Property:Theory movie
From CSDMS
This is a property of type Text.
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A calving glacier (also called tidewater glacier) is a glacier that ends in a body of water. Calving glaciers occur in Alaska, Arctic Canada, Patagonia, as well as along the Greenlandic Ice Sheet and Antarctica.
It is these systems that produce icebergs floating in the world oceans.
Calving glaciers behave very differently than land-based glaciers. Their velocity accelerates at the terminus, and they are much more dynamic than land-based glaciers. Calving glaciers need a large accumulation area to compensate for the ice mass lost by calving.
Calving rates of tidewater glaciers in Alaska were found to be controlled by the depth of the water at the glacier front (Brown et al., 1982).
Vc=CHw+D
Vc = calving speed (m/yr)
C = calving coefficient (27.1 +/- 2 per yr for a study of 13 Alaskan glaciers)
Hw = water depth at the glacier front (m)
D = constant (0 m/yr for a study of 13 Alaskan glaciers)
Calving glaciers can advance and retreat at great rates. Some of the Alaskan calving glaciers retreated over > 100 km in the last two centuries. +
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A debris flow is a fast moving mass of unconsolidated, saturated debris that looks like flowing concrete. They differentiate from a mudflow by terms of the viscosity of the flow. Flows follow a steepest descent generally, although they are known the “climb” opposite valley walls in extreme cases. The front of the debris flow, or the toe, forms a lobe, marking flow front. This lobe often contains a great deal of the larger sediments including cobbles and boulders. Early pulses or previous debris flows form levees that channel the flow until they are breached. The presence of older levees indicates the recurrence and characteristics of debris flows in a particular area. This can be an important indicator of past debris flow activity for developing land on alluvial fan terrace surfaces.
But, flows can carry clasts ranging in size from clay particles to boulders, and may contain woody debris. During later phases of the event, more viscous mud that contains sands, silts, and fines runs through the flowpath.
Debris flows can be triggered by large amounts of rainfall, snow melt, or glacial/permafrost melt, or a combination of all. Speed of debris flows can vary from 0.5 m/s to 16 m/s in extreme conditions.
Variables in the conditions that affect debris flow characteristics are slope, available sediment and vegetation in the flowpath.
Debris flow are extremely destructive to life and property.
This particular event happened on July 2nd, 2006. This is during the middle of the Southern Hemisphere's Austral Winter, but the temperature was unseasonally high at 32º C! It was the warmest July day ever recorded (pers. comm. W. Keller). This debris flow event is attributed to hydrothermal alteration of the local mountain flank and the melting of permafrost. +
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A debris flow is characterized as a liquefied mixture of sediment and water flowing down a slope. It is driven by the gravity acting on the sediment. +
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A delta is formed by the interaction of three main controls: river energy, wave energy or tidal energy. Deltas are often classified by their morphological characteristics and the dominant controlling factor cinfluencing its morphology. An open ocean basin has a potential for high wave energy. High wave interference causes conflicted or deflected river mouths. There is less influence from fluvial sources. In wave-dominated delta regions, breaking waves cause immediate mixing of fresh and salt water. Typically, the fresh water flow velocity decelerates rapidly. A bar may form in the immediate vicinity of the distributary mouth, often supplemented by landward migrating swash bars. The wave action reworks the sediment, making it much sandier than other types of deltas. Alternatively, sediment is delivered by the river and but it is immediately transported along the coast. The sediment is then deposited as beaches and bars and the development of distributaries is limited. Dominant directions of wave approach can result in asymmetric beach ridges, and may cause the progradation of a spit across the river mouth. This results in channel flow oblique or parallel to the shore.
For the theory behind the models of this coupled river and wave-dominated coast simulations see the Model Help of the Coastline Evolution Model: https://csdms.colorado.edu/wiki/Model_help:CEM and the Model help of HydroTrend: https://csdms.colorado.edu/wiki/Model_help:HydroTrend
This movie can be linked to the lab and lecture on coupled delta modeling:
https://csdms.colorado.edu/wiki/SurfaceDynamics_Modeling_CMT
https://csdms.colorado.edu/wiki/Labs_portal +
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A delta is formed by the interaction of three main controls: river energy, wave energy or tidal energy. Deltas are often classified by their morphological characteristics and the dominant controlling factor cinfluencing its morphology. An open ocean basin has a potential for high wave energy. High wave interference causes conflicted or deflected river mouths. There is less influence from fluvial sources. In wave-dominated delta regions, breaking waves cause immediate mixing of fresh and salt water. Typically, the fresh water flow velocity decelerates rapidly. A bar may form in the immediate vicinity of the distributary mouth, often supplemented by landward migrating swash bars. The wave action reworks the sediment, making it much sandier than other types of deltas. Alternatively, sediment is delivered by the river and but it is immediately transported along the coast. The sediment is then deposited as beaches and bars and the development of distributaries is limited. Dominant directions of wave approach can result in asymmetric beach ridges, and may cause the progradation of a spit across the river mouth. This results in channel flow oblique or parallel to the shore.
For the theory behind the models of this coupled river and wave-dominated coast simulations see the Model Help of the Coastline Evolution Model: https://csdms.colorado.edu/wiki/Model_help:CEM and the Model help of HydroTrend: https://csdms.colorado.edu/wiki/Model_help:HydroTrend +
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A glacial lake outburst flood occurs when massive amounts of meltwater are dramatically released. This can be for several reasons: when a lake contained by a glacier or a moraine dam drains. One distinguishes between a ‘Jökulhlaup’, if the lake formed subglacially, or a ‘marginal lake drainage’ if it was dammed between ice and the ground.
Glacial outburst flows can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake or cryoseism, volcanic eruptions under the ice, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base.
A jökulhlaup is thus a sub-glacial outburst flood. Jökulhlaup is an Icelandic term that has been adapted into the English language, and originally only referred to glacial outburst floods, which are triggered by volcanic eruptions, but now is accepted to describe any abrupt and large release of sub-glacial water.
Glacial lakes come in various sizes, but may hold millions to hundreds of millions of cubic meters of water. Catastrophic failure of the containing ice or glacial sediment can release this water over a timespan of minutes to days. Peak flows as high as 15,000 cubic meters per second have been recorded in these events. On a downstream floodplain, inundation can spread as much as 10 kilometers wide. Both scenarios are horrific threats to lives, property and infrastructure. +
A glacial lake outburst flood occurs when massive amounts of meltwater are dramatically released. This can be for several reasons: when a lake contained by a glacier or a moraine dam drains. One distinguishes between a ‘Jökulhlaup’, if the lake formed subglacially, or a ‘marginal lake drainage’ if it was dammed between ice and the ground.
Glacial outburst flows can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake or cryoseism, volcanic eruptions under the ice, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base.
A jökulhlaup is thus a sub-glacial outburst flood. Jökulhlaup is an Icelandic term that has been adapted into the English language, and originally only referred to glacial outburst floods, which are triggered by volcanic eruptions, but now is accepted to describe any abrupt and large release of sub-glacial water.
Glacial lakes come in various sizes, but may hold millions to hundreds of millions of cubic meters of water. Catastrophic failure of the containing ice or glacial sediment can release this water over a timespan of minutes to days. Peak flows as high as 15,000 cubic meters per second have been recorded in these events. On a downstream floodplain, inundation can spread as much as 10 kilometers wide. Both scenarios are horrific threats to lives, property and infrastructure. +
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A groyn is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. In some cases it keeps velocity in the main channel such that it is suitable for shipping.
In a river, groynes prevent bank erosion and ice-jamming, which in turn aids navigation. The areas between groups of groynes are groyne fields. Groynes can be made of wood, concrete, or rock piles. Their use goes back many centuries. +
A groyn is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. In some cases it keeps velocity in the main channel such that it is suitable for shipping.
In a river, groynes prevent bank erosion and ice-jamming, which in turn aids navigation. The areas between groups of groynes are groyne fields. Groynes can be made of wood, concrete, or rock piles. Their use goes back many centuries. +
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A landslide is a mass movement along a failure plane on a slope. Landslides occur when the stability threshold of a slope is overcome. The trigger can be abrupt, like an earthquake or more gradual due to a number of factors including:
# porewater pressure built up due to extensive rainfall, snow of glacier melt.
# undercutting of a slope by a river or wave erosion.
Fires and deforestation that change the water infiltration capacity of a slope do influence the probability of a landslide event happening.
A elaborate discussion on classification can be found here: http://en.wikipedia.org/wiki/Landslide_classification +
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A lot of background information on this eruption can be found on:
http://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallajökull +
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A tidal bore, also called aegir, is a tidal phenomenon in which the leading edge of the incoming tide forms a wave of water that travel up a river or narrow bay against the river current. As such, it is a true tidal wave.
Bores occur in relatively few locations, but they do occur worldwide, usually in areas with a large tidal range (typically more than 6 m between high and low water).
All these locations are shallow, narrowing rivers or fjords in which water is funneled via a broad bay. The funnel-like shape not only increases the height of the tide, but it can also decrease the duration of the flood tide down to a point where the flood appears as a sudden increase in the water level. The rising tide may force the tidal wave-front to move faster that a shallow water wave can propagate into water of that depth:<br>
T=L/(c+u)<br>
T = wave period<br>
L = wave length<br>
c = wave speed<br>
u = speed of current<br>
If the current flows counter the direction of wave propagation, then L will increase and the wave will get shorter and higher (upto the point of breaking).
Bore tides come in after extreme minus low tides created by the full or new moon (Chanson, 2004).
Bores take on various forms, ranging from a single breaking wavefront —like a shock wave — to ‘undular bores’ comprising a smooth wavefront followed by a train of secondary waves (whelps). Large bores can be dangerous for shipping.
Rivers that do have a tidal bore include the Amazon and Orinoco Rivers, in South America, the Hoogly River in the Ganges-Brahmaputra delta, several rivers in the UK, and rivers draining into the Bay of Fundy. The largest tidal bore occurs in the Qiantang River in China, it is 9m high and travels at 40 km/hr.
Tidal bores have distinct influence on sediment transport. The arrival of the borefront is associated with intense bed shear stress and bed scour. Suspended sediment is advected upwards in the wake of the tidal bore. This phase is associated with turbulent structure. The suspension of sediment is sustained by wave motion for several minutes to half an hour after the bore has passed (Chanson, 2004).
A tidal bore, also called aegir, is a tidal phenomenon in which the leading edge of the incoming tide forms a wave of water that travel up a river or narrow bay against the river current. As such, it is a true tidal wave.
Bores occur in relatively few locations, but they do occur worldwide, usually in areas with a large tidal range (typically more than 6 m between high and low water).
All these locations are shallow, narrowing rivers or fjords in which water is funneled via a broad bay. The funnel-like shape not only increases the height of the tide, but it can also decrease the duration of the flood tide down to a point where the flood appears as a sudden increase in the water level. The rising tide may force the tidal wave-front to move faster that a shallow water wave can propagate into water of that depth:<br>
T=L/(c+u)<br>
T = wave period<br>
L = wave length<br>
c = wave speed<br>
u = speed of current<br>
If the current flows counter the direction of wave propagation, then L will increase and the wave will get shorter and higher (upto the point of breaking).
Bore tides come in after extreme minus low tides created by the full or new moon (Chanson, 2004).
Bores take on various forms, ranging from a single breaking wavefront —like a shock wave — to ‘undular bores’ comprising a smooth wavefront followed by a train of secondary waves (whelps). Large bores can be dangerous for shipping.
Rivers that do have a tidal bore include the Amazon and Orinoco Rivers, in South America, the Hoogly River in the Ganges-Brahmaputra delta, several rivers in the UK, and rivers draining into the Bay of Fundy. The largest tidal bore occurs in the Qiantang River in China, it is 9m high and travels at 40 km/hr.
Tidal bores have distinct influence on sediment transport. The arrival of the borefront is associated with intense bed shear stress and bed scour. Suspended sediment is advected upwards in the wake of the tidal bore. This phase is associated with turbulent structure. The suspension of sediment is sustained by wave motion for several minutes to half an hour after the bore has passed (Chanson, 2004).
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An equilibrium beach profile results from steady modest wave forcing during the summer. Summer wave conditions move sand onto the beach, widening its profile.
Winter storm waves move sand offshore (see assocated animation.Summer and winter beach profiles are expressions of the seasonal cycle of wave energy. +
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An equilibrium winter beach profile results from more intense wave forcing during the winter. High winter wave conditions move sand away from the beach, cutting a wave platform. Unusually large storms may move all sands into deep water and leave skinny beaches for the early summer season.
Summer waves move sand back onshore (see associated animation) both summer and winter beach profiles are expressions of the seasonal cycle of wave energy. +
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Applied Model: WBMsed +
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Barnhart, K., Miller, C.R., Overeem, I., Kay. J., 2015. Mapping the future expansion of Arctic open water. Nature Climate Change. 2 November 2015. +
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Barrier Islands migrate over the shelf in response to sea level changes. The island first progrades outward, during sea level fall and then retrogrades when sea level is coming up again.
A elaborate discussion on classification can be found here:
http://science.howstuffworks.com/environmental/conservation/issues/barrier-island.htm +
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Based on observed data +
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Effects of high horizontal displacement rates on landscape evolution & pull-apart basins formation +
Basin and Landscape Dynamics (Badlands) is a parallel TIN-based landscape evolution model, built to simulate topography development at various space and time scales. The model is presently capable of simulating hillslope processes (linear diffusion), fluvial incision ('modified' SPL: erosion/transport/deposition), spatially and temporally varying geodynamic (horizontal + vertical displacements) and climatic forces which can be used to simulate changes in base level, as well as effects of climate changes or sea-level fluctuations. +
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Bed load transportation is a function of the fluid force per area, or shear stress on the stream bed. Shear stress is proportional to the specific weight of the fluid, the depth and the surface slope of the fluid. The frictional resisting force is proportional to the specific weight of the sediment and the diameter of the sediment. +
Bed load transportation is a function of the fluid force per area, or shear stress on the stream bed. Shear stress is proportional to the specific weight of the fluid, the depth and the surface slope of the fluid. The frictional resisting force is proportional to the specific weight of the sediment and the diameter of the sediment. +
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Bed load transportation is a function of the fluid force per area, or shear stress on the stream bed. Shear stress is proportional to the specific weight of the fluid, the depth and the surface slope of the fluid. The frictional resisting force is proportional to the specific weight of the sediment and the diameter of the sediment. +
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Bed load transportation is a function of the fluid force per area, or shear stress on the stream bed. Shear stress is proportional to the specific weight of the fluid, the depth and the surface slope of the fluid. The frictional resisting force is proportional to the specific weight of the sediment and the diameter of the sediment. +
Braided steams can occur in drainage basins that have high sediment content and/or in river environments that rapidly change channel depth and thus velocity such as alluvial fans, river deltas and peneplains. +
Braided steams can occur in drainage basins that have high sediment content and/or in river environments that rapidly change channel depth and thus velocity such as alluvial fans, river deltas and peneplains. +
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Close to 0.5 billion people live on, or near, world deltas, inclusively in many mega-cities. Ten countries (China, India, Bangladesh, Vietnam, Indonesia, Japan, Egypt, USA, Thailand, and the Philippines) account for 73% of the people that live in the world’s coastal zone, defined as within 10 m of mean sea level. 20th-century catchment developments and population and economic growth within subsiding deltas have placed these environments and their populations under a growing risk of coastal flooding, wetland loss, shoreline retreat, and loss of infrastructure.
To assess vulnerability of deltaic lowlands one has to look at a delta as a balance. A delta’s surface elevation above mean sea level can experience a vertical change relative to local mean sea level, ΔRSL. It is controlled by a summation of 5 factors:
(1) ΔRSL = A - ΔE - Cn - CA ± M
A delta’s Aggradation Rate (A) is determined from the volume of sediment delivered to and retained on the subaerial delta surface as new sedimentary layers due to flooding. A typically varies from 1 to 50 mm/y in deltas worldwide (See Table 1 in Syvitski et al., 2009). Most river floods bring large amounts of sediment to a delta’s surface. Reducing the number of distributary channels along with artificial levees can prohibit river flooding onto the delta plain. Flooding from ocean surges may still contribute additional turbid water.
ΔE is the Eustatic Sea Level Rate determined from changes to the volume of the global ocean over time, as influenced by fluctuations in the storage of terrestrial water (e.g. glaciers, ice sheets, groundwater, lakes, and reservoirs), and fluctuations in ocean water expansion due to water temperature changes. Presently ΔE is positive and contributes ≈1.8 to 3 mm/y (IPCC, 2007) under the anthropogenic influence of global warming. The IPCC projects that sea level will rise another 21 to 71 cm by 2070, with a best estimate of 44 cm averaged globally; it is becoming increasingly clear that the major ice sheets might contribute even more water over this period.
Natural Compaction (Cn), or Accelerated Compaction (CA) reduce the volume of deltaic deposits. Cn involves natural changes in the void space within sedimentary layers (e.g. dewatering, grain-packing realignment, and organic matter oxidation), and is typically ≤3 mm/y. CA is the anthropogenic contribution to volume change as a consequence of subsurface mining (oil, gas or groundwater), human-influenced soil drainage and accelerated oxidation. CA can exceed Cn by an order of magnitude.
M is the typically downward vertical movement of the land surface as influenced by the redistribution of earth masses (e.g. sea level fluctuations, growth of delta deposits, growth or shrinkage of nearby ice masses, tectonics, and deep-seated thermal subsidence). M is highly variable spatially but rates are typically between 0 and -5 mm/y.
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Confluences are a common element of river networks, especially in the lower reaches and the deltaic floodplain. They are characterized by large-scale turbulent motions. Confluences are even more common in braided river networks, and play an important role in reworking and transporting bedload material. +
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Confluences are a common element of river networks, especially in the lower reaches and the deltaic floodplain. They are characterized by large-scale turbulent motions. Confluences are even more common in braided river networks, and play an important role in reworking and transporting bedload material. +
Duperret et al. (2002) recently discussed bluff failure at Puys, 75 km to the northeast of the site of the video, Saint-Jouin-Bruneval. In that case they concluded that increased groundwater flow after heavy rain facilitated the collapse.
Coastal Rock Cliff Erosion by Collapse at Puys, France: The Role of Impervious Marl Seams within Chalk of NW Europe
Anne Duperret, Albert Genter, Rory N. Mortimore, Baptiste Delacourt and Mick R. De Pomerai
Journal of Coastal Research , Vol. 18, No. 1 (Winter, 2002), pp. 52-61 +
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Erosion rates along permafrost coastlines of Alaska’s North Slope have been increasing over the past few decades (from 1953 onwards). The coast around Drew Point, roughly between Point Barrow and Prudhoe Bay along the Beaufort Sea, consists of ice-rich bluffs of about 3-5m high.
Thermal energy accounts for most of the erosion potential along these ice-rich permafrost coastlines, so predictive models of coastal erosion require an understanding of how sea-ice and sea surface temperatures evolve, both through the summer ice-free season and interannually.
To describe patterns of nearshore SST in the Beaufort Sea a team of USGS, INSTAAR and the Naval Postgraduate School deployed wave and ocean temperature sensors offshore from the National Petroleum Reserve in Alaska (NPR-A) during the summer of 2009. These sensors were placed in a shore-normal array between 0.2 and 10 km offshore, in water depths ranging from ~1m to 7m. Second, data is available from meteorological stations on the Alaskan North Slope to summarize the regional weather patterns that drive observed changes in ocean waves and temperatures over this time period. And lastly, we use satellite data to summarize sea ice position and sea surface temperatures over the past decade.
As long as the sea ice is still hugging the coast, which can be upto Halfway July, erosion is very limited. Subsequently, early in the summer when sea ice remains near the coast, the nearshore open water area is sheltered from mixing and warms to its highest temperatures of the summer. Water nearshore can become very warm, up to 10 degrees C, and consequently high thermal erosion occurs along the coast. As the sea ice margin retreats in mid-summer, summertime storsm homogenizes the temperatures offshore, collapsing the offshore temperature gradient to less than 0.5 degrees C per km and dropping the nearshore temperatures by almost 5 degrees C. Thermal erosion potential is consequently reduced later in the summer.
In the Fall season the sea surface water temperature drops to about 2 to -1 degrees C and there may be less potential for erosion.
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Fluvial coastal reworking as a result of sea level change in glacial-interglacial time periods. +
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Fluvial system alternates between sediment storage and release due to autogenic slope fluctuations on the deltaic surface. Shoreline progradation rates increase during release events and slow during sediment storage. This process is entirely autogenic (internally generated, i.e., no external controls were changing to induce this process). +
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GIPL was used to simulate the dynamics of the active layer thickness and mean annual ground temperature, both retrospectively and prognostically, using climate forcing from Global Climate Models. GIPL is a numerical model based on a finite difference method for the non-linear Heat Conduction Equation.
In this model the process of soil freezing/thawing is occurring in accordance with the unfrozen water content curve, which is specific for each soil layer and for each geographical location. For each grid point on the map we used a one-dimensional multi-layer model of soil down to the depth of a constant geothermal heat flux (typically 500 to 1000 m). At the upper boundary, there are insulating layers of snow and vegetation that can change their properties with time. Special Enthalpy formulation of the energy conservation law makes it possible to use a coarse vertical resolution without loss of latent heat effects in phase transition zone even in case of fast temporally and spatially varying temperature fields. The new version of GIPL (GIPL 2.0) calculates soil temperature and liquid water content fields for the entire spatial domain with daily, monthly and yearly resolutions. The merge of the new GIPL and the GIS technique provides a unique opportunity to analyze spatial features of permafrost dynamics into the future. +
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Glacial surges are short-lived events where a glacier can move up to velocities 100 times faster than normal, and advance substantially. Surging glaciers are found in only a few areas: Svalbard, Canadian Arctic islands, and Alaska.
Glacial surges can take place at regular, periodic intervals. In some glaciers, surges can occur in fairly regular cycles with 15 to 100 or more surge events per year. In other glaciers, surging is unpredictable. In some glaciers, the period of stagnation and build-up between two surges typically lasts 10-200 years and is called the quiescent phase. During this period the velocities of the glacier are significantly lower, and during those periods the glaciers can retreat substantially.
Glaciers in Alaska exhibit surges with a sudden onset, extremely high (tens of meters/day) maximum flow rate and a sudden termination, often with a discharge of stored water. These are called Alaskan-type surges and it is suspected that these surges are hydrologically controlled. Outburst flows are often associated with these events.
Surges may also be caused by the supply of meltwater to the base of a glacier. Meltwater is important in reducing frictional restrictions to glacial ice flow. The distribution and pressure of water at the bed modulates the glaciers velocity and therefore mass balance. Meltwater may come from a number of sources, including supraglacial lakes, geothermal heating of the bed, conduction of heat into the glacier and latent heat transfers. There is a positive feedback between velocity and friction at the bed, high velocities will generate more frictional heat and create more meltwater. Crevassing is also enhanced by greater velocity flow which will provide further rapid transmission paths for meltwater flowing towards the bed. The evolution of the drainage system under the glacier may play a key role in surge cycles.
In contrast, surging glaciers in Svalbard appear to have a much slower surging cycle. Monaconbreen in Svalbard surged over several years, and maximum speeds were much less high than measured in Alaska.
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Global temperature distribution is derived from remote sensing data gathered from satellites. One of the instruments used in measuring land surface temperatures is ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) which is aboard the TERRA satellite. The orbiting satellites gather data regarding the reflection of various wavelength bands from earth’s surface which can then be used to create temperature profiles for a given region. These temperatures are then compared with local observing stations to validate and help calibrate the computed data. With global temperature data distributed over a large enough time scale, representative means can be created these means are then compiled to create global temperature profiles. +
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Gravity driven waves (swell) conserve energy as they move through the worlds oceans. Thus it is possible to track ocean energy as it moves through the worlds oceans and interacts with land forms.
Wave power is approximately calculated as
E=.125(pgH^2). Where E is energy, p is the density of water, g is acceleration due to gravity and H is wave height. +
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Heavier sediment settles first resulting in highly stratified delta formation. +
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High river water that does not overtop a levee yet, can still create a tremendous water pressure. This pressure creates a potential for groundwater seepage of the water, through the underlying, permeable aquifer into the lowlands that are protected from direct flooding by an largely impermeable levee.
Sand and water start bubbling up on the floodplain; usually indicating that undermining of the levee is going on. +
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In Arctic landscapes, recent warming has significantly altered geomorphic process rates. Along the Beaufort Sea coastline bounding Alaska’s North Slope, the mean annual coastal erosion rate has doubled from ~7 m/yr for 1955-1979 to ~14 m/yr for 2002-2007 (Mars and Houseknecht, 2007). Locally the erosion rate can reach 30 m/yr. We aim to understanding the processes that influence coastal erosion rates; since we want to predict the response of the coast and its adjacent landscape to a rapidly changing climate, with implications for sediment and carbon fluxes, oilfield infrastructure, and animal habitat.
The evolution of the permafrost bluffs on the North Slope is controlled by three conditions: length of the sea ice free season, warming sea water and wave and storm surge. During the sea ice-free season, relatively warm waters melt a notch into the ice-rich silt that comprises the 4-m tall bluffs. The bluffs ultimately fail by toppling of polygonal blocks bounded by mechanically weak ice-wedges that are spaced roughly 10-20 m apart. The toppled blocks then temporarily armor the coast against further attack.
The annual coastal retreat rate is controlled by the length of the sea ice-free season, water and air temperatures, and the wave history. Honoring the high ice content of the bluff materials, it is thought that subaerial melt plays a minor role, and that the notching of the base of the bluff acts as an melting dirty ice berg. In quantitative iceberg melting models the local instantaneous melt rate goes as the product of the temperature difference between seawater and bluff material, and the wave height. Calculated instantaneous melt rate can be adjusted to account for the ambient temperature of the permafrost and the presence of non-ice material in the bluffs. Once a block is sufficiently undercut to become unstable it will fail and topple. The latter process can be described as a torque balance. +
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Large and small dam emplacement in the USA. Data shown from the National Inventory of Dams (NID). +
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Liquid water is thought to move through the Greenland Ice Sheet as diffuse and channelized flow, and is governed by the pressure field created by the weight of overlying ice. This 2-D model combines the governing equations for both types of flow to model the movement of water in the Greenland Ice Sheet.
A video of the talk Mauro Werder gave at the CSDMS 2013 annual meeting is available on the CSDMS website,
https://csdms.colorado.edu/wiki/CSDMS_2013_annual_meeting_Mauro_Werder +
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Liquid water is thought to move through alpine glaciers as diffuse and channelized flow, and is governed by the pressure field created by the weight of overlying ice. This 2-D model combines the governing equations for both types of flow to model the movement of water in the the Gornergletscher, an alpine glacier in Switzerland.
A video of the talk Mauro Werder gave at the CSDMS 2013 annual meeting on glacial hydrology is available on the CSDMS website, https://csdms.colorado.edu/wiki/CSDMS_2013_annual_meeting_Mauro_Werder +
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Meandering rivers are ubiquitous in nature, but have been difficult to simulate in flumes.
The snake-like pattern found in meandering rivers occurs as meanders migrate as the outer bank of a river erodes sediment, and the inner curve of a river receives deposits of sediment. +
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Movement of sea ice unto a structure is called ice encroachment. This occurs in two dfferent modes: 'ride up' and 'pile-up'. Ride-up occurs when the ice is driven up the side slope intact, pile-up ocurs when the ice fails and buckles and bends into individual blocks.
It has been assumed that pile up would be more prevalent in shallow water, due to grounding of the ice and due to the fact that a river is very closeby. The river discharge starts draining unto the sea ice by May-June and makes the sea ice more weak and vulnerable for break-up. +
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Reference: Lehner, B., C. Reidy Liermann, C. Revenga, C. Vörösmarty, B. Fekete, P. Crouzet, P. Döll, M. Endejan, K. Frenken, J. Magome, C. Nilsson, J.C. Robertson, R. Rodel, N. Sindorf, and D. Wisser. 2011. High-Resolution Mapping of the World's Reservoirs and Dams for Sustainable River-Flow Management. Frontiers in Ecology and the Environment 9:494-502. DOI: 10.1890/100125. +
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Relating nested models of different oceanographic and climate events to model large-scale processes. +
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Rivers channels can develop a sinuous course through their valleys and lowlands. River with channels with high sinuosity are called meandering rivers. These systems develop over time, by outward migration of the cutbank and simultaneous growth of the pointbar. +
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Sea ice has retreated far into the Arctic Ocean in the last few years, with 2007 being record low over the last 30 years. The animations shows the evolution of sea ice through winter-spring-summer and fall for 2009, which was the secondmost low year. +
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See the topoflow model in the repository. +
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Shows the effects of reworking of different chronologically deposited sedimentary layers due to wave processes. +
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The Mississippi River floods in April and May 2011 are among the largest and most damaging along U.S. rivers in the past century, rivaling major floods in 1927 and 1993. The river water stage points to exceedance of the 500-year flood recurrence interval. Flood waters were derived from two storm systems associated with devastating tornadoes, which dumped record rainfall on the Mississippi River watershed in April 2011
In addition, snowmelt added to the high water levels and by the beginning of May the water stages were record-high. Areas along the Mississippi experiencing flooding include the states of Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
On May 3 and 4th, 2011 the US Army Corps of Engineers blasted breaches into the levee protecting the Bird's Point-New Madrid floodway, flooding 530 km2 of crops and farmland in Mississippi County, Missouri. The breach was induced to save Cairo, IL (population ~3000) at the confluence of the Ohio and Mississippi River and the rest of the levee system, from floodwaters. The breach displaced around 200 residents of Missouri's Mississippi and New Madrid counties, at the same time the city of Cairo was evacuated for safety, but remained unharmed.
Birds Point is part of the New Madrid Floodway Project. Prompted by the Great Flood of 1927 the US Army Corps of Engineers installed an earthen levee to protect nearby farmland. The section of the Levee at Birds Point was engineered so that when the water reached 61 feet (19 m) on the nearby Cairo flood gauge, the river would over-top the levee and erode it away. This would allow the river to fill the 133,000 acres (54,000 ha) floodway and relieve pressure on the levees.systems in place at nearby Cairo and Hickman, Kentucky. This area has been engineered to allow intentional flooding but has only been used twice (1937 and 2011).
The levee at Birds Point locally has a "fuse-plug design”; it contains 3,400 m of pipe that can be filled with liquid explosives and detonated to open the levee and activate the floodway. It was only the second time the floodway was ever activated on May 2, 2011, the earlier time being 1937. Three detonations took place in the late evening of May 2, and the following detonations on May 3.
The Mississippi River floods in May 2011 are among the largest and most damaging US floods in the past century, rivaling major floods in 1927 and 1993. The river water stage recorded point to exceedance of the 500-year flood recurrence interval. Flood waters were derived from two storm systems associated with devastating tornadoes, which dumped record rainfall on the Mississippi River watershed in April 2011.
In addition, snowmelt added to the high water levels and by the beginning of May the water stages were record-high. Areas along the Mississippi experiencing flooding include the states of Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
On May 3, 2011 the US Army Corps of Engineers blasted a breach into the levee protecting the Bird's Point-New Madrid floodway, flooding 530 km2 of crops and farmland in Mississippi County, Missouri. The breach was induced to save Cairo, IL (population ~3000) at the confluence of the Ohio and Mississippi River and the rest of the levee system, from floodwaters. The breach displaced around 200 residents of Missouri's Mississippi and New Madrid counties, at the same time the city of Cairo was evacuated for safety, but remained unharmed.
Birds Point is part of the New Madrid Floodway Project. Prompted by the Great Flood of 1927 the US Army Corps of Engineers installed an earthen levee to protect nearby farmland. The section of the Levee at Birds Point was engineered so that when the water reached 61 feet (19 m) on the nearby Cairo flood gauge, the river would over-top the levee and erode it away. This would allow the river to fill the 133,000 acres (54,000 ha) floodway and relieve pressure on the flood control systems in place at nearby Cairo, Illinois and Hickman, Kentucky. This whole area has been engineered to allow for intentional flooding but has only been used twice.
The levee at Birds Point locally has a "fuse-plug design”; it contains 3,400 m of pipe that can be filled with liquid explosives and detonated to open the levee and activate the floodway. It was only the second time the floodway was ever activated on May 2, 2011, the earlier time being 1937. Three detonations took place in the late evening of May 2, and the following detonations on May 3.
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The flow of water in rivers over loose sediments can lead to self organizing patterns, such as the ripples presented in this simulation.
Generally, as the strength of the flow of water increases, low-flow bed forms evolve from a flat surface, to ripples, and then dunes. As higher flows occur, anti-dunes and eventually pools and chutes form.
For more information see the related papers:
doi: 10.1002/wrcr.20457
doi: 10.1002/wrcr.20303
doi: 10.1029/2012WR011911 +
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The importance of the coastal zone as a zone of resources; ecosystem services, hydrocarbons, recreation is illustrated. +
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This is part of a study examining the evolution of a transition region between the arid and Mediterranean climates in Israel. The main soil production process in this region is Aeolian deposition of Loess type soils. The Loess accumulation has persisted throughout the late-Pleistocene and early Holocene, peeked about 18 kyr BP and ceased about 9 kyr PB.
The hillslopes in this region are now mostly depleted of soil cover with some loess patches at the foothills and deep loess deposits at the valleys (see figures). We set to examine the mechanisms and drivers (climatic and/or anthropogenic) that led to this landscape.
In this animation we used the mARM4D soil-landscape model to compare the sediment transport mechanisms on one small ridge. The three synchronized 80 kyr animations are for when (1) only fluvial transport is simulated (top-left), (2) only diffusive transport is simulated (top-right) and (3) when both are simulated (bottom-right). The plot on the bottom-left of the movie shows the temporal changes in the processes parameters (based on literature analysis) representing climatic and anthropogenic effects. +
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This landslide is a typical example of a deep-seated landslide. These are landslides in which the sliding surface is below the maximum rooting depth of trees (typically to depths greater than ten meters).
The video shows a scar in the hillslope of several 10's of meters high. It can also be seen that there is a very deep weathered soil (or regolith).
These events typically move slowly, only several meters per year, but occasionally move faster. This is what happened in this event, the slide already showed slow movement before speeding up. The people living in the town of Maierato were evacuated in time.
Whereas the video show the fresh scar, such hillslope scars can be mapped by concave scarps at the top and steep areas at the toe for many years after. +
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This movie just indicates the emplacements of larger reservoirs over time and gives an idea of how humans are impacting and controlling the hydrological cycle +
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This movie loops through sea ice concentration in the Chukchi and Beaufort Sea. Sea ice concentration (SSC) is measured by satellites on a daily basis. SSC has been measured from 1979 onwards, and thus provides us with a relatively long time-series to assess changes in the Arctic climate.
The animation loops through the year 2007, which was a relatively warm year with a low sea ice minimum.
The presence of sea ice impacts the time that waves and storm surge can affect the coast. Another parameter that affects waves and storm surge is the fetch-the distance that wind blows over open water. Here we show how we calculate each day the distance to the sea ice edge over all relevant directions (the grey lines). Then we pick the the average wind direction measured at the Barrow airfield for that day, and determine the fetch length in that specific direction (the red line). +
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Tsunami is a Japanese word, meaning 'harbor wave'. Japan is affected by tsunamis relatively frequently, because it is located near a plate subduction zone. The Pacific Plate subducts beneath Japan at a very high rate of ~8cm/year. The process of thrust faulting at these plate boundaries is associated with earthquakes and subsea oceanfloor displacements that cause tsunamis.
A magnitude 8.9/9.0 earthquake happened on March 11th, 2011. This was the 5th largest earthquake worldwide since 1900. According to the U.S. Geological Survey (USGS), the earthquake occurred at a depth of 24.4 kilometers beneath the seafloor. The March 11 earthquake was preceded by a series of large foreshocks on March 9, including an M7.2 event, and many aftershocks keep rattling Japan in the days after.
A tsunami can travel at a speed of 800km/hr in the deep ocean, but with very long wave length (about 15 min). When such a wave reaches shallower water nearshore, the wave length decreases, because its speed decreases. Then the backend of the wave starts catching up with the front end and and its amplitude starts to increase dramatically. The observations for the March 11th tsunami wave height when hitting the shoreline near Sendai are about 4m. At some localities where the water was focused due to the funneling action of the bays the wave reached a height of 7.3 m. It hit the shore about 1 hour and 10 minutes after the earthquake shock was recorded.
The tsunami traveled rapidly through the Pacific Ocean and reached Hawai after 8 hours and California after 11 hours, generating waves as high as 1.5-2 m there. +
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Tsunami is a Japanese word, meaning 'harbor wave'. Japan is affected by tsunamis relatively frequently, because it is located near a plate subduction zone. The Pacific Plate subducts beneath Japan at a very high rate of ~8cm/year. The process of thrust faulting at these plate boundaries is associated with earthquakes and subsea oceanfloor displacements that cause tsunamis.
A magnitude 8.9/9.0 earthquake happened on March 11th, 2011. This was the 5th largest earthquake worldwide since 1900.
A tsunami can travel at a speed of 800km/hr in the deep ocean, but with very long wave length (about 15 min). When such a wave reaches shallower water nearshore, the wave length decreases, because its speed decreases. Then the backend of the wave starts catching up with the front end and and its amplitude starts to increase dramatically. The observations for the March 11th tsunami wave height when hitting the shoreline near Sendai are about 4m. It hit the shore about 1 hour and 10 minutes after the earthquake shock was recorded. +
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WAVEWATCH III^TM is the third generation of wave models designed by NOAA and has significant improvements from previous generations of this model and other similar models. As stated by NOAA and the developers of WAVEWATCH IIITM; “WAVEWATCH III^TM solves the random phase spectral action density balance equation for wavenumber-direction spectra.” (NOAA website) This allows the model to evolve and follow swell patterns as they are generated and travel throughout the world’s oceans based on the conservative nature of energy in gravity driven ocean swell. Additionally, in the most recent version of WAVEWATCH III^TM there are options allowing for shallow water (surf zone) physics. At this stage they are fairly crude but usable. +
WAVEWATCH III^TM is the third generation of wave models designed by NOAA and has significant improvements from previous generations of this model and other similar models. As stated by NOAA and the developers of WAVEWATCH III^TM; “WAVEWATCH III^TM solves the random phase spectral action density balance equation for wavenumber-direction spectra.” (NOAA website) This allows the model to evolve and follow swell patterns as they are generated and travel throughout the world’s oceans based on the conservative nature of energy in gravity driven ocean swell. Additionally, in the most recent version of WAVEWATCH III^TM there are options allowing for shallow water (surf zone) physics. At this stage they are fairly crude but usable. +
WAVEWATCH III^TM is the third generation of wave models designed by NOAA and has significant improvements from previous generations of this model and other similar models. As stated by NOAA and the developers of WAVEWATCH III^TM; “WAVEWATCH III^TM solves the random phase spectral action density balance equation for wavenumber-direction spectra.” (NOAA website) This allows the model to evolve and follow swell patterns as they are generated and travel throughout the world’s oceans based on the conservative nature of energy in gravity driven ocean swell. Additionally, in the most recent version of WAVEWATCH III^TM there are options allowing for shallow water (surf zone) physics. At this stage they are fairly crude but usable. +
WAVEWATCH III^TM is the third generation of wave models designed by NOAA and has significant improvements from previous generations of this model and other similar models. As stated by NOAA and the developers of WAVEWATCH III^TM; “WAVEWATCH III^TM solves the random phase spectral action density balance equation for wavenumber-direction spectra.” (NOAA website) This allows the model to evolve and follow swell patterns as they are generated and travel throughout the world’s oceans based on the conservative nature of energy in gravity driven ocean swell. Additionally, in the most recent version of WAVEWATCH III^TM there are options allowing for shallow water (surf zone) physics. At this stage they are fairly crude but usable. +
WAVEWATCH III^TM is the third generation of wave models designed by NOAA and has significant improvements from previous generations of this model and other similar models. As stated by NOAA and the developers of WAVEWATCH III^TM; “WAVEWATCH III^TM solves the random phase spectral action density balance equation for wavenumber-direction spectra.” (NOAA website) This allows the model to evolve and follow swell patterns as they are generated and travel throughout the world’s oceans based on the conservative nature of energy in gravity driven ocean swell. Additionally, in the most recent version of WAVEWATCH III^TM there are options allowing for shallow water (surf zone) physics. At this stage they are fairly crude but usable. +
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Wave power, P, is calculated as a function of the significant wave height, Hs and wave period T (the time to complete one complete wave cycle):
P=(ρg^2 )/64π H_s^2 T
ρ = density of sea water, (on average 1050 kg/m3)
g=gravitational constant, (9.81m/s2)
π = 3.14 +
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With the inclusion of coastal processes the fluvial sediment becomes less stratified than when coastal processes that result in mixing aren't present. +
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Without the effects of coastal processes that result sediment mixing the fluvial sediment deposition remains highly stratified. +
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the definition of 'significant wave height' is as follows: the significant wave height (often annotated as Hs) is defined as the mean wave height (the distance from wave trough to wave crest) of the highest third of the waves. +
the definition of 'significant wave height' is as follows: the significant wave height (often annotated as Hs) is defined as the mean wave height (the distance from wave trough to wave crest) of the highest third of the waves. +
wave height, H, as the distance between the wave crest and trough.
Note that waves come in fields containing a large variety of heights; the wave height distribution. To describe the wave field with a single number scientists use the ‘Significant Wave Height’. The Significant Wave Height Hs, is the mean wave height of the one-third highest waves in the wave field. This measure is the closest to what a sailor on a ship would estimate as ‘the average wave height’. Apparently our eyes are drawn to see the larger waves. This movie shows the significant wave height every 3 hours, for theweek that the Katrina hurricane developed in the Caribbean and made landfall in New Orleans in the USA. +
