2017, covering both high- and low-melt years, we find inputs of surface meltwater to the subglacial system establishes channelised subglacial drainage with channels >1 m<sup>2</sup> extending 30-60 km inland depending on the amount of supraglacial runoff evacuated subglacially. The growth of channels is, however, not sufficiently fast to accommodate all inputs of meltwater from the surface, which means that basal water pressures are generally higher in warmer summers compared to cooler summers and lowest in winter months. As a result, the simulated flow of Store Glacier is such that velocities peak in warmer summers, though we suggest that higher surface melt levels may lead to sufficient channelisation for a widespread low-water-pressure system to evolve, which would reduce summer velocities. The results indicate that Greenland’s contribution to sea-level rise is sensitive to the evolution of the subglacial drainage system and especially the ability of channels to grow and accommodate surface meltwater effectively. We also posit that the pattern of plume melting encourages further calving by creating an indented calving front with ‘headlands’ that are laterally unsupported and therefore more vulnerable to collapse. We validate our simulations with a three-week record of iceberg calving events gathered using a terrestrial radar interferometer installed near the calving terminus of Store Glacier.</p>

scholarly journals ANALYTICAL SOLUTION OF BEACH PROFILE RESPONSE TO SEA LEVEL RISE - APPLICATION FOR TECTONIC MOVEMENT IN SENDAI, JAPAN

2018 ◽  
pp. 89
Author(s):  
Nquyen Xuan Tinh ◽  
Hitoshi Tanaka ◽  
Magnus Larson
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
Sea Water ◽  
Beach Profile ◽  
Equilibrium Concept ◽  
Water Level Change ◽  
Equilibrium Beach Profile ◽  
Specific Shape ◽  
Convolution Method

Kriebel and Dean (1993) developed a simple approach to quantify the beach profile response to a time-varying sea level. It is based on the equilibrium concept implying that if a beach profile is exposed to a constant wave and water level climate it will attain a specific shape ( i.e., the equilibrium beach profile; EBP). A change in the forcing conditions will make the profile move towards a new equilibrium state, which will be attained if these conditions prevail sufficiently long. For the case of typical sea level rise (SLR), the change in the forcing conditions is slow enough so that the profile has time to adjust towards the EBP at any given time. In this study, new analytical solutions are developed based on the convolution method to describe beach­ profile response to sea water level change.

scholarly journals Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Sea Level Rise ◽  
Sea Level ◽  
Preferential Flow ◽  
Sea Water ◽  
Saline Water ◽  
Seismic Survey ◽  
Salinity Distribution ◽  
Geological Structures ◽  
The North

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

scholarly journals A Study on the Decision for External Water Level of a River Considering Sea Level Rise

2016 ◽  
Vol 16 (4) ◽  
pp. 604-613
Author(s):  
Tai Ho Choo ◽  
Gwan Seon Yun ◽  
Yong Been Kwon ◽  
Si Hyung Ahn ◽  
Jong Gu Kim
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
External Water

scholarly journals Determining Extreme Still Water Levels for Design and Planning Purposes Incorporating Sea Level Rise: Sydney, Australia

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Phil J. Watson
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
Tide Gauge ◽  
Water Levels ◽  
Extreme Value Analysis ◽  
Tide Gauge Record ◽  
Value Analysis ◽  
Mean Sea Level ◽  
The Impact

This paper provides an Extreme Value Analysis (EVA) of the hourly water level record at Fort Denison dating back to 1915 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences that can drive ocean water levels higher at the coast. The analysis is based on the Peaks-Over-Threshold (POT) method using a fitted Generalised Pareto Distribution (GPD) function to estimate extreme hourly heights above mean sea level. The analysis highlights the impact of the 1974 East Coast Low event and rarity of the associated measured water level above mean sea level at Sydney, with an estimated return period exceeding 1000 years. Extreme hourly predictions are integrated with future projections of sea level rise to provide estimates of relevant still water levels at 2050, 2070 and 2100 for a range of return periods (1 to 1000 years) for use in coastal zone management, design, and sea level rise adaptation planning along the NSW coastline. The analytical procedures described provide a step-by-step guide for practitioners on how to develop similar baseline information from any long tide gauge record and the associated limitations and key sensitivities that must be understood and appreciated in applying EVA.

scholarly journals Impact of Sea-Level Rise on Sea Water Intrusion in Coastal Aquifers

Ground Water ◽  
2009 ◽  
Vol 47 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Adrian D. Werner ◽  
Craig T. Simmons
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Aquifers ◽  
Sea Water ◽  
Sea Water Intrusion ◽  
Water Intrusion

scholarly journals Assessing groundwater vulnerability to sea water intrusion in the coastline of the inner Puck Bay using GALDIT method

2018 ◽  
Vol 54 ◽  
pp. 00023 ◽  
Author(s):  
Dawid Potrykus ◽  
Anna Gumuła-Kawęcka ◽  
Beata Jaworska-Szulc ◽  
Małgorzata Pruszkowska-Caceres ◽  
Adam Szymkiewicz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Seawater Intrusion ◽  
Sea Water ◽  
Groundwater Vulnerability ◽  
Aquifer Vulnerability ◽  
Galdit Method ◽  
The Impact ◽  
Simulated Scenario ◽  
Puck Bay

In this research, GALDIT method was used to assess seawater intrusion in the coastal aquifer of the inner Puck Bay (Southern Baltic Sea). The impact of potential sea-level rise on groundwater vulnerability for years 2081-2100 was also considered. The study area was categorized into three classes of vulnerability: low, moderate and high. The most vulnerable area is the Hel Peninsula with northern part of the Kashubian Coastland. Increased class of aquifer vulnerability is also adopted to glacial valleys. The results of this research revealed that about 18.9% of the analyzed area is highly vulnerable to seawater intrusion, 25.3% is moderately vulnerable and 55.8% is potentially at low risk. The simulated scenario of predicted sea level rise shows enlargement of high vulnerability areas.

scholarly journals Water level changes, subsidence, and sea level rise in the Ganges–Brahmaputra–Meghna delta

2020 ◽  
Vol 117 (4) ◽  
pp. 1867-1876 ◽  
Author(s):  
Mélanie Becker ◽  
Fabrice Papa ◽  
Mikhail Karpytchev ◽  
Caroline Delebecque ◽  
Yann Krien ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Climate Mitigation ◽  
Vertical Land Motion ◽  
The Ganges ◽  
And Sea Level

Being one of the most vulnerable regions in the world, the Ganges–Brahmaputra–Meghna delta presents a major challenge for climate change adaptation of nearly 200 million inhabitants. It is often considered as a delta mostly exposed to sea-level rise and exacerbated by land subsidence, even if the local vertical land movement rates remain uncertain. Here, we reconstruct the water-level (WL) changes over 1968 to 2012, using an unprecedented set of 101 water-level gauges across the delta. Over the last 45 y, WL in the delta increased slightly faster (∼3 mm/y), than global mean sea level (∼2 mm/y). However, from 2005 onward, we observe an acceleration in the WL rise in the west of the delta. The interannual WL fluctuations are strongly modulated by El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) variability, with WL lower than average by 30 to 60 cm during co-occurrent El Niño and positive IOD events and higher-than-average WL, by 16 to 35 cm, during La Niña years. Using satellite altimetry and WL reconstructions, we estimate that the maximum expected rates of delta subsidence during 1993 to 2012 range from 1 to 7 mm/y. By 2100, even under a greenhouse gas emission mitigation scenario (Representative Concentration Pathway [RCP] 4.5), the subsidence could double the projected sea-level rise, making it reach 85 to 140 cm across the delta. This study provides a robust regional estimate of contemporary relative WL changes in the delta induced by continental freshwater dynamics, vertical land motion, and sea-level rise, giving a basis for developing climate mitigation strategies.

Linking weather types to tense dewatering situations of the Kiel Canal (NOK)

2020 ◽  
Author(s):  
Corinna Jensen ◽  
Jens Möller ◽  
Peter Löwe
Keyword(s):  
Sea Level Rise ◽  
Water Level ◽  
Sea Level ◽  
North Sea ◽  
Time Windows ◽  
Water Levels ◽  
Weather Types ◽  
The North ◽  
The North Sea ◽  
Kiel Canal

<p>Within the “Network of experts” of the German Federal Ministry of Transport and Digital Infrastructure (BMVI), the effect of climate change on infrastructure is investigated. One aspect of this project is the future dewatering situation of the Kiel Canal (“Nord-Ostsee-Kanal” (NOK)). The Kiel Canal is one of the world’s busiest man-made waterways navigable by seagoing ships. It connects the North Sea to the Baltic Sea and can save the ships hundreds of kilometers of distance. With a total annual sum of transferred cargo of up to 100 million tons it is an economically very important transportation way. Additionally to the transportation of cargo, the canal is also used to discharge water from smaller rivers as well as drainage of a catchments area of about 1500 km².</p><p>The canal can only operate in a certain water level range. If its water level exceeds the maximum level, the water must be drained into the sea. In 90% of the time, the water is drained into the North Sea during time windows with low tide. If the water level outside of the canal is too high, drainage is not possible and the canal traffic has to be reduced or, in extreme cases, shut down. Due to the expected sea level rise, the potential time windows for dewatering are decreasing in the future. With a decrease in operational hours, there will be substantial economic losses as well as an increase in traffic around Denmark.</p><p>To get a better understanding of what causes tense dewatering situations other than sea level rise a linkage between high water levels on the outside of the canal and weather types is made. Weather types describe large-scale circulation patterns and can therefore give an estimate on tracks of low-pressure systems as well as the prevailing winds, which can explain surges and water levels at the coast. This analysis is conducted for one weather type classification method based solely on sea level pressure fields. Weather types derived from regionally coupled climate models as well as reanalyses are investigated.</p>

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