Property:Extended movie description

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CHILD model simulation of a meandering river in its floodplain. The meander migrates through the floodplain, depositing channel sands in its bed. Associated movies are shown here: https://csdms.colorado.edu/wiki/Model:CHILD  +
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CU Science update featured a short movie on 'Sinking Deltas'. There is a widespread need to assess the vulnerability of the world’s population living in low-lying deltas to flooding, whether from intense rainfall, rivers or from hurricane-induced storm surges. High-resolution NASA SRTM topography data and MODIS satellite data along with georeferenced historical map analysis allows quantification of the extent of low-lying delta areas and the role of humans in contributing to their vulnerability. Thirty-three major deltas collectively include ~26,008 km2 of area below local mean sea level and ~96,000 km2 of vulnerable area below 2 m a.s.l. This vulnerable area may increase 50% under projected 21st Century eustatic sea level rise. Analysis of river sediment load data and of topographical changes show that these densely populated, intensively farmed landforms, that often host key economic structures, have been destabilized by human-induced accelerated sediment compaction due to water, oil and gas mining, and by reductions of incoming sediment from upstream dams and reservoirs and floodplain engineering.  +
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Credits to:<br> Albert Kettner, CU - INSTAAR<br> Greg Fiske, WHRC<br> Bernhard Peucker-Ehrenbrink, WHOI<br> The animation shows the size of river drainage basins, or watersheds, scaled to the mass of sediment transported by the rivers to the coastal oceans. The color code (upper right corner) corresponds to million tons (Mt) of sediment per week. The time bar on the bottom shows the progression throughout the year. The sun symbol on the map shows the movement of the high-point of the sun throughout the seasons as an alternative time marker.  +
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Cuspate spits are here simulated with the Coastline Evolution Model (CEM) of Andrew Ashton. Sediment transport occurs under the influence of longshore transport that is driven by wave action. Coastal spits form and built out with time, the colors are coded for depositional age. In this particular animation the incoming far-field wave distribution is weighted so that high angles with the shoreline are dominant, and the wave direction is predominantly from the left.  +
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Daily estimates of the sea ice concentration based on remotely-sensed passive microwave data for 2009. The red colors are 100% sea ice, whereas the blue colors show sea ice free conditions (also called open water).  +
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Emplacement of the topset by braided streams in an experimental fan-delta undergoing subsidence. Most significant alluvial processes are labeled.  +
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Erosion process and river response caused by the sudden removal of a sediment dam, top view.  +
Erosion process and river response caused by the sudden removal of a sediment dam, front view.  +
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Evolution of river valley landscape, stratigraphy, and geoarchaeology, Channel Sands (Transverse Section)  +
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Expansion of Sea Ice Free Days from 1920-2100 Sea ice covers large regions of the Arctic Ocean. At present, the northernmost waters remains frozen all year, in other regions seawater freezes every year when temperatures drop in October-November, and the sea ice thaws again when solar radiation is intense and long days prevail in the early summer. This sea ice dataset shows how long the ‘open water season’ lasts for any location in the Arctic region. The duration of open water is relevant for ecosystem and coastal processes, and human activities such as shipping, industrial development, fishing and indigenous mammal hunting. Maps of the open water season over 1920-2100 are calculated averaging output of 30 simulations of the Community Earth System Model (CESM). This climate model describes the physical processes of the atmosphere, ocean, land surface and sea ice and their interactions. For historical times, 1920-2005 in this specific case, the model can be forced by real-world observations of incoming solar radiation and concentrations of greenhouse gasses and aerosols. For the future, 2005-2100, a scenario has to be chosen; scientists have precisely defined a suite of different scenarios called ‘Representative Concentration Pathways’. The model simulations analyzed here used the ‘RCP 8.5’ scenario, which assumes that greenhouse gas emissions continue to rise throughout the 21st century. Sea ice can be seen to cover large parts of the Arctic in the mid-20th century. For example, at that time the open water season is as short as 2 month along the Alaskan and Siberian coasts. Other parts of the Arctic Ocean remain frozen all year, such as the Canadian Archipelago, where explorers stranded in the ice many times. Over the duration of the simulation global warming causes the open water season to vastly expand. The retreat of sea ice has started already in the late 20th century, and scientists have observed with satellites the expansion of the open water season over the last 35 years. The model predicts that by 2050, the entire Arctic coastal region will experience 60 additional days of ice-free conditions. A longer open water season triggers coastal change, because longer exposure to waves and storm surges cause erosion of the Arctic permafrost coast. Acceleration of erosion and coastal flooding is to be expected with the expansion of the open water season. Coastal villages in Arctic Alaska may need to be better protected or relocated in the future.  
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Floodplain evolution, Sediment age distribution in subsurface  +
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Fluvial deposition with minimal plume and wave reworking. Note the resulting highly stratified sediment deposition.  +
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Footage of the rapid outflow of water through the breach in the Mississippi River levee at Birds Point-New Madrid. 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.  +
Footage of the second set of detonations applied to breach the levee at Birds Point-New Madrid.On May 3-4, 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.  +
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Gravity currents move over different bedform topography, ranging from a flat bed to dunes and ribs. These experiments were conducted to evaluate the capacity of gravity currents to propagate over an array of identical obstacles to entrain sediment from the loose channel bed and to carry it downstream for some distance in the form of a turbidity current. First you can see how the structure, front velocity, energy balance and sediment entrainment capacity of a compositional gravity current is affected by the presence of the obstacles, and then you can see the effect of the shape and size of the obstacles.  +
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Here we see an aerial view of the massive floodwaters draining over the coastal plain/sandur in Iceland. This jokhulhlaup is associated with the volcanic eruption of April, 2010. The 2nd Eyjafjallajökull volcano eruption in south Iceland for 2010. It started on 14.04.2010. GPS coordinates of the eruption: 63.629° N, 19.630° W. Video by Icelandic National TV station RÚV. Music by Ceiri Torjussen; The movie show the shallow floodwater washing over the main highway of Iceland, and washing it out in several places. There was extensive damage to farm field and local houses of the debris/ash. The shallowness of the water can also be seen from the standing waves (again).  +
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Humans have manipulated rivers for thousands of years, but over the last 200 years dams on rivers have become rampant. Reservoirs and dams are constructed for water storage, to reduce the risk of river flooding, and for the generation of power. They are one of the major footprints of humans on Earth and change the world’s hydrological cycle. This dataset illustrates the construction of dams worldwide from 1800 to the present. We display all dams listed in the Global Reservoir and Dam Database (GRanD). It includes 6,862 records of reservoirs and their associated dams. All dams that have a reservoir with a storage capacity of more than 0.1 cubic kilometers are included, and many smaller dams were added where data were available. The total amount of water stored behind these dams sums to 6,2 km3. The red dots indicate the newly built dams and reservoirs each year, and the yellow dots represent the dams already in place. The dams and reservoirs do not only store water, they also trap the incoming sediment that the river transports. Consequently, much less sand and clay travels to the coast, where it would normally be depositing in the delta region. The reduced sediment load of major rivers has influenced the vulnerability of many deltas worldwide. Japan built many dams already in the early 19th century. Another early hotspot for dam construction was the US East Coast, where many medium-sized dams were constructed for grain milling and saw mills. In the 20th century, large engineering projects developed dams in more arid regions for drinking water and irrigation water storage, and worldwide for electric power generation. Most recently, large construction projects have been completed in China, including the Three Gorges Dam on the Yangtze River.  +
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Hurricane Ike developed in early September and passed over Cuba. It did heavy damage in Cuba (it was one of the most expensive hurricanes for that country ever). Ike developed in a category 2 hurricane and made landfall near Galveston, TX on September 13th, 2008. This animation shows results of a Delft3D simulation to study the effects of Hurricane Ike (2008) on the Wax Lake delta in Atchafalaya Bay, Louisiana (USA). The model domain is 25 by 30km. The movie shows salinity before, during and after this hurricane event. Water in the Wax lake delta is relatively fresh, during the entire period there was continuous river discharge being fed into the delta system. The river discharge is more important during high tides and storm events when brackish water progrades into the delta then under normal conditions. This is the pulsing of the system you can see in the beginning of the simulation. Hurricane Ike pushed saline water into the delta (the red color), at the peak of the event the entire delta was submerged and the salinity approached 20-25 ppt. Note that saline water persisted long in some of the Wax lake wetlands: even on the 18th of September, 5 days after the actual landfall there is still high salinity. This had a major effect on the wetland vegetation and would kill some of the freshwater species on the islands.  +
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Hurricane Rita was an intense tropical cyclone, which occurred in September 2005, a few weeks after hurricane Katrina. It was a really intense event, with high sustained winds (upto 38 m/s) and waves in the Gulf of Mexico were observed to be over 6 m high. The hurricane made landfall in Texas on September 24th, directly west of the area shown in this simulation. This animation shows results of a Delft3D simulation to study the effects of Hurricane Rita on the Wax Lake delta in Atchafalaya Bay, Louisiana (USA). The model domain is 25 by 30km. We are showing a set of parameters of this hurricane event to compare the erosion and sedimentation that occurred cumulatively over the entire event (this animation), the water level and wave height (other animations in the EKT repository). Sedimentation or erosion of sand in the Wax lake delta is rather low under normal conditions, perhaps a few cm's transported by the fastest ebb and flood tide currents. On September 24th 2005 hurricane Rita approaches and sedimentation and erosion become much more dramatic. When the hurricane makes landfall, the delta is inundated by 2-3 m of water and waves become as high as 1.6m. Bottom shear stress is then high and sediment can be easily transported. Note that erosion and sedimentation happen simultaneously; near the edges of channels there is rapid erosion (upto 40 cm over the entire storm), while nearby sediments are being deposited on the islands and bars. The erosion and sedimentation pattern is influenced by the exact storm track of this particular hurricane, the angle at which the waves apporach the coast determine the areas of most rapid change.  +
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Hurricane Rita was an intense tropical cyclone, which occurred in September 2005. It was a really intense event, with high sustained winds (upto 38 m/s) and waves in the Gulf of Mexico were observed to be over 6 m high. The hurricane made landfall in Texas on September 24th, directly west of the area shown in this simulation. This animation shows results of a Delft3D simulation to study the effects of Hurricane Rita on the Wax Lake delta in Atchafalaya Bay, Louisiana (USA). The model domain is 25 by 30km. We are showing a set of parameters of this hurricane event to compare the water level (this animation), the wave height and the erosion and deposition in the delta (other animations in the EKT repository). The water level in the Wax lake delta varies with the tidal cycle in the Atchafalaya Bay, you can see the tides flooding the delta and small islands and bars emerging during low tide. On September 24th 2005 hurricane Rita approaches and sets down the water, then the eye passes and the delta is inundated by 2-3 m of water.  +